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AS5030 8 BIT PROGRAMMABLE HIGH SPEED MAGNETIC ROTARY ENCODER
DATA SHEET
1.2
* *
1
General Description
Key Features
360contactless angular position encoding Two digital 8-bit absolute outputs: - Serial interface and - Pulse width modulated (PWM) output User programmable zero position High speed: up to 30,000 rpm Direct measurement of magnetic field strength allows exact determination of vertical magnet distance Serial read-out of multiple interconnected AS5030 devices using daisy chain mode Wide magnetic field input range: 20 ~ 80mT Wide temperature range: - 40C to + 125C Small Pb-free package: TSSOP 16
The AS5030 is a contactless magnetic rotary encoder for accurate angular measurement over a full turn of 360. It is a system-on-chip, combining integrated Hall elements, analog front end and digital signal processing in a single device. To measure the angle, only a simple two-pole magnet, rotating over the center of the chip is required. The absolute angle measurement provides instant indication of the magnet's angular position with a resolution of 8 bit = 256 positions per revolution. This digital data is available as a serial bit stream and as a PWM signal. In addition to the angle information, the strength of the magnetic field is also available as a 6-bit code. Data transmission can be configured for 1-wire (PWM), 2wires (CLK, DIO) or 3-wires (CLK, DIO, CS). A software programmable (OTP) zero position simplifies assembly as the zero position of the magnet does not need to be mechanically aligned. A Power Down Mode together with fast startup- and measurement cycles allows for very low average power consumption and makes the AS5030 also suitable for battery operated equipment.
* * *
* * * *
1.3
* * * * *
Applications
Contactless rotary position sensing Rotary switches (human machine interface) AC/DC motor position control Robotics Encoder for battery operated equipment
1.4
Block Diagram
Sin / Sinn / Cos / Cosn PWM Decoder
PWM DX
Figure 1: Typical arrangement of AS5030 and magnet
Sin
Angle
1.1
* * * * *
Benefits
Complete system-on-chip, no calibration required Flexible system solution provides absolute serial and PWM output Ideal for applications in harsh environments due to magnetic sensing principle High reliability due to non-contact sensing Robust system, tolerant to horizontal misalignment, airgap variations, temperature variations and external magnetic fields
Cos
Hall Array & Frontend Amplifier
tracking ADC & Angle decoder
Zero Pos.
Mag
AGC
Absolute Serial Interface (SSI)
DIO CS CLK C2 MagRngn
AGC power management OTP
PROG
Figure 2: AS5030 block diagram
Rev. 1.8
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Page 1 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
2
Package and Pinout
The AS5030 is available in a TSSOP16 package
Figure 3: TSSOP-16 package and pin-out
Pin# TSSOP
Symbol
Type
Description
1 2 3 4 5 6 7 8 9 10 11 12 13 14
MagRngn Prog_DI VSS T3_SINn T2_SIN T1_COSn T0_COS TC DX CLK CS DIO VDD C1
DO_T S S DO DI_ST DI_ST DIO S DI
Push-Pull output. Is HIGH when the magnetic field strength is too weak, e.g. due to missing magnet OTP Programming voltage supply pin. Leave open or connect to VDD if not used Supply ground This pin is used for factory testing. For normal operation it must be left unconnected. Inverse SIN (Sinn) output in SIN/COS output mode This pin is used for factory testing. For normal operation it must be left unconnected. SIN output in SIN/COS mode This pin is used for factory testing. For normal operation it must be left unconnected. Inverse COS (Cosn) output in SIN/COS mode This pin is used for factory testing. For normal operation it must be left unconnected. COS output in SIN/COS mode Test pin. Connect to VSS or leave unconnected Digital output for 2-wire operation and Daisy Chain mode Clock Input of Synchronous Serial Interface; Schmitt-Trigger input Chip Select for serial data transmission, active high; Schmitt-Trigger input, external pull-down resistor (~50k) required in read-only mode Data output / command input for digital serial interface Positive supply voltage, 4.5V to 5.5V Configuration input: connect to VSS for normal operation, connect to VDD to enable SIN-COS outputs. This pin is scanned at power-on-reset and at wakeup from one of the Ultra Low Power Modes Configuration input: connect to VSS for 3-wire operation, connect to VDD for 2-wire operation. This pin is scanned at power-on-reset and at wakeup from one of the Ultra Low Power Modes Pulse Width Modulation output, 2s pulse width per step (2s ~ 512s)
Table 1: Pin description
15 16
C2 PWM
DI DO
Pin types: S: DI_ST: DIO:
supply pin digital input / Schmitt-Trigger bi-directional digital pin
DO: DO_T: DI:
digital output digital output / tri-state digital input (standard CMOS; no pull-up or pull-down)
Rev. 1.8
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Page 2 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
3
AS5030 Parameter and Features List
Description 5V 10% Low Power Mode, non-operational: typ. 1.4mA Ultra Low Power Mode, non-operational: typ. 30A Normal operating mode: typ. 14mA. 21-bit Synchronous Serial Interface (SSI): 5 command bits, 2 data valid bits, 6 data bits for magnetic field strength, 8 data bits for angle. Configurable for 2-wire (Clock, Data) or 3-wire (Chip Select, Clock, Data) operation Daisy Chain mode for reading multiple encoders through a 2- or 3-wire interface. Zero Position Programming (OTP) 6 MHz data clock rate, 250 ~ 500kHz during programming DIO and CLK signals. 0.1 ~ 6MHz clock rate. Synchronization through time-out of CLK signal. Activated and deactivated by software commands. Low Power Mode: power down current = 1.4mA typ.; power up time <150s Ultra Low Power Mode : power down current = 30A typ.; power up time <500s CLK, CS = Schmitt trigger inputs Sine, inverse Sine, Cosine and inverse Cosine outputs. 360 per period. 30,000 rpm with locked ADC Resolution = 8 bit (1.406) Accuracy 2 with centered magnet 0.24rms (1 sigma) 2.26s / Step, PWM will be permanently low when angular data is not valid (e.g during startup). 4mA @ VDD = 5V (PWM, DIO, DX, MagRngn outputs) Through serial interface with static programming voltage on pin #2 (PROG) 16-bit OTP programming register. OTP user programming options: Angular zero position: 8 bit Hall element sensitivity: 2 bit Trimable in four steps with OTP programming (sensitivity) maximum/minimum ratio ~ 2.5:1. Field range window = 20 ~ 80mT (e.g. maximum sensitivity range = 20 ~ 48mT, minimum sensitivity range = 32 ~ 80mT by hardware: MagRngn pin indicates locked condition of ADC by software: LOCK1&2 status bits indicate locked condition of ADC Start-up time after shutdown < 2ms Start-up time after power-down from Ultra Low Power Mode : < 500s Start-up time after power-down from Low Power Mode : < 150s 2kV -40C ~ +125 C
Parameter Supply Voltage Supply Current Absolute Output; Serial Interface
SSI Clock rate 2-wire Readout Mode Power Down Modes Digital input cells SIN-COS mode Maximum Speed Resolution and Accuracy Transition Noise PWM output Digital Output Current OTP programming mode
Magnetic Field Range Non-Valid-Range indication Start upTimings ESD protection Operating Temperature
Rev. 1.8
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Page 3 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4
General Device Specifications
(operating conditions: Tamb = -40C to +125C, VDD5V = 4.5V ~ 5.5V, all voltages referenced to VSS, unless otherwise noted)
4.1
Absolute Maximum Ratings (non operating)
Symbol VDD Vin Iscr Min -0.3 VSS - 0.5 -100 2 137 JA 89 Tstrg Tbody 5 -55 125 260 85 Max 7 VDD + 0.5 100 Unit V V mA kV Norm: Jedec 17 Norm: MIL 883 E method 3015 Still Air / Single Layer PCB Still Air / Multilayer PCB Note (1) Except during OTP programming
Parameter Supply voltage Input Pin Voltage Input Current (latch up immunity) ESD Package Thermal Resistance Storage Temperature Soldering conditions, Body temperature (Pb-free package) Humidity non-condensing
C/W C/W
C C %
T=20s to 40s, Norm: IPC/JEDEC J-Std-020C. Lead finish 100% Sn "matte tin"
4.2
Operating Conditions
Symbol VDD Min 4.5 14 Typ Max 5.5 18 mA 18 22 2000 120 125 140 A C C Unit V No load on outputs. Minimum AGC (strong magnetic field) No load on outputs. Maximum AGC (weak or no magnetic field) Low Power Mode Ultra Low Power Mode -40F ~ +257F Note
Parameter Positive Supply Voltage
Operating Current
IDD
Power down current Ambient Temperature Junction Temperature
Ioff Tamb TJ -40
1400 30
Rev. 1.8
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Page 4 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.3
System Parameters
Symbol N Min Typ 8 1.406 1000 3800 500 150 Max Unit bit Startup from zero; AGC not regulated s Startup from zero until regulated AGC Startup from Power Down Mode Startup from Low Power Mode s s s s Analog signal path; over full temperature range step rate of tracking ADC; 1 step = 1.406 Total signal processing delay, analog + digital ( tda + tdd ) Internal lowpass filter centered magnet V V mV within horizontal displacement radius (4.4) rms (1 sigma) VDD rising VDD falling Hysteresis | PORr -PORf | Note
Parameter Resolution
Power Up Time
TPwrUp
Propagation delay Tracking rate Signal processing delay Analog filter time constant Accuracy Transition noise
tda tdd tdelay T 4.1 -2 INLcm TN PORr 3.5 3.0 -3 0.85
15 1.15 16.15 6.6
17 1.45 18.45 12.5 2 3 0.235 4.5 4.5
Power-On-Reset levels
PORf Hyst
500
Rev. 1.8
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Page 5 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.4
Magnet Specifications
Unit mm mm 80 30,000 52 mT Bmin 23 1 0.5 1 1.8 0.25 0.5 tkM -0.12 -0.035 mm mm mT rpm at chip surface, on a radius of 1mm to maintain locked state Tamb=25C, AGC@lower limit, 1 sigma = 2.5mT Tamb=25C, AGC@upper limit, 1 sigma = 1.5mT over x/y chip center Recommended distance; operation outside this range is possible, accuracy may be reduced from diagonal package center from diagonal IC center NdFeB Material SmCo Material Note diametrically magnetized
Recommended magnet: NdFeB 35H BR = 12.000 Gauss, O6mm x 2.5mm Parameter Symbol Min Typ Max Magnet diameter Magnet thickness Magnetic Input Range Magnet rotation speed Magnetic field high detection Magnetic field low detection Hall Array radius vertical distance of magnet Horizontal magnet displacement radius Recommended magnet material and temperature drift MD MT Bi vi Bmax 20 6 2.5
mm
%/K
4.5
Magnetic Field Alarm Limits
Symbol AGCFF AGC0 Min 20.3 44.5 100 Typ Max 23.6 52.2 121 Unit mT mT % Note AGC = FFH untrimmed, 25C, 1sigma AGC = 0H untrimmed, 25C, 1sigma see 4.6 Sensitivity increases with temperature which partly compensates the temperature coefficient of the magnet
Parameter Magnetic field too low alarm limit Magnetic field too high alarm limit Magnetic field alarm limit trim range Temperature coefficient of alarm ranges 1)
0.052
%/K
4.6
Hall Element sensitivity options
Symbol Min Typ 100 Max Unit Note
Parameter
sens = 00 (default; low sensitivity; see 5.2.4)
%
Hall Element sensitivity setting
sens
106 113 121
sens = 01 sens = 10 sens = 11 (high sensitivity)
Rev. 1.8
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Page 6 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.7
Programming parameters
SYMBOL VPROG IPROG TambPROG tPROG VR,prog VR,unprog 2.2 0 2 MIN 8.0 MAX UNIT NOTE static voltage at pin PROG
PARAMETER Programming Voltage Programming Current programming ambient temperature Programming time Analog readback voltage
8.5
100 85 4 0.5 3.5
V
mA C s V
during programming timing is internally generated during Analog Readback mode at pin PROG
4.8
DC Characteristics of Digital Inputs and Outputs
Symbol Min Typ Max Unit Note
Parameter
CMOS Inputs: CLK, CS, DIO, C1, C2
High level input voltage Low level input voltage Input leakage current VIH VIL ILEAK 0.7*VDD 0.3*VDD 1 V V A
CMOS Outputs: DIO, MagRngn, PWM, DX
High level output voltage Low level output voltage Capacitive load VOH VOL CL VDD-0.5 0.4 35 V V pF
source current <4mA sink current <4mA
CMOS Tristate Output: DIO
Tristate leakage current IOZ 1 A
CS = low
4.9
8-bit PWM Output
SYMBOL NPWM PWMIN PWMAX PWP fPWM Hyst 1.66 427 428 MIN TYP 8 2 2.26 578 581 1.72 1 2.85 731 734 MAX UNIT bit s/step s s s kHz bit NOTE
Parameter PWM resolution PWM pulse width PWM pulse width PWM period PWM frequency Digital hysteresis 2)
angle = 0 (00H) angle = 358.6 (FFH) over full temperature range 1) =1 / PWM period
at change of rotation direction
Notes: 1) The tolerance of the absolute PWM pulse width and frequency can be eliminated by using the duty cycle tON/(tON+tOFF) for angle measurement; see 4.18. 2) Hysteresis may be temporarily disabled by software: see 5.2.2
Rev. 1.8
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Page 7 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.10 Serial 8-bit Output
Parameter SYMBOL MIN TYP MAX UNIT NOTE
3-wire interface
Clock frequency Clock frequency fCLK tCLK fclk,P fCLK tCLK fclk,P tTO Hyst 166.6 250 0.1 166.6 250 16.6 27 1 500 6 MHz ns kHz MHz ns kHz ms bit
normal operation during OTP programming
2-wire interface
Clock frequency Clock frequency Synchronization timeout Digital hysteresis 1) 6 10,000 500 34.3
normal operation during OTP programming
Rising edge of CLK to internally generated chip select on pin DX at change of rotation direction
Note: 1) Hysteresis may be temporarily disabled by software: see 5.2.2
4.11 General Data Transmission Timings
Parameter rising CLK to CS chip select to positive edge of CLK chip select to drive bus externally setup time command bit data valid to positive edge of CLK hold time command bit data valid after positive edge of CLK float time positive edge of CLK for last command bit to bus float bus driving time positive edge of CLK for last command bit to bus drive setup time data bit data valid to positive edge of CLK hold time data bit data valid after positive edge of CLK hold time chip select positive edge CLK to negative edge of chip select bus floating time negative edge of chip select to float bus hold time data bit @ write access data valid to positive edge of CLK hold time data bit @ write access data valid after positive edge of CLK bus floating time negative edge of chip select to float bus Timeout period in 2-wire mode (from rising edge of CLK) See the Figure 5 for the corresponding timing diagram. Symbol t0 t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 tTO 20 Min 15 15 30 30 30 CLK/2 +0 CLK/2 +0 CLK/2 +0 30 0 50 30 50 24 30 CLK/2 CLK/2 +30 CLK/2 +30 CLK/2 +30 Max Unit ns ns ns ns ns ns ns ns ns ns ns ns ns ns s
Rev. 1.8
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Page 8 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.12 Connecting the AS5030
The following examples show various ways to connect the AS5030 to an external controller:
4.13 Serial 3-Wire R/W Connection
+5V VDD
13
VDD
Output Output Micro Controller I/O
VDD
In this mode, the AS5030 is connected to the external controller via three signals: Chip Select (CS), Clock (CLK) inputs and bi-directional DIO (Data In/Out) output. The controller sends commands over the DIO pin at the beginning of each data transmission sequence, such as reading the angle or putting the AS5030 in and out of the reduced power modes. A pull-down resistor (as shown in 4.14) is not required. C1 and C2 are hardware configuration inputs. C1 must always be connected to VSS, C2 selects 3-wire mode (C2 = low) or 2wire mode (C2 = high)
11 10 12
CS CLK DIO
AS5030
100n
VSS
C1 C2 VSS
14 15
VSS
3
Figure 4: SSI read/write serial data transmission
Figure 5: Timing diagram in 3-wire SSI R/W mode (timing values in 4.11: General Data Transmission Timings)
Serial bit sequence (16bit read/write): Write Command
C4 C3 C2 C1 C0 D15
D14
D13
D12
D11
D10
Read/Write Data
D9 D8 D7
D6
D5
D4
D3
D2
D1
D0
4.14 Serial 3-Wire Read-only Connection
+5V VDD
13
VDD
Output Output Micro Controller Input
VDD
11 10 12
10k... 100k
CS CLK DIO
AS5030
100n
If the AS5030 is only used to provide the angular data (no power down or OTP access) this simplified connection is possible. The Chip Select (CS) and Clock (CLK) connection is the same as in the R/W mode (see 4.13), but only a digital input pin (not an I/O pin) is required for the DIO connection. As the first 5 bits of the data transmission are command bits sent to the AS5030, both the microcontroller and the AS5030 are configured as digital inputs during this phase. Therefore, a pull-down resistor must be added to make sure that the AS5030 reads "00000" as the first 5 bits which sets the Read_Angle command. Note: all further application examples are shown in R/W mode, however read-only mode is also possible unless otherwise noted.
VSS
C1 C2 VSS
14 15
3
VSS
Figure 6: SSI read-only serial data transmission
Rev. 1.8
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Page 9 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
2-or 3-wire read-only serial bit sequence (21bit read):
D20 0 D19 0 D18 0 D17 0 D16 0 D15 C2 D14 lock D13 D5 D12 D4 Read D11 D10 AGC D3 D2 D9 D1 D8 D0 D7 D7 D6 D6 D5 D5 D4 D3 Angle D4 D3 D2 D2 D1 D1 D0 D0
Figure 7: Timing diagram in 2-wire and 3-wire SSI mode
4.15 Serial 2-Wire Connection (R/W Mode)
+5V VDD
15
VDD
13
VDD
9
DX
C2
By connecting the configuration input C2 to VDD, the AS5030 is configured to 2-wire data transmission mode. Only Clock (CLK) and Data (DIO) signals are required. A Chip Select (CS) signal is automatically generated by the DX output, when a time-out of CLK occurs (typ. 20s). Note: Read-only mode is also possible in this configuration
Output Micro Controller I/O
11 CS 10
CLK
AS5030
100n
12 DIO
VSS
C1
VSS
14
VSS
3
Figure 8: SSI R/W mode 2-wire data transmission
Figure 9: Timing diagram in 2-wire SSI mode
Rev. 1.8
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Page 10 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.16 Serial 2-wire Continuous Readout
The termination of each readout sequence by a timeout of CLK after the 22 nd clock pulse as described in 4.15 is the safest method to ensure synchronization, as each timeout of CLK resets the serial interface. However, it is not mandatory to apply a timeout of CLK and consequently synchronization after each reading. It is also possible to read several consecutive angle values without synchronization by simply continuing the CLK pulses without timeout after the 22 nd clock. The 23 rd clock is equal to the 1 st clock of the next measurement, etc... This is the fastest way to read multiple angle values, as there is no timeout period between the readings. It is still possible to synchronize the serial data transmission by a timeout of CLK after a given number of readouts (e.g. synchronize after every 5 th reading, etc...)
command phase
data phase
5 6 7 8 22 23 24
command phase
25
CLK
t0
1
2
3
4
t1
DX CS DIO read DIO write
t5
CMD4 CMD3 CMD2 CMD1 CMD0 CMD4 CMD3 CMD2
t6
D15 D14 D0
1st reading
2nd reading
Figure 10: Timing diagram in 2-wire SSI continuous readout
4.17 Serial 2-Wire Differential SSI Connection
+5V VDD
15
VDD
D+ DDD+
13
VDD
9 11 10
DX CS CLK
C2
Output Micro Controller
CLK
AS5030
100n
MAX 3081 or similar
Input
DI
D+ D-
D+ D-
VSS
12 DIO
With the addition of a RS-422 / RS485 transceiver, a fully differential data transmission, according to the 21-bit SSI interface standard is possible. To be compatible with this standard, the CLK signal must be inverted. This is done by reversing the Data+ and Data- lines of the transceivers. Note: This type of transmission is read-only.
C1
VSS
14
VSS
3
Figure 11: 2-wire SSI read-only mode
Figure 12: Timing diagram in 2-wire readonly mode (differential transmission)
SSI read-only serial bit sequence (21bit read):
D20 0
D19 0
D18 0
D17 0
D16 0
D15 C2
D14 lock
D13 D5
D12 D4
Read D11 D10 AGC D3 D2
D9 D1
D8 D0
D7 D7
D6 D6
D5 D5
D4 D3 Angle D4 D3
D2 D2
D1 D1
D0 D0
Rev. 1.8
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Page 11 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.18 1-Wire PWM Connection
+5V VDD
11
VDD CS
13
VDD
Micro Controller
Input
AS5030 16 PWM
C1 C2 VSS
100n
This configuration uses the least number of wires: only one line (PWM) is used for data, leaving the total number of connection to three, including the supply lines. This type of configuration is especially useful for remote sensors. Ultra Low Power Mode is not possible in this configuration, as there is no bi-directional data transmission. If the AS5030 angular data is invalid, the PWM output will remain at low state. Pins that are not shown may be left open. Note that the PWM output is invalid when the AGC is disabled (see 5.2.2).
VSS
14 15
VSS
3
Figure 13: Data transmission with pulse width modulated (PWM) output
The minimum PWM pulse width tON (PWM = high) is 1 LSB @ 0 (Angle reading = 00H). 1LSB = nom. 2.26s. The PWM pulse width increases with 1LSB per step. At the maximum angle 358.6 (Angle reading = FFH), the pulse width tON (PWM = high) is 256 LSB and the pause width tOFF (PWM = low) is 1 LSB. This leads to a total period (tON + tOFF) of 257LSB.
Position Angle 0 0 127 178.59 128 180 255 358.59
High 1 128 129 256
t_high 2.26s 287.02s 291.54s 578.56s
Low 256 129 128 1
t_low 578.56s 291.54s 287.02s 2.26s
Duty-Cycle 0.39% 49.4% 50.2% 99.6%
This means that the PWM pulse width is (position + 1) LSB, where position is 0....255. The tolerance of the absolute pulse width and -frequency can be eliminated by calculating the angle with the duty cycle rather than with the absolute pulse width:
tON angle[8 - bit ] = 257 tON + tOFF
-1
results in an 8-bit value from 00H to FFH,
angle[] =
tON 360 257 256 tON + tOFF
- 1
results in a degree value from 0 ~ 358.6 Note: the absolute frequency tolerance is eliminated by dividing tON by (tON+TOFF), as the change of the absolute timing effects both TON and TOFF in the same way.
Rev. 1.8
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Page 12 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.19 Analog Output
+5V VDD
11
CS
13
VDD
This configuration is similar to the PWM connection (only three lines including supply are required). With the addition of a lowpass filter at the PWM output, this configuration produces an analog voltage that is proportional to the angle. This filter can be either passive (as shown) or active. The lower the bandwidth of the filter, the less ripple of the analog output can be achieved.
16
>=4k7 >=4k7
100n
AS5030
PWM
Analog out
If the AS5030 angular data is invalid, the PWM output will remain at low state and thus the analog output will be 0V. Pins that are not shown may be left open. Note that the PWM output is invalid when the AGC is disabled (see 5.2.2).
C1 C2 VSS
>=1F
>=1F
14 15
VSS
3
Figure 14: Data transmission with pulse width modulated (PWM) output
Figure 15: Relation of PWM/Analog output with angle
4.20 Analog Sin/Cos outputs with external interpolator
+5V VDD 14 VDD DA 5 4 7 C1 Sin Sinn 13 VDD
micro controller
VSS
DA
Cos 6 Cosn
AS5030
100n
By connecting C1 to VDD, the AS5030 provides analog Sine and Cosine outputs (Sin, Cos) of the Hall array front-end for test purposes. These outputs allow the user to perform the angle calculation by an external ADC + C, e.g. to compute the angle with a high resolution. In addition, the inverted Sine and Cosine signals (Sinn, Cosn; see dotted lines) are available for differential signal transmission. The input resistance of the receiving amplifier or ADC should be greater than 100k. The signal lines should be kept as short as possible, longer lines should be shielded in order to achieve best noise performance.
Figure 16: Sine and Cosine outputs for external angle calculation
C2 VSS 15 3
VSS
The SIN / COS / SINn / COSn signals are amplitude controlled to ~1.3Vp (differential) by the internal AGC controller. The DC bias voltage is 2.25 V. If the SIN(n)- and COS(n)- outputs cannot be sampled simultaneously, it is recommended to disable the automatic gain control (see 5.2.2) as the signal amplitudes may be changing between two readings of the external ADC. This may lead to less accurate results.
Rev. 1.8
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Page 13 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
4.21 3-Wire Daisy Chain Mode
The Daisy Chain mode allows connection of more than one AS5030 to the same controller interface. Independent of the number of connected devices, the interface to the controller remains the same with only three signals: CSn, CLK and DO. In Daisy Chain mode, the data from the second and subsequent devices is appended to the data of the first device.
+5V VDD
13
VDD VDD
13
VDD
13
VDD
The 100nF buffer cap at the supply (shown only for the last device) is recommended for all devices. The total number of serial bits is: n*21, where n is the number of connected devices: e.g. for 2 devices, the serial bit stream is 42bits . For three devices it is 63 bits.
Micro Controller
Output Output I/O
11 10 12
AS5030 #1
CS CLK DIO C1 C2 VSS DX
11 10 12
AS5030 #2
CS CLK DIO C1 C2 VSS DX
AS5030 11 10 12
(last device) CS CLK DIO C1 C2 VSS DX 100n
VSS
14 15
VSS
3
14 15
3
14 15
3
Figure 17: Connection of devices in 3-wire Daisy Chain mode
CLK CS DIO
1
2
3
4
5
6
7
8
20
21
22
23
24
25
26
27
28
29
41
42
43
44
CMD4 CMD3 CMD2 CMD1 CMD0
D15
D14
D13
D0
CMD4 CMD3 CMD2 CMD1 CMD0
D15
D14
D13
D0
CMD4 CMD3 CMD2
AS5030 #1
Figure 18: Timing diagram in 3-wire Daisy Chain mode
AS5030 #2
AS5030 #3
4.22 2-Wire Daisy Chain Mode
+5V VDD
13
VDD VDD
13
VDD
13
VDD
15
C2
Micro Controller
11 10 12
CS
AS5030 #1
DX
11 10 12
AS5030 #2
CS CLK DIO C1 C2 VSS DX
AS5030 11 10 12
(last device) CS CLK DIO C1 DX 100n
Output I/O
CLK DIO C1 C2 VSS
VSS
VSS
14 15
VSS
3
14 15
3
14
3
Figure 19: 2-wire Daisy Chain mode
The AS5030 can also be connected in 2-wire Daisy Chain mode, requiring only two signals (Clock and Data) for any given number of daisy-chained devices. Note that the connection of all devices except the last device is the same as for the 3-wire connection (see Figure 17). The last device must have pin C2 (#15) set to high and feeds the DX signal to CS of the first device. Again, each device should be buffered with a 100nF cap (shown only for the last device).
Rev. 1.8
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Page 14 of 33
AS5030 8-bit Programmable Magnetic Rotary Encoder
The total number of serial bits is: n*21, where n is the number of connected devices. Note that this configuration requires one extra clock (#1) to initiate the generation of the CS signal for the first device. After reading the last device, the communication must be reset back to the first device by introducing a timeout of CLK (no rising edge for >24s)
Figure 20: Timing diagram in 2-wire Daisy Chain mode
5
5.1
AS5030 Programming
Programming Options
The AS5030 has an integrated 18 Bit OTP ROM for configuration purposes. 5.1.1 OTP Programming options
The OTP programming options can be set permanently by programming or temporarily by overwriting. Both methods are carried out over the serial interface, but with different commands (WRITE OTP, PROG OTP, see 5.2.4). Note: During the 18bit OTP programming, each bit needs 4 clock pulses to be validated. * Zero Position Programming This programming option allows the user to program any rotation angle of the magnet as the new zero position. This useful feature simplifies the assembly process as the magnet does not need to be mechanically adjusted to the electrical zero position. It can be assembled in any rotation angle and later matched to the mechanical zero position by zero position programming. The 8-bit user programmable zero position can be applied both temporarily (command WRITE OTP, #1FH) or permanently (command PROG OTP, #19H) Magnetic Field Optimization This programming option allows the user to match the vertical distance of the magnet with the optimum magnetic field range of the AS5030 by setting the sensitivity level. The 2-bit user programmable sensitivity setting can be applied both temporarily (command WRITE OTP, #1FH) or permanently (command PROG OTP, #19H) Reduced Power mode programming options
*
5.1.2
These temporary programming options are also carried out over the serial interface. See 5.2.2. * Low Power Mode Low Power Mode is a power saving mode with fast start-up. In Low Power Mode, all internal digital registers are frozen and the power consumption is reduced to max. 1.5mA. The serial interface remains active. Start-up from this mode to normal operation can be accomplished within 150s. This mode is recommended for applications, where low power, but fast start-up and short reading cycle intervals are required. Ultra Low Power Mode Ultra Low Power Mode is a power saving mode with even reduced power-down current consumption. In this mode, all chip functions are frozen and the power consumption is reduced to max. 50A. The serial interface remains active. Start-up from this mode to normal operation can be accomplished within 500s. This mode is recommended for applications, where very low average power consumption is required, e.g. for battery operated equipment. For example, in a cycled operation with 10 readings per second, the average power consumption of the AS5030 can be reduced to only 120A.
*
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AS5030 8-bit Programmable Magnetic Rotary Encoder
5.2
AS5030 Read / Write Commands
Data transmission with the AS5030 is handled over the 2-wire or 3-wire interface. The transmission protocol begins with sending a 5-bit command to the AS5030, followed by reading or writing 16 or 18 bits of data: 5.2.1
Command
16-bit Read Command
Bin Hex D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
RD ANGLE
00000
00
C2
lock
AGC 5:0
Angle 7:0
C2 Lock AGC
Angle 5.2.2
displays status of hardware pin C2 (pin #15) indicates that the AGC is locked. Data is invalid when this bit is 0 6-bit AGC register. Indicates the strength of the magnet (e.g. for pushbutton applications) 000000b indicates a strong magnetic field 111111b indicates a weak magnetic field ideally, the vertical distance of the magnet should be chosen such that the AGC value is in the middle (around 100000b) 8-bit Angle value; represents the rotation angle of the magnet. One step = 360/256 = 1.4 16-bit Write Command
These settings are temporary; they cannot be programmed permanently. The settings will be lost when the power supply is removed.
Command Bin Hex D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
EN PROG SET PWR MODE DIS HYST DIS AGC
10000 10001 10011 10101
10 11 13 15
1 0 ULP/ PSM LPn HYS 0 0
0
0
1
1
0
0
1 0 0 0
0
1
0
1
1
1
0
0
0
0
rst
0
0
AGC 5:0
FA
EN PROG ULP/LPn PSM HYS DIS AGC rst FA
this command must be sent with a fixed 16-bit code (8CAEH) to enable subsequent OTP access. selects the Ultra Low Power Mode, when bit PSM is set: 0 = Low Power Mode, 1 = Ultra Low Power Mode enables power saving modes: 0 = normal operation, 1 = reduced power mode selected by bit ULP/LPn disables the hysteresis of the digital serial and PWM outputs: 0 (default) = 1-bit hysteresis, 1 = no hysteresis disables the automatic gain control. The AGC will be frozen to a gain setting written in bits AGC 5:0 (D6:D1), bit FA must be set. General Reset: 0 = normal operation, 1 = perform general reset (required after return from reduced power modes) Freeze AGC; 0 = normal operation, 1= freeze AGC with the values stored in bits AGC 5:0. The PWM output will be invalid when bit FA is set.
5.2.3
18-bit OTP Read Commands
Note: to prohibit unintentional access to the OTP register, OTP PROG/write access is only enabled after the EN PROG command (see 5.2.2) has been sent. OTP access is locked again by sending a RD ANGLE or SET PWR MODE command. EN PROG has not to be sent before a READ OTP. During the 18bit OTP read/write transfer, each bit needs 4 clock pulses to be validated.
Command READ OTP ANALOG OTP RD Bin 01111 01001 Hex D17 0F 09
D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
reserved for factory settings reserved for factory settings
sens 1:0 sens 1:0
zero position 7:0 zero position 7:0
READ OTP reads the ANALOG OTP RD reads the sens reads the zero position reads the
contents of the OTP register in digital form. The reserved area may contain any value contents of the OTP register as an analog voltage at pin PROG (see 5.4) sensitivity setting of the Hall elements : 00 = high sensitivity, 11 = low sensitivity programmed zero position; the actual angle of the magnet which is displayed as 000
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AS5030 8-bit Programmable Magnetic Rotary Encoder
5.2.4
18-bit OTP Write Commands
During the 18bit OTP read/write transfer, each bit needs 4 clock pulses to be validated.
Command Bin Hex D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
WRITE OTP PROG OTP
11111 11001
1F 19
copy factory settings obtained from READ OTP command 00000000 reserved for factory settings,
sens 1:0 sens 1:0
zero position 7:0 zero position 7:0
WRITE OTP:
non-permanent ("soft write") modification of the OTP register. To set the reserved factory settings area properly, a preceding READ OTP command must be made to receive the correct setting for bits D17:D10. The WRITE OTP command must then set these bits in exactly the same way. Improper setting of the factory settings by a WRITE OTP command may cause malfunction of the chip. The OTP register, including the factory settings can be restored to default by a power-up cycle. For non-permanent writing, a programming voltage at pin PROG (#2) is not required. permanent modification of the OTP register. An unprogrammed OTP bit contains a `0, programmed bits are 1's. It is possible to program the OTP in several sequences. However, only a 0 can be programmed to 1. Once programmed, an OTP bit cannot be set back to 0. For subsequent programming, bits that are already programmed should be set to 0 to avoid double programming. During permanent programming, the factory settings D17:D10 should always be set to zero to avoid modification of the factory settings. Modifying the factory settings may cause irreversible malfunction of the chip. For permanent programming, a static programming voltage of 8.0-8.5V must be applied at pin PROG (#2) sets the sensitivity setting of the Hall elements : 00: gain factor = 1.65 (low sensitivity) 01: gain factor = 1.75 10: gain factor = 1.86 11: gain factor = 2.00 (high sensitivity) sets the user programmable zero position; the actual angle of the magnet which is displayed as 000
PROG OTP:
sens
zero position
Figure 21: Timing diagram in OTP 18bit read/write mode
5.3
+5V VDD
OTP Programming Connection
Programming of the AS5030 OTP memory does not require a dedicated programming hardware. The programming can be simply accomplished over the serial 3-wire interface (shown in Figure 22) or the optional 2-wire interface (shown in Figure 8). For permanent programming (command PROG OTP, #19H), a constant DC voltage of 8.0V ~ 8.5V (100mA) must be connected to pin #2 (PROG). For temporary OTP write ("soft write"; command WRITE OTP, #1FH), the programming voltage is not required. To secure unintentional programming, any modification of the OTP memory is only enabled after a special password (command #10H) has been sent to the AS5030.
13
VDD
Output Output I/O 8.0 - 8.5V
11 10 12
VDD CS CLK DIO
Micro Controller
AS5030
100n
2 PROG
10F 100n
VSS
C1 C2 VSS
14 15
VSS
Figure 22: OTP programming connection
3
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AS5030 8-bit Programmable Magnetic Rotary Encoder
Programming in Daisy Chain mode Programming in Daisy chain mode is possible for both 3-wire and 2-wire mode (see Figure 17 and Figure 19). For temporary programming (soft write), no additional connections are required. Programming is executed with the respective programming commands (see 5.2). For permanent programming, the programming voltage must be applied on pin#2 (PROG) of the device to be programmed. It is also possible to apply the programming voltage simultaneously to all devices, as the actual programming is only executed by a software command. A parallel connection of all PROG-pins allows digital programming verification but does not allow analog programming verification (see 5.4). If analog programming verification is required, each PROG pin must be selected individually for verification.
5.4
Programming Verification
+5V VDD
13
VDD
Output Output I/O
11 10 12
VDD CS CLK DIO AS5030 100n
After programming, the programmed OTP bits may be verified in two ways: - By digital verification: this is simply done by sending a READ OTP command (#0FH see 5.2.3). The structure of this register is the same as for the OTP PROG or OTP WRITE commands. - By analog verification: By sending an ANALOG OTP READ command (#09H), pin PROG becomes an output, sending an analog voltage with each clock, representing a sequence of the bits in the OTP register. A voltage of <500mV indicates a correctly programmed bit ("1") while a voltage level between 2.2V and 3.5V indicates a correctly unprogrammed bit ("0"). Any voltage level in between indicates improper programming.
Micro Controller
2 PROG
VSS
V
C1 C2 VSS
14 15
VSS
3
Figure 23: Analog OTP verification
6
AS5030 Status Indicators
Refer to 5.2.1
6.1
C2 Status Bit
This bit represents the hardware connection of the C2 configuration pin (#15) to determine, which hardware configuration is selected for the AS5030 in question. C2 = low : pin C2 is low, indicating that the AS5030 is in 3-wire mode or a member of a 2-wire daisy chain connection (except the last; see 4.21) C2 = high: pin C2 is high, indicating that the AS5030 is in 2-wire mode and/or the last member of a 2-wire daisy chain connection (see 4.22)
6.2
Lock Status Bit
The Lock signal indicates the ADC lock status. If Lock = low (ADC unlocked), the angle information is invalid. To determine a valid angular signal at best performance, the following indicators should be set: Lock = 1 AGC > 00H and < 2FH Note that the angle signal may also be valid (Lock = 1), when the AGC is out of range (00H or 2FH), but the accuracy of the AS5030 may be reduced due to the out of range condition of the magnetic field strength.
6.3
Magnetic Field Strength Indicators
The AS5030 is not only able to sense the angle of a rotating magnet, it can also measure the magnetic field strength (and hence the vertical distance) of the magnet. This extra feature can be used for several purposes: * as a safety feature by constantly monitoring the presence and proper vertical distance of the magnet * as a state-of-health indicator, e.g. for a power-up self test * as a pushbutton feature for rotate-and-push types of manual input devices
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AS5030 8-bit Programmable Magnetic Rotary Encoder
The magnetic field strength information is available in two forms: 6.3.1 Magnetic Field Strength Hardware Indicator:
Pin MagRngn (#1) will be low, when the magnetic field is too weak. The switching limit is determined by the value of the AGC. If the AGC value is <3FH , the MagRngn output will be high (green range), If the AGC is at its upper limit (3FH), the MagRngn output will be low (red range). 6.3.2 Magnetic Field Strength Software Indicator:
D13:D7 in the serial data that is obtained by command READ ANGLE (5.2.1) contains the 6-bit AGC information (see 5.2.1). The AGC is an automatic gain control that adjusts the internal signal amplitude obtained from the Hall elements to a constant level. If the magnetic field is weak, e.g. with a large vertical gap between magnet and IC, with a weak magnet or at elevated temperatures of the magnet, the AGC value will be high. Likewise, the AGC value will be lower when the magnet is closer to the IC, when strong magnets are used and at low temperatures. The best performance of the AS5030 will be achieved when operating within the AGC range. It will still be operational outside the AGC range, but with reduced performance especially with a weak magnetic field due to increased noise. 6.3.3 Factors Influencing the AGC Value
In practical use, the AGC value will depend on several factors: * the initial strength of the magnet. Aging magnets may show a reducing magnetic field over time which results in an increase of the AGC value. The effect of this phenomenon is relatively small and can easily be compensated by the AGC. * the vertical distance of the magnet. Depending on the mechanical setup and assembly tolerances, there will always be some variation of the vertical distance between magnet and IC over the lifetime of the application using the AS5030. Again, vertical distance variations can be compensated by the AGC * the temperature and material of the magnet. The recommended magnet for the AS5030 is a diametrically magnetized, 5-6mm diameter NdFeB (Neodymium-Iron-Boron) magnet. Other magnets may also be used as long as they can maintain to operate the AS5030 within the AGC range. Every magnet has a temperature dependence of the magnetic field strength. The temperature coefficient of a magnet depends on the used material. At elevated temperatures, the magnetic field strength of a magnet is reduced, resulting in an increase of the AGC value. At low temperatures, the magnetic field strength is increased, resulting in a decrease of the AGC value. The variation of magnetic field strength over temperature is automatically compensated by the AGC. 6.3.4 OTP Sensitivity Adjustment
To obtain best performance and tolerance against temperature or vertical distance fluctuations, the AGC value at normal operating temperature should be in the middle between minimum and maximum, hence it should be around 100000 (20H) To facilitate the "vertical centering" of the magnet+IC assembly, the sensitivity of the AS5030 can be adjusted in the OTP register in 4 steps. A sensitivity adjustment is recommended, when the AGC value at normal operation is close to its lower limit (around 00H ). The default sensitivity setting is 00H = high sensitivity. Any value >00H will reduce the sensitivity (see 5.2.4).
6.4
+5V VDD
"Pushbutton" Feature
Using the magnetic field strength software and hardware indicators described above, the AS5030 provides a useful method of detecting both rotation and vertical distance simultaneously. This is especially useful in applications implementing a rotate-and-push type of human interface (e.g. in panel knobs and switches). The MagRngn output is low, when the magnetic field is below the low limit (weak or no magnet) and high when the magnetic field is above the low limit (in-range or strong magnet). A finer detection of a vertical distance change, for example when only short vertical strokes are made by the pushbutton, is achieved by memorizing the AGC value in normal operation and triggering on a change from that nominal the AGC value to detect a vertical movement.
Figure 24: Magnetic field strength indicator
1k VDD LED1
13
VDD
1 Micro Controller Output
I/O Output
11 CS 10 CLK 12
DIO
MagRngn
AS5030 100n
VSS
C1 C2 VSS
14 15
VSS
3
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AS5030 8-bit Programmable Magnetic Rotary Encoder
7
High Speed Operation
The AS5030 is using a fast tracking ADC (TADC) to determine the angle of the magnet. The TADC has a tracking rate of 1.15s (typ). Once the TADC is synchronized with the angle, it sets the LOCK bit in the status register (see 5.2.1). In worst case, usually at start-up, the TADC requires a maximum of 127 steps (127 * 1.15S = 146.05s) to lock. Once it is locked, it requires only one cycle (1.15s) to track the moving magnet. The AS5030 can operate in locked mode at rotational speeds up to 30,000 rpm. In Low Power Mode or Ultra Low Power Mode, the position of the TADC is frozen. It will continue from the frozen position once it is powered up again. If the magnet has moved during the power down phase, several cycles will be required before the TADC is locked again. The tracking time to lock in with the new magnet angle can be roughly calculated as:
t LOCK = 1.15s NewPos - OldPos
tLOCK = OldPos = NewPos = time required to acquire the new angle after power up from one of the reduced power modes [s] Angle position when one of the reduced power modes is activated [] Angle position after resuming from reduced power mode []
7.1
Propagation Delay
The Propagation delay is the time required from reading the magnetic field by the Hall sensors to calculating the angle and making it available on the serial or PWM interface. While the propagation delay is usually negligible on low speeds it is an important parameter at high speeds. The longer the propagation delay, the larger becomes the angle error for a rotating magnet as the magnet is moving while the angle is calculated. The position error increases linearly with speed. The main factors contributing to the propagation delay are: 7.1.1 ADC Sampling Rate For high speed applications, fast ADC's are essential. The ADC sampling rate directly influences the propagation delay. The fast tracking ADC used in the AS5030 with a tracking rate of only 1.15s (typ.) is a perfect fit for both high speed and high performance. 7.1.2 Chip internal lowpass filtering A commonplace practice for systems using analog-to-digital converters is to filter the input signal by an anti-aliasing filter. The filter characteristic must be chosen carefully to balance propagation delay and noise. The lowpass filter in the AS5030 has a cut-off frequency of typ. 23.8kHz and the overall propagation delay in the analog signal path is typ. 15.6s. 7.1.3 Digital readout rate
Aside from the chip-internal propagation delay, the time required to read and process the angle data must also be considered. Due to its nature, a PWM signal is not very usable at high speeds, as you get only one reading per PWM period. Increasing the PWM frequency may improve the situation but causes problems for the receiving controller to resolve the PWM steps. The frequency on the AS5030 PWM output is typ. 1.95kHz with a resolution of 2s/step. A more suitable approach for high speed absolute angle measurement is using the serial interface. With a clock rate of up to 6MHz, a complete set of data (21bits) can be read in >3.5s
7.2
Total propagation delay of the AS5030
The total propagation delay of the AS5030 is the delay in the analog signal path and the tracking rate of the ADC: 15.6s + 1.15s = 16.75s. If only the SIN-/COS-outputs are used, the propagation delay is the analog signal path delay only (typ. 15.6s). Position Error over speed The angle error over speed caused by the propagation delay is calculated as: pd = rpm * 6 * 16.75E -6 in degrees.
In addition, the anti-aliasing filter causes an angle error calculated as: lpf = ArcTan [ rpm / ( 60*f0)]
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AS5030 8-bit Programmable Magnetic Rotary Encoder
Examples of the overall position error caused by speed, including both propagation delay and filter delay: Speed (rpm) 100 1000 10000 Total Position error (pd + lpf) 0.0175 0.175 1.75
8
Reduced Power Modes
The AS5030 can be operated in 3 reduced power modes. All 3 modes have in common that they switch off or freeze parts of the chip during intervals between measurements. In Low Power Mode or Ultra Low Power Mode, the AS5030 is not operational, but due to the fast start-up, an angle measurement can be accomplished very quickly and the chip can be switched to reduced power immediately after a valid measurement has been taken. Depending on the intervals between measurements, very low average power consumption can be achieved using such a strobed measurement mode. * Low Power Mode: reduced current consumption, very fast start-up. Ideal for short sampling intervals (<3ms) * Ultra Low Power Mode: further reduced current consumption, but slower start-up than Low Power Mode. Ideal for sampling intervals from 3....200ms * Power Cycle mode: zero power consumption (externally switched off) during sampling intervals, but slower start-up than Ultra Low Power Mode. Ideal for sampling intervals 200ms
8.1
Low Power Mode and Ultra Low Power Mode
R1: optional; see text
+5V VDD VDD on/off
VDD
Ion Ioff
ton
toff
The AS5030 can be put in Low Power Mode or Ultra Low Power Mode by simple serial commands, using the regular connection for 2-wire or 3-wire serial data transmission (Figure 4 , Figure 8) The required serial command is SET PWR MODE (11H, see 5.2.3): ULP/LPn 0 0 1 1 PSM 0 1 0 1 Mode Normal operation Low Power Mode Normal operation Ultra Low Power Mode
C1: optional; see text
100n
S
N
CS CLK DIO
Micro Controller
AS5030
VSS C1 C2 VSS
VSS
Figure 25: Low Power Mode and Ultra Low Power Mode connection
Note that after returning from Low Power Mode or Ultra Low Power mode to normal operation (PSM = 0), if the Hysteresis is enabled (Hys=0), a general reset must be performed: set bit RST and then clear bit RST using command 15H (see 5.2.2). The two following cases describe the typical loop programmed in the software: * Hys = 0 (1 LSB hysteresis):
1. 2. 3. 4. 5. 6. 7. 8. Wait for CPU interrupt or delay for next angle read (typ. <3ms in LP mode, typ>3ms in ULP mode) Wake up (PSM = 0) Set Reset (rst = 1) Clear Reset (rst = 0) Wait 0.15ms (Low Power Mode) or 0.5ms (Ultra Low Power Mode) Check if Lock = 1 then read angle Enable Low Power Mode or Ultra Low Power Mode (PSM=1) Return to 1
*
Hys = 1 (No hysteresis)
1. 2. 3. 4. 5. 6. Wait for CPU interrupt or delay for next angle read (typ. <3ms in LP mode, typ>3ms in ULP mode) Wake up (PSM = 0) Wait 0.15ms (Low Power Mode) or 0.5ms (Ultra Low Power Mode) Check if Lock = 1 then read angle Enable Low Power Mode or Ultra Low Power Mode (PSM=1) Return to 1.
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AS5030 8-bit Programmable Magnetic Rotary Encoder
The differentiator between Low Power Mode and Ultra Low Power Mode is the current consumption and the wake-up time to switch back to active operation. Mode Active operation Low Power Mode Ultra Low Power Mode Current Consumption (typ.) 14 mA 1.4 mA 30 A Wake-up Time to Active Operation 1.0 ms (without AGC) 3.8 ms(with locked AGC) 0.15 ms 0.5 ms
In both Reduced Power Modes, the AS5030 is inactive. The last state, e.g. the angle, AGC value, etc. is frozen and the chip starts from this frozen state when it resumes active operation. This method provides much faster start-up than a "cold start" from zero. If the AS5030 is cycled between active and reduced current mode, a substantial reduction of the average supply current can be achieved. The minimum dwelling time in active mode is the wake-up time. The actual active time depends on how much the magnet has moved while the AS5030 was in reduced power mode. The angle data is valid, when the status bit LOCK has been set (see 5.2.1). Once a valid angle has been measured, the AS5030 can be put back to reduced power mode. The average power consumption can be calculated as:
I avg =
I active ton + I power _ down toff ton + toff
sampling interval = ton + toff
where: Iavg Iactive: Ipower_down: ton: toff:
average current consumption current consumption in active mode current consumption in reduced power mode time period during which the chip is operated in active mode time period during which the chip is in reduced power mode
Example: Ultra Low Power Mode; sampling period = one measurement every 10ms. System constants = Iactive = 14mA, Ipower_down = 30A, ton(min) = 500s (startup from Ultra Low Power Mode):
I avg =
14 mA 500 s + 30 A * 9,5ms = 729 A 500 s + 9,5ms
see Figure 27 for an overview table of the average current consumption in the various reduced power modes. Reducing Power Supply Peak Currents An optional RC-filter (R1/C1) may be added to avoid peak currents in the power supply line when the AS5030 is toggled between active and reduced power mode. R1 must be chosen such that it can maintain a VDD voltage of 4.5V ~ 5.5V under all conditions, especially during long active periods when the charge on C1 has expired. C1 should be chosen such that it can support peak currents during the active operation period. For long active periods, C1 should be large and R1 should be small.
8.2
Power Cycling Mode
R1
Ion 0 ton toff ton toff
+5V VDD
VDD
10k
C1 >1F on/off
VDD
100n
S
N
CS CLK DIO
Micro Controller
The power cycling method shown in Figure 26 cycles the AS5030 by switching it on and off, using an external PNP transistor high side switch. This mode provides the least power consumption of all three modes; when the sampling interval is more than 400ms, as the current consumption in offmode is zero. It also has the longest start-up time of all modes, as the chip must always perform a "cold start" from zero, which takes about 1.9 ms (see 8.1). The optional filter R1/C1 may again be added to reduce peak currents in the 5V power supply line.
AS5030
VSS C1 C2 VSS VSS
Figure 26: Application example III: ultra-low power encoder
Figure 27 shows an overview of the average supply currents in the three reduced power modes, depending on the sampling interval. The graphs shows that the Low Power Mode is the best option for sampling intervals <4ms, while the Ultra Low Power Mode is the best option for sampling intervals between
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AS5030 8-bit Programmable Magnetic Rotary Encoder
4~400ms. At sampling intervals >400ms, the power cycling mode is the best method to minimize the average current consumption. The curves are based on the figures given in 8.1.
AS5030 average current consumption 5,0 4,5 4,0
avg. current consumption [mA]
3,5 3,0 2,5 2,0 Low Power Mode 1,5 1,0 0,5 0,0 1 10
sampling interval [ms]
Figure 27: Average current consumption of reduced power modes
Power Cycling Mode Ultra Low Power Mode 100 1000
9
Accuracy of the Encoder system
This chapter describes which individual factors influence the accuracy of the encoder system and how to improve them. Accuracy is defined as the difference between measured angle and actual angle. This is not to be confused with resolution, which is the smallest step that the system can resolve. The two parameters are not necessarily linked together. A high resolution encoder may not necessarily be highly accurate as well.
9.1
Quantization error
There is however a direct link between resolution and accuracy, which is the quantization error:
Figure 28: Quantization error of a low resolution and a high resolution system
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AS5030 8-bit Programmable Magnetic Rotary Encoder
The resolution of the encoder determines the smallest step size. The angle error caused by quantization cannot get better than 1/2 LSB. As shown in Figure 28, a higher resolution system (right picture) has a smaller quantization error, as the step size is smaller. For the AS5030, the quantization error is 1/2 LSB = 0.7
INL including quantization error
1,5 1 0,5 INL [] 0 -0,5 -1 -1,5 0 45 90 135 180 Angle steps INL Average (16x) 225 270 315 360
Figure 29: Typical INL error over 360
Figure 29 shows a typical example of an error curve over a full turn of 360 at a given X-Y displacement. The curve includes the quantization error, transition noise and the system error. The total error is ~2.2 peak/peak ( 1.1). The sawtooth-like quantization error (see also Figure 28) can be reduced by averaging, provided that the magnet is in constant motion and there are an adequate number of samples available. The solid bold line in Figure 29 shows the moving average of 16 samples. The INL (intrinsic non-linearity) is reduced to from ~ 1.1 down to ~ 0.3. The averaging however, also increases the total propagation delay, therefore it may be considered for low speeds only or adaptive; depending on speed (see also: 0, Position Error over speed ).
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9.2
Vertical distance of the magnet
The chip-internal automatic gain control (AGC) regulates the input signal amplitude for the tracking-ADC to a constant value. This improves the accuracy of the encoder and enhances the tolerance for the vertical distance of the magnet.
Linearity and AGC vs Airgap
64 56 48 Linearity [] AGC value 40 32 24 16 8 0 0 500 1000 1500 2000 Airgap [mm] [m] sample#1 sample#2 sample#3 sample#4 Linearity [] 1,2 1,0 2500 1,8 1,6 1,4 2,2 2,0
Figure 30: Typical curves for vertical distance versus ACG value on several untrimmed samples
As shown in Figure 30, the AGC value (left Y-axis) increases with vertical distance of the magnet. Consequently, it is a good indicator for determining the vertical position of the magnet, for example as a pushbutton feature, as an indicator for a defective magnet or as a preventive warning (e.g. for wear on a ball bearing etc.) when the nominal AGC value drifts away. If the magnet is too close or the magnetic field is too strong, the AGC will be reading 0, If the magnet is too far away (or missing) or if the magnetic field is too weak, the AGC will be reading 63 (3FH). The AS5030 will still operate outside the AGC range, but the accuracy may be reduced as the signal amplitude can no longer be kept at a constant level. The linearity curve in Figure 30 (right Y-axis) shows that the accuracy of theAS5030 is best within the AGC range, even slightly better at small airgaps (0.4mm ~ 0.8mm). At very short distances (0mm ~ 0.1mm) the accuracy is reduced, mainly due to nonlinearities in the magnetic field. At larger distances, outside the AGC range (~2.0mm ~ 2.5mm and more) the accuracy is still very good, only slightly decreased from the nominal accuracy. Since the field strength of a magnet changes with temperature, the AGC will also change when the temperature of the magnet changes. At low temperatures, the magnetic field will be stronger and the AGC value will decrease. At elevated temperatures, the magnetic field will be weaker and the AGC value will increase. Sensitivity trimming As the curves for the 4 samples in Figure 30 show, the AGC value will not show exactly the same value at a given airgap on each part. For example, at 1mm vertical distance, the AGC may read a value between ~11 ~ 24. This is because for normal operation an exact trimming is not required since the AGC is part of a closed loop system. However, the AS5030 offers an optional user trimming in the OTP (see 5.2.4) to allow an even tighter AGC tolerance for applications where the information about magnetic field strength is also utilized, e.g. for rotate-and-push types of knobs, etc...
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AS5030 8-bit Programmable Magnetic Rotary Encoder
10 Choosing the proper magnet
typ. 6mm diameter
N
S
Magnet axis R1
There is no strict requirement on the type or shape of the magnet to be used with the AS5030. It can be cylindrical as well as square in shape. The key parameter is that the vertical magnetic field Bz, measured at a radius of 1mm from the rotation axis is sinusoidal with a peak amplitude of 20 ~ 80mT (see Figure 31).
10.1 Magnet Placement:
Ideally, the center of the magnet, the diagonal center of the IC and the rotation axis of the magnet should be in one vertical line. The lateral displacement of the magnet should be within 0.25mm from the IC package center or 0.5mm from the IC center, including the placement of the chip within the IC package. The vertical distance should be chosen such that the magnetic field on the die surface is within the specified limits. The typical distance "z" between the magnet and the package surface is 0.5mm to 1.8mm with the recommended magnet (6mm x 2.5mm). Larger gaps are possible, as long as the required magnetic field strength stays within the defined limits. A magnetic field outside the specified range may still produce acceptable results, but with reduced accuracy. The out-of-range condition will be indicated, when the AGC is at the limits (AGC= 0 : field too strong; AGC=63=(3FH): field too weak or missing magnet.
Magnet axis
Vertical field component
N
S
R1 concentric circle; radius 1.0 mm Vertical field component Bz (20...80mT)
0
360
360
Figure 31: Vertical magnetic fields of a rotating magnet
Bz; 6mm magnet @y=0; z=1mm
N
1 50
S
1 00
50
0
-50
-1 00
Hall elements (side view)
-1 50 3,5 2,5 1 ,5 0,5 -0,5 -1 ,5 -2,5 -3,5 X - dis pla c e m e nt [ m m ]
Figure 32: Bz field distribution along the x-axis of a 6mmO diametric magnetized magnet
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AS5030 8-bit Programmable Magnetic Rotary Encoder
Figure 32 shows a cross sectional view of the vertical magnetic field component Bz between the north and south pole of a 6mm diameter magnet, measured at a vertical distance of 1mm. The poles of the magnet (maximum level) are about 2.8mm from the magnet center, which is almost at the outer magnet edges. The magnetic field reaches a peak amplitude of ~ 106mT at the poles. The Hall elements are located at a radius of 1mm (indicated as squares at the bottom of the graph). Due to the side view, the two Hall elements at the Y-axis are overlapping at X = 0mm, therefore only 3 Hall elements are shown. At 1mm radius, the peak amplitude is ~ 46mT, respectively a differential amplitude of 92mT. The vertical magnetic field Bz follows a fairly linear pattern up to about 1.5mm radius. Consequently, even if the magnet is not perfectly centered, the differential amplitude will be the same as for a centered magnet. For example, if the magnet is misaligned in X-axis by -0.5mm, the two X-Hall sensors will measure 70mT (@x = -1.5mm) and -22mt (@x = -0.5mm). Again, the differential amplitude is 92mT. At larger displacements however, the Bz amplitude becomes nonlinear, which results in larger errors that mainly affect the accuracy of the system (see also Figure 34)
BZ; 6mm magnet @ Z=1mm
N
125 100 75 50 25
Bz [mT]
area of X-Y-misalignment from center: +/- 0.5mm
circle of Hall elements on chip: 1mm radius
0 -25 -50 -75 -100 -125
4 3 2 2 1 0 -3 -1 -2 -3 -4 -2
4 3 2
S
-1
1 0
Y-displacement [mm]
X-displacement [mm]
Figure 33: Vertical magnetic field distribution of a cylindrical 6mm O diametric magnetized magnet at 1mm gap
Figure 33 shows the same vertical field component as Figure 32, but in a 3-dimensional view over an area of 4mm from the rotational axis.
10.2 Lateral displacement of the magnet
As shown in the magnet specifications (4.4), the recommended horizontal position of the magnet axis with respect to the IC package center is within a circle of 0.25mm radius. This includes the placement tolerance of the IC within the package. Figure 34 shows a typical error curve at a medium vertical distance of the magnet around 1.2mm (AGC = 24). The X- and Y- axis of the graph indicate the lateral displacement of the magnet center with respect to the IC center. At X = Y = 0, the magnet is perfectly centered over the IC. The total displacement plotted on the graph is for 1mm in both directions. The Z-axis displays the worst case INL error over a full turn at each given X-and Y- displacement. The error includes the quantization error of 0.7 (see 0). For example, the accuracy for a centered magnet is between 1.0 ~ 1.5 (spec = 2 over full temperature range). Within a radius of 0.5mm, the accuracy is better than 2.0 (spec = 3 over temperature).
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AS5030 8-bit Programmable Magnetic Rotary Encoder
INL vs. Displacement: AS5030 for AGC24
4,500-5,000 4,000-4,500 5,000 4,500 4,000 3,500 3,000 2,500 INL [] 2,000 1,500 1,000 0,500 0,000 -1000 -750 -500 -250 0 250 X Displacem ent [m ] 500 750 1000 3,500-4,000 3,000-3,500 2,500-3,000 1000 750 500 250 0 -250 -500 -750 -1000 Y Displacem ent [m ] 2,000-2,500 1,500-2,000 1,000-1,500 0,500-1,000 0,000-0,500
Figure 34: Typical error curve of INL error over lateral displacement (including quantization error)
10.3 Magnet size
Figure 32 to Figure 34 in this chapter describe a cylindrical magnet with a diameter of 6mm. Smaller magnets may also be used, but since the poles are closer together, the linear range will also be smaller and consequently the tolerance for lateral misalignment will also be smaller. If the 0.25mm lateral misalignment radius (rotation axis to IC package center) is too tight, a larger magnet can be used. Larger magnets have a larger linear range and allow more misalignment. However at the same time the slope of the magnet is more flat which results in a lower differential amplitude. This requires either a stronger magnet or a smaller gap between IC and magnet in order to operate in the amplitude-controlled area (AGC > 0 and AGC < 63). In any case, if a magnet other than the recommended 6mm diameter magnet is used, two parameters should be verified: * Verify that the magnetic field produces a sinusoidal wave, when the magnet is rotated. Note: this can be done with the SIN-/COS- outputs of the AS5030, e.g. rotate the magnet at constant speed and analyze the SIN- (or COS-) output with an FFT-analyzer. It is recommended to disable the AGC for this test (see 4.20). Verify that the Bz-Curve between the poles is as linear as possible (see Figure 32). This curve may be available from the magnet supplier(s). Alternatively, the SIN- or COS- output of the AS5030 may also be used together with an X-Y- table to get a Bz-scan of the magnet (as in Figure 32 or Figure 33) Furthermore; the sinewave tests described above may be re-run at defined X-and Y- misplacements of the magnet to determine the maximum acceptable lateral displacement range. It is recommended to disable the AGC for both these tests (see 4.20).
*
Note: for preferred magnet suppliers, please refer to the austriamicrosystems website (Rotary Encoder section).
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AS5030 8-bit Programmable Magnetic Rotary Encoder
11 Package Drawings and Markings
16-Lead Thin Shrink Small Outline Package TSSOP-16
AYWWIZZ AS5030
Dimensions
Symbol A A1 A2 b c D E E1 e K L 0 0.45 0.05 0.8 0.19 0.09 4.9 6.2 4.3 5 6.4 4.4 0.65 0.60 0.10 1 mm Min Typ Max 1.2 0.15 1.05 0.30 0.20 5.1 6.6 4.48 8 0.75 .002 0.031 0.007 .004 0.193 0.244 0.169 0 .018 0.197 0.252 0.173 .0256 .024 8 .030 .004 0.039 Min inch Typ Max .047 .006 0.041 0.012 .008 0.201 0.260 0.176
Marking: AYWWIZZ A: Pb-Free Identifier Y: Last Digit of Manufacturing Year WW: Manufacturing Week I: Plant Identifier ZZ: Traceability Code JEDEC Package Outline Standard: MO - 153 Thermal Resistance Rth(j-a): 89 K/W in still air, soldered on PCB IC's marked with a white dot or the letters "ES" denote Engineering Samples
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AS5030 8-bit Programmable Magnetic Rotary Encoder
12 Ordering Information
Delivery: Tape and Reel (1 reel = 4500 devices) Tubes (1 box = 100 tubes a 96 devices) for delivery in tubes for delivery in tape and reel
Order # AS5030ATSU Order # AS5030ATST
13 Recommended PCB Footprint
Recommended Footprint Data A B C D E mm 7.26 4.93 0.36 0.65 4.91 inch 0.286 0.194 0.014 0.0256 0.193
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AS5030 8-bit Programmable Magnetic Rotary Encoder
Table of contents
1 General Description ....................................................................................................................................................... 1 1.1 1.2 1.3 1.4 2 3 4 Benefits.................................................................................................................................................................. 1 Key Features .......................................................................................................................................................... 1 Applications............................................................................................................................................................ 1 Block Diagram ........................................................................................................................................................ 1
Package and Pinout ....................................................................................................................................................... 2 AS5030 Parameter and Features List .............................................................................................................................. 3 General Device Specifications ........................................................................................................................................ 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 Absolute Maximum Ratings (non operating) ............................................................................................................. 4 Operating Conditions .............................................................................................................................................. 4 System Parameters................................................................................................................................................. 5 Magnet Specifications ............................................................................................................................................. 6 Magnetic Field Alarm Limits .................................................................................................................................... 6 Hall Element sensitivity options ............................................................................................................................... 6 Programming parameters ........................................................................................................................................ 7 DC Characteristics of Digital Inputs and Outputs ...................................................................................................... 7 8-bit PWM Output ................................................................................................................................................... 7 Serial 8-bit Output ............................................................................................................................................... 8 General Data Transmission Timings ..................................................................................................................... 8 Connecting the AS5030 ....................................................................................................................................... 9 Serial 3-Wire R/W Connection.............................................................................................................................. 9 Serial 3-Wire Read-only Connection ..................................................................................................................... 9 Serial 2-Wire Connection (R/W Mode) ................................................................................................................ 10 Serial 2-wire Continuous Readout ...................................................................................................................... 11 Serial 2-Wire Differential SSI Connection ........................................................................................................... 11 1-Wire PWM Connection .................................................................................................................................... 12 Analog Output ................................................................................................................................................... 13 Analog Sin/Cos outputs with external interpolator ............................................................................................... 13 3-Wire Daisy Chain Mode .................................................................................................................................. 14 2-Wire Daisy Chain Mode .................................................................................................................................. 14
5
AS5030 Programming .................................................................................................................................................. 15 5.1 5.2 5.3 5.4 Programming Options ........................................................................................................................................... 15 AS5030 Read / Write Commands ........................................................................................................................... 16 OTP Programming Connection............................................................................................................................... 17 Programming Verification ...................................................................................................................................... 18
6
AS5030 Status Indicators ............................................................................................................................................. 18 6.1 6.2 6.3 6.4 C2 Status Bit ........................................................................................................................................................ 18 Lock Status Bit ..................................................................................................................................................... 18 Magnetic Field Strength Indicators......................................................................................................................... 18 "Pushbutton" Feature ............................................................................................................................................ 19
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AS5030 8-bit Programmable Magnetic Rotary Encoder
7
High Speed Operation .................................................................................................................................................. 20 7.1 7.2 Propagation Delay ................................................................................................................................................ 20 Total propagation delay of the AS5030 .................................................................................................................. 20
8
Reduced Power Modes ................................................................................................................................................. 21 8.1 8.2 Low Power Mode and Ultra Low Power Mode ......................................................................................................... 21 Power Cycling Mode ............................................................................................................................................. 22
9
Accuracy of the Encoder system ................................................................................................................................... 23 9.1 9.2 Quantization error ................................................................................................................................................. 23 Vertical distance of the magnet ............................................................................................................................. 25 Choosing the proper magnet ..................................................................................................................................... 26 10.1 10.2 10.3 Magnet Placement:............................................................................................................................................ 26 Lateral displacement of the magnet.................................................................................................................... 27 Magnet size ...................................................................................................................................................... 28 Package Drawings and Markings ............................................................................................................................... 29 Ordering Information ................................................................................................................................................ 30 Recommended PCB Footprint ................................................................................................................................... 30
10
11 12 13
Table of contents ................................................................................................................................................................ 31 Copyrights .......................................................................................................................................................................... 33 Disclaimer .......................................................................................................................................................................... 33 Contact Information ............................................................................................................................................................. 33
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AS5030 8-bit Programmable Magnetic Rotary Encoder
Copyrights
Copyright (c) 1997-2007, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered (R). All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. This product is protected by U.S. Patent No. 7,095,228.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters austriamicrosystems AG A-8141 Schloss Premstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com
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