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SC628A
LED Flash Driver
POWER MANAGEMENT Features
Input supply voltage range -- 3.0V to 5.5V Charge pump modes -- 1x, 1.5x and 2x Flash LED -- 1000mA max in flash mode, 275mA max continuous for spotlight Charge pump frequency -- 250kHz I2C compatible interface -- up to 400kHz External flash control pin to sync with camera One second flash time out with disable feature Automatic sleep mode (flash off ) -- IQ = 100A Low shutdown current -- 0.1A (typical) Ultra-thin package -- 3mm x 3mm x 0.6mm Fully WEEE and RoHS compliant
Charge Pump with 1000mA Flash Mode, 275mA Spotlight Mode, and I2C Interface Description
The SC628A is a high efficiency charge pump LED driver using Semtech's proprietary charge pump technology. Performance is optimized for use in single-cell Li-ion battery applications. The load and supply conditions determine whether the charge pump operates in 1x, 1.5x, or 2x mode. The charge pump provides continuous spotlight mode current or pulsed flash mode current to an LED using a dedicated current sink. In flash mode, a flash-timeout feature turns off the flash if active for longer than 1 second. In spotlight mode, the timeout feature is disabled to allow continuous operation of the LED. The SC628A uses an I2C compatible serial interface to set the flash mode or the spotlight mode current. The flash/ spotlight output is triggered via either the I2C interface or a dedicated flash enable pin (FLEN). In sleep mode, the device reduces quiescent current to 100A while continuing to monitor the serial interface. Total current reduces to 0.1A in shutdown.
Applications
Cellular phone flash PDA flash
Typical Application Circuit
VBAT = 3.0V to 5.5V CIN 4.7F I2C Data I C Clock Flash Control Enable Control
2
FLASH
IN SDA SCL FLEN EN
OUT
SC628A
COUT 4.7F
FL AGND PGND C1+ C1C2+ C2-
C1 2.2F
C2 2.2F
US Patents: 6,504,422; 6,794,926 July 14, 2009 1
SC628A
Pin Configuration
OUT C1+ C2+ C1IN
Ordering Information
Device
SC628AULTRT(1)(2) SC628AEVB
15 TOP VIEW 14 13 12 T 11 9 10
FLEN
Package
MLPQ-UT-20 3x3 Evaluation Board
20 C2PGND FL NC NC 1 2 3 4 5 6
19
18
17
16 NC NC NC EN SDA
Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. (2) Lead-free package only. Device is WEEE and RoHS compliant.
7
8
AGND
MLPQ-UT-20; 3x3, 20 LEAD JA = 40C/W
Marking Information
628A yyww xxxx
yyww = Date Code xxxx = Semtech Lot No.
SCL
NC
NC
2
SC628A
Absolute Maximum Ratings
IN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 OUT (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 C1+, C2+ (V) . . . . . . . . . . . . . . . . . . . . . . . -0.3 to (VOUT + 0.3) Pin Voltage - All Other Pins (V) . . . . . . . . . . . -0.3 to (VIN + 0.3) OUT Short Circuit Duration . . . . . . . . . . . . . . . . . Continuous ESD Protection Level(1) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Recommended Operating Conditions
Ambient Temperature Range (C) . . . . . . . . -40 < TA < +85 IN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 < VIN < 5.5 OUT (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 < VOUT < 5.25
Thermal Information
Thermal Resistance, Junction to Ambient(2) (C/W) . . . . 40 Maximum Junction Temperature (C) . . . . . . . . . . . . . . +150 Storage Temperature Range (C) . . . . . . . . . . . . -65 to +150 Peak IR Reflow Temperature (10s to 30s) (C) . . . . . . . +260
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended. NOTES: (1) Tested according to JEDEC standard JESD22-A114-B. (2) Calculated from package in still air, mounted to 3" x 4.5", 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
Electrical Characteristics
Unless otherwise noted, TA = +25C for Typ, -40C to +85C for Min and Max, TJ(MAX) = 125C, VIN = 3.0V to 4.2V, CIN = COUT = 4.7F (ESR = 0.03), C1 = C2 = 2.2F (ESR = 0.03), size code 0603 (1608 metric) for all capacitors
Parameter
Supply Specifications Shutdown Current
Symbol
Conditions
Min
Typ
Max
Units
IQ(OFF)
Shutdown, VIN = 4.2V Sleep, EN = VIN Charge pump in 1x mode
0.1 100 3.8 4.6 4.6
2 160 4.65 5.85 5.85
A A
Total Quiescent Current
IQ Charge pump in 1.5x mode Charge pump in 2x mode mA
Fault Protection Output Short Circuit Current Limit Over-Temperature Flash Mode Safety Timer(1) Charge Pump Over-Voltage Protection IOUT(SC) TOTP tFL(MAX) VOVP Flash sink active OUT pin open circuit, VOUT = VOVP rising threshold 0.75 5.3 OUT pin shorted to GND 450 160 1.00 5.7 1.25 6.0 mA C s V
3
SC628A
Electrical Characteristics (continued)
Parameter
Fault Protection (continued) VUVLO Undervoltage Lockout VUVLO-HYS Charge Pump Electrical Specifications Maximum Total Output Current Flash Current Settling Time Flash Current Setting Flash Current Accuracy 1x Mode to 1.5x Mode Falling Transition Voltage 1.5x Mode to 2x Mode Falling Transition Voltage Current Sink Off-State Leakage Current Pump Frequency IOUT(MAX) tFL_SET IFL IFL_ACC V TRANS1x V TRANS1.5x IBLn fPUMP VIN > 3.5V, VOUT(MAX) = 4.0V maximum time for current to settle Nominal setting for FL VIN = 3.7V, IFL = 450mA, TA = 25C IOUT = 150mA, VOUT = 3.3V IOUT = 150mA, VOUT = 4.5V(2) VIN = VFL = 4.2V VIN = 3.2V 25 -13 5 3.37 1000 1 1000 13 mA ms mA % V Hysteresis 800 mV Increasing VIN 2.7 V
Symbol
Conditions
Min
Typ
Max
Units
3.3
V
0.1 250
1
A kHz
Digital I/O Electrical Specifications (FLEN, EN) Input High Threshold Input Low Threshold Input High Current Input Low Current VIH VIL IIH IIL VIN = 5.5V VIN = 3.0V VIN = 5.5V VIN = 5.5V -1 -1 1.4 0.4 +1 +1 V V A A
I2C Interface
Interface complies with slave mode I2C interface as described by Philips I2C specification version 2.1 dated January, 2000. VB-IL Digital Input Voltage VB-IH SDA Output Low Level Digital Input Current Hysteresis of Schmitt Trigger Inputs Maximum Glitch Pulse Rejection I/O Pin Capacitance IB-IN VHYS tSP CIN IDIN (SDA) 3mA -0.2 0.1 1.4 0.4 0.2 V V A V 0.4 V
50 10
ns pF
4
SC628A
Electrical Characteristics (continued)
Parameter
I2C Timing Clock Frequency SCL Low Period(3) SCL High Period(3) Data Hold Time(3) Data Setup Time(3) Setup Time for Repeated START Condition(3) Hold Time for Repeated START Condition(3) Setup Time for STOP Condition(3) Bus-Free Time Between STOP and START(3) Interface Start-up Time(3) fSCL tLOW tHIGH tHD_DAT tSU_DAT tSU_STA tHD_STA tSU_STO tBUF tEN Bus Start-up Time After EN Pin is Pulled High 1.3 0.6 0 250 0.6 400 440 kHz s s s ns s
Symbol
Conditions
Min
Typ
Max
Units
0.6
s
0.6
s
1.3
s
1
ms
Notes: (1) Once tripped, flash output will remain disabled until FLEN pin is cycled or reset via serial interface. (2) Test voltage is VOUT = 4.5V -- a relatively extreme LED voltage -- to force a transition during test. Typically VOUT = 3.3V for the white LED at 100mA. (3) Guaranteed by design
5
SC628A
Typical Characteristics
Spotlight Current -- 25mA
31 VOUT = 2.97V, IOUT = 25mA, TA = 25C
Flash Current -- 400mA
460 VOUT = 3.41V, IOUT = 400mA, TA = 25C
29
440
27
420
IFL (mA)
25
IFL (mA)
4.2 3.9 3.6 3.3 3 2.7
400
23
380
21
360
19
340
VIN (V)
4.2
3.9
3.6
VIN (V)
3.3
3
2.7
Spotlight Current -- 100mA
115 VOUT = 3.14V, IOUT = 100mA, TA = 25C
Flash Current -- 875mA
1175 VOUT = 3.69V, IOUT = 875mA, TA = 25C
110
1075
105
IFL (mA)
975
IFL (mA)
4.2 3.9 3 2.7
100
875
95
775
90
675
85
575 4.2 3.9 3.6 VIN (V) 3.3 3 2.7
3.6
VIN (V)
3.3
Spotlight Current -- 275mA
350 VOUT = 3.32V, IOUT = 275mA, TA = 25C
1300
Flash Current -- 1000mA
VOUT = 3.72V, IOUT = 1000mA, TA = 25C
325
1200
300
1100
IFL (mA)
275
IFL (mA)
4.2 3.9 3.6 VIN (V) 3.3 3 2.7
1000
250
900
225
800
200
700 4.2 3.9 3.6 VIN (V) 3.3 3 2.7
6
SC628A
Typical Characteristics (continued)
Spotlight Efficiency -- 25mA
100 VOUT = 2.97V, IOUT = 25mA, TA = 25C
Spotlight Efficiency -- 275mA
100 VOUT = 3.32V, IOUT = 275mA, TA = 25C
90
90
% Efficiency
80
% Efficiency
3.9 3.6 2.7
80
70
70
60
60
50 4.2
VIN (V)
3.3
3
50
4.2
3.9
3.6
VIN (V)
3.3
3
2.7
Spotlight Efficiency -- 100mA
100 VOUT = 3.14V, IOUT = 100mA, TA = 25C
Flash Efficiency -- 400mA
100 VOUT = 3.41V, IOUT = 400mA, TA = 25C
90
90
% Efficiency
% Efficiency
80
80
70
70
60
60
50 4.2
3.9
3.6
VIN (V)
3.3
3
2.7
50 4.2
3.9
3.6
VIN (V)
3.3
3
2.7
7
SC628A
Typical Characteristics (continued)
Spotlight Mode Ripple -- 1x Mode
IOUT = 275mA, TA = 25C, Spotlight Mode
Spotlight Mode Ripple -- 1.5x Mode
IOUT = 275mA, TA = 25C, Spotlight Mode
VIN (100mVAC/div)
VIN (100mVAC/div)
VOUT (100mVAC/div)
VOUT (100mVAC/div)
IOUT (200mADC/div) 0mA-- Time (4.0s/div)
IOUT (200mADC/div) 0mA-- Time (4.0s/div)
Flash Mode Ripple -- 1x Mode
IOUT = 1000mA, TA = 25C, Flash Mode VIN (200mVAC/div) VIN (200mVAC/div)
Flash Mode Ripple -- 1.5x Mode
IOUT = 1000mA, TA = 25C, Flash Mode
VOUT (200mVAC/div) VOUT (200mVAC/div)
IOUT (500mADC/div)
IOUT (500mADC/div)
0mA--
Time (4.0s/div)
0mA--
Time (4.0s/div)
Flash Mode Ripple -- 2x Mode
IOUT = 1000mA, TA = 25C, Flash Mode VIN (200mVAC/div)
Flash Current Pulse
VIN = 3.7V, IOUT = 1000mA, TA = 25C, tON = 100ms VFLEN (2VDC/div) 0V-- VOUT (2VDC/div)
VOUT (200mVAC/div)
0V-- IOUT (500mADC/div) 0mA--
IOUT (500mADC/div)
0mA--
Time (4.0s/div)
Time (40ms/div)
8
SC628A
Typical Characteristics (continued)
Flash Mode Safety Timer
VIN = 4.2V, IOUT = 1000mA, TA = 25C VFLEN (2VDC/div) 0V--
VOUT (2VDC/div) 0V-- IOUT (500mADC/div) 0mA-- Time (200ms/div)
Output Open Circuit Protection
VIN = 3.7V, TA = 25C
VFLEN (2VDC/div) 0V-- VOUT (2VDC/div)
0V--
IOUT (500mADC/div) 0mA-- Time (200ms/div)
Output Short Circuit Current Limit
VIN = 3.7V, VOUT = 0V, TA = 25C
VFLEN (2VDC/div) 0V--
VOUT (2VAC/div) 0V--
IOUT (500mADC/div) 0mA-- Time (200ms/div)
9
SC628A
Pin Descriptions
Pin #
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 T
Pin Name
C2PGND FL NC NC NC NC AGND SCL FLEN SDA EN NC NC NC OUT C2+ C1+ IN C1THERMAL PAD
Pin Function
Negative connection to bucket capacitor 2 -- requires a 2.2F capacitor connected to C2+ Ground pin for high current charge pump and Flash LED driver Current sink output for flash LED(s) Unused pin -- do not terminate Unused pin -- do not terminate Unused pin -- do not terminate Unused pin -- do not terminate Analog ground pin -- connect to ground and separate from PGND current I2C clock input pin Control pin for flash LED(s) -- high = ON, low = OFF I2C bi-directional data pin -- used for read and write operations for all internal registers (refer to Register Map and I2C Interface sections) Chip enable -- active high -- low state resets all registers (see register map table) Unused pin -- do not terminate Unused pin -- do not terminate Unused pin -- do not terminate Charge pump output -- all LED anode pins should be connected to this pin -- requires a 4.7F capacitor to PGND Positive connection to bucket capacitor 2 -- requires a 2.2F capacitor connected to C2Positive connection to bucket capacitor 1 -- requires a 2.2F capacitor connected to C1Battery voltage input -- connect with a 4.7F capacitor to PGND Negative connection to bucket capacitor 1 -- requires a 2.2F capacitor connected to C1+ Thermal pad for heatsinking purposes -- connect to ground plane using multiple vias -- not connected internally
10
SC628A
Block Diagram
C1+ 18 C120 C2+ 17 C21
IN
19
mAhXLifeTM Fractional Charge Pump (1x, 1.5x, 2x)
16 2
OUT PGND
EN SDA FLEN SCL
12 11 10 9 I2 C Compatible Interface and Logic Control Oscillator 4 5 6 Current Setting DAC Flash Output Current Sink 7 3 NC NC NC NC FL
NC
13 Bandgap Reference 15 NC
AGND
8 14 NC
11
SC628A
Applications Information
General Description
This design is optimized for handheld applications supplied from a single Li-Ion cell and includes the following key features: The device also requires a 4.7F capacitor on the IN pin and a 4.7F capacitor on the OUT pin to minimize noise and support the output drive requirements. Capacitor case size is an important factor in the performance of the SC628A. Due to the poor DC coefficient of the 0402 size (1005 metric), 0603 size (1608 metric) capacitors are strongly recommended to achieve the rated electrical specifications and performance shown in the typical characteristics section. Capacitors with X7R or X5R ceramic dielectric are strongly recommended for their low ESR and superior temperature and voltage characteristics. Y5V capacitors should not be used as their temperature coefficients make them unsuitable for this application.
* * *
A high efficiency fractional charge pump that supplies power to the flash LED An LED flash output that provides up to 1000mA of momentary current or up to 275mA of continuous spotlight current An I2C compatible interface that provides control of all device functions
High Current Fractional Charge Pump
The flash output is supported by a high efficiency, high current fractional charge pump output at the OUT pin. The charge pump multiplies the input voltage by 1, 1.5, or 2 times. The charge pump switches at a fixed frequency of 250kHz in 1.5x and 2x modes and is disabled in 1x mode to save power and improve efficiency. The mode selection circuit automatically selects the 1x, 1.5x or 2x mode based on circuit conditions. Circuit conditions such as low input voltage, high output current, or high LED voltage place a higher demand on the charge pump output. A higher numerical mode may be needed momentarily to maintain regulation at the OUT pin during intervals of high demand, such as the high current of an LED flash or the droop at the IN pin during a supply voltage transient. The charge pump responds to these momentary high demands, setting the charge pump to the optimum mode (1x, 1.5x or 2x), as needed to deliver the output voltage and load current while optimizing efficiency. Hysteresis is provided to prevent mode toggling. The charge pump requires two bucket capacitors for low ripple operation. One capacitor must be connected between the C1+ and C1- pins and the other must be connected between the C2+ and C2- pins as shown in the typical application circuit diagram. These capacitors should be equal in value, with a minimum capacitance of 2.2F to support the charge pump current requirements.
LED Flash and Spotlight Current Sink
A single output current sink is provided to drive both flash and spotlight functions. In flash mode, this current sink provides up to 1000mA for a flash LED or array of parallel LEDs. Flash current settings are available in 21 values from 300mA to 1000mA. Flash steps increments are no larger than 75mA nominally. Some additional settings that have smaller increments of 50mA, 25mA and 12.5mA. Table 1 on page 12 contains detailed current setting information for flash mode. The FLEN pin directly triggers the FLASH function when pulled high, or it can be wired to IN to enable software control via the serial interface. In spotlight mode, the output can be set for up to 275mA of continuous current. Settings are available in 25mA increments from 25mA to 275mA, with some additional settings that have smaller increments of 12.5mA. Table 2 on page 13 contains detailed current setting information for spotlight mode. Continuous operation above 275mA is not recommended due to high power dissipation.
Flash and Spotlight Safety Timer
A safety timer disables the flash and spotlight output current sink if the sink remains active for an extended period. The timer protects the SC628A and the LED from high power dissipation that can cause overheating. The
12
SC628A
Applications Information (continued)
timer's default state is on, but the timer may be disabled via the serial interface to allow continuous output current in spotlight mode. The safety timer affects only the FL pin and will turn off the sink after a period of 1 second. The timer may be reset by either forcing the FLEN pin low or by resetting the Flash/Spotlight control bits via the interface. Over-Temperature Protection The Over-Temperature (OT) protection circuit helps prevent the device from overheating and experiencing a catastrophic failure. When the junction temperature exceeds 160C, the device goes into thermal shutdown with all outputs disabled until the junction temperature is reduced. All register information is retained during thermal shutdown. Charge Pump Output Current Limit The device also limits the charge pump current at the OUT pin. When OUT is shorted to ground, the typical output current is 400mA. The current limiting is triggered by an output under-voltage lockout below 2V. The output returns to normal when the short is removed and OUT is above 2.5V. Above 2.5V, a minimum current limit of 1000mA applies. LED Float Detection Float detect is a fault detection feature of the LED current sink output. If the output is programmed to be enabled and an open circuit fault occurs on the current sink, the resulting open loop will cause the output voltage to change to the default condition VOUT = 3.0V. The output will remain 3.0V until the loop is once again completed by an LED or the output is re-programmed to the off state.
Shutdown State
The device is disabled when the EN pin is low. All registers are reset to default condition when EN is low.
Sleep Mode
When the LED is off, sleep mode is activated. This is a reduced current mode that helps minimize overall current consumption by turning off the clock and the charge pump while continuing to monitor the serial interface for commands.
I C Compatible Interface Functions
All device functions can be controlled via the I2C compatible interface. The interface is described in detail in the Serial Interface section of the datasheet.
2
Protection Features
The SC628A provides several protection features to safeguard the device from catastrophic failures. These features include:
* * * *
Output Open Circuit Protection Over-Temperature Protection Charge Pump Output Current Limit LED Float Detection
Output Open Circuit Protection Over-Voltage Protection (OVP) is provided at the OUT pin to prevent the charge pump from producing an excessively high output voltage. In the event of an open circuit at OUT, the charge pump runs in open loop and the voltage rises up to the OVP limit. OVP operation is hysteretic, meaning the charge pump will momentarily turn off until VOUT is sufficiently reduced. The maximum OVP threshold is 6.0V, allowing the use of a ceramic output capacitor rated at 6.3V with no fear of over-voltage damage.
13
SC628A
Applications Information (continued)
PCB Layout Considerations
The layout diagram in Figure 1 illustrates a proper two-layer PCB layout for the SC628A and supporting components. Following fundamental layout rules is critical for achieving the performance specified in the Electrical Characteristics table. The following guidelines are recommended when developing a PCB layout:
* * *
* *
*
Place all bypass and decoupling capacitors -- C1, C2, CIN, and COUT as close to the device as possible. All charge pump current passes through IN, OUT, and the bucket capacitor connection pins. Ensure that all connections to these pins make use of wide traces so that the resistive drop on each connection is minimized. The thermal pad should be connected to the ground plane using multiple vias to ensure proper thermal connection for optimal heat transfer.
Make all ground connections to a solid ground plane as shown in the example layout (Figure 3). If a ground layer is not feasible, the following groupings should be connected: PGND -- CIN, COUT AGND -- Ground Pad If no ground plane is available, PGND and AGND should be routed back to the negative battery terminal as separate signals using thick traces.
GND
OUT
GND
IN
Figure 2 -- Layer 1
CIN
C1 C2
COUT
C2-
OUT
C1+
C2+
C1-
IN
NC
PGND
NC
FL
SC628A
NC
NC
EN
NC
SDA
AGND
NC
NC
FLEN
SCL
Figure 3 -- Layer 2 Figure 1 -- Recommended PCB Layout
14
SC628A
Register Map
Address
0x02
D7
D6
D5
0(1)
D4
FLTO
D3
D2
D1
D0
Reset Value
0x10
Description
Flash/Spotlight Control
Flash/Spotlight Bits
Flash/Spotlight Bits
Notes: (1) Always write a 0 to this bit
Register and Bit Definitions
Flash/Spotlight Control Register (0x02) This register is used to select the flash or spotlight current and to configure the flash time-out feature. Bits D7, D6, D3, D2, D1, D0 The value of bits D7, D6, D3, D2, D1, and D0 are used to set the current for the flash and spotlight modes. Flash current values are set in accordance with Table 1 on page 12, and spotlight current values are set in accordance with Table 2 on page 13. FLTO This bit is used to enable the flash safety time-out feature. The default state is enabled with FLTO = 1. If this bit is set, the device will turn off the flash after a nominal period of 1s. Two ways to re-enable the flash function after a safety time-out are: Pull the FLEN pin low to reset the flash function Clear and re-write bits D7, D6 D3, D2, D1, and D0.
* *
15
SC628A
Register and Bit Definitions (continued)
Table 1 -- Flash Current Codes(1)
Data Bits for Register 02h D7
x(2) 0 0 1 0 1 0 1 0 1 0 1 0 0 0 1 0 1 1 1 1 1
Flash Current D2
0 0 1 1 1 0 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 1
8 Bit Word Hex
00h 5Bh 5Dh D5h 1Eh 9Ah 13h D9h 15h DDh 17h DFh 19h 1Bh 1Dh 95h 1Fh 97h 99h 9Bh 9Dh 9Fh
D6
x(2) 1 1 1 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0
D5
0(3) 0 0 0
(3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3)
D4
1(4) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
(4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4)
D3
0 1 1 0 1 1 0 1 0 1 0 1 1 1 1 0 1 0 1 1 1 1
D1
0 1 0 0 1 1 1 0 0 0 1 1 0 1 0 0 1 1 0 1 0 1
D0
0 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
IFL (mA)
OFF 300 325 337.5 350 375 400 412.5 450 487.5 500 525 550 600 650 675 700 750 825 875 950 1000
0 0 0 0
0 0
0 0 0 0 0 0 0 0
0(3) 0(3) 0(3) 0(3)
1(4) 1(4) 1(4) 1(4)
Notes: (1) Use only the data values shown in Table 1 for flash function. (2) Either 1 or 0. (3) Always write a 0 to this bit. (4) Write a 1 to set the FLTO bit for flash mode.
16
SC628A
Register and Bit Definitions (continued)
Table 2 -- Spotlight Current Codes(1)
Data Bits for Register 02h D7
x(2) 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0
Spotlight Current D2
0 0 0 0 1 1 1 0 1 1 0 0 1 1 1 0
8 Bit Word Hex
00h 42h C2h 02h 46h 04h C6h 4Ah 06h 4Eh CAh 08h 45h 47h CEh 49h
D6
x(2) 1 1 0 1 0 1 1 0 1 1 0 1 1 1 1
D5
0(3) 0 0 0
(3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3)
D4
0(4) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
(4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (4)
D3
0 0 0 0 0 0 0 1 0 1 1 1 0 0 1 1
D1
0 1 1 1 1 0 1 1 1 1 1 0 0 1 1 0
D0
0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1
IFL (mA)
OFF 25 37.5 50 75 100 112.5 125 150 175 187.5 200 225 250 262.5 275
0 0 0 0 0 0 0 0 0 0 0 0
(3) (3) (3) (3)
(4) (4) (4) (4)
Notes: (1) Use only the data values shown in Table 2 for spotlight function. (2) Either 1 or 0. (3) Always write a 0 to this bit. (4) Write a 0 to reset the FLTO bit for spotlight mode.
17
SC628A
Serial Interface
The I2C General Specification
The SC628A is a read-write slave-mode I C device and complies with the Philips I2C standard Version 2.1, dated January 2000. The SC628A has four user-accessible internal 8-bit registers. The I2C interface has been designed for program flexibility, supporting direct format for write operation. Read operations are supported on both combined format and stop separated format. While there is no auto increment/decrement capability in the SC628A I2C logic, a tight software loop can be designed to randomly access the next register independent of which register you begin accessing. The start and stop commands frame the data-packet and the repeat start condition is allowed if necessary.
2
by an eighth bit indicating a write. The SC628A I2C then acknowledges that it is being addressed, and the master responds with an 8 bit data byte consisting of the register address. The slave acknowledges and the master sends the appropriate 8 bit data byte. Once again the slave acknowledges and the master terminates the transfer with the stop condition [P]. Combined Format -- Read After the start condition [S], the slave address is sent, followed by an eighth bit indicating a write. The SC628A I2C then acknowledges that it is being addressed, and the master responds with an 8 bit data byte consisting of the register address. The slave acknowledges and the master sends the repeated start condition [Sr]. Once again, the slave address is sent, followed by an eighth bit indicating a read. The slave responds with an acknowledge and the previously addressed 8 bit data byte; the master then sends a non-acknowledge (NACK). Finally, the master terminates the transfer with the stop condition [P]. Stop Separated Reads Stop-separated reads can also be used. This format allows a master to set up the register address pointer for a read and return to that slave at a later time to read the data. In this format the slave address followed by a write command are sent after a start [S] condition. The SC628A then acknowledges it is being addressed, and the master responds with the 8-bit register address. The master sends a stop or restart condition and may then address another slave. After performing other tasks, the master can send a start or restart condition to the SC628A with a read command. The device acknowledges this request and returns the data from the register location that had previously been set up.
SC628A Limitations to the I2C Specifications
The SC628A only recognizes seven bit addressing. This means that ten bit addressing and CBUS communication are not compatible. The device can operate in either standard mode (100kbit/s) or fast mode (400kbit/s).
Slave Address Assignment
The seven bit slave address is 0110 111x. The eighth bit is the data direction bit. 0x6E is used for a write operation, and 0x6F is used for a read operation.
Supported Formats
The supported formats are described in the following subsections. Direct Format -- Write The simplest format for an I2C write is direct format. After the start condition [S], the slave address is sent, followed
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SC628A
Serial Interface (continued)
I2C Direct Format Write
S Slave Address W A Register Address A Data A P
S - Start Condition W - Write = `0' A - Acknowledge (sent by slave) P - Stop condition
Slave Address - 7-bit Register address - 8-bit Data - 8-bit
I2C Stop Separated Format Read
Register Address Setup Access S Slave Address W A Register Address A P S
S - Start Condition W - Write = `0' R - Read = `1' A - Acknowledge (sent by slave) NAK - Non-Acknowledge (sent by master) Sr - Repeated Start condition P - Stop condition
Master Addresses other Slaves Slave Address B S/Sr
Register Read Access Slave Address RA Data NACK P
Slave Address - 7-bit Register address - 8-bit Data - 8-bit
I2C Combined Format Read
S Slave Address WA Register Address A Sr Slave Address R A Data NACK P
S - Start Condition W - Write = `0' R - Read = `1' A - Acknowledge (sent by slave) NAK - Non-Acknowledge (sent by master) Sr - Repeated Start condition P - Stop condition
Slave Address - 7-bit Register address - 8-bit Data - 8-bit
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SC628A
Outline Drawing -- MLPQ-UT-20 3x3
B
A
D
DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM MAX
A A1 A2 b D D1 E E1 e L N aaa bbb .020 .000 .024 .002 0.50 0.00 0.60 0.05 (.006) .006 .008 .010 .114 .118 .122 .061 .067 .071 .114 .118 .122 .061 .067 .071 .016 BSC .012 .016 .020 20 .003 .004 (0.1524) 0.15 0.20 0.25 2.90 3.00 3.10 1.55 1.70 1.80 2.90 3.00 3.10 1.55 1.70 1.80 0.40 BSC 0.30 0.40 0.50 20 0.08 0.10
PIN 1 INDICATOR (LASER MARK)
E
A2 A aaa C A1 e LxN E/2 E1
2 1 N
SEATING PLANE C D1
D/2 bxN bbb
NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
CAB
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS . 3. DAP is 1.90 x 190mm.
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SC628A
Land Pattern -- MLPQ-UT-20 3x3
H R DIM C G H K P R X Y Z DIMENSIONS INCHES (.114) .083 .067 .067 .016 .004 .008 .031 .146 MILLIMETERS (2.90) 2.10 1.70 1.70 0.40 0.10 0.20 0.80 3.70
(C)
K
G
Z
Y X P NOTES: 1. 2.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE.
3.
Contact Information
Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com
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