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WM2614 Quad 12-bit Serial Input Voltage Output DAC
Production Data, June 1999, Rev 1.0
FEATURES
* * * * Quad 12-bit DAC voltage output DAC Dual 2.7V to 5.5V supply (separate digital and analogue supplies) DNL 0.4 LSB, INL 1.5 LSB Low power consumption: 5.5mW, slow mode - 5V supply 3.3mW, slow mode - 3V supply TMS320, (Q)SPITM , and MicrowireTM compatible serial TM TM interface Programmable settling time of 4 s or 12 s typical
DESCRIPTION
The WM2614 is a quadruple 12-bit voltage output, resistor string, digital-to-analogue converter. Each DAC can be individually powered down under software control. A hardware controlled mode is provided that powers down all DACs. Power down reduces current consumption to 10nA. The device has been designed to interface efficiently to industry standard microprocessors and DSPs, including the TMS320 family. The WM2614 is programmed with a 16-bit serial word comprising of a DAC address, individual DAC control bits and a 12-bit value. The WM2614 has provision for two supplies: one supply for the serial interface (DVDD, DGND) and one for the DACs, reference buffers and output buffers (AVDD, AGND). This enables a typical application where the device can be controlled via a microprocessor operating on a 3V supply, with the DACs operating on a 5V supply. Alternatively, the supplies can be tied together in a single supply application. Excellent performance is delivered with a typical DNL of 0.4 LSBs. The settling time of the DAC is programmable to allow the designer to optimize speed versus power dissipation. The output stage is buffered by a x2 gain near rail-to-rail amplifier, which features a Class AB output stage. DACs A and B can have a different reference voltage to DACs C and D. The device is available in a 16-pin TSSOP package. Commercial temperature (0 to 70C) and Industrial temperature (-40 to 85C) variants are supported.
* *
APPLICATIONS
* * * * * * * Battery powered test instruments Digital offset and gain adjustment Battery operated/remote industrial controls Machine and motion control devices Wireless telephone and communication systems Speech synthesis Arbitrary waveform generation
ORDERING INFORMATION
DEVICE WM2614CDT WM2614IDT TEMP. RANGE 0 to 70C -40 to 85 C PACKAGE 16-pin TSSOP 16-pin TSSOP
BLOCK DIAGRAM
AVDD (16) DVDD (1) REFINAB (15) REFINCD (10) DAC A REFERENCE INPUT BUFFER
TYPICAL PERFORMANCE
1 AVDD = DVDD = 5V, VREF = 2.048V, Speed = Fast mode, Load = 10k/100pF 0.8
DAC OUTPUT BUFFER X2 (14) OUTA
WM2614
DIN (4) data FS (7) 16-BIT SHIFT REGISTER AND CONTROL LOGIC 14-BIT DATA AND CONTROL HOLDING LATCH
X1
0.6
12-BIT DAC LATCH
0.4
NCS (6)
2-BIT CONTROL LATCH
POWERDOWN/ SPEED CONTROL
DNL (LSB)
(13) OUTB (12) OUTC (11) OUTD
SCLK (5)
0.2
0
-0.2
DAC B
-0.4
DAC C POWER-ON RESET
-0.6
-0.8
DAC D
-1
(9) AGND (8) DGND (3) NLDAC (2) NPD
0
512
1024
1536
2048 DIGITAL CODE
2559
3071
3583
4095
WOLFSON MICROELECTRONICS LTD
Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK Tel: +44 (0) 131 667 9386 Fax: +44 (0) 131 667 5176 Email: sales@wolfson.co.uk http://www.wolfson.co.uk
Production Data Datasheets contain final specifications current on publication date. Supply of products conforms to Wolfson Microelectronics' terms and conditions. 2614Mastera.doc June 18, 1999 14:36
(c)1999 Wolfson Microelectronics Ltd.
WM2614
Production Data Rev 1.0
PIN CONFIGURATION
DVDD NPD NLDAC DIN SCLK NCS FS DGND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 AVDD REFINAB OUTA OUTB OUTC OUTD REFINCD AGND
PIN DESCRIPTION
PIN NO 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 NAME DVDD NPD NLDAC DIN SCLK NCS FS DGND AGND REFINCD OUTD OUTC OUTB OUTA REFINAB AVDD TYPE Supply Digital input Digital input Digital input Digital input Digital input Digital input Ground Ground Analogue input Analogue output Analogue output Analogue output Analogue output Analogue input Supply Digital supply. Power down. Powers down all DACs overriding their individual power down settings and all output stages. This pin is active low. Load DAC. Digital input active low. NLDAC must be taken low to update the DAC latch from the holding latches. Serial data input. Serial clock input. Chip select. This pin is active low. Frame synchronisation for serial output data. Digital ground. Analogue ground. Voltage reference input for DACs C and D. DAC D output. DAC C output. DAC B output. DAC A output. Voltage reference input for DACs A and B. Analogue supply. DESCRIPTION
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical Characteristics at the test conditions specified ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage of this device. CONDITION Supply voltages, DVDD to DGND, AVDD to AGND Supply voltage differences, AVDD to DVDD Digital input voltage Reference input voltage Operating temperature range, TA Storage temperature Lead temperature 1.6mm (1/16 inch) soldering for 10 seconds WOLFSON MICROELECTRONICS LTD WM2614CDT WM2614IDT -2.8V -0.3V -0.3V 0C -40C -65C MIN MAX 7V 2.8V DVDD + 0.3V AVDD + 0.3V 70C 85C 150C 260C Production Data Rev 1.0 June 1999 2
Production Data Rev 1.0
WM2614
RECOMMENDED OPERATING CONDITIONS
PARAMETER Supply voltage High-level digital input voltage Low-level digital input voltage Reference voltage to REFINAB, REFINCD Load resistance Load capacitance Serial clock rate Operating free-air temperature Note: SYMBOL AVDD, DVDD VIH VIL VREF RL CL fSCLK TA WM2614CDT WM2614IDT 0 -40 DVDD = 2.7V to 5.5V DVDD = 2.7V to 5.5V See Note 2 10 100 20 70 85 TEST CONDITIONS MIN 2.7 2 0.8 AVDD - 1.5 TYP MAX 5.5 UNIT V V V V k pF MHz C C
Reference voltages greater than AVDD/2 will cause output saturation for large DAC codes.
WOLFSON MICROELECTRONICS LTD
Production Data Rev 1.0 June 1999 3
WM2614 ELECTRICAL CHARACTERISTICS
Production Data Rev 1.0
Test Conditions: RL = 10k, CL = 100pF. AVDD = DVDD = 5V 10%, VREF = 2.048V and AVDD = DVDD = 3V 10%, VREF = 1.024V over recommended operating free-air temperature range (unless noted otherwise). PARAMETER Static DAC Specifications Resolution Integral non-linearity Differential non-linearity Zero code error Gain error D.c. power supply rejection ratio Zero code error temperature coefficient Gain error temperature coefficient DAC Output Specifications Output voltage range Output load regulation Power Supplies Active supply current IDD No load, VIH = DVDD, VIL = 0V AVDD = 5V, VREF = 2.048V Slow AVDD = 5V, VREF = 2.048V Fast AVDD = 3V, VREF = 1.024V Slow AVDD = 3V, VREF = 1.024V Fast See Note 8 Power down supply current No load, all digital inputs 0V or DVDD See Note 9 Dynamic DAC Specifications Slew rate DAC code 128 to 4095, 10%-90% Slow Fast See Note 10 Settling time DAC code 128 to 4095 Slow Fast See Note 11 Glitch energy Signal to noise ratio SNR Code 2047 to 2048 fs = 400ksps, fOUT = 1kHz, BW = 20kHz, See Note 12 Signal to noise and distortion ratio SNRD fs = 400ksps, fOUT = 1kHz, BW = 20kHz, See Note 12 Total harmonic distortion THD fs = 400ksps, fOUT = 1kHz, BW = 20kHz, See Note 12 Spurious free dynamic range SPFDR fs = 400ksps, fOUT = 1kHz, BW = 20kHz, See Note 12 WOLFSON MICROELECTRONICS LTD Production Data Rev 1.0 June 1999 4 56 70 dB -68 -56 dB 54 66 dB 66 10 74 nV-s dB 12.0 4.0 s s 0.5 2.5 1.0 4.0 V/s V/s 0.01 10 A 1.6 3.8 1.2 3.2 2.4 5.6 1.8 4.8 mA 2k to 10k load See Note 7 0 0.1 AVDD - 0.1 0.25 V % INL DNL ZCE GE d.c. PSRR See Note 1 See Note 2 See Note 3 See Note 4 See Note 5 See Note 6 See Note 6 12 bits SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
1.5 0.4
3 0.25 0.5 10 10
4 1 12 0.6
LSB LSB mV % FSR mV/V ppm/C ppm/C
Production Data Rev 1.0 Test Conditions: RL = 10k, CL = 100pF. AVDD = DVDD = 5V 10%, VREF = 2.048V and AVDD = DVDD = 3V 10%, VREF = 1.024V over recommended operating free-air temperature range (unless noted otherwise). PARAMETER Reference Reference input resistance Reference input capacitance Reference feedthrough Reference input bandwidth RREFIN CREFIN VREF = 1VPP at 1kHz + 1.024V dc, DAC code 0 VREF = 0.2VPP + 1.024V dc DAC code 2048 Slow Fast Digital Inputs High level input current Low level input current Input capacitance Notes: 1. 2. IIH IIL CI Input voltage = DVDD Input voltage = 0V 3 1 -1 0.5 1 10 5 -75 SYMBOL TEST CONDITIONS MIN TYP MAX
WM2614
UNIT
M pF dB
MHz MHz A A pF
Integral non-linearity (INL) is the maximum deviation of the output from the line between zero and full scale (excluding the effects of zero code and full scale errors). Differential non-linearity (DNL) is the difference between the measured and ideal 1LSB amplitude change of any adjacent two codes. A guarantee of monotonicity means the output voltage changes in the same direction (or remains constant) as a change in digital input code. Zero code error is the voltage output when the DAC input code is zero. Gain error is the deviation from the ideal full scale output excluding the effects of zero code error. Power supply rejection ratio is measured by varying AVDD from 4.5V to 5.5V and measuring the proportion of this signal imposed on the zero code error and the gain error. Zero code error and Gain error temperature coefficients are normalised to VREF. Output load regulation is the difference between the output voltage at full scale with a 10k load and 2k load. It is expressed as a percentage of the full scale output voltage with a 10k load. IDD is measured while continuously writing code 2048 to the DAC. For VIH < DVDD - 0.7V and VIL > 0.7V supply current will increase. Typical supply current in power down mode is 10nA. Production test limits are wider for speed of test. Slew rate results are for the lower value of the rising and falling edge slew rates. Settling time is the time taken for the signal to settle to within 0.5LSB of the final measured value for both rising and falling edges. Limits are ensured by design and characterisation, but are not production tested. SNR, SNRD, THD and SPFDR are measured on a synthesised sinewave at frequency fOUT generated with a sampling frequency fs.
3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
WOLFSON MICROELECTRONICS LTD
Production Data Rev 1.0 June 1999 5
WM2614 SERIAL INTERFACE
tWL SCLK 1 tSUD DIN D15 tSUCSFS NCS tWHFS FS tSUFSCLK tHD D14 D13 D12 D1 D0 2 tWH 3 4 5 15 16
Production Data Rev 1.0
tSUC16CS
tSUC16FS
Figure 1 Timing Diagram Test Conditions: RL = 10k, CL = 100pF. AVDD = DVDD = 5V 10%, VREF = 2.048V and AVDD = DVDD = 3V 10%, VREF = 1.024V over recommended operating free-air temperature range (unless noted otherwise). SYMBOL tSUCSFS tSUFSCLK tSUC16FS TEST CONDITIONS Setup time NCS low before negative FS edge. Setup time FS low before first negative SCLK edge. Setup time, sixteenth negative SCLK edge after FS low on which D0 is sampled before rising edge of FS. Setup time, sixteenth positive SCLK edge (first positive after D0 sampled) before NCS rising edge. If FS is used instead of the sixteenth positive edge to update the DAC, then the setup time is between the FS rising edge and the NCS rising edge. Pulse duration, SCLK high. Pulse duration, SCLK low. Setup time, data ready before SCLK falling edge. Hold time, data held valid after SCLK falling edge. Pulse duration, FS high. MIN 10 8 10 TYP MAX UNIT ns ns ns
tSUC16CS
10 25 25 8 5 20
ns ns ns ns ns ns
tWHCLK tWLCLK tSUDCLK tHDCLK tWHFS
WOLFSON MICROELECTRONICS LTD
Production Data Rev 1.0 June 1999 6
Production Data Rev 1.0
WM2614
TYPICAL PERFORMANCE GRAPHS
3
5V = VDD, V REF = 2.048V, Speed = Fast mode, Load = 10k/100pF 2
1
INL - LSB
0
-1
-2
-3 0 512 1024 1536 2048 DIGITAL CODE 2559 3071 3583 4095
Figure 2 Integral Non-Linearity
0.4 0.4
AVDD = DVDD = 3V, VREF = 1V, Input Code = 0
0.35 0.35
AVDD = DVDD = 5V, VREF = 2V, Input Code = 0
0.3
0.3
OUTPUT VOLTAGE - V
OUTPUT VOLTAGE - V
0.25
0.25
0.2
0.2
0.15
0.15
0.1
0.1
0.05
0.05
0 0 1 2 3 4 5 ISINK - mA 6 7 8 9
Slow
0 10
Fast
0
1
2
3
4
5 ISINK - mA
6
7
8
Slow
9
Fast
10
Figure Sink 3 Current AVDD = DVDD = 3V
2.06
Figure 4 Sink Current AVDD = DVDD = 5V
4.1
AVDD = DVDD = 3V, VREF = 1V, Input Code = 4095
4.095 2.055
AVDD =DVDD = 5V, VREF = 2V, Input Code = 4095
4.09 OUTPUT VOLTAGE - V 2.05
OUTPUT VOLTAGE - V
4.085
2.045
4.08
2.04 4.075
2.035 0 1 2 3 4 5 ISOURCE - mA 6 7 8 9
Slow
4.07 10
Fast
0
1
2
3
4
5 ISOURCE - mA
6
7
8
9 Slow
10 Fast
Figure 5 Source Current AVDD = DVDD = 3V
Figure 6 Source Current AVDD = DVDD = 5V
WOLFSON MICROELECTRONICS LTD
Production Data Rev 1.0 June 1999 7
WM2614 DEVICE DESCRIPTION
GENERAL FUNCTION
Production Data Rev 1.0
The device uses a resistor string network buffered with an op amp to convert 12-bit digital data to analogue voltage levels (see Block Diagram). The output voltage is determined by the reference input voltage and the input code according to the following relationship: Output voltage = 2(VREF ) INPUT 1111 1111 : 1000 1000 0111 0000 0000 1111 : 0000 0000 0000 0000 0001 0000 0001 0000 1111 1111 CODE 4096 OUTPUT 2(VREF ) : 2(VREF ) 2(VREF ) 2049 4096 4095 4096
2048 = VREF 4096 2047 4096 1 4096
2(VREF ) : 2(VREF )
0V
Table 1 Binary Code Table (0V to 2VREFIN Output), Gain = 2
POWER ON RESET
An internal power-on-reset circuit resets the DAC register to all 0s on power-up.
BUFFER AMPLIFIER
The output buffer has a near rail-to-rail output with short circuit protection and can reliably drive a 2k load with a 100pF load capacitance.
EXTERNAL REFERENCE
The reference voltage input is buffered which makes the DAC input resistance independent of code. The REFIN pin has an input resistance of 10M and an input capacitance of typically 5pF. The reference voltage determines the DAC full-scale output.
HARDWARE CONFIGURATION OPTIONS
The device has two configuration options that are controlled by device pins.
DEVICE POWER DOWN
The device can be powered-down by pulling pin NPD (Pin 2) high. This powers down all DACs overriding their individual power down settings. This will reduce power consumption to typically 10nA. When the power down function is released the device reverts to the DAC code set prior to power down.
SIMULTANEOUS DAC UPDATE
The NLDAC pin (Pin 3) can be held high to prevent serial word writes from updating the DAC latches. By writing new values to multiple DACs then pulling NLDAC low, all new DAC codes are loaded into the DAC latches simultaneously.
WOLFSON MICROELECTRONICS LTD
Production Data Rev 1.0 June 1999 8
Production Data Rev 1.0
WM2614
SERIAL INTERFACE
Explanation of data transfer: First, the device has to be enabled with NCS set to low. Then, a falling edge of FS starts shifting the data bit-per-bit (starting with the MSB) to the internal register on the falling edges of SCLK. After 16 bits have been transferred, the next rising edge on SCLK or FS causes the content of the shift register to be moved to the DAC holding latch. If NLDAC is low, the DAC latch will also updated immediately. The serial interface of the device can be used in two basic modes: * * four wire (with chip select) three wire (without chip select)
Using chip select (four wire mode), it is possible to have more than one device connected to the serial port of the data source (DSP or microcontroller). If there is no need to have more than one device on the serial bus, then NCS can be tied low.
SERIAL CLOCK AND UPDATE RATE
Figure 1 shows the device timing. The maximum serial rate is: fSCLKmax = 1 = 20MHz tWCH min + tWCL min
The digital update rate is limited to an 800ns period, or 1.25MHz frequency. However, the DAC settling time to 12 bits limits the update rate for large input step transitions.
SOFTWARE CONFIGURATION OPTIONS
The 16 bits of data can be transferred with the sequence shown in Table 2. D11-D0 contains the 12-bit data word. D15-D12 hold the programmable options. D15 A1 D14 A0 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
PWR SPD
New DAC value (12 bits)
Table 2 Register Map
DAC ADDRESSING
A particular DAC (A, B, C, D) within the device is selected by A1 and A0 within the input word. A1 0 0 1 1 A0 0 1 0 1 DAC ADDRESS DAC A DAC B DAC C DAC D
PROGRAMMABLE SETTLING TIME
Settling time is a software selectable 12s or 4s, typical to within 0.5LSB of final value. This is controlled by the value of D12 and associated DAC address. A ONE defines a settling time of 4s, a ZERO defines a settling time of 12s for that DAC.
PROGRAMMABLE POWER DOWN
The power down function is controlled by D13. A ZERO configures that DAC as active, a ONE configures that DAC into power down mode. When the power down function is released the device reverts to the DAC code set prior to power down.
WOLFSON MICROELECTRONICS LTD
Production Data Rev 1.0 June 1999 9
WM2614 PACKAGE DIMENSIONS
DT: 16 PIN TSSOP (5.0 x 4.4 x 1.0 mm)
Production Data Rev 1.0
DM013.A
b
16
e
9
E1
E
GAUGE PLANE 1 8
D 0.25 c A A2 A1 L
-C0.05 C
SEATING PLANE
Symbols A A1 A2 b c D e E E1 L REF: MIN ----0.05 0.80 0.19 0.09 4.90
4.30 0.45 0o
Dimensions (mm) NOM --------1.00 --------5.00 0.65 BSC 6.4 BSC 4.40 0.60 ----JEDEC.95, MO-153
MAX 1.20 0.15 1.05 0.30 0.20 5.10
4.50 0.75 8o
NOTES: A. ALL LINEAR DIMENSIONS ARE IN MILLIMETERS. B. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE. C. BODY DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSION, NOT TO EXCEED 0.25MM. D. MEETS JEDEC.95 MO-153, VARIATION = AB. REFER TO THIS SPECIFICATION FOR FURTHER DETAILS.
WOLFSON MICROELECTRONICS LTD
Production Data Rev 1.0 June 1999 10

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