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Table of Contents
AD5686R/AD5685R/AD5684R Quick Start Guide
Quad, 16-/14-/12-Bit, Voltage Output DACs with a 2 ppm/ºC Reference, SPI Interface
Figure 1. Functional Block Diagram
Features
- High relative accuracy (INL): ±2 LSB maximum (16-bit AD5686R)
- Low drift 2.5 V on-chip reference: 2 ppm/°C typical temperature coefficient
- Tiny 3 mm × 3 mm 16-lead LFCSP or 16-lead TSSOP package
- Total unadjusted error (TUE): 0.1 % of FSR maximum
- Offset error: 1.5 mV maximum
- Gain error: 0.1% of FSR maximum
- High drive capability: 20 mA, 0.5 V from supply rails
- User selectable gain of 1 or 2 (GAIN pin)
- Reset to zero scale or midscale (RSTSEL pin)
- 1.8 V logic compatibility
- 50 MHz SPI interface
- 2.7 V to 5.5 V power supply
- −40°C to +105°C temperature range
Pin Configurations
Figure 2. 16-Lead LFCSP
Figure 3. 16-Lead TSSOP
Table 1. Function Descriptions for Quick Start
| Mnemonic | Description |
|---|---|
| VOUTA | Analog output voltage from DAC A. |
| VOUTB | Analog output voltage from DAC B. |
| VOUTC | Analog output voltage from DAC C. |
| VOUTD | Analog output voltage from DAC D. |
| Connect to serial interface. | |
| SCLK | Connect to serial interface. |
| SDIN | Connect to serial interface. |
| SDO | No connect. |
| VREF | No connect. |
| VDD | Connect to 5 V supply. Decouple with 10 μF and 0.1 μF capacitors. |
| GND | Connect to ground. |
| Tie low. | |
| RSTSEL | Tie to GND to power up to zero scale. |
| GAIN | Tie to GND. DAC outputs have a span from 0 V to VREF. |
| Tie high. | |
| VLOGIC | Connect to serial interface supply voltage. |
Shift Register Contents
Figure 4. Shift Register Contents (AD5686R)
Table 2. Command Definitions
| Command | ||||
|---|---|---|---|---|
| C3 | C2 | C1 | C0 | Description |
| 0 | 0 | 0 | 0 | No operation |
| 0 | 0 | 0 | 1 | Write to Input Register n (Dependent on LDAC) |
| 0 | 0 | 1 | 0 | Update DAC Register n with contents of Input Register n |
| 0 | 0 | 1 | 1 | Write to and update DAC Channel n |
| 0 | 1 | 0 | 0 | Power down/power up DAC |
| 0 | 1 | 0 | 1 | Hardware |
| 0 | 1 | 1 | 0 | Software reset (power-on reset) |
| 0 | 1 | 1 | 1 | Internal reference setup register |
| 1 | 0 | 0 | 0 | Set up DCEN register (daisy-chain enable) |
| 1 | 0 | 0 | 1 | Set up readback register (readback enable) |
| 1 | 0 | 1 | 0 | Reserved |
| … | … | … | … | Reserved |
| 1 | 1 | 1 | 1 | Reserved |
Transfer Function
where:
D is the decimal equivalent.
N is the number of bits.
Simple Write: Example 1
To update Channel A, write the following over the serial interface: 0001 XXX1 1000000000000000
(four command bits, four address bits, 16 data bits for the AD5686R).
This updates Channel A to midscale. GAIN = 1, VOUTA = 1.25 V.
This updates Channel A to midscale. GAIN = 1, VOUTA = 1.25 V.
Figure 5. Simple Write—Update Channel A)
Simple Write: Example 2
To update Channel B, write the following over the
serial interface: 0001 XX1X 1000000000000000.
This updates Channel B to midscale. GAIN = 1, VOUTB = 1.25 V.
This updates Channel B to midscale. GAIN = 1, VOUTB = 1.25 V.
Figure 6. Simple Write—Update Channel B
Simple Write: Example 3
To update both Channel A and Channel B, write the following over the serial interface:
0001 XX11 1111111111111111. This updates both channels to full scale. GAIN = 1, VOUTB = 2.5 V, VOUTA = 2.5 V.
Figure 7. Simple Write—Update Channel A and Channel B
/srv/wiki.analog.com/data/pages/resources/quick-start/ad5686r.txt · Last modified: 03 Jan 2013 20:42 by 127.0.0.1