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AD5686R/AD5685R/AD5684R快速發(fā)射指南

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資料介紹

This version (25 Apr 2012 13:54) was approved by Padraic O Reilly.The Previously approved version (16 Apr 2012 11:58) is available.

AD5686R/AD5685R/AD5684R Quick Start Guide

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
V_OUTA	Analog output voltage from DAC A.
V_OUTB	Analog output voltage from DAC B.
V_OUTC	Analog output voltage from DAC C.
V_OUTD	Analog output voltage from DAC D.
	Connect to serial interface.
SCLK	Connect to serial interface.
SDIN	Connect to serial interface.
SDO	No connect.
V_REF	No connect.
V_DD	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 V_REF.
	Tie high.
V_LOGIC	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 mask register
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

$V_OUT = V_REF * Gain delim{[}{D/2^N}{]}$
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, V_OUTA = 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, V_OUTB = 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, V_OUTB = 2.5 V, V_OUTA = 2.5 V.