DAC8812 Datasheet, PDF (13/29 Pages) Texas Instruments – Dual, Serial Input 16-Bit Multiplying Digital-to-Analog Converter

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8 Detailed Description
DAC8812
SBAS349D – AUGUST 2005 – REVISED JANUARY 2016
8.1 Overview
The DAC8812 contains two 16-bit, current-output, digital-to-analog converters (DACs). Each DAC has its own
independent multiplying reference input. The DAC8812 uses a 3-wire, SPI-compatible serial data interface, with a
configurable asynchronous RS pin for half-scale (MSB = 1) or zero-scale (MSB = 0) preset. In addition, an LDAC
strobe enables two channel simultaneous updates for hardware synchronized output voltage changes.
8.2 Functional Block Diagram
D0
D1
D2
D3
D4
D5
16
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
SDI
A0
A1
CLK
CS
EN
Input
Register _R
Input
Register R
DAC ^A
B
Decode
Power-On
Reset
V_REFA B
DAC A
Register _R
DAC A
DAC B
Register R
DAC B
R_FBA
I_OUTA
A_GNDA
R_FBB
I_OUTB
A_GNDB
DGND
RS MSB
LDAC
8.3 Feature Description
8.3.1 Digital-to-Analog Converters
The DAC8812 contains two current-steering R-2R ladder DACs. Figure 30 shows a typical equivalent DAC. Each
DAC contains a matching feedback resistor for use with an external I-to-V converter amplifier. The R_FBX pin is
connected to the output of the external amplifier. The I_OUTX pin is connected to the inverting input of the external
amplifier. The A_GNDX pin should be Kelvin-connected to the load point in the circuit requiring the full 16-bit
accuracy.
V_REFX
2R
R
2R
R
2R
R
R
5 kW
V_DD
R_FBX
S2
S1
I_OUTX
A_GNDX
DGND
Digital interface connections omitted for clarity.
Switches S1 and S2 are closed, V_DD must be powered.
Figure 30. Typical Equivalent DAC Channel
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