DAC8830-EP_16 Datasheet, PDF (17/32 Pages) Texas Instruments – 16-Bit, Ultra-Low Power, Voltage-Output Digital-to-Analog Converters

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DAC8830-EP
DAC8831-EP
THEORY OF OPERATION
SGLS334C – AUGUST 2006 – REVISED APRIL 2007
General Description
The DAC8830 and DAC8831 are single, 16-bit, serial-input, voltage-output DACs. They operate from a single
supply ranging from 2.7 V to 5 V, and typically consume 5 μA. Data is written to these devices in a 16-bit word
format, via an SPI serial interface. To ensure a known power-up state, these parts were designed with a
power-on reset function. The DAC8830 and DAC8831 are reset to zero code. In unipolar mode, the DAC8830
and DAC8831 are reset to 0V, and in bipolar mode, the DAC8831 is reset to –V_REF. Kelvin sense connections
for the reference and analog ground are included on the DAC8831.
Digital-to-Analog Sections
The DAC architecture for both devices consists of two matched DAC sections and is segmented. A simplified
circuit diagram is shown in Figure 45. The four MSBs of the 16-bit data word are decoded to drive 15 switches,
E1 to E15. Each of these switches connects one of 15 matched resistors to either AGND or V_REF. The remaining
12 bits of the data word drive switches S0 to S11 of a 12-bit voltage mode R-2R ladder network.
R
R
V_OUT
2R
2R
2R
2R
2R
2R
2R
V_REF
S0
S1
S11
E1
E2
E15
12−Bit R−2R Ladder
Four MSBs Decoded into
15 Equal Segments
Figure 45. DAC Architecture
Output Range
The output of the DAC is
V_OUT = (V_REF × Code/65536)
Where:
Code = Decimal data word loaded to the DAC latch
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