AMC7812B_15 Datasheet, PDF (40/92 Pages) Texas Instruments – 12-Bit Analog Monitoring and Control Solution with Multichannel ADC, DACs, and Temperature Sensors

AMC7812B
SBAS625A – SEPTEMBER 2013 – REVISED SEPTEMBER 2013
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DAC OPERATION
The device contains 12 DACs that provide digital control with 12 bits of resolution using an internal or external
reference. The DAC core is a 12-bit string DAC and output buffer. The DAC drives the output buffer to provide an
output voltage. Refer to the DAC configuration register for details. Figure 91 shows a function block diagram of
the DAC architecture. The DAC latch stores the code that determines the output voltage from the DAC string.
The code is transferred from the DAC-n-data register to the DAC latch when the internal DAC-load signal is
generated.
DAC
Data
Register
DAC
Latch
12-Bit
Resistor
String
DAC Load⁽¹⁾
Gain Bits
Gain Logic
Gain
V_OUT
(1) Internal DAC load is generated by writing '1' to the ILDAC bit in synchronous mode. In asynchronous mode, the DAC
latch is transparent.
Figure 91. DAC Block Diagram
Resistor String
The resistor string structure is shown in Figure 92. The resistor string consists of a string of resistors, each of
value R. The code loaded to the DAC latch determines at which node on the string the voltage is tapped off to be
fed into the output amplifier. The voltage is tapped off by closing one of the switches connecting the string to the
amplifier. This architecture is inherently monotonic, voltage out, and low glitch. The resistor string architecture is
also linear because all the resistors are of equal value.
R
R
R
To Output
Amplifier
R
R
40
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Figure 92. Resistor String
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