AMC7891 Datasheet, PDF (30/41 Pages) Texas Instruments – Analog Monitor and Control Circuit with 10-Bit, Multi-Channel ADC and Four DACs, Temperature Sensor, and 12 GPIOs

AMC7891
SBAS518A – AUGUST 2011 – REVISED DECEMBER 2011
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DAC OPERATION
The AMC7891 contains 4 independent DACs that provide analog control with 10 bits of resolution using an
internal reference. Each DAC core consists of a 10-bit string DAC and an output voltage buffer.
The DAC latch stores the code that determines the output voltage from the DAC string. The code is transferred
from the DACn_data registers to the DACn data latches when the internal DAC load signal is generated.
dacn_data
Register Value
DACn
Data Latch
10-bit
Resistor String
VOUT
DACOUTn
DAC Load ⁽¹⁾
(1) Internal DAC load is generated by writing '1' to the dac_load bit in synchronous mode. In
asynchronous mode, the DAC latch is transparent.
Figure 33. DAC Block Diagram
The resistor string structure is shown in Figure 34. It 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 has inherent monotonicity, voltage output, and low glitch. It is also linear because all the
resistors are of equal value.
R
R
R
To Output
Amplifier
R
R
30
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Figure 34. Resistor String
Product Folder Link(s): AMC7891
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