AMC7836 Datasheet, PDF (26/88 Pages) Texas Instruments – AMC7836 High-Density, 12-Bit Analog Monitor and Control Solution With Multichannel ADC, Bipolar DACs, Temperature Sensor, and GPIO Ports

AMC7836
SLAS986C – NOVEMBER 2014 – REVISED APRIL 2016
Feature Description (continued)
Serial Interface DAC Data Register
WRITE
READ
1
0
READBACK bit
AVCC
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DAC
Buffer
Register
DAC
Active
Register
0
Resistor String
UPDATE
command
0x000
1
Clear State
(register or alarm-
generated)
DAC
Output Range
Configuration
VO
DAC output
Clamp
Offset
Clamp State
(reset event or
DAC power down)
Figure 49. DAC Block Diagram
AVSS
5_{» 6 × AVSS}
7.3.1.1.1 Auto-Range Detection
After power-on or a reset event the output range for each DAC group is set automatically by the voltage present
in the corresponding AV_SS pin (AV_EE, AV_SSB, AV_SSC or AV_SSD). When the AV_SS voltage of a DAC group is lower
than the threshold value, AV_SSTH, the output for that DAC group is automatically configured to the –10 to 0 V
range. Conversely, if the DAC group AV_SS voltage is higher than AV_SSTH, the DAC-group output is automatically
set to the 0 to 5 V range. The auto-range detector results for each DAC group are stored in the general status
register (address 0x72).
In addition to a power-on or reset event, the auto-range detector is also enabled by a register write to the DAC
power down registers (address 0xB2 through 0xB3) or the device configuration register (address 0x02).
Although the initial output-range setting is determined by the auto-range detector, the output range for each
DAC-group can be afterwards configured to any of the available output ranges (–10 to 0 V, –5 to 0 V, 0 to 5 V, or
0 to 10 V) through the DAC range registers (address 0x1E through 0x1F).
NOTE
The power-on-reset and clamp-voltage value of each DAC group is set by the
corresponding AV_SS pin and is independent of the DAC output range. In some
applications, matching the clamp-voltage setting to the operating voltage range is
imperative. For those applications, the recommended connections for the AV_SS pin are:
AGND for the positive output ranges, in which case the clamp voltage is 0 V; a negative
supply voltage with a lower value than the minimum DAC output voltage (–5 V or –10 V)
for the selected negative output range, in which case the unloaded clamp voltage is
determined by the value of the negative supply voltage (see Figure 50).
Although not a recommended operating condition, the device allows a DAC group to
operate in a positive output range even if its clamp voltage is negative (AV_SS connected to
a negative supply voltage).
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