AMC7836_15 Datasheet, PDF (40/87 Pages) Texas Instruments – AMC7836 High-Density, 12-Bit Analog Monitor and Control Solution With Multichannel ADC, Bipolar DACs, Temperature Sensor, and GPIO Ports

AMC7836
SLAS986B – NOVEMBER 2014 – REVISED FEBRUARY 2015
www.ti.com
7.4.2 All-Negative DAC Range Mode
In the AMC7836 all-negative DAC range mode, each of the four DAC groups is set to a negative voltage output
range (–5 to 0 V or –10 to 0 V).
Although the maximum DAC output does not exceed 0 V, the common AV_CC voltage (AV_CC = AV_{CC_AB} =
AV_{CC_CD}) must still satisfy a minimum voltage of 4.5 V to comply with the device operating conditions. In this
case a recommended approach is to tie the AV_CC, AV_DD, and DV_DD supply pins to a common potential.
The minimum DAC output for each group cannot be lower than the voltage on the corresponding AV_SS pins
(AV_EE, AV_SSB, AV_SSC, and AV_SSD). The AV_SS pins are not required to be tied to the same potential and typically
the negative voltage at each AV_SS pin is dictated by the desired operating DAC negative output range. One
exception is the AV_EE pin which must be the lowest potential in the device. The thermal pad should be either tied
to the same potential as the AV_EE pin or left disconnected. Table 6 lists the typical configurations for this mode.
PIN
AV_DD
DV_DD
IOV_DD
AV_{CC_AB}, AV_{CC_CD}
AV_EE
AV_SSB, AV_SSC, AV_SSD
Thermal Pad
Table 6. All-Negative DAC Range Mode Typical Configuration
NOTES
TYPICAL CONNECTION
5V
DV_DD must be equal to AV_DD.
IOV_DD must be equal to or less than DV_DD.
The AV_{CC_AB} and AV_{CC_CD} pins must be tied
to the same potential (AV_CC).
AV_EE must be the lowest potential in the
device.
AV_EE must be less than or equal to the
minimum possible output voltage for DAC
group A.
5V
1.8 V to 5 V
5V
AV_EE ≤ –5 V
AV_EE ≤ –10 V
AV_SSn must be less than or equal to the
minimum possible output voltage for DAC
group n (n = B, C, D).
AV_EE ≤ AV_SSn ≤ –5 V
AV_EE ≤ AV_SSn ≤ –10 V
AV_EE or,
Floating
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. In the all-negative DAC range mode all AV_SS pins should be connected to a
voltage lower than AV_SSTH. If this condition is satisfied, all four DAC groups will initialize by default to the –10- to
0-V range. Because the negative clamp voltage is only dependent on the voltage in the AV_SS pin, the default
–10- to 0-V output range presents no risk even when the AV_SS voltage is greater than –10 V. In this case the
DAC group output should be modified to the –5 to 0 V range after initialization by setting the corresponding DAC
range register (address 0x1E to 0x1F) to 101b.
40
Submit Documentation Feedback
Product Folder Links: AMC7836
Copyright © 2014–2015, Texas Instruments Incorporated