DAC8760: Only Use Current Output

Livia,

If they remove R121 and the OPA2277, then the the output amplifier of the DAC will lose feedback. This may cause the device to draw extra current. Note that the VOUT output looks like this:

The connection from VOUT to VSENSE is needed to make sure the op-amp is in a proper feedback mode. Without the feedback, the output stage of the op amp will still try to drive the output to the proper output. For this device, the IOUT can be shut down, and the VOUT operated alone. However, the IOUT cannot be operated alone without the VOUT. 

I would note that if they only want to use IOUT, then the DAC8750 is a good substitute. If they do continue to use the external op amp and R121, I would also remove C145, which is the capacitance for the CCOMP pin to VOUT. The output isn't driving a high capacitance, so the CCOMP capacitance isn't required.

Joseph Wu

Livia,

Actually, I need to correct my last comments. Leaving the VOUT should be ok even without the connection to +VSENSE. The RANGE bits do allow for the IOUT to be operated without the VOUT. By using the device this way, the VOUT amplifier should be disabled.

Joseph Wu