Part Number: DAC8775
Tool/software:
Hi,
We use the DAC8775 in our PLC AO-module project.
Now we test the Settling Time of DAC8775 but the waveform is about more than 1ms, it is slow that it is only 15-30us in the datasheet, please kindly review our schematic diagram,
provide your comment if there are any error;
Our design: output 4channels, and 0-10V range.
the below waveform is the the rise time is 1ms, the fall time is 6ms, the SW configuration is default:
Zhang,
I think the issue is that there is a large capacitance used for CCOMP in the circuit. In the schematic, you can see it on each of the outputs circled here:
This capacitance is generally used for capacitive load stability. The problem is that with the stability, the bandwidth of the buffer amplifier is smaller, and the settling time becomes longer. This is noted in the pin list for the CCOMP_x.
If they want to experiment with it, they can completely remove the CCOMP capacitor and test it. I would also note that because the CCOMP node is an internal node, it is sensitive to transient voltages on the output of the device (coupled into the device through the capacitor). I generally recommend a capacitor 470pF or smaller for CCOMP.
Joseph Wu
