Other Parts Discussed in Thread: PCM1796
We're doing development on an audio product and decided to go with a current output DAC so we could scale for the voltages we need. The PCM1796 seemed like a good fit as it has an onboard volume control, I2C interface capability, etc. To test the device, the application circuit (figure 35 in datasheet) was constructed, with Rf = 1K8 and Cf = 3n3, and slightly different values for the capacitors attached to the Vcom and Vcc1 pins. The problem is that when measured, there's ~ -6.2V DC at the output of both I/V converters (there is a 0.34mV DC difference at the op-amp inputs pins). After the differential-to-single-ended conversion, gain and buffering this results in ~0.8V DC at the output. This is far higher than acceptable yet after several different attempts to remove it, the problem remains. Even when the DAC is held in the reset state the -6.2V DC remains at the outputs of I/V stage. Has anyone else had this problem, or is it a known issue? What possible causes could there be for this issue? Any suggestions or help would be welcome and appreciated.
