TPS731: The out voltage of TPS73115M is wrong

Hi, 

There must be some leakage pushing up the voltage of the TPS731. The feedback network of the TPS731 has a ~80K pull-down from VOUT to GND. The LDO can only source current and any sinking would be due to the feedback path. Do you get the same results if you increase the value of R380? Another idea might be to put a fixed load on the LDO to prevent any leakage in the system from pushing the voltage up.

I hope this helps.

Hi

   I calculated that the wrong out voltage of LDO is actually due to a ~80K pull-down resistor . I got a correct value when I put a 1kΩ resistor on the LDO. But I'm not sure Is there a risk?  If I change TPS731 to a voltage reference, will it work? 

  Thank you.

Hi, 

Adding a pull-down at the output poses no risk to the LDO. Any LDO can work as a reference as long as any leakage current pulling up the output is swamped out by the load current. This is why adding the 1K resistor worked.

I hoped this helps.