DRV8305: Current sensing with Gain = 4

Part Number:DRV8305

Hi team,

as my customer got no answer on the original post, I am reposting the old one. Please take care that we get an answer soon:

We had a problem while measuring the current over the RDS_on from the low-side mosfet. While the high time of the PWM, the current output is 200mV higher than in the low time.

The yellow graph is the OP output, red the measured current in the phase with the current sensor, green = OP_in+, blue = OP_in-

When we change the VREF divider from 4 to k = 2, the output signal is as expected. See following graph:

Do you have an idea what can cause this problem? Is it possible to set the VREF to 0? and does the DRV8323 also have this issue?

Thank you and kind regards,

Felix