Dear TI and Experts,
We are testing the DRV8703 to evaluate if this should be used in a new product series. The system is operating, we do however see some gate signals we did not expect. On the two high side gates we see a varying gate voltage when PWM'ing with constant duty cycle (e..g. 80%) and we have traced this to the charge pump, which runs as describes in the datasheet except that the frequency of this is varying. The voltage pins are close part of the time and far part of the time. This means that part of the time it shoot very often and some milliseconds later it shoots at a lower frequency and then cycling back to the higher frequency. This causes that the charge pumped voltage is not constant. Question: Is it really the case that the frequency of the charge pump circuitry should vary all the time?
We do naturally have the 100bF on CPH and CPL located just underneath the pins. And a 1uF on VCP and 100R from VM to VDRAIN as specified.
What can cause this, is this part of the IC behavior? What can be done to mitigate this?
Thanks
Best, Christian
