Our BLDC application is operating with the DRV8350 FHRTAR. Our oprating range for VM is between 19V to 42V.
we measure the current over shuint resistors and via an INA826 (see current measurement circuit). THe INA 826 delivers the current signal LA_MTR_CURR_SENS.
WE have identified that the chargepump generate ground bounce which let jump the ground this destroy our current meassurement. The ground bounce moves the reference point some 100 mV up or down.
THE current meassurement performed during a churge-pump event has a fault caused by the reference point movement ( caused by ground bounce)..
We have identified when VM is set to 12V, the ground bounce ist not happen. WHen VM is increased the ground bounce is acting..
Exist a solution on Charge pump side of the DRV8350 which is able to prevent the ground bounce in the supply range from 19V to 42V ? CUrrently it is not possible to spent an own 12V DC/DC-supply for the DRV8350.
Current meassurtement circuit
DRV8350 circuit
THe following figure shows the example measuremnt of the ground bounce.
Signal1:Meassure the PCB-GND at a Starpoint on the PCB. (Reference is the GND of the external Powersupply.)
Signal2: Is meassured at DRV8350 PIN 1 (CPH).
.Signal 3: Output signal from the INA826 signal LA_MTR_CURR_SENS.
