Other Parts Discussed in Thread: TPS25910
Hello TI
I was wondering if there could be any anomalies on the supply voltage side (Vcc) that might break the DRV11873's sensorless commutation logic where it could cause a cross conduction event(s) that could result in damage to the controller's internal MOSFETs?
A 3rd party vendor has implemented the DRV11873 motor controller on a fan assembly that we use. Upon pulling one of the failed units apart, it was discovered that all three high switches are failed dead short with the low side switches intact. We have a load switch (TPS25910) that controls the Vcc to the fan assembly. I know that the DRV11873 has logic internally to clamp the Vcc rail in the event of a braking event but I assume the core logic imposes the AVS function only if a braking event is commanded through the PWM interface. If the supply voltage is abruptly shut off by the load switch, I assume the AVS does not work. If a load switch generated inductive spike on the Vcc rail occurs, can it muck with the zero cross detect logic to create a shoot through event(s). This is just a theory...any additional insight you could provide would be of great help.
best regards,
Craig MacKinnon
Product Developer, Electrical
Christie Digital Systems
