Hi Thorsten,
Thank you for the additional information, and for studying the documents prior to contacting us.
A few questions about the scope captures and the overall system:
1) What resistance value did you place in series with the low side gate driver?
2) When measuring the low side gate voltage, where is the signal and GND reference? It should be at the gate of the transistor and the ground reference should be at the top of the sense resistor. This will confirm that the voltage spike shown on the low side could be turning the low side FET on.
3) How hot are the FETs? Are they contributing to the bulk of the board heat?
4) How is the thermal pad connected to the board? Is it one large ground plane where the DRV8711 dissipate the heat generated inside the device?
5) How much current is the 5V regulator providing?
Please try the following and let us know if you see a difference:
1) Reduce the IDRIVEP to the minimum. This should minimize coupling from the high side FET turning on to the low side gate.
2) If using a series resistor closer to 120Ohms, please lower the sense resistor to 47Ohms
Thank you for the additional information, and for studying the documents prior to contacting us.
A few questions about the scope captures and the overall system:
1) What resistance value did you place in series with the low side gate driver?
2) When measuring the low side gate voltage, where is the signal and GND reference? It should be at the gate of the transistor and the ground reference should be at the top of the sense resistor. This will confirm that the voltage spike shown on the low side could be turning the low side FET on.
3) How hot are the FETs? Are they contributing to the bulk of the board heat?
4) How is the thermal pad connected to the board? Is it one large ground plane where the DRV8711 dissipate the heat generated inside the device?
5) How much current is the 5V regulator providing?
Please try the following and let us know if you see a difference:
1) Reduce the IDRIVEP to the minimum. This should minimize coupling from the high side FET turning on to the low side gate.
2) If using a series resistor closer to 120Ohms, please lower the sense resistor to 47Ohms