Hi Jon,
It could be possible that both your High-Side and Low-Side MOSFETs are latched-on from charge deposited on the gate during your testing and assembly. The DRV8308's gate drive is not active while the driver is off, so if you haven't powered on the driver yet the MOSFET gate will still retain any charge originally deposited on it.
You could try powering on the driver with the ENABLE pin inactive, this will force all the gate-outputs low. If you're worried about damaging your MOSFETs you could perform this test with your power supply current limited at < 100 mA, the DRV8308 will only draw 120 uA in standby mode and should sink any deposited charge from the MOSFET gates.
It could be possible that both your High-Side and Low-Side MOSFETs are latched-on from charge deposited on the gate during your testing and assembly. The DRV8308's gate drive is not active while the driver is off, so if you haven't powered on the driver yet the MOSFET gate will still retain any charge originally deposited on it.
You could try powering on the driver with the ENABLE pin inactive, this will force all the gate-outputs low. If you're worried about damaging your MOSFETs you could perform this test with your power supply current limited at < 100 mA, the DRV8308 will only draw 120 uA in standby mode and should sink any deposited charge from the MOSFET gates.