DRV8307 DRV8308 OCP of mosfet

Hi Jiang,

jiang xiu said:

1.Does Drv8307/8 measure the voltage across  VM and pin-U to determine whether the high side MOSFET-U is over current or not?

If it is in this way, it means that the pin VM of drv8307/8 and the motor power VM must be tired together?

Yes, the voltage from VM to the phase output is measured to determine if an OCP event has occurred. It is recommended to connect the VM of the DRV8307/8 to the VM of the motor for this reason. Another reason to make this connection is to ensure the Vgs of the high side FET is optimal.

jiang xiu said:

2. Does Drv8307/8 use pin-ISEN and pin-U to determine whether the low side MOSFET-U is over current or not?

Yes, for the low side the voltage from the phase output to ISENSE is measured.

jiang xiu said:

3. Can l add a RC filter on pin-ISEN?

Yes, you can. If you add a filter please note you are increasing the response time of the circuit.

jiang xiu said:

4.can l add a OPAMP to amplify the Rsense voltage and then connect to pin-ISEN?

We will have to investigate this. If the device does not monitor the negative current through the sense resistor, this may be possible.

Another two question,
1.when low side gate drive turn off the low side MOS, there is a large current from the low side MOS-gate. Does the large current flow to GND directly or flow to ISEN and then then RC filter and then finally go through the Rsense to GND?
2.Recently I used drv8307 to drive a large size power mosfet (Infineon IPB011N04L 40V 1.1mOhm 180A ,gate charge max 180nC)
,it failed. It failed at the low driven current ability -30mA. Because my PCB is already completed (we have received the sample from factory). Now I decide to use drv8308(130mA) to drive the Infineon IPB011N04L(gate charge max 180nC) .will it be successful to drive the large capacity power mosfet if I ignore the switching loss( due to the slow ramp-up/down voltage)?

Hi Jiang,

Wilson has answered your two questions HERE