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DRV8320: Reverse supply protection on VM and VDRAIN

Intellectual 320 points

Replies: 11

Views: 118

Part Number: DRV8320

Dear support,

I am designing a system level reverse battery (RB) protection scheme for several DRV ICs, as part of a surge stopper design. The potential issue I have is that the disconnect time of the RB circuit during a fault condition is most likely not fast enough to prevent large reverse currents passing through the DRVs and causing EOS.  My intention, therefore, is to add a diode from VDRAIN to VM, and a 100 Ohm resistor into VDRAIN to limit the reverse clamp current to <20mA (assuming the VDS monitor accuracy isn't compromised). There is a FET body diode from ground to VM as part of the surge stopper regulator so the DRV supply will be transiently clamped to <-2V until the RB pass FET is switched off. I'm aware that the VM and VDRAIN voltages need to be close to maintain the high-side VGS drive. The VCP cap will be referenced to the VM pin.

I'd be obliged if you could let me know if the above is acceptable and if there are any other DRV paths I need to protect.

Can you also provide me with the input impedance spec for the VDRAIN pin?  

Kind regards