Why MP2760 EVK using bidirectional power switch for input OVP

Battery Management
#1

In MEZS7-1S-4SPDCharger EVK, it is using two N-MOSFET with common source back to back for the input overvoltage protection.
Understand that this setup is to achieve bidirectional power switch.
However, since this is for the Vin pin protection, voltage only flow from VBUS to VIN pin.
So what is the reason to setup for bidirectional?
Is it to prevent the voltage flow from the capacitors (C16, C17, C19, C20, C21) back to the VBUS?

Thank you.

#2

Hi Jackson,
Thank you for utilizing MPS Tecnical Forum,

That is a great question, the orientation of switches are for input disconnect control.

You may read more in MP2760 datasheet for operation of ACGATE pin/driver on page 26/27.

Kind Regards,
Nouman

#3

Hi Nouman,

I understand this is for input disconnect control for the input overvoltage protection.
However, in the datasheet, this can be done using one MOSFET instead of two.
I believe the purpose to setup two N-MOSFET with common source back to back is for bidirectional power control.
Hence, my question is why do we need bidirectional in this case since this is to control the voltage into Vin pin switch is only mean for input (one direction) only.

#4

Reverse polarity protection??

#5

Jackson and John,
I will get back to you soon on this.

Regards,
Nouman

#6

Jackson and John,
Following up on this,

We can just one MOSFET, it’s not necessary to use back-back FET in the application.
The AFET2 is used as VBUS FET in sourcing mode.

Regards,
Nouman