I am designing a BMS circuit for a 48V battery pack.

For the switching mechanism, I thought of using a MOSFET as a switch. I thought I could use an N-channel enhancement MOSFET, but I am having trouble figuring out the MOSFET calculations.

The input to the drain would be 48V. When the MOSFET is on, the source would also be 48V. If I choose a 2V VGs threshold MOSFET, I would need to apply minimum 50V to the gate, right?

I want to control the MOSFET using a microcontroller GPIO pin (3.3V or 5V,) so I need some help here.

  • 1
    \$\begingroup\$ Since the gate of the MOSFET has to be VGS volts higher than the source, a special IC is needed to translate the logic level at the CTL lead into the much higher gate voltage. see electronics.stackexchange.com/questions/188745/… . , only you have to select the adequate IC for yourself, the high-side driver is a generic name. Product recommendations are frowned here. \$\endgroup\$
    – V.V.T
    Commented Nov 4, 2022 at 6:46
  • \$\begingroup\$ The threshold voltage is only specified at a fairly low source current - you need volts on the gate to switch the rated current. Yes you are correct about the gate voltage needing to be above 50V. Is there a specific reason that you didn’t choose a p-Chan device and avoid the problem? \$\endgroup\$
    – Kartman
    Commented Nov 4, 2022 at 13:16
  • 1
    \$\begingroup\$ BMS circuits often switch the negative path to avoid this problem. \$\endgroup\$
    – Jens
    Commented Nov 4, 2022 at 13:36
  • \$\begingroup\$ @Kartman Hello,I am kind of new the switching mechanism using mosfets.Could you kindly expand on how i can use a P channel device to avoid the problem \$\endgroup\$ Commented Nov 7, 2022 at 6:31
  • \$\begingroup\$ @Jens So if i use the N channel mosfet for low side switching source would be connected to ground and we can control the turning on and off using a MCU GPIO pin right? Also I read somewhere that low side switching is not recommended for power path switching \$\endgroup\$ Commented Nov 7, 2022 at 6:32


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