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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.

JRE
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Just Living
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    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 https://electronics.stackexchange.com/questions/188745/high-side-driver-and-low-side-driver . , only you have to select the adequate IC for yourself, the high-side driver is a generic name. Product recommendations are frowned here. – V.V.T Nov 04 '22 at 06:46
  • 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? – Kartman Nov 04 '22 at 13:16
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    BMS circuits often switch the negative path to avoid this problem. – Jens Nov 04 '22 at 13:36
  • @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 – Just Living Nov 07 '22 at 06:31
  • @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 – Just Living Nov 07 '22 at 06:32
  • @JustLiving - you have basically two choices, high side or low side switching. Since you’re dealing with a battery, low side switching is a viable solution as the battery itself is electrically floating and that your electronics don’t have other paths to the real world. Otherwise use a p-Chan mosfet. Battery + to source, drain to load +. You’ll need a zener diode across source and gate to limit the voltage to around 20V. It’s a common problem so there’s plenty of examples to refer to. – Kartman Nov 07 '22 at 11:55
  • @Kartman Thanks for the information. Could kindly help me out by providing a link or reference on how to implement the P channel mosfet as high side switch,im not finding it exactly – Just Living Nov 08 '22 at 10:12

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