Lithium Battery Voltage Protection Circuit

Post Reply
parkview
Guru Maker
Posts: 572
Joined: Tue Jun 24, 2014 8:25 pm
Location: Busselton
Contact:

Lithium Battery Voltage Protection Circuit

Post by parkview » Thu Sep 22, 2022 6:15 pm

This circuit uses the XC61CC3002MR which is a 3.0 volt voltage supervisor IC. This IC will output a HIGH 3.3V on the output if the IN voltage is 3.0V or above. When the IN voltage drops below 3.0V, it will output a LOW voltage. I am using this to keep Q5 MOSFET switched on, which in turn pulls Q6 gate to ground, which switches it on. R21 limits the current needed to switch Q5.

The Power Switch when switched off, will pull Q5 to ground, switching it off, even if the voltage supervisor is outputting a HIGH. When the switched is in the ON position, it places the battery voltage onto Q5 gate, which switches it on. If the voltage supervisor IC detects a battery voltage lower than 3.0V it then outputs a LOW, which will override the switched battery voltage as it is protected via R20, a 10K ohm resistor.

And this is what my test circuit looked like deadbug style on a 1.27mm pref board. Of course the MOSFETs can be any size you need, as long as you take into account the Vgs specs and how hard they will turn on over a 3V to 4.2V range:
Battery_Protection_Test-Circuit.png
Battery_Protection_Test-Circuit.png (537.22 KiB) Viewed 284 times
Attachments
Battery_Protection_Schematic.png
Battery_Protection_Schematic.png (17.35 KiB) Viewed 284 times

Post Reply