Battery and external power switching circuit, MOS on and off conditions

QWE4562009

Battery and external power switching circuit, MOS on and off conditions [Copy link]

Battery and external power switching circuit, MOS on and off conditions

1. Battery and external power switching circuit, is there a simpler circuit that can realize the function of automatic power switching?

2. The conditions for MOS to turn on and off are: NMOS turns on when VGS is greater than or equal to 0 and greater than or equal to Vth, and PMOS turns off when VGS is greater than or equal to 0 and greater than or equal to Vth?

lehuijie

If you want to be simple, just find a battery protection chip. One chip and one MOS can solve the problem.

qwqwqw2088

Just a reminder, the MOS tube AO3401A in the picture of the original poster is a P tube

When UGS<0, the PMOS tube is turned on. The voltage of the gate G of the P tube must be less than the source voltage.

QWE4562009

qwqwqw2088 posted on 2021-7-2 14:53 Just a reminder, the MOS tube AO3401A in the original poster's picture is a P tube. When UGS<0, the PMOS tube is turned on. The voltage of the gate G of the P tube must be less than the source...

What about NMOS? Many people say that PMOS can be turned off as long as the voltage at point G is equal to S.