Help with NMOS reverse connection protection

我是cl

Help with NMOS reverse connection protection [Copy link]

Hello everyone, is there any expert who uses NMOS for power supply + extremely anti-reverse connection? The gate pin uses a charge pump to provide control voltage. I think it should be feasible in theory. However, in actual use, NMOS will get abnormally hot, reaching 170℃ in a few minutes at room temperature. Can NMOS be used for power supply + extremely anti-reverse connection? Please give me some advice. Thank you.

qwqwqw2088

The selected MOS tube should have enough power, use a larger heat sink, apply silicone grease, or replace it with a MOS with a small internal resistance and add an appropriate heat sink. The reason why it gets hot is not because of the use of NMOS. For anti-reverse, NMOS is placed at the ground end and controlled by the positive electrode. For PMOS, it is placed at the positive electrode and controlled by the ground end. They are all used in the same way. It may be selected based on the circuit form or cost issues

timewh

NMOS as power supply + extremely anti-reverse connection requires a boost circuit that is greater than the power input voltage by one MOS turn-on voltage, otherwise only PMOS can be used.

我是cl

timewh posted on 2018-1-28 11:46 NMOS as power supply + extremely anti-reverse connection requires a boost circuit with a MOS turn-on voltage greater than the power input voltage, otherwise it can only be PMOS

Yes, there is a charge pump boost circuit, but NMOS heats up abnormally. I would like to ask if there is an actual product that uses NMOS as power supply + extremely anti-reverse connection. The circuit diagram is attached. KL87 is a 12V input power supply, and VCP is the charge pump output, which is generally 22V.

仙猫

Is this too complicated? Of course, N-MOS tubes can be used, but they should be ground switches, without charge pumps.

一株草

have a look