MOSFET Anti-Reverse Connection: N-Channel or P-Channel?

MOSFET Anti-Reverse Connection: N-Channel or P-Channel?

In circuit design, both diodes andFETs can be used for anti-reverse connection. However, diodes have the issues of voltage drop and power consumption, making them only suitable for low-current low-power scenarios. Therefore, in most cases, we will use a MOSFET anti-reverse connection circuit.

The question then arises: should we choose an-channel MOSFET or a P-channel MOSFET?

Typically, we give priority to N-channel MOSFETs. This is because N-channel MOSs usually have a lower on-resistance than P-channel MOSFETs.

N-Channel MOSFET Anti-Reverse Connection Circuit

The Nchannel MOSFET is connected to the negative pole of the power supply, and the MOSFET conducts when a high voltage is applied to the gate. Resistor R1 a voltage bias for the MOSFET, using the MOSFET's switch characteristics to control the circuit's conduction and disconnection, thereby preventing damage to the load to reverse power connection.

When the power supply is connected correctly, R1 provides a VGS voltage for the MOSFET, causing it to conduct in saturation; the power supply is connected in reverse, the MOSFET cannot conduct, playing the role of anti-reverse connection. This effectively solves the problems of excessive voltage drop and consumption in the traditional diode power supply anti-reverse connection scheme.

Additionally, D1 in the circuit is a zener diode, which prevents the-source voltage from being too high, avoiding the MOSFET from being punctured.

P-Channel MOSFET Anti-Reverse Connection Circuit

The Pchannel MOSFET anti-reverse connection circuit can also achieve the anti-reverse connection function. The P-channel MOSFET is connected to the positive pole of the power, and the MOSFET conducts when a low voltage is applied to the gate. However, since N-channel MOSFETs not only have a lower on-res than P-channel MOSFETs but are also relatively cheaper, N-channel MOSFETs are often the better choice in practical applications