Diotec Semiconductor AG

Diode: Simple and Robust

Placing a diode in the power path is the simplest solution and requires no additional driver circuitry.

Its main drawback is the forward voltage drop, which results in continuous power dissipation during normal operation. For the devices in Diotec’s portfolio, the forward voltage is less than 0.55 V at 10 A, making this approach reliable but less efficient in higher-current applications.

P-Channel MOSFET: Lower Losses

A P-channel MOSFET significantly reduces the voltage drop to less than 0.12 V at 10 A, while requiring only a simple gate-drive circuit.

Because the MOSFET is connected on the high side, the system ground return path remains unaffected. The main drawback is the limited range of suitable P-channel MOSFETs.

N-Channel MOSFET: Wider Device Selection

Using an N-channel MOSFET in the ground return path offers the same low conduction losses while benefiting from Diotec’s wide selection of N-channel MOSFETs.

The trade-off is that the MOSFET's on-resistance causes a voltage drop in the ground return path, shifting the system ground reference. This ground offset can affect applications with sensitive analog or communication circuits.

Matching the Topology to the Application

Each topology addresses reverse polarity protection differently. A diode offers simplicity, a P-channel MOSFET minimizes conduction losses while preserving the systems ground reference, and an N-channel MOSFET provides greater device availability at the expense of a shifted ground reference.

The best solution depends on the applications specific requirements and the performance, efficiency and design trade-offs that can be accepted.

Find out more about Diotec’s MOSFET portfolio here: https://diotec.com/en/all-products.html#all