14 POWER SEMICONDUCTORS www.littelfuse.com Issue 2 2024 Power Electronics Europe www.power-mag.com Comparing N-Channel and P-Channel MOSFETs: Which is best for your application? This article compares the n-channel and p-channel power MOSFETs, introduces the complete Littelfuse p-channel power MOSFETs portfolio, and explores target applications. Introduction Driving a high-side (HS) p-channel MOSFET without an additional voltage source or a charge pump is uncomplicated, resulting in significantly simplified designs, space savings, reduced part count, and improved cost efficiency. While n-channel power MOSFETs require a positive gate-source voltage to activate, p-channel MOSFETs need a negative gate-source voltage. Using a cross-sectional view, Figure 1 illustrates the differences between n-channel and pchannel MOSFETs. Their reverse doping profiles are the key distinction: p-channel MOSFETs rely on holes as the majority charge carriers, generating hole current, while n-channel devices utilize electrons, creating electron current. Due to electrons’ superior mobility, approximately two to three times that of holes, moving holes in a p-channel device is more challenging than electrons in an n-channel device. This approach leads to higher area-specific onstate resistance in p-channel MOSFETs compared to n-channel MOSFETs. Consequently, achieving equivalent onstate resistance (RDS(on)) performance is impractical for p-channel MOSFETs of the same chip size as n-channel MOSFETs. In order to achieve a similar on-state resistance RDS(on) as n-channel MOSFETs, pchannel MOSFETs require a two to threetimes larger die size. As a result, in more high-current applications, where low conduction losses are critical, the large die p-channel MOSFETs with very low RDS(on) are not the optimal choice. While the p-channel device’s larger chip size Figure 1. Cross sections comparison of n- and p-channel power MOSFETs
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