www.littelfuse.com POWER SEMICONDUCTORS 15 www.power-mag.com Issue 2 2024 Power Electronics Europe offers improved thermal performance, it exhibits higher switching losses and larger intrinsic capacitances. When the system operates at a high switching frequency, this disadvantage significantly impacts overall efficiency, thermal management, and system cost. In low-frequency applications with significant conduction losses, a pchannel MOSFET should match the RDS(on) of an n-channel MOSFET, requiring a larger chip area. Conversely, in highfrequency applications prioritizing switching losses, a p-channel MOSFET should align with the total gate charges of an n-channel counterpart, often having a similar chip size, but a lower current rating. Therefore, making the right p-channel MOSFET selection demands careful consideration of the device RDS(on) and gate charge (Qg) specifications, as well as the thermal performance. P-Channel Power MOSFETs from Littelfuse The Littelfuse p-channel power MOSFETs have traditionally served in a limited range of applications. However, recent increases in demand for low-voltage (LV) applications have created a broader scope for p-channel power MOSFETs. The simplicity of Littelfuse p-channel solutions for HS applications makes them attractive for non-isolated point-ofload and LV inverters (< 120 V) solutions. Littelfuse offers a range of industrial qualified p-channel power MOSFETs with the highest voltage class rating, lowest RDS(on) and Qg, high avalanche energy rating, excellent switching performance, and superior safe operating area (SOA) with best-in-class performance in both standard industrial and unique isolated packages. Littelfuse p-channel power MOSFETs retain the essential features of comparable n-channel power MOSFETs, such as fast switching, efficient gatevoltage control, and excellent temperature stability. Figure 2 presents the p-channel power MOSFETs’ key highlights offered by Littelfuse, including: Standard P and PolarP™ planar devices have voltage ratings from -100 to -600 V and current ratings from -2 to -170 A. PolarP™ offers optimized cell structure with low area-specific on-state resistance and improved switching performance. Standard P benefits from a better SOA performance. Trench P utilizing a more dense trench gate cell structure offers very low RDS(on), low gate charge, fast body diode, and faster switching with device voltages ranging from -50 V to -200 V and currents from -10 A to -210 A. The latest addition to the portfolio, the IXTY2P50PA (-500 V, -2 A, 4.2 Ω), is the first AEC-Q101 automotive-grade pchannel power MOSFET available from Littelfuse. Littelfuse p-channel MOSFETs drive a broad range of automotive and industrial applications like: battery protection, reverse polarity protection, HS load switches, DC-DC converters, onboard chargers, and LV inverters. P-Channel MOSFETs in Half-Bridge Applications Figure 3 illustrates the contrast between circuits using complementary MOSFETs and those using n-channel MOSFETs. Nchannel MOSFETs are commonly found in the power stage in half-bridge (HB) applications. However, n-channel HS switches necessitate a bootstrap circuit to generate a gate voltage that is floating with reference to the source of the HS MOSFET or an isolated power supply to turn on, as depicted in Figure 3a. Hence, the advantage of using n-channel devices comes at the cost of increased complexity in gate driver design, leading to more Figure 2. P-channel power MOSFET portfolio available from Littelfuse Figure 3. How to simplify the HS driver in HB application from a) N-cT to b) pchannel MOSFET as HS switch.
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