MOSFETs are critical in power electronics, but their performance is significantly influenced by parasitic parameters. Parasitic inductances, such as source inductance (Lₛ) from bonding wires and PCB traces, and drain inductance (Lₚ) from packaging, directly affect switching dynamics. Lₛ causes delayed turn-on/off and resonance with input capacitance (Ciss), leading to gate voltage oscillations. Meanwhile, Lₚ limits di/dt during turn-on but induces voltage overshoots during turn-off, increasing power losses .
Parasitic capacitances, including Ciss, Coss, and Crss (Miller capacitance), also play a role. Crss, in particular, amplifies input capacitance via the Miller effect, slowing switching speeds and degrading efficiency . To mitigate these issues, drive circuits must provide sufficient gate current to charge/discharge Ciss rapidly. Gate resistors (Rg) are essential to dampen oscillations and control switching speeds—smaller Rg reduces losses but may increase EMI, while larger Rg improves stability at the cost of efficiency .
Layout optimization is equally crucial. Shortening gate-source loops and using ground planes minimize parasitic inductance. Bypass capacitors near the driver ensure transient current demands are met. For high-power applications, dedicated drivers like TC4420 offer fast response and high current capability, while protection components (e.g., TVS diodes) safeguard against overvoltage .
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