shootthrough

Shootthrough is a failure mode in switching power electronics where both devices in a switching leg (for example the high-side and low-side transistors in an H-bridge or half-bridge) conduct at the same time. This creates a direct, low-impedance path from supply to ground, often resulting in a large current spike and potential damage to components or protection circuits.

Causes of shootthrough include timing errors in gate drive signals, insufficient dead time between turning off one switch and turning on the other, driver faults, or rapid switching transients that couple through parasitics. Indirect causes can be mismatched device characteristics, poor PCB layout, or inadequate protection in the gate driver. Shootthrough is particularly risky in high-current, high-speed applications such as motor drives, DC-DC converters, and switching amplifiers.

Consequences can be severe: excessive current can cause overheating, device destruction, fuse or circuit-breaker trips, reduced efficiency, and increased electromagnetic interference. In some cases the supply voltage may momentarily ring or collapse, affecting other circuit sections.

Prevention and mitigation focus on preventing overlap of conduction. Key measures include incorporating dead time in gate drive signals, using drivers with anti-shoot-through protection, and ensuring proper timing margins and synchronization. Robust design also involves careful layout to minimize parasitic coupling, current limiting or soft-start features, snubbers, and reliable fault or protection circuits. Regular testing and monitoring of cross-conduction current help verify that shootthrough is not occurring under normal and fault conditions.

See also: dead time, cross-conduction, high-side/low-side drivers, PWM, protection circuitry.