3 kW bidirectional TVS for 30 V automotive rails
The STMicroelectronics SM30T35CAY is a bidirectional Zener TVS diode from the SM30TY TRANSIL™ series, qualified to AEC-Q101 for automotive applications. It protects a 30 V nominal rail, clamping a 10/1000 µs surge to 48.4 V maximum while handling 62 A peak pulse current and 3000 W peak pulse power. The DO-214AB (SMC) package is a surface-mount footprint common in engine-control units, body controllers, and any 12 V or 24 V vehicle bus that sees load-dump or inductive-kick transients.
48.4 V clamp — what the load actually sees
The 48.4 V maximum clamping voltage at 62 A is the number that matters for downstream silicon stress. A 30 V reverse standoff means the diode is invisible to the rail under normal operation; leakage is negligible. When a surge hits, the TVS folds the transient to 48.4 V, which keeps a typical 40 V-rated downstream DC-DC or linear regulator inside its absolute-maximum rating. The 3 kW peak pulse rating (10/1000 µs waveform) covers the energy of a standard automotive load-dump pulse per ISO 7637-2, pulse 5a or 5b, depending on the suppression level needed.
The AEC-Q101 qualification means this part has passed the automotive stress tests: high-temperature reverse bias, humidity, power and temperature cycling, and ESD. The SMC package has a large copper slug on the bottom — the board's thermal vias and copper pour directly affect how much continuous power the part can sink. For repetitive pulses, derate the peak power per the datasheet's pulse-width curve.
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