The STMicroelectronics SM15T24A is a single-channel, unidirectional TRANSIL™ TVS diode in the SM15T series, rated for 1500W peak pulse power (10/1000µs waveform). That 1.5 kW rating means it can clamp a substantial transient without self-destructing — think motor-drive inductive kickback, lightning-induced surges on outdoor cabling, or load-dump events in industrial 24V DC rails. The 20.5V reverse standoff voltage sits below the nominal 24V bus, so it stays out of the way during normal operation and only conducts when the line spikes above 22.8V typical breakdown.
Clamping voltage and surge current — the protection envelope
When the transient hits, the SM15T24A clamps at a maximum of 42.8V while shunting up to 234A of peak pulse current (8/20µs waveform). That 42.8V ceiling is the number you check against the absolute-maximum voltage rating of your downstream power-stage components — if the DC-DC converter or load switch can't survive 43V, you need a higher-voltage TVS or a secondary clamp. The 234A peak current rating gives headroom for short, high-energy surges common in industrial and telecom environments.
Housed in a DO-214AB (SMC) surface-mount package, the SM15T24A is a standard footprint for this power class — rework-friendly, solder-reflow compatible, and widely second-sourced.