The STMicroelectronics SM15T22CA is a bidirectional Zener-type transient voltage suppression diode from the SM15T, TRANSIL™ series. It is designed for general-purpose overvoltage protection on power and signal lines, clamping transients up to 1500W peak pulse power. The 18.8V reverse standoff voltage makes it suitable for protecting 12V or 15V rails against surges and ESD events.
The 20.9V minimum breakdown voltage ensures the device starts conducting before the protected circuitry sees damaging overvoltage, while the 39.3V maximum clamping voltage at 254A peak pulse current (8/20µs waveform) limits the let-through voltage to a safe level for downstream components. The single bidirectional channel means one device replaces two unidirectional diodes in series, saving board space and reducing part count for AC or bipolar signal protection.
The SMC body provides adequate creepage distance for the 1500W dissipation level.