The STMicroelectronics SMCJ10CA-TR is a bidirectional TRANSIL™ TVS diode in the SMCJ series, rated for 1500W peak pulse power (10/1000µs waveform) with a 10V reverse standoff voltage and 21.7V clamping point.
1500W peak pulse — sizing the protection
The 1500W peak pulse power rating (8/20µs waveform, 461A Ipp) tells you this part can clamp a substantial surge — think lightning-induced transients on outdoor signal lines or inductive load dump in industrial 24V systems. The 10V reverse standoff means it stays out of the way on a 5V or 3.3V rail, but the 11.1V minimum breakdown gives a guard band before it starts conducting. For a 12V nominal rail you would step up to the SMCJ12A or SMCJ12CA variant.
Bidirectional, single-channel, DO-214AB
The SMC footprint is a standard surface-mount package; the same pad layout works for the whole SMCJ family if you need to change voltage later.