This is a surface mounted bidirectional transistor-transient voltage suppressor (TVS) device made by Yageo Corporation. It is an SMC type component (DO-214AB), 5V rated with a peak pulse power dissipation PPP of 600W at 8/20 µs waveform. It is RoHS compliant, meaning it is free from hazardous materials like lead, mercury, cadmium, hexavalent chromium, and polybrominated biphenyls and or polybrominated diphenyl ethers. The SMDJ18CA series are designed to protect voltage sensitive components such as MOSFETs, IGBTs, SCRs, diodes, and transistors from voltage or electrical spikes.