Automotive-grade Zener for 15 V rail clamping
It is designed to clamp transients on a 15 V nominal rail, with a minimum breakdown voltage of 16.7 V and a maximum clamping voltage of 32.5 V at the peak pulse current. The 400 W peak pulse power rating (8/20 µs waveform) gives it headroom for load-dump and inductive kickback events common in automotive ECUs, body controllers, and sensor modules.
400 W peak pulse — sizing the protection for the BOM
For a 15 V rail, the 32.5 V clamp voltage means the diode will hold the line well below the typical 40 V absolute maximum of downstream 12 V-rated ICs. The 71 A peak pulse current rating (8/20 µs) confirms it can handle direct strikes from inductive loads like relays, solenoids, or small motors without secondary protection. Power line protection is not integrated — this is a standalone Zener clamp, not a TVS array with series elements, so the PCB trace impedance and any upstream fuse or PTC should be considered in the overall protection scheme.
Active lifecycle and automotive qualification
This makes it suitable for production programs that require a documented reliability pedigree and a stable supply commitment. The base product number is SM4T18, so the 'Y' suffix denotes the specific AEC-Q101 variant — verify the exact ordering code against your BOM to avoid substituting the commercial-grade SM4T18A.