TVS diode with automotive-grade qualification
The 1.5SMBJ54A-H: It clamps a 54 V reverse standoff to 87.1 V maximum at a peak pulse current of 17.3 A.
Clamping voltage and breakdown tolerance
The 17.3 A peak pulse current rating at the 10/1000 µs waveform defines the surge-handling capacity — a fault exceeding this current will push the device outside its safe operating area, so the upstream fuse or PTC must coordinate to clear before the TVS reaches its peak current limit. The single unidirectional channel means this diode conducts only in the forward direction during an overvoltage event; for bidirectional protection on AC or bipolar rails, two devices or a bidirectional variant from the same series would be needed.
The SMB footprint is a common industry standard — the same pad layout is shared across many 1.5 kW TVS diodes, so a board designed for a competitor's SMB part will accept this device without a layout change. Power line protection is not supported — this device is intended for signal and low-power rail clamping, not for direct connection to mains or high-current power buses where a higher-energy MOV or GDT would be required.
Sourcing and lifecycle posture
The 1.5SMBJ54A-H is listed as Active — Bourns continues to manufacture this part with no announced end-of-life.