The 1.5SMBJ28A-H carries AEC-Q101 qualification, which is the automotive discrete semiconductor reliability standard — not the same as AEC-Q100 for ICs, but the same PPAP and zero-defect intent. For an OEM auditor reviewing the TVS on a 28V supply rail, the Q101 grade means the part has been through the full suite of pre- and post-stress electrical tests, high-temperature reverse bias, and temperature cycling per AEC-Q101-006. This is the differentiator from the standard 1.5SMBJ28A (non-H suffix). The 'H' suffix signals the automotive flow — the silicon and package are the same, but the screening and lot traceability differ. A Tier-1 ECU build that ships against a PPAP gate must use the H-suffix variant; the industrial-grade sibling does not carry the AEC-Q101 cert and the OEM will flag it.
1500W peak pulse — sizing the protection for the rail
For a 28V nominal rail, the reverse standoff voltage of 28V means this diode does not conduct at the normal operating voltage — it sits across the rail as a high-impedance shunt until the transient exceeds the minimum breakdown voltage of 31.1V. The clamping voltage is 45.4V maximum at the 33.1A peak pulse current. That clamp voltage determines whether downstream 40V-rated components survive an unclamped surge. The 33.1A peak pulse current is the maximum the diode can shunt without exceeding the 1500W limit. In a real automotive transient — say a 150V load-dump pulse clamped by the alternator — the TVS must absorb the remaining energy. The 1500W rating means this part handles moderate transients on a 28V rail; for higher energy events a larger package (e.g. 5.0SMDJ series) would be required.
DO-214AA (SMB) surface-mount package is the standard footprint for the 1500W class — the same pad layout as the industrial 1.5SMBJ28A. The part is unidirectional, single-channel. For AC or bidirectional clamping (e.g. data lines), two back-to-back parts or a bidirectional variant (1.5SMBJ28CA-H) would be needed. Power line protection is not supported — this is a signal-rail or low-power-supply TVS, not a mains-class protector.