AEC-Q101 Zener TVS for 138 V rails
The 1.5KE170HE3/54: It clamps transients on a 138 V nominal DC bus — the standoff voltage — and begins avalanche breakdown at a minimum of 153 V. The junction temperature range of -55 to 175 °C covers under-hood ambient plus self-heating during the pulse — derate the peak power above 25 °C per the TransZorb application note.
Through-hole DO-201AA / DO-27 axial package — the leads are 0.96 mm diameter tin-plated copper. The body length is 9.1 mm; the anode end is marked with a band. This footprint is legacy; a board designed for surface-mount TVS arrays (SMC, SMB) will not accept this package without a through-hole adapter or a board spin. The 1.5KE170HE3/54 is obsolete — Vishay no longer manufactures it.