AEC-Q101 TransZorb — the automotive-grade TVS in DO-214AB
The 1.5SMC220CAHM3_A/I is a Vishay TransZorb bidirectional Zener TVS diode from the 1.5SMC series, qualified to AEC-Q101. That means it passed the automotive-grade reliability stress sequence — temperature cycling, HAST, and high-temperature reverse bias — with PPAP documentation available for an OEM auditor. This is not an industrial part dressed as automotive; the AEC-Q101 mark is on the reel label and the datasheet. Packaged in DO-214AB (SMC), the body measures roughly 7.1 mm × 6.2 mm with a seated height around 2.6 mm — a standard footprint for 1500 W TVS diodes. Surface-mount assembly; the copper pad area under the cathode tab sets the RthJA, so the PCB layout determines how much steady-state power the part can dissipate before the junction hits 150°C.
185 V rail protection — clamping window and pulse handling
The clamping factor — 328 V / 209 V = 1.57 — is tight for a 1500 W device, meaning the downstream components see less overvoltage stress per transient event. Rated 1500 W peak pulse power (1.5 kW) per the 10/1000 µs exponential waveform. Derate this figure above 25°C ambient per the datasheet curve — at 125°C the peak pulse power is roughly 60 % of the 25°C rating. The bidirectional configuration (single die, both polarities) means a single part clamps positive and negative transients without a series diode.
Active production — sourcing for the BOM line
Operating junction temperature range -65°C to 150°C covers the full automotive underhood temperature band — a grade-1 AEC-Q101 device, suitable for engine-bay and chassis-mount locations where ambient hits 105°C or higher.