What the 1.5SMC91H actually is
The 1.5SMC91H is a unidirectional Zener-type TVS (Transient Voltage Suppressor) from Taiwan Semiconductor's 1.5SMC series, qualified to AEC-Q101 for automotive environments. It clamps voltage transients on a single data or power line by conducting in the reverse direction once the standoff voltage is exceeded — the 73.7V typical reverse standoff defines the working rail the protected circuit sees in normal operation, while the 81.9V minimum breakdown is where the device first begins to conduct, and the 131V clamping maximum is what the downstream circuitry actually survives under the 10/1000 µs surge waveform.
Peak pulse ratings — what 1500W means for the protection window
Peak pulse power of 1500W (1.5 kW) at the standard 10/1000 µs waveform sets the surge energy the part can absorb and dissipate without degradation — this is the primary selection axis for a board-level TVS in telecom infrastructure, where lightning-induced surges on long cable runs are the design-case event. The corresponding 12A peak pulse current confirms the device handles the current the 131V clamping ceiling forces through the diode under that surge; together, 131V × 12A = 1,572W, close to the 1,500W rating and confirming the datasheet is internally consistent on this axis. For telecom outdoor units mounted in direct sun, the 150°C Tj ceiling gives headroom before the absolute-maximum limit is reached under sustained surge stress.
The DO-214AB (SMC) package is the mid-power TVS footprint — the cathode bar at the center of the package denotes the unidirectional polarity, and the wide metal pad on the underside carries the thermal path to the board. Surface-mount termination suits pick-and-place assembly; tape-and-reel packaging is the standard automotive reel quantity format.
The 1.5SMC91H carries Active lifecycle status — Taiwan Semiconductor continues production as a standard catalog line.