Zener TVS diode, 1500 W peak pulse, 17.1 V standoff
The 1.5SMC20A R7G: Its 17.1 V reverse standoff voltage means the protected rail can run at 17.1 V DC with negligible leakage; the device begins to avalanche at a minimum of 19 V and clamps at 27.7 V when the surge current reaches 56 A. The 27.7 V clamping ceiling is the voltage the downstream circuitry must survive — a 24 V bus with a 20 % tolerance sits at 28.8 V, so this part gives only 0.9 V of headroom above the clamp. For a 12 V or 15 V rail the margin is comfortable.
Package and temperature range
Housed in a DO-214AB (SMC) surface-mount package, the 1.5SMC20A R7G shares the standard footprint used across the 1.5SMC family. The junction temperature range spans -55°C to 150°C, covering both cold-start and under-hood ambient conditions without derating concerns. The unidirectional channel clamps only positive transients relative to ground — for AC lines or bidirectional protection, a different variant in the same package is needed.
Listed as Active by Taiwan Semiconductor, so there is no end-of-life risk for current or new designs.