TRANSIL™ bidirectional TVS for 30 V rail protection
The STMicroelectronics SMBJ30CA-TR is a bidirectional Zener-type transient voltage suppression diode from the TRANSIL™ SMBJ series, designed to clamp overvoltage events on a 30 V nominal rail. It delivers 600 W peak pulse power per the 10/1000 µs waveform, with a minimum breakdown voltage of 33.3 V and a maximum clamping voltage of 48.4 V at the rated 13 A peak pulse current. The DO-214AA (SMB) surface-mount package suits automated assembly for general-purpose protection in industrial, telecom, and power-supply circuits.
Clamping voltage and surge current — what they mean for rail protection
The 48.4 V max clamping voltage at 13 A peak pulse current sets the upper bound the protected circuitry must survive. For a 30 V rail, that's roughly 1.6× the nominal — a typical margin for downstream components rated at 60 V or higher. The 600 W peak pulse rating assumes the standard 10/1000 µs double-exponential waveform; shorter pulses (e.g. 8/20 µs) allow higher peak current, but the datasheet's 13 A figure at 10/1000 µs is the conservative reference for worst-case coordination. Bidirectional construction (single device, one channel) means polarity-independent clamping — no concern about reverse insertion on AC signal lines or floating DC rails. The 33.3 V minimum breakdown ensures the device stays transparent below the nominal rail voltage plus tolerance.
Housed in the DO-214AA (SMB) body — a low-profile, JEDEC-registered surface-mount package with tin-plated terminations. No power line protection feature (internal diode structure only; no integrated series element).