TVS diode for 150V rail protection
The SMBJ150A-13-F: Its 167V minimum breakdown voltage and 243V maximum clamping at 2.5A peak pulse current (10/1000µs waveform) mean it starts conducting just above the operating voltage and holds the spike below 243V — enough to protect downstream silicon rated for 250V or higher.
The operating temperature range spans -55°C to 150°C junction, so it works in industrial enclosures and outdoor gear without a derating headache at the hot end. General-purpose application classification means no special automotive or medical qualification — fine for most commercial and industrial boards.
Board-fit and orientation
Surface-mount in DO-214AA (SMB) — the cathode band is clearly marked on the body, so orientation is one look. The package is large enough to hand-solder with a fine tip if you are prototyping or doing a field repair without a reflow oven. No power line protection feature — this is a signal- or low-power rail TVS, not meant for mains or high-energy AC lines. For a 150V DC bus or a 120V AC secondary rectified rail, it fits; for direct 240V mains, look at a higher-energy MOV or a dedicated power TVS.