170V rail clamp — what the ratings mean for the protected line
The SMBJ170A-13: Its 189V minimum breakdown voltage means the device starts conducting before the rail exceeds that threshold, and the 275V maximum clamp at the rated 2.2A peak pulse current sets the voltage the downstream circuitry sees during a surge event. The -55°C to 150°C junction temperature range covers both cold-start telecom cabinets and hot industrial enclosures without derating concern at the ambient extremes.
Package and board-fit — DO-214AA SMB footprint
Housed in the DO-214AA (SMB) package, the SMBJ170A-13 shares the same 2-lead footprint as the rest of the SMBJ family. The SMB package is larger than the SMA variant, offering better thermal dissipation for the 600W pulse — the copper pad area under the cathode tab on the PCB sets the junction-to-ambient thermal resistance for repetitive surges. Tape & Reel packaging supports automated pick-and-place for volume production.
Active production and sourcing posture
The part carries no power line protection rating — it is intended for signal and DC rail transient suppression, not AC mains clamping.