What this TVS does in the circuit
The 1N6279A is a unidirectional Zener TVS diode from onsemi's Mosorb™ series, designed to clamp transient overvoltage spikes on a DC rail. It handles a peak pulse power of 1500W (1.5kW) for an 8/20µs waveform, which covers most industrial surge events from inductive load switching or lightning-coupled transients. Its reverse standoff voltage is 18.8V, with a breakdown range starting at 20.9V and clamping at 30.6V at rated current. That means it protects a 15V or 18V supply rail without conducting during normal operation, then shunts the spike before it reaches downstream silicon.
Package and mounting for field replacement
Housed in a DO-201AD axial-lead package, it is a through-hole part. On a repair bench or in the field, you can swap it with a soldering iron and a pair of cutters — no hot-air station needed. The axial leads are clearly polarized with a cathode band, so orientation is hard to mess up even without a magnifier. The junction temperature range spans -65°C to 175°C, so it survives the thermal cycling of outdoor or under-hood environments. No power line protection built in — this is a low-voltage signal or DC rail clamp, not an AC mains suppressor.
Sourcing reality: obsolete, but still findable
onsemi lists the 1N6279A as Obsolete. That means no ongoing production — no last-time-buy window is currently open. For a BOM line that needs this exact part, the only channel is existing distributor stock or the open market. We source per RFQ; availability and price vary by date code and quantity. The base product number is 1N6279, so the 'A' suffix indicates a tighter breakdown tolerance. If your board can accept a standard-tolerance part, the 1N6279 (non-A) may still be available in some channels — confirm the spec before substituting.