TVS for 342 V rails — what the ratings mean
The STMicroelectronics P6KE400CARL is a bidirectional Zener TVS diode from the P6KE TRANSIL™ series, designed for general-purpose transient overvoltage protection on DC or AC lines. It clamps at 706 V maximum under the 8/20 µs pulse shape, with a peak pulse power rating of 600 W. The 342 V reverse standoff voltage means it stays transparent on a nominal 300–340 V bus, only conducting once the transient exceeds the 380 V minimum breakdown threshold. Packaged in a DO-15 (DO-204AC) axial through-hole body, it suits telecom, industrial, and power-supply secondary-side protection where a bidirectional clamp simplifies layout.
Obsolete — last-time-buy already closed
The P6KE400CARL is marked Obsolete by STMicroelectronics. No last-time-buy window remains open through the factory channel. Sourcing now runs through independent distribution, where date-code provenance and stock authenticity are the buyer's main risk.
DO-15 axial package — mounting and thermal notes
Through-hole DO-15 (DO-204AC) axial body. Lead spacing and hole diameter follow the standard DO-15 footprint. The 600 W peak pulse rating assumes a 25 °C ambient with the leads soldered into a PCB with adequate copper pad area for heat sinking. Derate linearly above 25 °C per the TRANSIL series curve. No power line protection feature — this is a straight transient clamp, not a filtered or coordinated protector.
Bidirectional — one device for bipolar transients
A single bidirectional channel handles both positive and negative overvoltage events, which saves a diode and board area compared to back-to-back unidirectional Zeners. The 180 pF typical capacitance at 1 MHz is high enough to load a high-speed data line, but acceptable for power rails, relay coils, or low-frequency signal lines where the 342 V standoff is needed.