TVS protection for 376 V rails — what the ratings mean
The STMicroelectronics P6KE440CARL is a bidirectional Zener TVS diode from the P6KE TRANSIL™ series, rated for 600 W peak pulse power (10/1000 µs waveform). It is designed to clamp transients on a nominal 376 V reverse standoff rail, with a minimum breakdown voltage of 418 V and a maximum clamping voltage of 776 V at the peak pulse current of 5.2 A (8/20 µs). The single bidirectional channel means it can handle surges of either polarity without needing two devices in series — useful for AC-coupled or floating lines in general-purpose industrial equipment, power supplies, and telecom infrastructure.
The manufacturer has marked the P6KE440CARL as obsolete. For existing designs that require this exact clamping voltage and footprint, procurement will need to source from independent distribution or qualified surplus channels. Any stock offered should be verified for date-code authenticity and traceability — especially important for safety-critical or long-life applications where counterfeit or aged inventory could compromise protection performance. If a design is still in development, consider evaluating a current-production TVS from the same P6KE family or a comparable series with a similar standoff voltage and DO-15 package.
Package and mounting for retrofit
The P6KE440CARL comes in a DO-204AC (DO-15) axial-lead through-hole package. This is a standard footprint for through-hole TVS diodes, and the axial leads simplify hand-replacement or wave-solder assembly. The 175 pF typical capacitance at 1 MHz is low enough for most signal-line protection, but it is worth checking against the operating frequency if the diode is placed on a data line rather than a power rail.