1500W bidirectional Zener TVS in a through-hole axial package
The 1.5KE39CA: It clamps transients at 53.9V maximum while conducting 28.2A peak pulse current, making it a fit for protecting 24V DC rails or similar circuits where the reverse standoff voltage of 33.3V sits above the nominal bus voltage. The DO-201AA (DO-27) axial leaded package is through-hole mounted, which means it handles the thermal pulse of a 1500W surge without the board-level heat-spreading a surface-mount TVS would need. The leads are thick enough to solder into a plated through-hole without wicking issues, and the body is large enough to mark clearly — pin 1 is not a concern on a bidirectional part.
Peak pulse power and the protection window
The 1500W peak pulse rating (10/1000µs) is the headline number, but what matters for the circuit is the clamping voltage: 53.9V maximum at 28.2A. That means a 24V rail seeing a surge will be held below 54V, which is within the abs-max rating of most 60V-rated downstream components. The breakdown voltage range starts at 37.1V minimum, so the device starts conducting before the rail exceeds the safe operating area of the load. The junction temperature rating is the same as the storage range, so the part does not derate until the ambient approaches 175°C — rare in practice, but useful for high-temperature enclosures or near heat sources.
Active lifecycle and sourcing posture
Littelfuse lists the 1.5KE39CA as Active. The 1.5KE series is a long-running standard, so date codes and lot traceability are straightforward to obtain.