Device identity and protection window
The 1.5KE39CA/54: Its 33.3V reverse standoff voltage and 37.1V minimum breakdown voltage define the clamping threshold, with a maximum clamp of 53.9V at 27.8A peak pulse current. The bidirectional configuration means a single device clamps transients of either polarity — useful on AC signal lines or DC rails where the polarity could reverse during a fault.
Package and board integration
Housed in a DO-201AA (DO-27) axial-lead through-hole package, the 1.5KE39CA/54 mounts directly into a PCB or terminal block. The axial leads handle the thermal cycling of repetitive surges better than a surface-mount package of the same power rating — the lead frame conducts heat into the board copper. The Tape & Reel (TR) packaging variant (the /54 suffix) is the standard reel format for automated insertion equipment. No power-line protection is claimed — this device is intended for signal and low-voltage DC rail transient suppression, not mains AC clamping.
Sourcing reality for an obsolete line item
Vishay lists the 1.5KE39CA/54 as Obsolete. No official successor order code is recorded in the lifecycle data. If the board uses hand-insertion or low-volume assembly, the reel format still works — the parts are loose on the reel and can be cut from the carrier tape.