Protection window and pulse capability
The 1.5KE43CA-T: The 40.9V minimum breakdown voltage ensures the avalanche region is reached well before the clamp voltage, giving the downstream circuitry a defined protection threshold.
This makes it suitable for outdoor telecom cabinets, motor drive power stages, and engine-bay electronics where ambient heat soaks the PCB. The DO-201AA / DO-27 axial-lead through-hole package is a legacy footprint still common in power supplies and industrial control boards. The through-hole mount provides better thermal transfer to the board than a surface-mount equivalent at this power level — the leads carry surge current into the copper pour.
Sourcing reality for an obsolete part
Diodes Incorporated has marked the 1.5KE43CA-T as obsolete. For a repair or a short-run production line that cannot respin the board, the axial DO-201 footprint is widely supported by other TVS families. A pin-compatible cross-reference from a different brand can be evaluated at RFQ time, but no direct drop-in replacement from Diodes is listed.