Key ratings and what they mean for your BOM
The 1.5KE540-E3/73: The 1.5KE540-/73 is a 1500 W (1.5 kW) peak pulse power Zener TVS diode from Vishay's TransZorb series, designed to clamp transients in general-purpose circuit protection roles. Its 437 V reverse standoff voltage means it remains transparent below that DC level, only conducting when a surge exceeds the threshold. Clamping is rated at 772 V maximum at a peak pulse current of 1.94 A (10/1000 µs waveform). This is the voltage the load sees during a transient — a downstream 600 V-rated capacitor would be stressed beyond its rating during the clamp event. Breakdown occurs at a minimum of 486 V, so the device starts conducting between 486 V and the clamping voltage, protecting sensitive semiconductors on a 437 V nominal rail from overvoltage damage.
The axial leads suit point-to-point wiring or PCB through-hole mounting on legacy boards where surface-mount TVS diodes are not an option. The supplier device package code is 1.5KE, confirming mechanical interchangeability with other 1.5KE-series parts on the same PCB layout. Supplied in Tape & Box (TB) format, though for an obsolete part the packaging at time of procurement will be lot-specific.
Sourcing and compliance reality
Vishay lists this part as obsolete. As a Zener TVS diode, the device is inherently RoHS-compliant in its construction (lead-free terminations per Vishay's standard).