What the 55.1 V standoff means for your rail
The 1.5KE68-E3/73: The 55.1 V reverse standoff is the maximum continuous DC voltage the TVS can sit across without conducting appreciable leakage — a 48 V nominal bus with 10 % tolerance (52.8 V max) stays below this threshold, so the diode does not load the rail during normal operation. When the transient hits, breakdown begins at 61.2 V minimum and the diode clamps the surge to 98 V maximum at 15.3 A — the clamping voltage is what downstream semiconductors must survive without secondary breakdown. The 1500 W peak pulse rating is derated above 25 °C; at the 175 °C maximum junction temperature the device is still specified for pulse handling, but the effective peak power drops per the datasheet derating curve.
Package and board integration
Supplied in a DO-201AA (DO-27) axial-lead package, through-hole mounted — the lead bend forms a low-inductance path when the body sits flush against the board, which matters for the clamping response time in fast transients. Single unidirectional channel — correct polarity matters; reverse insertion places the junction in forward conduction and the protection is lost.