Transient suppression window for 256 V rails
The 1.5KE300A-E3/54: It clamps at 414 V maximum, with a reverse standoff of 256 V and a minimum breakdown of 285 V — this window protects 240–256 V DC rails from surges without conducting during normal operation. The 3.6 A peak pulse current rating (10/1000 µs) defines the surge capacity at the clamping voltage; for shorter transients the device absorbs significantly more energy per the datasheet's peak-pulse-power derating curve.
Package and board integration
Housed in a DO-201AA (DO-27) axial-lead package, the 1.5KE300A-/54 mounts through-hole — the large body and lead diameter handle the thermal pulse of a 1.5 kW surge without lifting pads or cracking solder joints. The TransZorb® series uses a glass-passivated junction for low leakage and stable breakdown over the full temperature range. This is a general-purpose protection diode with no internal power-line filtering (Power Line Protection: No), so it is intended for signal or DC bus clamping, not AC mains filtering.