Surge clamp for 300 V rails
The 1.5KE350ARL is a unidirectional Zener transient-voltage-suppression diode from STMicroelectronics' 1.5KE TRANSIL series, designed to clamp voltage transients on DC power rails and signal lines up to 299 V reverse standoff. Its 332 V minimum breakdown voltage triggers conduction during an overvoltage event, shunting the surge current through the device before the protected circuitry sees the clamped voltage.
1500 W peak pulse — what it buys you
The clamping voltage peaks at 618 V at the rated 16 A peak pulse current (8/20 µs waveform), so the downstream equipment sees a hard ceiling well below the typical 800–1000 V failure threshold of a 400 V-rated MOSFET or IGBT.
Capacitance and signal integrity
With 430 pF capacitance at 1 MHz, this diode loads the line with a moderate capacitive burden. Fine for DC power rails and low-frequency signal lines (e.g., 24 V PLC inputs, relay coils), but it will round off fast edges on a high-speed data bus. For RS-485 or CAN lines, look at a lower-capacitance TVS in the same family.
Active status, no LTB pressure
The DO-201 axial package is a standard through-hole form factor that remains widely supported. No official second-source cross-reference is published, but the 1.5KE series is a common footprint — a P6KE350A shares the same DO-201 package and similar electrical ratings, though the P6KE is rated 600 W peak pulse versus 1500 W here.