TVS diode for 40V rail protection
The SMCJ40CE3/TR13 is a Zener-type transient voltage suppressor from Microchip Technology, rated for 1500W peak pulse power (10/1000µs waveform). It protects a 40V nominal rail, with a breakdown voltage range starting at 44.4V and clamping at 71.4V maximum under the peak pulse current of 21A. This single bidirectional channel device handles surge events in general-purpose applications such as power supplies, telecom equipment, and industrial controls.
Clamping voltage and surge current
The 71.4V maximum clamping voltage at 21A peak pulse current defines the voltage the protected circuitry must survive. For a 40V rail, this leaves a 31.4V margin above nominal — typical for TVS diodes in this power class. The 1500W rating is measured with a 10/1000µs waveform; shorter pulses allow higher peak current before the device reaches its thermal limit. The device does not include power line protection features — it is a standalone transient suppressor for signal or DC power rails.
The base product number SMCJ40 covers a family of voltage variants; this specific 'C' suffix indicates bidirectional polarity, and '' denotes lead-free / RoHS-compliant construction.