170V standoff, 1500W bidirectional TVS in DO-214AB
The SMCJ170CE3/TR13 is a bidirectional Zener TVS diode from Microchip Technology, rated for a reverse standoff voltage of 170V and a peak pulse power of 1500W (1.5kW) under the 10/1000µs waveform. It clamps transients at 304V maximum with a peak pulse current of 4.9A. The single bidirectional channel means it protects against both positive and negative surges — useful on AC lines or bipolar DC rails where polarity isn't fixed.
Breakdown voltage and clamping margin
Minimum breakdown voltage is 189V, so the part starts conducting before the rail hits 190V. The clamping ceiling at 304V gives a 115V window between breakdown and clamp — enough headroom for most 170V-rated equipment without letting the surge through to downstream silicon. The 4.9A peak pulse current rating at 10/1000µs tells you the surge it can absorb; for shorter pulses the peak current is higher, but the energy limit stays the same.