What the 47.8V breakdown buys your rail
The SMBJ43CE3/TR13 is a Zener TVS diode from Microchip Technology, rated for 600W peak pulse power per the 10/1000µs waveform. The 47.8V minimum breakdown voltage sets the clamp threshold — the diode starts conducting at that point, shunting surge current away from the protected circuit. Reverse standoff is 43V (typical), meaning the diode stays off below that rail voltage. For a 36V or 42V bus, this part leaves margin before the breakdown knee.
Clamping and current handling
Maximum clamping voltage at peak pulse current is 76.7V — that is the voltage the load sees during the surge event. The peak pulse current itself is 7.8A for the 10/1000µs waveform. Single bidirectional channel means one device protects both polarities on the same line, saving board space versus two unidirectional diodes back-to-back.
Microchip lists the SMBJ43CE3/TR13 as Active. Store the reels dry; the DO-214AA body is not moisture-sensitive per typical Microchip handling, but standard MSL precautions apply for long-term shelf storage.
The wide range means the clamping voltage and leakage shift predictably across temperature — derate peak pulse power above 25°C per the datasheet curve. Surface-mount DO-214AA (SMB) package — the same footprint as many industry-standard TVS diodes. The two-pad layout is straightforward; the cathode band on the body marks the bidirectional orientation (no polarity concern for a bidirectional device).