Sizing the surge clamp for a 28 V rail
The SMCJ28CAE3/TR13 is a Zener-type bidirectional TVS diode rated for 1500W (1.5kW) peak pulse power per the 10/1000 µs waveform, clamping a 33 A surge to 45.4 V maximum. The 28 V reverse standoff voltage sits just above a nominal 24 V or 28 V DC rail, so the diode stays transparent during normal operation and only conducts when the line exceeds the 31.1 V minimum breakdown threshold. The single bidirectional channel means the same device protects both polarities on a signal pair or an AC line — no need to series two unidirectional parts. The DO-214AB (SMC) package footprint is shared across the SMCJ family, so a layout designed for a 5.0 V or 40 V variant accepts this 28 V part without board changes.
The 45.4 V maximum clamping voltage at 33 A peak pulse current sets the upper voltage that downstream components must survive. For a 28 V rail, that is a 62 % headroom above the nominal — typical for a TVS protecting a DC bus with a 20–30 % transient margin. The 31.1 V minimum breakdown voltage ensures the device does not trigger on normal rail ripple or load transients within the operating envelope.
No stock-holding claim is made; the part is sourced per RFQ through our supply channel.