43V rail protection — what the clamping numbers mean on your bench
The SMAJ43CA-13: With a 43V reverse standoff voltage, this TVS sits across a 36V or 42V nominal rail without conducting leakage. The breakdown is guaranteed at 47.8V minimum, so the diode stays off under normal operating conditions and only starts clamping when the transient pushes the rail above that threshold. The clamping voltage is 69.4V maximum at the rated 5.7A peak pulse current (10/1000µs waveform). That 69.4V ceiling is what the downstream ICs see during a surge — verify the absolute-max rating of the protected device stays above this clamp level. The 400W peak pulse power is the energy handling capacity for that waveform; shorter pulses (8/20µs) allow higher peak current before the junction reaches its thermal limit.
DO-214AC footprint and temperature envelope
Housed in the standard DO-214AC (SMA) surface-mount package, with the supplier device package also listed as SMA. The footprint matches the common JEDEC outline for this power class — reflow profile follows the solder paste manufacturer's recommendation for the lead-free finish. The operating junction temperature range spans -55°C to +150°C, which covers automotive under-hood, industrial enclosures, and outdoor telecom cabinets without derating concerns at the high end.