TVS clamping rating and standoff selection
The 5.0SMDJ78CA-QH: The 78 V reverse standoff typ sits above the nominal rail it protects; when a transient exceeds that threshold, the device clamps the voltage at 126 V maximum, allowing the 39.7 A peak pulse current to flow through the diode and away from the load. This 126 V clamping ceiling is the design limit — the downstream IC sees that voltage, not the full surge amplitude, so the protected rail must tolerate 126 V briefly during an event.
Package and reel sourcing
Supplied on Tape & Reel in the standard SMC footprint — the DO-214AB land pattern is consistent across most TVS families in this case size, but any footprint substitution should verify the clamping voltage and peak current match the Bourns spec, not just the package.