Consider a 12Vdc automotive power supply design where +12V power connects first to a Vc=49.9V bidirectional TVS diode (e.g., TPSMB36CA) and subsequently connects to an SB370 Schottky diode. The SB370 is used for reverse polarity protection and was chosen over a 1N4004 for its lower forward voltage drop.
A Load Dump spike could be 100V to 125V in some cars, but the TVS would clamp that spike to Vc=49.9V. The SB370 datasheet cites Vr=70V (DC blocking voltage) and Vr-rms (RMS Reverse Voltage) = 49V. The Vr=70V of the SB370 is higher than the Vc=49.9V of the TVS and therefore would appear to be safe, but what of the Vr-rms=49V spec (0.9V lower than Vc)? Does the Vr-rms spec not matter in this automotive DC circuit?