I have a question regarding transient voltage spikes based on ISO 7637-1/2.
For positive voltage impulses, you would want to use unipolar TVS diodes in reverse mode to clamp the voltage to the TVS diodes' clamping voltage. For reverse polarity, a Schottky diode in series to the load would be ideal. But in this case of reverse polarity, a second TVS diode needs to be placed to limit current through the other, forward-biased TVS diode.
Hence, would a generic circuit like the one below be enough to meet ISO7637-1/2 in theory?
I've seen some circuits that add two Zener diodes after the Schottky diode in clamping mode tied to ground while only using 1 clamped (unipolar) TVS diode in front of the Schottky diode.
Those two Zener diodes just do the same job as the bipolar TVS diode would do - or am I missing out on something?
Source: How to protect input against both ESD and reverse polarity?