Question about a specific scenario:
In an (vehicle) environment where a "normal" voltage ranges between 24-29V I have a circuit that uses the NCV7805BTG 5V linear regulator to supply 5V for an ATTiny.
I want to protect this circuit from voltage spikes during (jump) starting or when there is heavy equipment being used, for example a winch, that may cause voltage fluctuations. I read that starting may cause voltage peaks up to 180V.
The NCV7800-datasheet is a bit vague (at least to me) about the absolute maximum voltage for this regulator. The way I read it, it's 40V.
I was thinking to use a TVS diode, but, as I understand it (and I'm new to this, so I may read it wrong), I would need a TVS with a working voltage < 29V and a clamping voltage of max. 40V. Correct? However, no such a TVS diode seem to exist. I recon the closest one is a 15KE30A, which starts breaking down at 28.5V and has a clamping of 41.5V.
What should I do? And how bad is it that if it starts breaking down slightly earlier (heat?/power loss)? Perhaps I should use Zeners instead (how?)?
Now, there is a chance that I'm overthinking this, so any field experience on the topic is welcome! Thanks!
-- reason I use the NCV7800 is that it's the only through-hole regulator I could find that can supply 5V and has an automotive rating. --