Does a shunt regulator like 431L (datasheet), wired like this
(VKA is not connected to anything) help protect other electronics supplied from INPUT net (battery connection)?
INPUT net also supplies 4V directly to 4 small dc motors, which I believe generate quite large voltage/current spikes at start, stop, or from sudden stop (due to propeller hitting an objetc for example). INPUT net also powers an LDO that powers MCU, sensors, etc.
I am confused, because it is trying to keep VKA constant, then when the spike comes, VKA will change, then 431L should sink the spike fast to keep VKA at 2.5V, but there are two facts that go versus this: the 431L can only sink 100mA, that looks little, so maybe it burns? And there is 1K resistor before the 431L, so maybe the spike just ignores the 431L and goes directly to the LDO and next electronics, generating noise, maybe burning them? So the 431L would protect nothing?
Or maybe the 4V motor spikes are not so dangerous and I should forget about protection?
Please help me understand this, or point me to some reading about this. Thank you very much for your time.