On 09/05/2020 16:09, Dave Plowman (News) wrote:

That does seem the likely explanation. Although there is also a zener to
take care of possible over voltage.


The zener will only protect from over voltage if the current is limited
to less than the power rating of the device. If the protection diode
wasn't in place and 12V from a battery, capable of supplying 10s or 100s
of Amps were connected t0 the 5V output the zener would instantly
destruct, possibly giving a short circuit.

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