This invention is helpful to servicing personnel, manufacturing personnel or R&D personnel who are
trying to find the root cause of a system shutdown when traced to a particular power supply with a
blown fuse or a tripped circuit breaker, the cause of which could have been (1) an output load
overcurrent condition or (2) an input overvoltage input condition that activated the internal crowbar
circuit which shorted the input or output to protect the load, and this invention solves the ambiguity
with an added LED and associated circuitry to indicate that it was the crowbar activation that caused to
fault when the LED is lit. The LED will stay lit until manually serviced by replacing or resetting a separate
fusing device, so the problem may be found and acknowledged. A software or firmware action would
probably never be expected to reset the memorised overvoltage indication but a digital port might
monitor the state of the LED for software diagnostic schemes.
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INC, HP, "A CROWBAR CIRCUIT WITH OVERVOLTAGE ACTIVATION INDICATION", Technical Disclosure Commons, (November 29, 2018)