Electronic – Can electronics be damaged by undervolting it

damagepower supplyvoltage

I was wondering if there are some particularly important mechanism by which one can break electronics, when undervolting it. Its pretty obvious that lots of electronics will not work properly if undervolted, but what about permanent damage? The question was motivated by repair work. I was wondering about what sorts of secondary effects one should look for when a damaged power supply was involved.

I imagine motors could be damaged if they stalled due to undervolting.

So what are specific mechanisms for permemenant damage due to undervolting (or better put undersupplying)? Are there even any?

To add to the question, what are components or simple circuits that fail when undersupplied?

Best Answer

Damage by undervoltage is not as common as by overvoltage, but it is not unheard of.

An example: a simple circuit that has a power mosfet driving a motor. The intention is that the mosfet is either completely on or completely off. In both cases the power dissipated by the mosfet is very low:

  • when it is on the power is low because the o-fully-on resistance of the mosfet is very low, hence the voltage across it is also very low, so the power (V*I) is low.
  • when it is off the full voltage of the power is across the mosfet, but the current is almost zero, hence the power is almost zero too.

A mosfet needs a certain voltage at its gate to turn fully on. 8V is a typical value. A simple driver circuit could get this voltage directly from the power that also feeds the motor. When this voltage is too low to turn the mosfet fully on a dangerous situation (from the point of view of the moseft) can arise: when it is half-on, both the current through it and the voltage across it can be substantial, resulting in a dissipation that can kill it. Death by undervoltage.

Note that I started by assuming a simple circuit. In practice a serious circuit like this would have an undervoltage protection.