Editing Hot swapping (section)

=== Power electronics ===
The DC power supplies to a hot-swap component are usually [[pre-charge]]d by dedicated long pins that make contact before the main power pins.  These pre-charge pins are protected by a circuit that limits the inrush current to an acceptable value that cannot damage the pins nor disturb the supply voltage to adjacent slots.  The pre-charge circuit might be a simple series [[resistor]], a [[negative temperature coefficient]] (NTC) resistor, or a [[current-limiter]] circuit.  Further protection can be provided by a "soft-start" circuit that provides a managed ramp-up of the internal DC supply voltages within the component.

A typical sequence for a hot-swap component being plugged into a slot could be as follows:
#Long ground pins make contact; basic electrical safety and ESD protection becomes available.
#Long (or medium) pre-charge pins make contact; decoupling capacitors start to charge up.
#Real time delay of tens of milliseconds.
#Short power/signal pins make contact.
#Connector becomes fully seated; power-on reset signal asserted within component
#Soft-start circuit starts to apply power to the component.
#Real time delay of tens of milliseconds.
#Soft-start circuit completes sequence; power-on reset circuit deasserted
#Component begins normal operation.

Hot-swap power circuits can now be purchased commercially in specially designed [[Application-specific integrated circuit|ASICs]] called hot-swap power managers (HSPMs).