Inrush Current Limiting

The inrush current limitation is an important protective measure within a power supply that prevents the input current from running up too fast or impermissibly high current peaks.

The current peaks are caused by the input filter of a clocked power supply. Each power supply has a more or less generously dimensioned input memory (capacitor) (see also Hold Up Time). The resulting high charging current when applying the input voltage cannot be accepted at this level, as components could be damaged.
The simplest countermeasure is a thermistor connected in series to the input. Back