Programmable Power Supply, known as PPS, is an optional feature within USB Power Delivery that allows the charger and device to adjust voltage and current in small steps, rather than only choosing from a handful of fixed power profiles.
This fine grained control lets a device request exactly the voltage it needs at any moment, which can reduce heat generated by internal power conversion and support the fast charging modes used by many current smartphones. Not every PD charger includes PPS, so a phone that requests fast PPS based charging may charge more slowly, but still safely, on a charger without it.
When shopping for a charger meant for fast phone charging, checking for explicit PPS support alongside the wattage rating is worth doing, since PPS support is what actually unlocks a phone's fastest wired charging speed in many cases. See our Power Delivery guide for the wider context.
