Programmable power supplies are digitally controlled power sources that provide accurate and adjustable levels of voltage, current, and frequency. They include a processor, voltage/current programming circuits, current shunt, and voltage/current read-back circuits. Remote sensing functions compensate for voltage drops in the load leads by providing feedback of the actual voltage at the load. Over-voltage and over-current protection modes are also available. Comparators continuously monitor the output voltage against a program reference value. If the output value exceeds the reference value, a trigger signal is sent to a silicon-controlled rectifier (SCR) across the output, shutting off the source to the load. Most programmable power supplies are subjected to extensive testing and burn-in periods to ensure long-term performance.

