There are plenty of similar terms like Pulse Duration Modulation, Pulse Time Modulation or Variable Duty Cycle Control but they all mean the same thing. I think the most popular term is Pulse-Width Modulation because it ties in with the PWM acronym referred to in most microcontroller data sheets.

The simplest form of pulse-width control that we are all familiar with is a basic electrical room heater. The desired room temperature can be adjusted by turning a thermostat control knob. When the room temperature is reached, you hear a click, and the power to the heating element is turned off. Once the temperature drops a bit, it clicks again and turns back on, repeating the cycle. The hotter you set the thermostat, the longer the on phase lasts and the shorter the off phase becomes to maintain the higher room temperature.

This works because there’s always a lower temperature threshold that triggers the heating and an upper threshold that stops it. The closer these thresholds are to eac...