The PWM for LEDs for current control is often used when resistors would make it too expensive. Most LEDs have a ability to handle a lot of current for a short period in time. If you average the on/off time the average power rating of the LED is within specs. Whether you’re using them for indication, communication, lighting, or just for some added cool factor to a project, all LEDs have one thing in common: they are unable to regulate current. Without a limited current flow, LEDs will eventually fail. Sometimes catastrophically. pLYk00.