Methods, devices, techniques, systems, and integrated circuits are disclosed for variably controlling a switch on time for a driver, which may enhance iTHD. In one example, a device includes an input voltage sensor configured to detect an input voltage, and a variable switch on time generator, operatively connected to the input voltage sensor to receive a signal indicative of the input voltage. The variable switch on time generator is configured to determine a variable switch on time based at least in part on the detected input voltage, and output the determined variable switch on time for controlling switch on timing of a driver switch.