An example controller for a power converter includes an input voltage sensor, a current sensor, an oscillator, a timing and multiplier circuit, and a drive signal generator. The input voltage sensor receives an input signal representative of an input voltage and the current sensor senses a current in a power switch. The oscillator generates a signal having a switching frequency and the timing and multiplier circuit adjusts the switching frequency of the signal to be proportional to a value that is the input voltage multiplied by a time it takes the current in the power switch to change between two current values. The drive signal generator drives the power switch into the on state for an on time period and an off state for an off time period in response to the current in the power switch and in response to the signal having the switching frequency.