An example integrated circuit controller includes a pulse width modulation (PWM) circuit and a timing circuit. The PWM circuit controls a switch to regulate an output of a power supply in response to a switch current flowing through the switch and in response to a clock signal having a switching period. The timing circuit provides the clock signal and includes a timing capacitor where the switching period of the clock signal is equal to a charging time that the timing capacitor charges to an upper reference voltage plus a discharging time that the timing capacitor discharges to a lower reference voltage. The timing circuit increases the charging time of the timing capacitor by decreasing a rate at which the timing capacitor is charged to increase the switching period of the clock signal if an on time of the switch is greater than or equal to a threshold time.