Abstract: A PWM control unit is provided. A comparison unit compares an output voltage with a reference voltage to generate a first compared result, and controls a voltage of a first node. A constant current source is coupled to the first node. A storage module is coupled to the first node and receives a ground voltage. A first comparator compares the output voltage with the voltage of the first node to generate a turn-on signal. A second comparator compares the voltage of the first node with the input voltage to generate an output signal. A logic gate generates a turn-off signal according to the turn-on and output signals. When each of the turn-on and output signals is at a first level, a logic gate asserts the turn-off signal at a second level. The PWM generator combines the turn-on and turn-off signals to generate a PWM signal.

Abstract: A PWM control unit is provided. A comparison unit compares an output voltage with a reference voltage to generate a first compared result, and controls a voltage of a first node. A constant current source is coupled to the first node. A storage module is coupled to the first node and receives a ground voltage. A first comparator compares the output voltage with the voltage of the first node to generate a turn-on signal. A second comparator compares the voltage of the first node with the input voltage to generate an output signal. A logic gate generates a turn-off signal according to the turn-on and output signals. When each of the turn-on and output signals is at a first level, a logic gate asserts the turn-off signal at a second level. The PWM generator combines the turn-on and turn-off signals to generate a PWM signal.