DC-DC converter control method and DC-DC converter control circuit

摘要

The transient response of an output voltage to a load fluctuation is improved, in a switching power source that carries out a PWM control. In a DC-DC converter wherein a switching element of an output stage is controlled by a drive signal, whose pulse width is set at a minimum value, output from a PWM signal generating circuit based on an output voltage output from an error amplifier in accordance with the difference between a feedback voltage in accordance with an output voltage of the output stage and a reference voltage, there is provided a minimum pulse width detector circuit that supplies a current to a phase compensation capacitor when the pulse width of the drive signal is at the minimum value, thus preventing the output voltage from dropping below a value corresponding to the minimum value when the load fluctuates, and improving transient response characteristics of the output voltage.

主权项

1. A method of controlling a DC-DC converter including an error amplifier that amplifies and outputs a difference in voltage between a feedback voltage output from an output stage and a reference voltage, a phase compensation capacitor connected to an output of the error amplifier, and a PWM (pulse width modulation) signal generating circuit that outputs an output signal driving a switching element of the output stage, the output signal having a pulse width that changes in accordance with an output voltage of the error amplifier, the method comprising:
setting a non-zero minimum value for the pulse width of the output signal of the PWM signal generating circuit; and supplying a current to the phase compensation capacitor, in response to detecting that the pulse width of the output signal has become less than the non-zero minimum value.