DC-DC converter, timing signal generating circuit, and operating method thereof

摘要

A DC-DC converter including an output stage, a feedback loop, a pulse-width modulation (PWM) generating circuit, and a driving circuit is disclosed. The output stage is coupled to an input voltage and an output inductor to provide an output voltage. The feedback loop is coupled to the output inductor and receives the output voltage to generate a control signal. The PWM generating circuit is coupled to the feedback loop and receives the control signal. The PWM generating circuit also includes a timing signal generating unit which makes the PWM generating circuit to generate a PWM signal according to a correction voltage. The correction voltage is reacted in the output voltage and a first current source related to the input voltage. The driving circuit is coupled to the output stage and the PWM generating circuit and receives the PWM signal to control the operation of the output stage.

主权项

1. A DC-DC converter, coupled to an input voltage and an output inductor, the DC-DC converter comprising:
an output stage, coupled to the input voltage and the output inductor and providing an output voltage; a feedback loop, coupled to the output inductor and receiving the output voltage to generate a control signal; a pulse-width modulation (PWM) generating circuit, coupled to the feedback loop and receiving the control signal, wherein the PWM generating circuit comprises a timing signal generating unit, the timing signal generating unit generates an on-time signal according to a correction voltage of the timing signal generating unit and the PWM generating circuit generates a PWM signal according to the on-time signal, and the correction voltage responds the output voltage and a first current source of the timing signal generating unit, and the first current source is a function of the input voltage, and the first current source is varied with a changing of the input voltage; and a driving circuit, coupled to the output stage and the PWM generating circuit and receiving the PWM signal to control the operation of the output stage, wherein the timing signal generating unit comprises: a first comparator having a first input terminal and a second input terminal; a correction circuit comprising the first current source and a correction resistor, wherein the first input terminal of the first comparator is coupled between the first current source and the correction resistor, wherein the correction circuit further comprises a first buffer unit coupled between a terminal of the correction resistor and the output voltage; and a timing signal circuit comprising a second current source, a switch, and a-capacitor, wherein the timing signal circuit is coupled to the second input terminal of the first comparator.