Power converter circuit and control circuit thereof

Abstract

This disclosure provides a power converter circuit and its control circuit. The control circuit includes a proportional-integral (PI) circuit, a ramp generation circuit, and a comparator circuit. The PI circuit is coupled to the voltage output of the power converter circuit and outputs a proportional compensation signal and an integral compensation signal based on a reference signal and a feedback signal associated with the voltage output. The ramp generation circuit outputs a reference ramp signal and a ramp signal based on the reference signal. The comparator circuit is coupled to the PI circuit and the ramp generation circuit, receives the proportional compensation signal, the integral compensation signal, the reference ramp signal, and the ramp signal to output a trigger pulse signal, and generates a pulse in the trigger pulse signal when a first sum of the integral compensation signal and the ramp signal is greater than a second sum of the proportional compensation signal and the reference ramp signal.

Claims

1. A control circuit suitable for a power converter circuit, comprising: a proportional-integral circuit coupled to a voltage output terminal of the power converter circuit, configured to proportionally scale a first difference between a feedback signal associated with the voltage output terminal and a reference signal to output a proportional compensation signal, and to integrate a second difference between the reference signal and the feedback signal to output an integral compensation signal; a ramp generation circuit configured to output a reference ramp signal and a ramp signal based on the reference signal; and a comparator circuit coupled to the proportional-integral circuit and the ramp generation circuit, configured to receive the proportional compensation signal, the integral compensation signal, the reference ramp signal, and the ramp signal to output a trigger pulse signal, and to generate a pulse in the trigger pulse signal when a first sum of the integral compensation signal and the ramp signal is greater than a second sum of the proportional compensation signal and the reference ramp signal.

2. The control circuit as claimed in claim 1, wherein the proportional-integral circuit comprises: a proportional circuit for receiving the reference signal and the feedback signal, and for scaling the first difference associated with the feedback signal minus the reference signal to output the proportional compensation signal; and an integral circuit for receiving the reference signal and the feedback signal, and for integrating the second difference associated with the reference signal minus the feedback signal to output the integral compensation signal.

3. The control circuit as claimed in claim 2, wherein the proportional circuit comprises: an amplifier circuit, wherein a non-inverting input of the amplifier circuit is used to receive the feedback signal; a first resistor, wherein a first terminal of the first resistor is used to receive the reference signal, and a second terminal of the first resistor is coupled to an inverting input of the amplifier circuit; and a second resistor, wherein a first terminal of the second resistor is coupled to the second terminal of the first resistor and the inverting input of the amplifier circuit, and a second terminal of the second resistor is coupled to an output of the amplifier circuit, and wherein the output of the amplifier circuit outputs the proportional compensation signal.

4. The control circuit as claimed in claim 2, wherein the integrating circuit comprises: a transconductance amplifier circuit, wherein a non-inverting input of the transconductance amplifier circuit is used to receive the reference signal, and an inverting input of the transconductance amplifier circuit is used to receive the feedback signal; and a capacitor, wherein a first terminal of the capacitor is coupled to an output terminal of the transconductance amplifier circuit, and a second terminal of the capacitor is coupled to a ground terminal, and wherein the output terminal of the transconductance amplifier circuit outputs the integration compensation signal.

5. The control circuit as claimed in claim 1, wherein the proportional-integral circuit comprises: an operational circuit for receiving the reference signal and the feedback signal, and for outputting a first error signal, wherein the first error signal indicates the second difference; an inverting circuit coupled to the operational circuit for performing an inverse operation on the first error signal and for outputting a second error signal, wherein the second error signal indicates the first difference; an integrating circuit coupled to the operational circuit for performing an integral operation on the first error signal to output the integral compensation signal; and a proportional circuit coupled to the inverting circuit for scaling the second error signal to output the proportional compensation signal.

6. The control circuit as claimed in claim 1, wherein the ramp generation circuit comprises: a capacitor coupled to a first node and a ground terminal, wherein the ramp signal is output from the first node; a transconductance amplifier circuit coupled to the first node for receiving the reference signal and converting the reference signal into a reference current to charge the capacitor by the reference current, such that a voltage level of the ramp signal rises according to a preset slope; and a reset circuit coupled to the first node and the ground terminal for generating a discharge path between the first node and the ground terminal in response to a pulse in the trigger pulse signal, such that the voltage level of the ramp signal decreases to a ground voltage at the ground terminal.

7. The control circuit as claimed in claim 6, wherein the transconductance amplifier circuit comprises: a current generating circuit for generating a first current flowing through a second node and a third node based on the reference signal, and for generating the reference ramp signal at the third node based on the first current; and a current mirror circuit coupled to the second node and the first node, and for generating the reference current to the first node based on the first current.

8. The control circuit as claimed in claim 1, wherein the comparison circuit comprises: a comparator for comparing the proportional compensation signal, the integral compensation signal, the reference ramp signal, and the ramp signal to output a comparison signal, wherein a first inverting input of the comparator is used to receive the reference ramp signal, a second inverting input of the comparator is used to receive the proportional compensation signal, a first non-inverting input of the comparator is used to receive the integral compensation signal, and a second non-inverting input of the comparator is used to receive the ramp signal; and a pulse generation circuit coupled to an output of the comparator and used to generate the trigger pulse signal based on a voltage level of the comparison signal.

9. The control circuit as claimed in claim 1, wherein the comparison circuit comprises: a first operational circuit coupled to the proportional-integral circuit for receiving the proportional compensation signal and the reference ramp signal, and for generating a first operational signal, wherein the first operational signal indicates the second sum associated with the proportional compensation signal and the reference ramp signal; and a second operational circuit coupled to the proportional-integral circuit for receiving the integral compensation signal and the ramp signal, and for generating a second operational signal, wherein the second operational signal indicates the first sum associated with the integral compensation signal and the ramp signal; A comparator is used to compare the first operation signal and the second operation signal to output a comparison signal, wherein an inverting input of the comparator is used to receive the first operation signal and a non-inverting input of the comparator is used to receive the second operation signal; and a pulse generation circuit is coupled to an output of the comparator and used to generate the trigger pulse signal according to a voltage level of the comparison signal.

10. A power converter circuit for receiving an input voltage at a voltage input terminal and outputting an output voltage at a voltage output terminal, comprising: a power stage circuit coupled to the voltage input terminal and coupled to the voltage output terminal via an inductor; and a control circuit coupled to the power stage circuit and the voltage output terminal for generating a proportional compensation signal, an integral compensation signal, a reference ramp signal, and a ramp signal based on a reference signal and a feedback signal associated with the output voltage, and for adjusting an operating frequency of the power stage circuit to increase the output voltage when a first sum of the integral compensation signal and the ramp signal is greater than a second sum of the proportional compensation signal and the reference ramp signal, wherein the control circuit scales a first difference between the feedback signal and the reference signal to output the proportional compensation signal, and integrates a second difference between the reference signal and the feedback signal to output the integral compensation signal.

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