Voltage detecting circuit for switching converters and the method thereof

摘要

A voltage detecting circuit used with a switching converter. The switching converter having an energy storage component, a first power switch and a second switch. The voltage detecting circuit has a sample and hold circuit configured to sample and hold the voltage at the connection node of the energy storage component and the first power switch when the first power switch is OFF and the second power switch is ON; and an average circuit configured to average the sampled voltage during a switching period to generate a detecting signal in proportional to the output voltage of the switching converter.

主权项

1. A voltage detecting circuit used with a switching converter, wherein the switching converter comprises an energy storage component, a first power switch and a second power switch coupled to the energy storage component, and the energy storage component stores energy when the first power switch is ON and provides energy to a load when the first power switch is OFF, the voltage detecting circuit comprising:
a sample and hold circuit having an input terminal and an output terminal, wherein the input terminal is coupled to a connection node of the energy storage component and the first power switch, and wherein the sample and hold circuit samples the voltage at the connection node when the first power switch is OFF and the second power switch is ON, and provides a sampled signal at the output terminal; and an average circuit having an input terminal and an output terminal, wherein the input terminal is coupled to the output terminal of the sample and hold circuit to receive the sampled signal, and the average circuit performs an arithmetic operation on the sampled signal and provides a detecting signal based on the sampled signal at the output terminal, wherein the detecting signal is in proportional to the output voltage; wherein the average circuit comprises: a first switch having a first terminal, a second terminal and a control terminal, wherein the first terminal is coupled to the output terminal of the sample and hold circuit, and the control terminal is configured to receive a first control signal, and wherein the first switch is turned ON by the first control signal when the first power switch is ON, and is turned OFF by the first control signal when the first power switch is OFF; a second switch having a first terminal, a second terminal and a control terminal, wherein the first terminal is coupled to the second terminal of the first switch, the second terminal is coupled to a reference ground, and the control terminal is configured to receive a second control signal, and wherein the second switch is turned ON by the second control signal when the second power switch is ON, and is turned OFF by the second control signal when the second power switch is OFF; and a low pass filter circuit having an input terminal coupled to the connection node of the first switch and the second switch, and an output terminal configured to provide a detecting signal indicating the output voltage of the switching converter.