Power supply circuit with PFC function, and automatic gain control circuit therefor and control method thereof
First Claim
1. A power supply circuit, comprising:
- an automatic gain control circuit, including;
a voltage-to-current converter circuit for converting an input voltage to a regulation current;
a current-to-voltage converter circuit, which is coupled to the voltage-to-current converter circuit, for converting the regulation current to a regulation voltage;
a low-pass filter circuit, which is coupled to the current-to-voltage converter circuit, for obtaining a low frequency signal from the regulation voltage; and
a comparison circuit, which is coupled to the low-pass filter circuit, for generating a control signal according to the low frequency signal and a reference voltage; and
a load driver circuit, which is coupled to the current-to-voltage converter circuit, for converting the input voltage or the regulation voltage to the output voltage and supplying an output current, wherein the output current is in phase with the regulation voltage;
wherein the control signal is inputted to the voltage-to-current converter circuit or the current-to-voltage converter circuit, for adjusting a conversion ratio from the input voltage to the regulation current, or from the regulation current to the regulation voltage.
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Accused Products
Abstract
The present invention discloses a power supply circuit with power factor correction (PFC) function, and an automatic gain control circuit therefor and a control method thereof. The power supply circuit includes the automatic gain control circuit and a load driver circuit. The automatic gain control circuit converts an input voltage to a regulation voltage, and the load driver circuit generates an output current according to the regulation voltage. The automatic gain control circuit automatically adjust the regulation voltage such that the regulation voltage has a substantially fixed amplitude or fixed average value under different input voltages of different specifications, and the output current provided by the load driver circuit varies in phase with the input voltage to provide a PFC function.
12 Citations
25 Claims
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1. A power supply circuit, comprising:
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an automatic gain control circuit, including; a voltage-to-current converter circuit for converting an input voltage to a regulation current; a current-to-voltage converter circuit, which is coupled to the voltage-to-current converter circuit, for converting the regulation current to a regulation voltage; a low-pass filter circuit, which is coupled to the current-to-voltage converter circuit, for obtaining a low frequency signal from the regulation voltage; and a comparison circuit, which is coupled to the low-pass filter circuit, for generating a control signal according to the low frequency signal and a reference voltage; and a load driver circuit, which is coupled to the current-to-voltage converter circuit, for converting the input voltage or the regulation voltage to the output voltage and supplying an output current, wherein the output current is in phase with the regulation voltage; wherein the control signal is inputted to the voltage-to-current converter circuit or the current-to-voltage converter circuit, for adjusting a conversion ratio from the input voltage to the regulation current, or from the regulation current to the regulation voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An automatic gain control circuit of a power supply circuit, wherein the power supply circuit is for converting an input voltage to an output voltage and supplying an output current, wherein the output current is in phase with the input voltage, the automatic gain control circuit comprising:
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a voltage-to-current converter circuit, for converting the input voltage to a regulation current; a current-to-voltage converter circuit, which is coupled to the voltage-to-current converter circuit, for converting the regulation current to a regulation voltage; a low-pass filter circuit, which is coupled to the current-to-voltage converter circuit, for obtaining a low frequency signal from the regulation voltage; and a comparison circuit, which is coupled to the low-pass filter circuit, for generating a control signal according to the low frequency signal and a reference voltage; wherein the control signal is inputted to the voltage-to-current converter circuit or the current-to-voltage converter circuit, for adjusting a conversion ratio from the input voltage to the regulation current, or from the regulation current to the regulation voltage. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification