Feedback control circuit and method thereof

• US 9,712,057 B1
• Filed: 07/21/2016
• Issued: 07/18/2017
• Est. Priority Date: 01/15/2016
• Status: Active Grant

• Current Assignee: Realtek Semiconductor Corp.
• Original Assignee: Realtek Semiconductor Corp.
• Inventors: Lin, Chih-Cheng, Chen, Shih-Chieh
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): Demisse, Afework
• Application Number:
  US15/216,657
• Publication Number:
  US 20170207702A1
• Time in Patent Office: 362 Days
• Field of Search: 323223, 323241, 323271, 323282-285
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Disclosed are a feedback control circuit and a method thereof. The feedback control circuit includes a voltage comparator, a calibration voltage generator and processor. The voltage comparator receives a middle-point voltage and a calibration voltage, compares the middle-point voltage and calibration voltage, and outputs a reference voltage pulse signal. The calibration voltage generator generates the calibration voltage and outputs it to a switch driving circuit and the voltage comparator. The processor compares the pulse widths of the reference voltage pulse signal and a predetermined voltage pulse signal, and accordingly outputs a control signal to the calibration voltage generator to fine tune the calibration voltage. The switch driving circuit outputs a switch driving signal to a switching regulating circuit to adjust the timing when to turn on or off switches in the switching regulating circuit.

Claims

1. A feedback control circuit, used to adjust the timing for turning on or off switches in a switching regulating circuit wherein the switch regulating circuit is electrically connected to a switch driving circuit, the feedback control circuit comprising:

a voltage comparator, receiving and comparing a calibration voltage and a middle-point voltage of the switch regulating circuit and outputting a reference voltage pulse signal;

a calibration voltage generator, electrically connected to the voltage comparator and the switch driving circuit, generating and transmitting the calibration voltage to the switch driving circuit and the voltage comparator; and

a processor, receiving the reference voltage pulse signal and a predetermined voltage pulse signal, comparing pulse widths of the reference voltage pulse signal and the predetermined voltage pulse signal and outputting a control signal to the calibration voltage generator to adjust the calibration voltage;

wherein the switch driving circuit outputs a set of switching driving signals to the switch regulating circuit according to the calibration voltage, to adjust the timing when to turn on or off the switches in the switching regulating circuit.

2. The feedback control circuit according to claim 1,

wherein the calibration voltage generator lowers the calibration voltage according to the control signal if the pulse width of the reference voltage pulse signal is larger than the pulse width of the predetermined voltage pulse signal;

and

wherein the calibration voltage generator raises the calibration voltage according to the control signal if the pulse width of the reference voltage pulse signal is smaller than the pulse width of the predetermined voltage pulse signal.

3. The feedback control circuit according to claim 1, wherein the switch driving signals comprise an upper-bridge switch driving signal and a lower-bridge switch driving signal, and the switch regulating circuit comprises:

an upper-bridge switch, having a gate receiving the upper-bridge switch driving signal and having a source receiving a power voltage; and

a lower-bridge switch, having a gate receiving the lower-bridge switch driving signal, having a drain electrically connected to a drain of the upper-bridge switch and having a source electrically connected to a grounding voltage, wherein the middle-point voltage is the voltage of drain of the lower-bridge switch;

an inductor, having one end electrically connected to a drain of the lower-bridge switch;

a resistor, having one end electrically connected to the other end of the inductor; and

a capacitor, having one end electrically connected to the other end of the resistor and having the other end electrically connected to the grounding voltage.

4. The feedback control circuit according to claim 1, wherein the processor comprises:

a first counter, electrically connected to the voltage comparator, receiving the reference voltage pulse signal, and converting the pulse width of the reference voltage pulse signal into a first counting value;

a second counter, receiving the predetermined voltage pulse signal, and converting the pulse width of the predetermined voltage pulse signal into a second counting value; and

a controller, electrically connected to the first counter and the second counter, receiving and comparing the first counting value and the second counting value, and outputting the control signal to the calibration voltage generator according to a comparison result, to adjust the calibration voltage.

5. The feedback control circuit according to claim 4, wherein the first counter and the second counter simultaneously receive a clock signal, and the second counting value is predetermined.

6. The feedback control circuit according to claim 4,

wherein the calibration voltage generator lowers the calibration voltage according to the control signal if the first counting value is larger than the second counting value;

and

wherein the calibration voltage generator raises the calibration voltage according to the control signal if the first counting value is smaller than the second counting value.

7. A feedback control method, used in a feedback control circuit, the feedback control circuit comprising a voltage comparator, a calibration voltage generator and a processor, wherein the feedback control circuit is used to adjust the timing for turning on or off switches in a switching regulating circuit, the switch regulating circuit is electrically connected to a switch driving circuit, the calibration voltage generator is electrically connected to the voltage comparator and the switch driving circuit, and the processor is electrically connected to the voltage comparator and the calibration voltage generator, the feedback control method comprising:

receiving and comparing a calibration voltage and a middle-point voltage of the switch regulating circuit and outputting a reference voltage pulse signal, via the voltage comparator;

generating and transmitting a calibration voltage to the switch driving circuit and the voltage comparator via the calibration voltage generator; and

receiving a predetermined voltage pulse signal, comparing the pulse widths of the predetermined voltage pulse signal and the reference voltage pulse signal, and outputting a control signal to the calibration voltage generator to adjust the calibration voltage, wherein the switch driving circuit outputs a set of switch driving signals to the switch regulating circuit according to the calibration voltage, to adjust the timing when to turn on or off switches in the switching regulating circuit.

8. The feedback control method according to claim 7,

wherein the calibration voltage generator lowers the calibration voltage according to the control signal if the pulse width of the reference voltage pulse signal is larger than the pulse width of the predetermined voltage pulse signal;

and

wherein the calibration voltage generator raises the calibration voltage according to the control signal if the pulse width of the reference voltage pulse signal is smaller than the pulse width of the predetermined voltage pulse signal.

9. The feedback control method according to claim 7, wherein the processor comprises:

a first counter, electrically connected to the voltage comparator, receiving the reference voltage pulse signal, and converting the pulse width of the reference voltage pulse signal into a first counting value;

a second counter, receiving the predetermined voltage pulse signal, and converting the pulse width of the predetermined voltage pulse signal into a second counting value; and

a controller, electrically connected to the first counter and the second counter, receiving and comparing the first counting value and the second counting value, and outputting the control signal to the calibration voltage generator according to a comparison result, to adjust the calibration voltage.

10. The feedback control method according to claim 9,

wherein lowering the calibration voltage via the calibration voltage generator according to the control signal if the first counting value is larger than the second counting value;

and

wherein raising the calibration voltage via the calibration voltage generator according to the control signal if the first counting value is smaller than the second counting value.