Switched mode power supply and controlling method thereof

• US 6,333,862 B1
• Filed: 08/11/1999
• Issued: 12/25/2001
• Est. Priority Date: 08/11/1998
• Status: Expired due to Term

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Lee, Dong Ju, Pyeon, Dae Beum
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US09/373,075
• Time in Patent Office: 867 Days
• Field of Search: 363/16, 363/17, 363/20, 363/21, 363/95, 363/97, 363/131
• US Class Current: 363/21.01
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/0041 Control circuits in which a clock signal is selectively enabled or disabled
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• 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

A power supply circuit includes a power converter and a control circuit. The power converter converts AC power to DC power, and the control circuit controls operation of the power converter. The control circuit repeatedly enables the conversion operation of the power converter for a first predetermined period of time and disables the conversion operation for a second predetermined period of time, greater than said first predetermined period of time, in a power saving mode of operation.

Claims

1. A power supply circuit, comprising:

a power converter converting AC power to DC power to supply the DC power to at least one load;

a control circuit controlling operation of the power converter, the control circuit detecting if the load consumes the DC power, and placing the power supply circuit in a power-saving mode if the load does not consume power for a predetermined amount of time, the control circuit repeatedly enabling the conversion operation of the power converter for a first predetermined period of time and disabling the conversion operation for a second predetermined period of time, greater than said first predetermined period of time, in the power savings mode of operation.

2. The power supply circuit of claim 1, wherein the power converter is the only power converter.

3. The power supply circuit of claim 1, wherein the control circuit automatically repeatedly enables and disables the conversion operation in the power saving mode.

4. The power supply circuit of claim 1, wherein the ratio of the first predetermine period of time to a sum of the first and second predetermined periods of time is less than or equal to 0.025.

5. The power supply circuit of claim 1, wherein the control circuit comprises:

a detector detecting an output DC voltage of the power converter;

a driving controller controlling operation of the power converter based on output from the detector so that the power converter outputs the DC voltage at a constant level.

6. The power supply circuit of claim 5, wherein the control circuit further comprises:

a feedback control circuit generating a first control signal; and

wherein

the driving controller enables and disables the conversion operation of the power converter based on the control signal.

7. The power supply circuit of claim 6, wherein the feedback control circuit comprises:

a microcomputer generating a second control signal indicating whether to enable or disable the power converter, the microcomputer generating the second control signal to enable the conversion operation of the power converter for the first predetermined period of time and to disable the conversion operation for the second predetermined period of time in the power saving mode of operation; and

a signal feedback circuit generating the first control signal based on the second control signal.

8. The power supply circuit of claim 7, wherein the signal feedback circuit comprises:

an opto-isolator operating in accordance with the second control signal; and

a first switching device turning on and off to supply the first control signal to the driving controller based on output from the opto-isolator.

9. The power supply circuit of claim 8, wherein the opto-isolator is a photo-coupler.

10. The power supply circuit of claim 8, wherein

the driving controller includes a second switching device which turns on and off to enable the conversion operation;

and

the first switching device turns the second switching device off for the second predetermined period of time to disable the power conversion operation in the power savings mode.

11. The power supply circuit of claim 7, wherein

the driving controller includes a first switching device which turns on and off to enable the conversion operation;

and

the signal feedback circuit generates the first control signal to turn off the first switching device during the second predetermined period of time in the power savings mode.

12. The power supply circuit of claim 7, wherein the control circuit further comprises:

a back-up power storage unit supplying power to the microcomputer when the power converter is disabled; and

wherein

the microcomputer receives the DC voltage from the power converter as a source of power.

13. The power supply circuit of claim 6, wherein

the driving controller includes a first switching device, which turns on and off to enable the conversion operation, and control circuitry, which controls operation of the first switching device based on the output of the detector and a power supplied to the power supply circuit;

and

the feedback control circuit includes a second switching device controlling a supply of power to the control circuitry as a first control signal, a third switch controlling operation of the second switch, and feedback circuitry controlling operation of the third switch such that the second switch cuts off the supply of power to the control circuitry during the second predetermined period of time in the power savings mode.

14. The power supply circuit of claim 1, wherein the control circuit comprises:

a first switching device, which turns on and off to enable the conversion operation; and

a feedback control circuit turning the first switching device off during the second predetermined period of time in the power savings mode.

15. The power supply circuit of claim 14, wherein the feedback control circuit comprises:

a second switching device controlling operation of the first switching device; and

a controller controlling operation of the second switching device to turn the first switching device off during the second predetermined period of time in the power savings mode.

16. The power supply circuit of claim 15, wherein the feedback control circuit further comprises:

a detector detecting an output DC voltage of the power converter; and

a third switching device controlling operation of the first switching device based on output from the detector so that the power converter outputs the DC voltage at a constant level.

17. The power supply circuit of claim 1, wherein the control circuit comprises:

a switching device selectively supplying a source of AC power to the power converter; and

a feedback control circuit controlling operation of the switching device so that the switching device disconnects the source of AC power from the power converter during the second predetermined period of time in the power savings mode.

18. The power Supply circuit of claim 1, wherein the control circuit is powered by a DC voltage output from the power converter, and includes a back-up power storage unit supplying power when the power converter is disabled.

19. The power supply circuit of claim 1, wherein

the power converter provides a plurality of DC voltage outputs;

and

the control circuit includes a switching unit selectively outputting each of the DC voltage outputs.

20. A power supply circuit, comprising:

a power converter converting AC power to DC power to supply the DC power to at least one load; and

a control circuit controlling operation of the power converter, the control circuit detecting if the load consumes the DC power, and placing the power supply circuit in a power saving mode if the load does not consume power for a predetermined amount of time, controlling a supply of the AC power to the power converter such that the power converter is periodically disconnected from the AC power during the power savings mode.

21. The power supply circuit of claim 20, wherein the control circuit comprises:

a first switching device selectively supplying the AC power to the power converter in response to a control signal; and

a feedback circuit generating the control signal such that the first switching device periodically disconnects the AC power from the power converter during the power savings mode.

22. The power supply circuit of claim 21, wherein the feedback circuit comprises:

a photo-coupler generating the control signal in response to an instruction signal; and

a microcomputer generating the instruction signal.

23. The power supply circuit of claim 21, wherein the control circuit further comprises:

a detector detecting an output DC voltage of the power converter; and

a driving controller controlling operation of the power converter based on output from the detector so that the power converter outputs the DC voltage at a constant level.

24. A method of supplying power, comprising:

detecting whether at least one load connected to a power converter consumes power output from the power converter,

judging that operation in a power savings mode should occur when the detecting step indicates that the load has not consumed power for a predetermined amount of time; and

alternately enabling and disabling a power conversion operation of a power converter such that the power conversion operation is enabled for a first predetermined period of time and is disabled for a second predetermined period of time, greater than the first predetermined period of time, when the judging step judges that operation in the power savings mode should occur.

25. The method of claim 24, wherein the ratio of the first predetermined period of time to a sum of the first and second predetermined periods of time is less than or equal to 0.025.

26. The method of claim 24, further comprising:

receiving input instructing that a normal mode of power conversion should occur; and

continuously enabling the power conversion operation in response to the received input.

27. The method of claim 24, wherein the first predetermined period of time corresponds to a charging time of a back-up power storage unit in a control circuit controlling operation of the power converter, and the second predetermined period of time corresponds to a discharging time of the back-up power storage unit.

28. The method of claim 24, wherein the enabling and disabling step enables and disables the power conversion operation by connecting and disconnecting an AC power source to and from the power converter.

29. The method of claim 28, wherein the first predetermined period of time corresponds to a charging time of a back-up power storage unit in a control circuit controlling operation of the power converter, and the second predetermined period of time corresponds to a discharging time of the back-up power storage unit.

30. A power supply circuit, comprising:

a power converter converting AC power to DC power to supply the DC power to at least one load;

a detector detecting an output DC voltage of the power converter;

a driving controller controlling operation of the power converter based on output from the detector and a control signal so that the power converter outputs the DC voltage at a constant level;

a microcomputer determining based on output of the detector if the load consumes the DC power, placing the power supply circuit in a power saving mode if the load does not consume power for a predetermined amount of time, and generating the control signal to enable the conversion operation of the power converter for the first predetermined period of time and to disable the conversion operation for the second predetermined period of time in the power saving mode of operation, the microcomputer receiving power from the power converter when the power converter is enabled; and

a back-up power storage unit supplying power to the microcomputer when the power converter is disabled.

31. The power supply circuit of claim 30, wherein the back-up power supply stores the DC power output from the power converter when the power converter is enabled.

32. The power supply circuit of claim 31, wherein the backup power supply includes a capacitor.