Power supply circuit and method for driving the same

• US 9,304,523 B2
• Filed: 01/15/2013
• Issued: 04/05/2016
• Est. Priority Date: 01/30/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Takahashi, Kei, Hiroki, Masaaki
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US13/741,468
• Publication Number:
  US 20130193874A1
• Time in Patent Office: 1,176 Days
• Field of Search: 315/186, 315/200.R, 315/247, 315/291, 315/307, 315/312, 315/278, 315/297, 363/126, 363/127, 363/21.04, 363/21.11, 323/271
• US Class Current: 1/1
• CPC Class Codes: G05F 1/468 characterised by reference voltage circuitry, e.g. soft start, remote shutdown
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 7/00 Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
• CPC Class Codes: H05B 44/00 Circuit arrangements for operating electroluminescent light sources for operating light emitting diodes H05B45/00
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A power supply circuit with high power efficiency is provided. Alternatively, a power supply circuit with high power efficiency that is suitable for driving a light-emitting device is provided. The power supply circuit can switch current control in which driving is controlled based on information on current flowing through a load and voltage control in which driving is controlled based on information on voltage applied to a load. In a period during which voltage control is performed, a current detector for detecting current flowing through the load is deactivated so that current does not flow through the current detector.

Claims

1. A power supply circuit comprising:

a power converter;

a load;

a first detector comprising a first resistor and a first switch;

a second detector comprising at least a second resistor and a third resistor; and

a controller being electrically connected to the first detector and the second detector,

wherein a first terminal of the load is electrically connected to the power converter and a first terminal of the second resistor,

wherein a second terminal of the load is electrically connected to a first terminal of the first resistor, a first terminal of the first switch, and a first terminal of the third resistor,

wherein a second terminal of the first resistor is electrically connected to a second terminal of the first switch,

wherein a second terminal of the second resistor is electrically connected to a second terminal of the third resistor, and

wherein the controller is configured to generate a signal based on at least one of a potential supplied from the first detector and a potential supplied from the second detector, and supply the signal to the power converter.

2. The power supply circuit according to claim 1, wherein the second terminal of the first resistor and the second terminal of the first switch are grounded.

3. The power supply circuit according to claim 1,

wherein the controller comprises a second switch and a capacitor,

wherein a first terminal of the second switch is electrically connected to the second terminal of the second resistor,

wherein a second terminal of the second switch is electrically connected to a first terminal of the capacitor, and

wherein a second terminal of the capacitor is electrically connected to the first terminal of the third resistor.

4. The power supply circuit according to claim 3,

wherein the second switch comprises a transistor, and

wherein a channel formation region of the transistor comprises an oxide semiconductor layer.

5. The power supply circuit according to claim 1, wherein the controller comprises a first AD converter electrically connected to the first terminal of the first resistor, a second AD converter electrically connected to the second terminal of the second resistor, and a storage device electrically connected to the first AD converter and the second AD converter.

6. The power supply circuit according to claim 1,

wherein the controller is configured to generate the signal based on the potential of the first terminal of the first resistor when the first resistor is not short-circuited and the first switch is OFF state, and

wherein the controller is configured to generate the signal based on the potential of the second terminal of the second resistor when the first resistor is short-circuited and the first switch is ON state.

7. A power supply circuit comprising:

a power converter;

a load;

a first detector comprising a first resistor and a first switch;

a second detector comprising at least a second resistor and a third resistor; and

a controller being electrically connected to the first detector and the second detector,

wherein a first terminal of the load is electrically connected to the power converter and a first terminal of the second resistor,

wherein a second terminal of the load is electrically connected to a first terminal of the first resistor, a first terminal of the first switch, and a first terminal of the third resistor,

wherein a second terminal of the first resistor is electrically connected to a second terminal of the first switch,

wherein a second terminal of the second resistor is electrically connected to a second terminal of the third resistor, and

wherein the controller is configured to generate a signal based on at least one of a potential of the first terminal of the first resistor and a potential of the second terminal of the second resistor, and supply the signal to the power converter.

8. The power supply circuit according to claim 7, wherein the second terminal of the first resistor and the second terminal of the first switch are grounded.

9. The power supply circuit according to claim 7,

wherein the controller comprises a second switch and a capacitor,

wherein a first terminal of the second switch is electrically connected to the second terminal of the second resistor,

wherein a second terminal of the second switch is electrically connected to a first terminal of the capacitor, and

wherein a second terminal of the capacitor is electrically connected to the first terminal of the third resistor.

10. The power supply circuit according to claim 9,

wherein the second switch comprises a transistor, and

wherein a channel formation region of the transistor comprises an oxide semiconductor layer.

11. The power supply circuit according to claim 7, wherein the controller comprises a first AD converter electrically connected to the first terminal of the first resistor, a second AD converter electrically connected to the second terminal of the second resistor, and a storage device electrically connected to the first AD converter and the second AD converter.

12. The power supply circuit according to claim 7,

wherein the controller is configured to generate the signal based on the potential of the first terminal of the first resistor when the first resistor is not short-circuited and the first switch is OFF state, and

wherein the controller is configured to generate the signal based on the potential of the second terminal of the second resistor when the first resistor is short-circuited and the first switch is ON state.

13. A power supply circuit comprising:

a power converter;

a load;

a first detector comprising a first resistor and a first switch;

a second detector comprising at least a second resistor and a third resistor; and

a controller being electrically connected to the first detector and the second detector,

wherein a first terminal of the load is electrically connected to the power converter and a first terminal of the second resistor,

wherein a second terminal of the load is electrically connected to a first terminal of the first resistor, a first terminal of the first switch, and a first terminal of the third resistor,

wherein a second terminal of the first resistor is electrically connected to a second terminal of the first switch,

wherein a second terminal of the second resistor is electrically connected to a second terminal of the third resistor,

wherein the controller is configured to generate a signal based on at least one of a potential of the first terminal of the first resistor and a potential of the second terminal of the second resistor, and supply the signal to the power converter, and

wherein the load comprises a light-emitting element.

14. The power supply circuit according to claim 13, wherein the second terminal of the first resistor and the second terminal of the first switch are grounded.

15. The power supply circuit according to claim 13,

wherein the controller comprises a second switch and a capacitor,

wherein a first terminal of the second switch is electrically connected to the second terminal of the second resistor,

wherein a second terminal of the second switch is electrically connected to a first terminal of the capacitor, and

wherein a second terminal of the capacitor is electrically connected to the first terminal of the third resistor.

16. The power supply circuit according to claim 15,

wherein the second switch comprises a transistor, and

wherein a channel formation region of the transistor comprises an oxide semiconductor layer.

17. The power supply circuit according to claim 13, wherein the controller comprises a first AD converter electrically connected to the first terminal of the first resistor, a second AD converter electrically connected to the second terminal of the second resistor, and a storage device electrically connected to the first AD converter and the second AD converter.

18. The power supply circuit according to claim 13,

wherein the controller is configured to generate the signal based on the potential of the first terminal of the first resistor when the first resistor is not short-circuited and the first switch is OFF state, and

wherein the controller is configured to generate the signal based on the potential of the second terminal of the second resistor when the first resistor is short-circuited and the first switch is ON state.