Load current management circuit

• US 8,749,174 B2
• Filed: 08/31/2011
• Issued: 06/10/2014
• Est. Priority Date: 08/31/2011
• Status: Expired due to Fees

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Angeles, Christian Pura
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US13/223,080
• Publication Number:
  US 20130049622A1
• Time in Patent Office: 1,014 Days
• Field of Search: 315/307, 315/308, 315/291, 315/DIG.4, 315/193, 315/185.R, 315/246, 315/276, 315/219, 315/224
• US Class Current: 315/307
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

A circuit includes a switching power converter and a load current management circuit. The switching power converter provides a first current that varies between a first current value and a second current value in response to a dimming control signal. The load current management circuit provides a second current that varies between the second current value and a third current value in response to the dimming control signal. The second current varies in accordance with the first current. For example, the second current increases as the first current decreases and the second current decreases as the first current increases. In one example, the second current value corresponds to a required minimum load current for the power converter to regulate an output voltage.

Claims

1. A circuit comprising:

a switching power converter that is operative to provide a first current in response to a dimming control signal; and

a load current management circuit that is operative to provide a second current in response to the dimming control signal, wherein the second current increases as the first current decreases.

2. The circuit of claim 1 wherein the second current decreases as the first current increases.

3. The circuit of claim 1 comprising a load that consumes a third current, wherein the third current is based on the first current and the second current.

4. The circuit of claim 3 wherein the load comprises at least one light emitting diode.

5. The circuit of claim 3 wherein:

the first current varies between a first current value and a second current value based on the dimming control signal;

the second current varies between the second current value and a third current value based on the dimming control signal; and

the third current is approximately the first current value when first current is approximately the first current value and the second current is approximately the third current value.

6. The circuit of claim 5 wherein the first current value is greater than the second current value and the second current value is greater than the third current value.

7. The circuit of claim 1 wherein the load current management circuit comprises a signal controlled current source, operatively coupled in parallel to a load, that is operative to provide the second current based on the dimming control signal.

8. The circuit of claim 7 wherein the load current management circuit comprises an inverter circuit, operatively coupled to the signal controlled current source, that is operative to provide an inverted signal based on the dimming control signal.

9. The circuit of claim 7 wherein the load current management circuit comprises a pulse width modulation to analog converter circuit that is operative to provide an analog signal based on a duty ratio of the dimming control signal.

10. The circuit of claim 5 wherein the second current value corresponds to a required minimum load current for the power converter to regulate an output voltage.

11. A circuit comprising:

a switching power converter that is operative to provide a first current that varies between a first current value and a second current value in response to a dimming control signal; and

a load current management circuit that is operative to provide a second current that varies between the second current value and a third current value in response to the dimming control signal, wherein the second current varies in accordance with the first current.

12. The circuit of claim 11 wherein the second current increases as the first current decreases.

13. The circuit of claim 11 wherein the second current decreases as the first current increases.

14. The circuit of claim 11 wherein the second current value corresponds to a required minimum load current for the power converter to regulate an output voltage.

15. The circuit of claim 11 comprising a load that consumes a third current, wherein the third current is based on the first current and the second current.

16. The circuit of claim 15 wherein the load comprises at least one light emitting diode.

17. The circuit of claim 11 wherein the load current management circuit comprises a signal controlled current source, operatively coupled in parallel to a load, that is operative to provide the second current based on the dimming control signal.

18. The circuit of claim 17 wherein the load current management circuit comprises an inverter circuit, operatively coupled to the signal controlled current source, that is operative to provide an inverted signal based on the dimming control signal.

19. The circuit of claim 17 wherein the load current management circuit comprises a pulse width modulation to analog converter circuit that is operative to provide an analog signal based on a duty ratio of the dimming control signal.

20. The circuit of claim 11 wherein the second current value corresponds to a required minimum load current for the power converter to regulate an output voltage.