METHOD AND APPARATUS FOR STARTING UP

• US 20130242622A1
• Filed: 03/14/2013
• Published: 09/19/2013
• Est. Priority Date: 03/14/2012
• Status: Active Grant

• Current Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Choi, Jinho, Shu, Biing Long, PENG, Hao
• Granted Patent: US 9,093,907 B2
• Time in Patent Office: Days
• US Class Current: 363/21.12
• 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: H02M 3/33546 with automatic control of the output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/385 using flyback topology

Abstract

Aspects of the disclosure provide a method. The method includes receiving an input voltage rectified from an alternating current (AC) power supply, detecting a time duration that the input voltage is between a first threshold voltage and a second threshold voltage, determining a line voltage of the AC power supply based on the time duration, and regulating a time for turning on a switch to transfer energy via a transformer based on the detected line voltage.

Claims

1. A method, comprising:

receiving an input voltage rectified from an alternating current (AC) power supply;

detecting a time duration that the input voltage is between a first threshold voltage and a second threshold voltage;

determining a line voltage of the AC power supply based on the time duration; and

regulating a time for turning on a switch to transfer energy via a transformer based on the detected line voltage.

2. The method of claim 1, further comprising:

regulating the time for turning on the switch to transfer energy via the transformer at a power up based on an assumption that the AC power supply is a high line AC power supply with a dimmer.

3. The method of claim 2, wherein regulating the time for turning on the switch to transfer energy via the transformer at the power up comprises:

regulating the time for turning on the switch to limit a substantially constant peak current flowing through the switch.

4. The method of claim 3, wherein regulating the time for turning on the switch to limit the substantially constant peak current flowing through the switch further comprises:

generating pulses with a pulse width modulated based on a sensed current.

5. The method of claim 1, wherein determining the line voltage of the AC power supply based on the time duration comprises:

determining the line voltage to be a high line voltage when a ratio of the detected time duration to an AC cycle is lower than a first value; and

determining the line voltage to be a low line voltage when the ratio is high than a second value that is higher than the first value.

6. The method of claim 1, further comprising:

determining whether a dimmer exists based on the time duration.

7. The method of claim 6, wherein determining whether the dimmer exists based on the time duration further comprises:

determining that the dimmer exists when the time duration is smaller than a threshold.

8. A circuit comprising:

a detector configured to receive an input voltage rectified from an alternating current (AC) power supply, and detect a time duration that the input voltage is between a first threshold voltage and a second threshold voltage; and

a controller configured to determine a line voltage of the AC power supply based on the time duration and regulate a time for turning on a switch to transfer energy via a transformer based on the detected line voltage.

9. The circuit of claim 8, wherein the controller is configured to regulate the time for turning on the switch to transfer energy via the transformer at a power up based on an assumption that the AC power supply is a high line AC power supply with a dimmer.

10. The circuit of claim 9, wherein the controller is configured to regulate the time for turning on the switch to limit a substantially constant peak current flowing through the switch at the power up.

11. The circuit of claim 10, wherein the controller is configured to generate pulses with a pulse width modulated based on a sensed current.

12. The circuit of claim 8, wherein the controller is configured to determine the line voltage to be a high line voltage when a ratio of the time duration to an AC cycle is lower than a first value and determine the line voltage to be a low line voltage when the ratio is high than a second value that is higher than the first value.

13. The circuit of claim 8, wherein the controller is configured to determine whether a dimmer exists based on the time duration.

14. The circuit of claim 13, wherein the controller is configured to determine that the dimmer exists when the time duration is smaller than a threshold.

15. An apparatus comprising:

an energy transfer module configured to transfer electric energy from a AC power supply to an output device;

a detector configured to receive an input voltage rectified from the alternating current (AC) power supply, and detect a time duration that the input voltage is between a first threshold voltage and a second threshold voltage; and

a controller configured to determine a line voltage of the AC power supply based on the time duration and regulate a time for turning on a switch of the energy transfer module to transfer energy via a transformer based on the detected line voltage.

16. The apparatus of claim 15, wherein the controller is configured to regulate the time for turning on the switch to transfer energy via the transformer at a power up based on an assumption that the AC power supply is a high line AC power supply with a dimmer.

17. The apparatus of claim 16, wherein the controller is configured to regulate the time for turning on the switch to limit a substantially constant peak current flowing through the switch at the power up.

18. The apparatus of claim 17, wherein the controller is configured to generate pulses with a pulse width modulated based on a sensed current.

19. The apparatus of claim 15, wherein the controller is configured to determine the line voltage to be a high line voltage when a ratio of the time duration to an AC cycle is lower than a first value and determine the line voltage to be a low line voltage when the ratio is high than a second value that is higher than the first value.

20. The apparatus of claim 15, wherein the controller is configured to determine an existence of a dimmer when the time duration is smaller than a threshold.