Current shaping for dimmable LED

Patent metadata

Field	Value
Publication number	US-9480112-B2
Application number	US-201414550259-A
Country	US
Kind code	B2
Filing date	Nov 21, 2014
Priority date	May 24, 2013
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

Aspects of the disclosure provide a circuit that includes a detector and a controller. The detector is configured to detect a firing start by a triode for alternating current (TRIAC) in a power supply. The controller is configured to control a switch in connection with a magnetic component in response to the firing start to shape a profile of a current pulled from the power supply to satisfy a latch current requirement and a hold current requirement of the TRIAC.

First claim

What is claimed is:

1. A circuit, comprising:
a detector to detect a firing start by a triode for alternating current (TRIAC) in a power supply based on a voltage output from a rectifier that rectifies an alternative current (AC) voltage from the power supply; and
a controller to vary a pulse width modulation (PWM) signal to voltage-control a switch in connection with a magnetic component in response to the firing start to turn on the switch, and turn off the switch when a switch current flowing through the magnetic component rises to a first peak current limit in a duration, and turn on the switch, and turn off the switch when the switch current flowing through the magnetic component rises to a second peak current limit in order to shape a profile of a current pulled from the power supply to satisfy a latch current requirement and a hold current requirement of the TRIAC.

2. The circuit of claim 1 , wherein the controller is configured to control at least one of a peak current limit and/or a frequency for generating the PWM signal to pull the current at a first level to enable enough latch current for the TRIAC at the firing start.

3. The circuit of claim 1 , wherein the controller is configured to control at least one of a peak current limit and a frequency for generating the PWM signal to pull the current at a second level that is lower than the first level to enable enough hold current for the TRIAC after the firing start.

4. The circuit of claim 1 , wherein the controller is configured to control at least one of a peak current limit and a frequency for generating the PWM signal to control at least one of a rising edge delay for the current to rise to the first level, a rising edge slope for the current to rise to the first level, a duration for the current to above a threshold, and a falling edge slope for the current to fall from the first level to the second level and to disable the PWM signal generation.

5. The circuit of claim 1 , wherein the detector detects the switching current passing through the switch, and the controller controls the switch according to the detected switching current to shape the current pulled from the power supply.

6. The circuit of claim 5 , wherein the current pulled from the power supply includes the switching current, and a damping current by a damping circuit.

7. The circuit of claim 6 , wherein a capacitance of the damping circuit is smaller than a specific value.

8. An apparatus, comprising:
a switch in connection with a magnetic component for transferring energy from an energy source to a load; and
an integrated circuit (IC) chip comprising:
a detector to detect a firing start by a triode for alternating current (TRIAC) in the energy source based on a voltage output from a rectifier that rectifies an alternative current (AC) voltage from the energy source; and
a controller to vary a pulse width modulation (PWM) signal to voltage-control the switch in response to the firing start to turn on the switch, and turn off the switch when a switch current flowing through the magnetic component rises to a first peak current limit in a duration, and turn on the switch, and turn off the switch when the switch current flowing through the magnetic component rises to a second peak current limit in order to shape a profile of a current pulled from the energy source to satisfy a latch current requirement and a hold current requirement of the TRIAC.

9. The apparatus of claim 8 , wherein the controller is configured to control at least one of a peak current limit and a frequency for generating the PWM signal to pull the current at a first level to enable enough latch current for the TRIAC at the firing start.

10. The apparatus of claim 8 , wherein the controller is configured to control at least one of a peak current limit and a frequency for generating the PWM signal to pull the current at a second level that is lower than the first level to enable enough hold current for the TRIAC after the firing start.

11. The apparatus of claim 8 , wherein the controller is configured to control at least one of a peak current limit and a frequency for generating the PWM signal to control at least one of a rising edge delay for the current to rise to the first level, a rising edge slope for the current to rise to the first level, a duration for the current to above a threshold, and a falling edge slope for the current to fall from the first level to the second level and to disable the PWM signal generation.

12. The apparatus of claim 8 , wherein the detector detects the switching current passing through the switch, and the controller controls the switch according to the detected switching current to shape the current pulled from the power supply.

13. The apparatus of claim 8 , further comprising:
a damping circuit to pull a damping current in response to the firing start, and the current pulled from the energy source including the switching current, and the damping current.

14. The apparatus of claim 8 , wherein the apparatus does not include a damping circuit, and the controller controls the switch in response to the firing start to shape the switching current to satisfy operation requirements of the TRIAC.

15. A method, comprising:
detecting a firing start by a triode for alternating current (TRIAC) in a power supply based on a voltage output from a rectifier that rectifies an alternative current (AC) voltage from the power supply;
generating a pulse width modulation (PWM) signal to voltage-control a switch in connection with a magnetic component in response to the firing start;
turning on the switch, and turning off the switch when a switch current flowing through the magnetic component rises to a first peak current limit in a duration; and
turning on the switch, and turning off the switch when the switch current flowing through the magnetic component rises to a second peak current limit in order to shape a profile of a current pulled from the power supply to satisfy a latch current requirement and a hold current requirement of the TRIAC.

16. The method of claim 15 , wherein generating the PWM signal to voltage-control the switch in connection with the magnetic component in response to the firing start to shape the profile of the current pulled from the power supply to satisfy the latch current requirement and the hold current requirement of the TRIAC further comprises:
controlling at least one of a peak current limit and a frequency for generating the PWM signal to pull the current at a first level to enable enough latch current for the TRIAC at the firing start.

17. The method of claim 15 , wherein generating the PWM signal to voltage-control the switch in connection with the magnetic component in response to the firing start to shape the profile of the current pulled from the power supply to satisfy the latch current requirement and the hold current requirement of the TRIAC further comprises:
controlling at least one of a peak current limit and a frequency for generating the PWM signal to pull the current at a second level that is lower than the first level to enable enough hold current for the TRIAC after the firing start.

18. The method of claim 15 , further comprising:
controlling at least one of a peak current limit and a frequency for generating the PWM signal to control at least one of a rising edge delay for the current to rise to the first level, a rising edge slope for the current to rise to the first level, a duration for the current to above a threshold, and a falling edge slope for the current to fall from the first level to t

Assignees

• Marvell World Trade Ltd
• Marvell World Trade Ltd

Inventors

• Sutardja Sehat
• Sutardja Pantas
• Zhang Wanfeng

Classifications

• H02M1/4258 Primary

  using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage (H02M1/4241 takes precedence) · CPC title

• H05B45/10

  Controlling the intensity of the light · CPC title

• H02M3/33507

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title

• H02M7/219

  in a bridge configuration · CPC title

• H02M3/335

  using semiconductor devices only · CPC title