Light-emitting diode driving circuit

• US 8,884,538 B2
• Filed: 12/27/2012
• Issued: 11/11/2014
• Est. Priority Date: 05/30/2012
• Status: Active Grant

• Current Assignee: Macroblock, Inc.
• Original Assignee: Macroblock, Inc.
• Inventors: Li, Yan-Cun, Cheng, Chin-Chung
• Primary Examiner(s): WHITE, DYLAN C
• Application Number:
  US13/728,624
• Publication Number:
  US 20130320872A1
• Time in Patent Office: 684 Days
• Field of Search: 315/201, 323/227, 323/291, 363/74
• US Class Current: 315/201
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A light-emitting diode (LED) driving circuit includes a power factor correction (PFC) circuit and a driving controller. The PFC circuit controls a power factor of the LED driving circuit. The LED driving circuit includes an inductor, a switch, a current detection circuit, and a time detection circuit. The inductor senses an inductor current and provide energy to at least one LED. The switch connected to the inductor is conducted according to a driving signal. The current detection circuit connected to the switch detects inductor current information. The time detection circuit connected to the switch detects an energy discharging time during which the inductor current decrease from a peak value to zero. The driving controller connected to the switch, the current detection circuit, and the time detection circuit outputs the driving signal to the switch according to the voltage level and the energy discharging time.

Claims

1. A light-emitting diode (LED) driving circuit for driving at least one LED, the LED driving circuit comprising:

a power factor correction (PFC) circuit for controlling a power factor of the LED driving circuit, the PFC circuit at least comprising;

an inductor, a first end of the inductor being connected to a positive end of a power supply source, the inductor being configured to extract an inductor current and providing energy to at least one LED;

a switch connected to a second end of the inductor, the switch being conducted according to a driving signal;

a current detection circuit connected to the switch for detecting a inductor current information; and

a time detection circuit connected to the switch for detecting an energy discharging time during which the inductor current decreases to zero from the peak value; and

a driving controller connected to the switch, the current detection circuit, and the time detection circuit, the driving controller being configured to output the driving signal to the switch according to the inductor current information and the energy discharging time.

2. The LED driving circuit according to claim 1, wherein a first end of the time detection circuit being connected to a first end of the switch and the second end of the inductor, a second end of the time detection circuit being connected to a ground, a third end of the time detection circuit being connected to the driving controller, a first end of the current detection circuit being connected to a second end of the switch and the driving controller, a second end of the current detection circuit being connected to the ground, and a third end of the switch being connected to the driving controller.

3. The LED driving circuit according to claim 2, wherein the current detection circuit comprising a first resistor, a first end of the first resistor being connected to the second end of the switch and the driving controller, and a second end of the first resistor being connected to the ground.

4. The LED driving circuit according to claim 2, wherein the time detection circuit comprising a second resistor and a third resistor, a first end of the second resistor being connected to the second end of the inductor and the first end of the switch, a second end of the second resistor being connected to a first end of the third resistor, a second end of the third resistor being connected to the ground, and the second end of the second resistor and the first end of the third resistor being connected to the driving controller.

5. The LED driving circuit according to claim 2, further comprising:

an output capacitor, a first end of the output capacitor being connected to the first end of the inductor; and

a rectifier, a first end of the rectifier being connected to the second end of the inductor, the first end of the time detection circuit, and the first end of the switch, a second end of the rectifier being connected to a second end of the output capacitor.

6. The LED driving circuit according to claim 2, further comprising:

a rectifier, a second end of the rectifier being connected to the first end of the inductor; and

an output capacitor, a first end of the output capacitor being connected to a first end of the rectifier, a second end of the output capacitor being connected to the second end of the inductor, the first end of the time detection circuit, and the first end of the switch.

7. The LED driving circuit according to claim 1, wherein the PFC circuit further comprising:

a rectifier, a first end of the rectifier being connected to the first end of the switch and the second end of the inductor, and a second end of the rectifier being connected to the time detection circuit.

8. The LED driving circuit according to claim 7, wherein the first end of the rectifier being connected to a first end of the switch and the second end of the inductor, a first end of the current detection circuit being connected to a second end of the switch, a second end of the current detection circuit being connected to a ground, a first end of the time detection circuit being connected to the second end of the rectifier, a second end of the time detection circuit being connected to a ground, a third end of the time detection circuit being connected to the driving controller, and a third end of the switch being connected to the driving controller.

9. The LED driving circuit according to claim 7, wherein the current detection circuit comprising a first resistor, a first end of the first resistor being connected to the second end of the switch and the driving controller, and a second end of the first resistor being connected to the ground.

10. The LED driving circuit according to claim 7, wherein the time detection circuit comprising a second resistor and a third resistor, a first end of the second resistor being connected to the second end of the rectifier, a second end of the second resistor being connected to a first end of the third resistor, a second end of the third resistor being connected to the ground, and the second end of the second resistor and the first end of the third resistor being connected to the driving controller.

11. The LED driving circuit according to claim 7, further comprising:

an output capacitor, a first end of the capacitor being connected to the first end of the inductor, and a second end of the capacitor being connected to the second end of the rectifier and the first end of time detection circuit.

12. A light-emitting diode (LED) driving circuit for driving at least one LED, the LED driving circuit comprising:

a power factor correction (PFC) circuit for controlling a power factor of the LED driving circuit, the PFC circuit comprising;

a transformer having a primary coil and a secondary coil, a first end of the primary coil being connected to a positive end of a power supply source, the transformer being configured to extract an inductor current, the secondary coil being coupled to energy stored in the primary coil to provide energy to the at least one LED;

a switch connected to a second end of the primary coil, the switch being conducted according to a driving signal;

a current detection circuit connected to the switch, the current detection circuit being used to detect an inductor current information; and

a time detection circuit connected to the switch and the second end of the primary coil, the time detection circuit being configured to detect an energy discharging time during which the inductor current decreases from a peak value to zero; and

a driving controller connected to the switch, the current detection circuit, and the time detection circuit, the driving controller being configured to output the driving signal to the switch according to the inductor current information and the energy discharging time.

13. The LED driving circuit according to claim 12, wherein a first end of the time detection circuit being connected to a first end of the switch and the second end of the primary coil, a second end of the time detection circuit being connected to a ground, a third end of the time detection circuit being connected to the driving controller, a first end of the current detection circuit being connected to a second end of the switch, a second end of the current detection circuit being connected to the ground, and a third end of the switch being connected to the driving controller.

14. The LED driving circuit according to claim 13, wherein the current detection circuit comprising a first resistor, a first end of the first resistor being connected to the second end of the switch, a second end of the first resistor being connected to the ground, and the first end of the first resistor and the second end of the switch being connected to the driving controller.

15. The LED driving circuit according to claim 13, wherein the time detection circuit comprising a second resistor and a third resistor, a first end of the second resistor being connected to the second end of the primary coil and the first end of the switch, a second end of the second resistor being connected to a first end of the third resistor and the driving controller, and a second end of the third resistor being connected to the ground.

16. The LED driving circuit according to claim 12, further comprising:

a rectifier, a first end of the rectifier being connected to a first end of the secondary coil; and

an output capacitor, a first end of the output capacitor being connected to a second end of the rectifier, and a second end of the output capacitor being connected to a second end of the secondary coil.

17. The LED driving circuit according to claim 12, further comprising:

an output capacitor, a first end of the output capacitor being connected to a first end of the secondary coil; and

a rectifier, a second end of the rectifier being connected to a second end of the secondary coil, and a first end of the rectifier being connected to a second end of the output capacitor.

18. The LED driving circuit according to claim 12, wherein the transformer is reverse polarity.