Active Bleeder Circuit Triggering TRIAC in All Phase and Light Emitting Device Power Supply Circuit and TRIAC Control Method Using the Active Bleeder Circuit

• US 20130169177A1
• Filed: 12/27/2012
• Published: 07/04/2013
• Est. Priority Date: 12/30/2011
• Status: Active Grant

• Current Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Original Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Inventors: Liao, Chia-Wei, Chen, Pei-Yuan, Van Roy, Roland, Liu, Jing-Meng, Hsin, Leng-Nien
• Granted Patent: US 8,884,537 B2
• Time in Patent Office: Days
• US Class Current: 315/200.R
• CPC Class Codes: G05F 1/10 Regulating voltage or current G05F1/02 takes precedence; for electric railways B60M3/02
• CPC Class Codes: G05F 1/455 with phase control
• CPC Class Codes: G05F 3/02 Regulating voltage or current
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The present invention discloses an active bleeder circuit capable of triggering a tri-electrode AC switch (TRIAC) circuit in all phase. The active bleeder circuit receives a rectified signal having an OFF phase and an ON phase. The active bleeder includes: a detection circuit for generating a detection signal according to the rectified signal and accumulating the detection signal in the OFF phase of the rectified signal; and a current sinker circuit coupled to the detection circuit, for generates a latching current to trigger the TRIAC circuit by operating a switch when the detection signal exceeds a predetermined level. The present invention also discloses a light emitting device power supply circuit and a TRIAC control method using the active bleeder circuit.

Claims

1. A light emitting device power supply circuit, comprising:

a tri-electrode AC switch (TRIAC) dimmer circuit, for generating a phase-cut AC dimming signal, wherein the phase-cut AC dimming signal has an OFF phase and an ON phase;

a rectifier circuit, which is coupled to the TRAIC dimmer circuit, for generating a rectified dimming signal according to the phase-cut AC dimming signal, wherein the rectified dimming signal has an OFF phase and an ON phase corresponding to the OFF phase and the ON phase of the phase-cut AC dimming signal;

a light emitting device driver circuit, for driving a light emitting circuit according to the rectified dimming signal; and

an active bleeder circuit, including;

a detection circuit, which is coupled to the rectifier circuit, for generating a detection signal and accumulating the detection signal in the OFF phase; and

a current sinker circuit, which is coupled to the detection circuit, for generating a latching current to trigger the TRIAC dimmer circuit by operating a switch therein when the detection signal exceeds a predetermined level.

2. The light emitting device power supply circuit of claim 1, wherein the current sinker circuit turns OFF the switch therein to stop generating the latching current in the ON phase.

3. The light emitting device power supply circuit of claim 1, wherein the detection circuit includes:

a conversion device, for converting the rectified dimming signal to the detection signal; and

a storage device, for storing and accumulating the detection signal.

4. The light emitting device power supply circuit of claim 3, wherein the detection circuit further includes an OFF control circuit, for turning OFF the switch of the current sinker circuit in the ON phase.

5. The light emitting device power supply circuit of claim 4, wherein the OFF control circuit includes a Zener diode, which has a reverse end coupled to the detection signal, and a forward end coupled to a relatively lower level, such that when a voltage difference between the detection signal and the relatively lower level exceeds a reverse breakdown voltage of the Zener diode, the Zener diode turns ON reversely.

6. The light emitting device power supply circuit of claim 3, wherein the detection circuit further includes a reset circuit, for resetting the detection signal.

7. The light emitting device power supply circuit of claim 6, wherein the reset circuit includes a diode, which has a forward end coupled to the storage device, and a reverse end for receiving a reset signal to reset the detection signal.

8. An active bleeder circuit, comprising:

a detection circuit, coupled to a rectified signal having an OFF phase and an ON phase, for generating a detection signal according to the rectified signal and accumulating the detection signal in the OFF phase of the rectified signal; and

a current sinker circuit, which is coupled to the detection circuit, for generating a latching current by operating a switch therein when the accumulated detection signal exceeds a predetermined level.

9. The active bleeder circuit of claim 8, wherein the current sinker circuit turns OFF the switch therein to stop generating the latching current in the ON phase.

10. The active bleeder circuit of claim 8, wherein the detection circuit includes:

a conversion device, for converting the rectified signal to the detection signal; and

a storage device, for storing and accumulating the detection signal.

11. The active bleeder circuit of claim 10, wherein the detection circuit further includes an OFF control circuit, for turning OFF the switch of the current sinker circuit in the ON phase.

12. The active bleeder circuit of claim 11, wherein the OFF control circuit includes a Zener diode, which has a reverse end coupled to the detection signal, and a forward end coupled to a relatively lower level, such that when a voltage difference between the detection signal and the relatively lower level exceeds a reverse breakdown voltage of the Zener diode, the Zener diode turns ON reversely.

13. The active bleeder circuit of claim 10, wherein the detection circuit further includes a reset circuit, for resetting the detection signal.

14. The active bleeder circuit of claim 13, wherein the reset circuit includes a diode, which has a forward end coupled to the storage device, and a reverse end for receiving a reset signal to reset the detection signal.

15. A TRIAC (tri-electrode AC switch) control method, comprising:

receiving a rectified signal having an OFF phase and an ON phase, wherein the rectified signal is generated by rectifying a phase-cut AC signal generated by a TRIAC circuit;

generating a detection signal according to the rectified signal and accumulating the detection signal in the OFF phase; and

when the accumulated detection signal exceeds a predetermined level, generating a latching current to trigger the TRIAC circuit.

16. The TRIAC control method of claim 15 further comprising:

stopping generating the latching current in the ON phase.

17. The TRIAC control method of claim 15, wherein the step of generating and accumulating the detection signal includes:

charging a capacitor by a current according to the rectified signal in the OFF phase.

18. The TRIAC control method of claim 17 further comprising:

discharging the capacitor in the ON phase.

19. The TRIAC control method of claim 15, wherein the step of generating and accumulating the detection signal further includes:

resetting the detection signal periodically.