SYSTEMS AND METHODS FOR REGULATING LED CURRENTS

• US 20130147379A1
• Filed: 01/06/2012
• Published: 06/13/2013
• Est. Priority Date: 12/08/2011
• Status: Active Grant

• Current Assignee: On-Bright Electronics (Shanghai) Co., Ltd. (Orthosie Investment Holdings Ltd.)
• Original Assignee: On-Bright Electronics (Shanghai) Co., Ltd. (Orthosie Investment Holdings Ltd.)
• Inventors: Zhou, Jun, Zhang, Yunchao, Fang, Lieyi
• Granted Patent: US 10,299,322 B2
• Time in Patent Office: Days
• US Class Current: 315/210
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/345 Current stabilisation; Maintaining constant current
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/50 responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• CPC Class Codes: H05B 47/24 Circuit arrangements for protecting against overvoltage
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

System and method for regulating one or more currents. The system includes a system controller, an inductor, a first resistor, a switch and a first diode. The system controller includes a first controller terminal and a ground terminal, the system controller being configured to output a drive signal at the first controller terminal. The inductor includes a first inductor terminal and a second inductor terminal, the first inductor terminal being coupled to the ground terminal, the second inductor terminal being coupled to one or more light emitting diodes. The first resistor includes a first resistor terminal and a second resistor terminal, the first resistor terminal being coupled to the ground terminal. The switch is configured to receive the drive signal and coupled to the second resistor terminal. The first diode includes a first diode terminal and a second diode terminal and coupled to the first resistor.

Claims

1. A system for regulating one or more currents, the system comprising:

a system controller including a first controller terminal and a ground terminal, the system controller being configured to output a drive signal at the first controller terminal;

an inductor including a first inductor terminal and a second inductor terminal, the first inductor terminal being coupled to the ground terminal, the second inductor terminal being coupled to one or more light emitting diodes;

a first resistor including a first resistor terminal and a second resistor terminal, the first resistor terminal being coupled to the ground terminal;

a switch configured to receive the drive signal and coupled to the second resistor terminal; and

a first diode including a first diode terminal and a second diode terminal and coupled to the first resistor, the second diode terminal being coupled to the one or more light emitting diodes.

2. The system of claim 1 wherein:

the switch is further configured to, in response to the drive signal, allow a first current to flow through the first resistor and the inductor; and

the inductor is configured to generate an output voltage at the second inductor terminal based on at least information associated with the first current.

3. The system of claim 2 wherein:

the system controller further includes a second controller terminal and a third controller terminal;

the system controller is further configured to receive a feedback signal at the second controller terminal and a sensing signal at the third controller terminal, the feedback signal being associated with the output voltage, the sensing signal being associated with the first current; and

the system controller is further configured to adjust the driving signal based on at least information associated with the feedback signal and the sensing signal.

4. The system of claim 3 wherein the second controller terminal is coupled indirectly to the ground terminal through at least a second resistor and coupled indirectly to the second inductor terminal through at least a third resistor and a second diode.

5. The system of claim 4 wherein the third controller terminal is coupled indirectly to the ground terminal through at least a first capacitor and coupled indirectly to the second resistor terminal through at least a fourth resistor.

6. The system of claim 5 wherein:

the system controller further includes a fourth controller terminal; and

the fourth controller terminal is coupled indirectly to the switch through at least a fifth resistor, coupled indirectly to the second inductor terminal through at least a Zener diode and a third diode, and coupled indirectly to the ground terminal through at least a second capacitor.

7. The system of claim 6 wherein:

the system controller further includes a fifth controller terminal; and

the fifth controller terminal is coupled indirectly to the ground terminal through at least a third capacitor.

8. The system of claim 1 wherein:

the second resistor terminal is coupled to the first diode terminal; and

the first diode terminal is coupled to the switch.

9. The system of claim 1 wherein:

the first resistor terminal is coupled to the first diode terminal; and

the first diode terminal is coupled to the ground terminal.

10. A system for regulating one or more currents, the system comprising:

a system controller including a first controller terminal and a ground terminal, the system controller being configured to output a drive signal at the first controller terminal;

a transformer including a primary winding and a secondary winding, the primary winding including a first winding terminal and a second winding terminal, the secondary winding including a third winding terminal and a fourth winding terminal, the first winding terminal being coupled to the ground terminal, the second winding terminal being coupled to one or more light emitting diodes, the third winding terminal being coupled to the ground terminal;

a first resistor including a first resistor terminal and a second resistor terminal, the first resistor terminal being coupled to the ground terminal;

a switch configured to receive the drive signal and coupled to the second resistor terminal; and

a first diode including a first diode terminal and a second diode terminal and coupled to the first resistor, the second diode terminal being coupled to the one or more light emitting diodes.

11. The system of claim 10 wherein:

the second resistor terminal is coupled to the first diode terminal; and

the first diode terminal is coupled to the switch.

12. The system of claim 10 wherein:

the first resistor terminal is coupled to the first diode terminal; and

the first diode terminal is coupled to the ground terminal.

13. A system for regulating one or more currents, the system comprising:

a system controller configured to output a drive signal to a switch and to receive a sensed signal from a resistor connected to the switch and an inductor, the resistor and the inductor being connected directly or indirectly to one or more light emitting diodes;

wherein;

the drive signal is associated with one or more switching periods, each of the one or more switching periods including an on-time period for the switch and an off-time period for the switch;

each of the one or more switching periods is equal to a ratio multiplied by a demagnetization period for a demagnetization process associated with the inductor, the ratio being larger than 1; and

an average magnitude of a first current flowing through the one or more light emitting diodes is proportional to a peak magnitude of the sensed signal within each of the one or more switching periods.

14. The system of claim 13 wherein the peak magnitude of the sensed signal within each of the one or more switching periods is proportional to a peak magnitude of a second current flowing through the inductor within a corresponding switching period.

15. The system of claim 14 wherein the system controller is further configured to keep the peak magnitude of the second current constant.

16. A system for regulating one or more currents, the system comprising:

a modulation-and-drive component configured to output a drive signal to a switch, the drive signal being associated with at least one switching period including an on-time period for the switch and a demagnetization period for a demagnetization process;

a sample-and-hold component configured to receive a sensed signal related to a first current flowing through the switch, sample the sensed signal at the middle of the on-time period, and hold the sampled sensed signal;

an amplification component configured to receive the held and sampled sensed signal during the demagnetization period and generate an amplified signal;

an error amplifier configured to receive the amplified signal during the demagnetization period and generate, with at least a first capacitor, an integrated signal; and

a comparator configured to receive at least the integrated signal and output a comparison signal to the modulation-and-drive component based on at least information associated with the integrated signal.

17. The system of claim 16 wherein:

the modulation-and-drive component includes a modulation component and a gate driver;

wherein;

the modulation component is configured to receive at least the comparison signal and generate a modulation signal based on at least information associated with the comparison signal, the modulation signal being at a first logic level during the on-time period and at a second logic level during at least the demagnetization period; and

the gate driver is configured to receive at least the modulation signal and generate the drive signal based on at least information associated with the modulation signal.

18. The system of claim 17 wherein the modulation component includes a flip-flop component.

19. The system of claim 16 wherein:

the sample-and-hold component includes a timing component and a second capacitor;

wherein;

the timing component is configured to generate a timing signal; and

the second capacitor is configured to, in response to the timing signal, receive the sensed signal during a predetermined period of time and hold the sensed signal sampled at the end of the predetermined period of time.

20. The system of claim 19 wherein the predetermined period of time starts at the beginning of the on-time period and ends at the middle of the on-time period.

21. The system of claim 16 wherein the error amplifier is further configured to receive a reference signal and generate the integrated signal based on at least information associated with the reference signal and the amplified signal.

22. The system of claim 21 wherein an average magnitude of a second current flowing through one or more light emitting diodes is proportional to a ratio between a magnitude of the reference signal and an amplification factor associated with the amplification component, the second current being related to the sensed signal.

23. A system for regulating one or more currents, the system comprising:

a modulation-and-drive component configured to output a drive signal to a switch, the drive signal being associated with at least one switching period including an on-time period for the switch and a demagnetization period for a demagnetization process;

an amplification component configured to, during the demagnetization period, receive a sensed signal related to a first current flowing through the switch and generate an amplified signal;

an error amplifier configured to receive the amplified signal during the demagnetization period and generate, with at least a first capacitor, an integrated signal; and

a comparator configured to receive at least the integrated signal and output a comparison signal to the modulation-and-drive component based on at least information associated with the integrated signal.

24. The system of claim 23 wherein:

the modulation-and-drive component includes a modulation component and a gate driver;

wherein;

the modulation component is configured to receive at least the comparison signal and generate a modulation signal based on at least information associated with the comparison signal, the modulation signal being at a first logic level during the on-time period and at a second logic level during at least the demagnetization period; and

the gate driver is configured to receive at least the modulation signal and generate the drive signal based on at least information associated with the modulation signal;

25. The system of claim 23 wherein the error amplifier is further configured to receive a reference signal and generate the integrated signal based on at least information associated with the reference signal and the amplified signal.

26. The system of claim 25 wherein an average magnitude of a second current flowing through one or more light emitting diodes is proportional to a ratio between a magnitude of the reference signal and an amplification factor associated with the amplification component, the second current being related to the sensed signal.

27. A method for regulating one or more currents, the method comprising:

receiving a sensed signal from a resistor connected to a switch and an inductor;

processing information associated with the sensed signal;

generating a drive signal for the switch based on at least information associated with the sensed signal;

processing information associated with the drive signal; and

generating a current flowing through one or more light emitting diodes based on at least information associated with the drive signal, the one or more light emitting diodes being connected directly or indirectly to the resistor and the inductor;

wherein;

the drive signal is associated with one or more switching periods, each of the one or more switching periods including an on-time period for the switch and an off-time period for the switch;

each of the one or more switching periods is equal to a ratio multiplied by a demagnetization period for a demagnetization process associated with the inductor, the ratio being larger than 1; and

the current is proportional to a peak magnitude of the sensed signal within each of the one or more switching periods.

28. A method for regulating one or more currents, the method comprising:

generating a drive signal for a switch, the drive signal being associated with at least one switching period including an on-time period for the switch and a demagnetization period for a demagnetization process;

receiving a sensed signal related to a current flowing through the switch;

processing information associated with the sensed signal;

sampling the sensed signal at the middle of the on-time period;

holding the sampled sensed signal;

receiving the held and sampled sensed signal during the demagnetization period;

processing information associated with the received held and sampled sensed signal;

generating an amplified signal based on at least information associated with the received held and sampled sensed signal;

receiving the amplified signal;

processing information associated with the amplified signal;

generating an integrated signal based on at least information associated with the amplified signal;

receiving at least the integrated signal;

processing information associated with the integrated signal; and

generating a comparison signal based on at least information associated with the integrated signal.

29. A method for regulating one or more currents, the method comprising:

generating a drive signal for a switch, the drive signal being associated with at least one switching period including an on-time period for the switch and a demagnetization period for a demagnetization process;

receiving a sensed signal related to a current flowing through the switch during the demagnetization period;

processing information associated with the received sensed signal;

generating an amplified signal based on information associated with the received sensed signal;

receiving the amplified signal;

processing information associated with the amplified signal;

generating an integrated signal based on at least information associated with the amplified signal;

receiving at least the integrated signal;

processing information associated with the integrated signal;

generating a comparison signal based on at least information associated with the integrated signal; and

receiving the comparison signal.