LED DRIVING DEVICE

• US 20170354008A1
• Filed: 05/24/2017
• Published: 12/07/2017
• Est. Priority Date: 06/02/2016
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Korea Semiconductor Limited (ON Semiconductor Corporation)
• Inventors: EUM, Hyun-Chul, JUNG, Doo-Yong, KIM, Young-Jong
• Granted Patent: US 10,004,121 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/1566 with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
• 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 3/33515 with digital control
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/31 Phase-control circuits
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/50 responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A LED driving device is provided, which includes a LED string including at least one LED element, at least one channel connected to the at least one LED element, a current regulator configured to regulate a current flowing through the at least one channel according to at least one corresponding control voltage, and a control signal generating circuit configured to generate a control signal based on a difference between a reference voltage and a comparative voltage. The comparative voltage is determined based on a sensing voltage, and the sensing voltage corresponds to an LED current flowing through the LED string. The control signal generating circuit is further configured to generate the at least one corresponding control voltage based on the control signal.

Claims

1. A LED driving device, comprising:

a LED string comprising at least one LED element;

at least one channel connected to the at least one LED element;

a current regulator configured to regulate a current flowing through the at least one channel according to at least one corresponding control voltage; and

a control signal generating circuit configured to generate a control signal based on a difference between a reference voltage and a comparative voltage, the comparative voltage being based on a sensing voltage, the sensing voltage corresponding to an LED current flowing through the LED string,

wherein the control signal generating circuit is further configured to generate the at least one corresponding control voltage based on the control signal.

2. The LED driving device of claim 1, wherein the control signal generating circuit comprises an amplifier configured to generate the control signal by amplifying a difference between the comparative voltage and the reference voltage.

3. The LED driving device of claim 2, wherein the control signal generating circuit further comprises a reference voltage generator configured to generate the reference voltage, the reference voltage being a DC voltage.

4. The LED driving device of claim 2, wherein the control signal generating circuit further comprises a reference voltage generator configured to generate the reference voltage based on a dimming signal, the dimming signal controlling dimming of the LED string.

5. The LED driving device of claim 4, wherein the LED driving device generates the dimming signal based on a phase angle voltage, the phase angle voltage being determined to proportional to a phase angle of an input voltage supplied to the LED string.

6. The LED driving device of claim 5, wherein the LED driving device generates the phase angle voltage by filtering the input voltage, and generates the dimming signal according to the phase angle voltage.

7. The LED driving device of claim 1, wherein the control signal generating circuit comprises a reference voltage generator configured to generate the reference voltage based on a feedback voltage, the feedback voltage being a DC voltage generated by amplifying and compensating a difference between the sensing voltage and a feedback reference voltage, the feedback reference voltage having a constant level.

8. The LED driving device of claim 7, wherein the reference voltage generator comprises a feedback amplifier comprising an inverting input terminal and a non-inverting input terminal, the sensing voltage being inputted to the inverting input terminal, the feedback reference voltage being inputted to the non-inverting input terminal.

9. The LED driving device of claim 7, wherein the feedback reference voltage is a dimming signal for controlling dimming of the LED string.

10. The LED driving device of claim 1, wherein the control signal generating circuit generates the reference voltage according to an input detection voltage, is the input detection voltage being obtained by detecting an input voltage supplied to the LED string.

11. The LED driving device of claim 10, wherein the reference voltage generator generates the input detection voltage by dividing the input voltage using two resistors connected in series to each other.

12. The LED driving device of claim 10, wherein the reference voltage generator generates the input detection voltage by detecting a current flowing through a resistor, the input voltage being applied to the resistor.

13. The LED driving device of claim 10, wherein the LED driving device detects a point in time when the input voltage reaches zero, and generates the input detection voltage synchronized with the input voltage based on the detected point in time.

14. The LED driving device of claim 10, wherein the control signal generating circuit comprises a reference voltage generator configured to generate the reference voltage by adding a dimming signal to the input detection voltage, the dimming signal controlling dimming of the LED string.

15. The LED driving device of claim 10, wherein the control signal generating circuit comprises a reference voltage generator configured to generate the reference voltage by multiplying the input detection voltage by a dimming signal, the dimming signal controlling dimming of the LED string.

16. The LED driving device of claim 10, wherein the control signal generating circuit comprises a reference voltage generator configured to generate the reference voltage by adding a feedback voltage to the input detection voltage, the feedback voltage being obtained based on a difference between the sensing voltage and a feedback reference voltage, the feedback reference voltage having a constant level.

17. The LED driving device of claim 10, wherein the control signal generating circuit comprises a reference voltage generator configured to generate the reference voltage by multiplying the input detection voltage by a feedback voltage, the feedback voltage being obtained based on a difference between the sensing voltage and a feedback reference voltage, the feedback reference voltage having a constant level.

18. The LED driving device of claim 10, wherein the control signal generating circuit generates the control signal by amplifying a difference between the reference voltage and the comparative voltage, the comparative voltage being obtained by subtracting a dimming signal from the sensing voltage, the dimming signal controlling dimming of the LED string.

19. The LED driving device of claim 10, wherein the control signal generating circuit generates the control signal by amplifying a difference between the reference voltage and the comparative voltage, the comparative voltage being obtained by dividing the sensing voltage by a dimming signal, the dimming signal controlling dimming of the LED string.

20. The LED driving device of claim 10, wherein the control signal generating circuit generates the control signal by amplifying a difference between the reference voltage and the comparative voltage, the comparative voltage being obtained by subtracting a feedback voltage from the sensing voltage, wherein the feedback voltage is generated by amplifying and compensating a difference between the sensing voltage and a feedback reference voltage, the feedback reference voltage having a constant level.

21. The LED driving device of claim 10, wherein the control signal generating circuit generates the control signal by amplifying a difference between the reference voltage and the comparative voltage, the comparative voltage being obtained by dividing the sensing voltage by a feedback voltage, wherein the feedback voltage is generated by amplifying and compensating a difference between the sensing voltage and a feedback reference voltage, the feedback reference voltage having a constant level.

22. The LED driving device of claim 2, wherein, when the reference voltage is a DC voltage, a bandwidth of the amplifier is lower than a line frequency, an average of the sensing voltage being regulated to the DC voltage.

23. The LED driving device of claim 2, wherein, when the reference voltage is a sinusoidal wave that follows an input voltage supplied to the LED string, a bandwidth of the amplifier is higher than a line frequency, the sensing voltage being regulated to follow the sinusoidal wave.