Illumination driving circuit

• US 8,648,543 B1
• Filed: 11/21/2012
• Issued: 02/11/2014
• Est. Priority Date: 11/21/2012
• Status: Expired due to Fees

• Current Assignee: Himax Analogic, Inc. (Himax Technologies Incorporated)
• Original Assignee: Himax Analogic, Inc. (Himax Technologies Incorporated)
• Inventors: Fan, Hang-Yu
• Primary Examiner(s): LE, DON P
• Application Number:
  US13/682,838
• Time in Patent Office: 447 Days
• Field of Search: 315/200.R, 315/209.R, 315/224, 315/283, 315/291, 315/307
• US Class Current: 315/200.R
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 47/10 Controlling the light source

Abstract

An illumination driving circuit for driving a light-emitting load includes a system voltage source, a switch component, an inductor component, an inductor-current sensing module and a control module. The switch component is coupled between the system voltage source and the light-emitting load. The inductor component is connected in series between the system voltage source and the light-emitting load. The inductor-current sensing module includes a sensing resistor component connected in series between the switch component and the inductor component. The control module is configured for controlling the conductive state of the switch component. An inductor-current sensing terminal of the controlling module is coupled to a node between the sensing resistor component and the switch component. The control module calculates an inductor-current through the inductor component according to a voltage level on the inductor-current sensing terminal.

Claims

1. An illumination driving circuit for driving a light-emitting load, the illumination driving circuit comprising:

a system voltage source;

a switch component coupled between the system voltage source and the light-emitting load;

an inductor component connected in series between the switch component and the light-emitting load;

an inductor-current sensing module comprising a sensing resister component connected in series between the switch component and the inductor component; and

a control module coupled to a controlling terminal of the switch component and configured for controlling a conductive state of the switch component, a virtual ground terminal of the control module being coupled between the sensing resister component and the inductor component, an inductor-current sensing terminal of the control module being coupled between the sensing resister component and the switch component, the control module calculating an inductor-current through the inductor component according to a voltage level of the inductor-current sensing terminal.

2. The illumination driving circuit of claim 1, wherein the system voltage source comprises:

an alternating-current voltage input; and

a rectifier circuit coupled between the alternating-current voltage input and the switch component.

3. The illumination driving circuit of claim 1, wherein the illumination driving circuit further comprises an input-voltage sensing module coupled to an input-voltage sensing terminal of the control module, the input-voltage sensing module comprises:

a first voltage-dividing resistor component coupled between the system voltage source and the input-voltage sensing terminal;

a second voltage-dividing resistor component coupled between the virtual ground terminal and the input-voltage sensing terminal; and

a capacitor component coupled between the virtual ground terminal and the input-voltage sensing terminal.

4. The illumination driving circuit of claim 3, wherein the input-voltage sensing module is configured for sensing an input-voltage from the system voltage source and transmitting the input-voltage to the input-voltage sensing terminal of the control module, and accordingly the control module synchronizes a phase of the inductor-current to the input-voltage.

5. The illumination driving circuit of claim 1, wherein the inductor-current sequentially goes through the switch component, the sensing resistor component, the inductor component and the light-emitting load.

6. The illumination driving circuit of claim 5, wherein the control module senses the inductor-current according to a resistance of the sensing resistor component and a voltage difference between the inductor-current sensing terminal and the virtual ground terminal.

7. The illumination driving circuit of claim 1, wherein the illumination driving circuit further comprises a voltage activation module coupled to an activation sensing terminal of the control module, the voltage activation module comprises:

a resistor component coupled between the system voltage source and the activation sensing terminal;

a diode coupled between the light-emitting load and the activation sensing terminal; and

a capacitor component coupled between the virtual ground terminal and the activation sensing terminal.

8. The illumination driving circuit of claim 7, wherein, when the switch component is turned off initially, the input-voltage of the system voltage source charges the capacitor via the resistor component of the voltage activation module, such that a voltage level of the activation sensing terminal is elevated until the voltage level of the activation sensing terminal reaches a activation threshold voltage of the control module, and then the control module turns on the switch component.

9. The illumination driving circuit of claim 8, wherein the illumination driving circuit further comprises an output capacitor component shunt connected with the light-emitting load, after the switch component is turned on, the input-voltage of the system voltage source is configured for accumulating energy in the inductor component and the output capacitor component via the switch component until the voltage level of the inductor-current sensing terminal reaches a lockout threshold voltage of the control module, and then the control module turns off the switch component.

10. The illumination driving circuit of claim 9, wherein after the control module turns off the switch component, the inductor component releases energy to the light-emitting load and generates the inductor-current, the control module monitors the inductor-current by the voltage level of the inductor-current sensing terminal, the control module turns on the switch component again when the inductor-current is less than an inductor threshold current.

11. An illumination driving method, suitable on a illumination driving circuit for driving a light-emitting load, the illumination driving circuit comprising a system voltage source, a switch component, an inductor component, an inductor-current sensing module and a control module, a virtual ground terminal of the control module being coupled between a sensing resister component of the inductor-current sensing module and the inductor component, an inductor-current sensing terminal of the control module being coupled between the sensing resister component and the switch component, the illumination driving method comprising:

calculating an inductor-current through the inductor component according to a voltage level of the inductor-current sensing terminal; and

controlling a conductive state of the switch component according to the inductor-current.

12. The illumination driving method of claim 11, further including:

sensing an input-voltage from the system voltage source; and

transmitting the input-voltage to an input-voltage sensing terminal of the control module; and

synchronizing a phase of the inductor-current to the input-voltage according to the input-voltage.

13. The illumination driving method of claim 11, further including:

senses the inductor-current according to a resistance of the sensing resistor component and a voltage difference between the inductor-current sensing terminal and the virtual ground terminal.

14. The illumination driving method of claim 11, wherein the illumination driving circuit further comprises a voltage activation module coupled to an activation sensing terminal of the control module, the voltage activation module comprises a resistor component, a diode and a capacitor component, the illumination driving method further includes:

when the switch component is turned off initially, charging the capacitor via the resistor component of the voltage activation module; and

elevating a voltage level of the activation sensing terminal until the voltage level of the activation sensing terminal reaches a activation threshold voltage of the control module; and

turning on the switch component when the voltage level of the activation sensing terminal reaches a activation threshold voltage of the control module.

15. The illumination driving method of claim 14, wherein the illumination driving circuit further comprises an output capacitor component, the illumination driving method further includes:

after the switch component is turned on, accumulating energy in the inductor component and the output capacitor component via the switch component until the voltage level of the inductor-current sensing terminal reaches a lockout threshold voltage of the control module; and

turning off the switch component when the voltage level of the inductor-current sensing terminal reaches a lockout threshold voltage of the control module.

16. The illumination driving method of claim 15, wherein the illumination driving method further includes:

after the switch component is turned off, releasing energy from the inductor component to the light-emitting load, so as generate the inductor-current;

monitoring the inductor-current by the voltage level of the inductor-current sensing terminal;

turning on the switch component again when the inductor-current is less than an inductor threshold current.