Light emitting device power supply circuit, light emitting device control circuit and identifiable light emitting device circuit therefor and identification method thereof

• US 9,000,685 B2
• Filed: 01/18/2014
• Issued: 04/07/2015
• Est. Priority Date: 01/22/2013
• Status: Active Grant

• Current Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Original Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Inventors: Cheng, Chih-Tai, Lin, Chi-Hsiu, Chen, Pei-Yuan
• Primary Examiner(s): Tran, Thuy Vinh
• Assistant Examiner(s): Kaiser, Syed M
• Application Number:
  US14/158,806
• Publication Number:
  US 20140203730A1
• Time in Patent Office: 444 Days
• Field of Search: 315/178, 315/307, 315/309, 315/224, 362/20
• US Class Current: 315/307
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]

Abstract

The present invention discloses a light emitting device power supply circuit, a light emitting device control circuit and an identifiable light emitting device circuit therefor, and an identification method thereof. The light emitting device control circuit includes an operation signal generation circuit and an identification circuit. The operation signal generation circuit determines whether the light emitting device control circuit operates in an identified mode or amiss mode according to an enable signal. In the identified mode, the light emitting device control circuit operates a power stage circuit to supply an output current to an identifiable light emitting device circuit. In the miss mode, an output voltage is maintained at a predetermined level. The identification circuit determines whether the light emitting device control circuit switches from the miss mode to the identified mode according to whether the output voltage meets a condition.

Claims

1. A light emitting device power supply circuit, for identifying an identifiable light emitting device circuit to determine whether to operate in an identified mode or a miss mode and supply an output current to the identifiable light emitting device circuit in the identified mode, wherein the identified mode indicates that the identifiable light emitting device circuit is normally coupled to the light emitting device power supply circuit, and the miss mode indicates that the identifiable light emitting device circuit is not normally coupled to the light emitting device power supply circuit, the light emitting device power supply circuit comprising:

a power stage circuit, for operating at least one power switch therein according to an operation signal in the identified mode, to convert an input voltage to an output voltage, and supply the output current to the identifiable light emitting device circuit;

a level control circuit, for controlling the output voltage at a predetermined level in the miss mode;

an identification circuit, for determining whether the miss mode is changed to the identified mode according to whether the output voltage meets a predetermined condition, and generating an enable signal correspondingly; and

an operation signal generation circuit, for generating the operation signal according to a feedback signal when the enable signal indicates the identified mode;

wherein the identification circuit includes;

a first comparison circuit, for generating a first comparison signal according to the output voltage and a first reference level, wherein the first reference level is higher than the predetermined level;

a second comparison circuit, for generating a second comparison signal according to the output voltage and a second reference level, wherein the second reference level is lower than the predetermined level; and

a determination circuit, which is coupled to the first comparison circuit and the second comparison circuit, and outputs the enable signal, wherein the determination circuit determines a level of the enable signal according to the first comparison signal and/or the second comparison signal.

2. The light emitting device power supply circuit of claim 1, wherein the identification circuit generates the enable signal after a delay time period from when the output voltage meets the predetermined condition.

3. The light emitting device power supply circuit of claim 1, wherein the level control circuit includes a voltage divider circuit, the voltage divider circuit including a first bias circuit and a second bias circuit connected in series, wherein a connection node between the first bias circuit and the second bias circuit is electrically connected to the output voltage.

4. The light emitting device power supply circuit of claim 3, wherein a level of the output voltage changes while the identifiable light emitting device circuit changes from being not normally coupled to being normally coupled.

5. The light emitting device power supply circuit of claim 1, wherein the predetermined condition is:

the output voltage being lower than a reference level, and the reference level being lower than the predetermined level.

6. A light emitting device control circuit, for identifying an identifiable light emitting device circuit to determine whether to operate in an identified mode or a miss mode, the light emitting device control circuit comprising:

an operation signal generation circuit, for generating an operation signal according to a feedback signal in the identified mode to operate at least one power switch in a power stage circuit, such that an input voltage is converted to an output voltage and an output current is supplied to the identifiable light emitting device circuit; and

an identification circuit, which is coupled to the operation signal generation circuit, for determining whether the miss mode is changed to the identified mode according to whether the output voltage meets a predetermined condition, and correspondingly generating an enable signal which is sent to the operation signal generation circuit, such that the light emitting device control circuit operates in the identified mode;

wherein the identified mode indicates that the identifiable light emitting device circuit is normally coupled to the light emitting device power supply circuit, and the miss mode indicates that the identifiable light emitting device circuit is not normally coupled to the light emitting device power supply circuit, and wherein the output voltage is controlled at a predetermined level in the miss mode;

wherein the identification circuit includes;

a first comparison circuit, for generating a first comparison signal according to the output voltage and a first reference level, wherein the first reference level is higher than the predetermined level;

a second comparison circuit, for generating a second comparison signal according to the output voltage and a second reference level, wherein the second reference level is lower than the predetermined level; and

a determination circuit, which is coupled to the first comparison circuit and the second comparison circuit, and outputs the enable signal, wherein the determination circuit determines a level of the enable signal according to the first comparison signal and/or the second comparison signal.

7. The light emitting device control circuit of claim 6, wherein the identification circuit generates the enable signal after a delay time period from when the output voltage meets the predetermined condition.

8. The light emitting device control circuit of claim 6, wherein a level of the output voltage changes while the identifiable light emitting device circuit changes from being not normally coupled to being normally coupled.

9. The light emitting device control circuit of claim 6, wherein the predetermined condition is:

the output voltage being lower than a reference level, and the reference level being lower than the predetermined level.

10. The light emitting device control circuit of claim 6, wherein the power stage circuit is coupled to a level control circuit which includes a voltage divider circuit, the voltage divider circuit including a first bias circuit and a second bias circuit connected in series, wherein a connection node between the first bias circuit and the second bias circuit is electrically connected to the output voltage.

11. An identifiable light emitting device circuit for a light emitting device control circuit, wherein the light emitting device control circuit is for identifying the identifiable light emitting device circuit to determine whether to operate in an identified mode or a miss mode, such that in the identified mode, the light emitting device control circuit operates at least one power switch in a power stage circuit to convert an input voltage to an output voltage and supply an output current to the identifiable light emitting device circuit, and in the miss mode, the output voltage is controlled at a predetermined level, wherein the identified mode indicates that the identifiable light emitting device circuit is normally coupled to the light emitting device power supply circuit, and the miss mode indicates that the identifiable light emitting device circuit is not normally coupled to the light emitting device power supply circuit, the identifiable light emitting device circuit comprising:

at least one light emitting device, for coupling to the power stage circuit and lighting by receiving the output current in the identified mode; and

a passive device circuit, which is coupled to the light emitting device, for providing an impedance such that the output voltage is changed when the miss mode is changed to the identified mode, whereby the light emitting device control circuit determines that the identifiable light emitting device circuit is normally coupled to the light emitting device power supply circuit.

12. An identification method of identifying an identifiable light emitting device circuit, comprising:

controlling an output voltage at a predetermined level when the identifiable light emitting device circuit is not normally coupled to the output voltage;

providing an impedance in the identifiable light emitting device circuit;

setting the output voltage to a predetermined condition by the impedance in the identifiable light emitting device circuit when the identifiable light emitting device circuit changes from being not normally coupled to being normally coupled to the output voltage;

determining whether the identifiable light emitting device circuit changes from being not normally coupled to being normally coupled according to whether the output voltage meets the predetermined condition; and

determining that the identifiable light emitting device circuit changes from being normally coupled to being not normally coupled when the output voltage is lower than a first reference level, wherein the first reference level is higher than the predetermined level;

wherein the predetermined condition is;

the output voltage being lower than a second reference level, and the second reference level being lower than the predetermined level.

13. The identification method of claim 12, further comprising:

delaying a delay time period after determining the identifiable light emitting device circuit changing from being not normally coupled to being normally coupled, and after the delay time period, enabling a power stage circuit to supply an output current to the identifiable light emitting device circuit.

14. An identification method of identifying an identifiable light emitting device circuit, comprising:

controlling an output voltage at a predetermined level when the identifiable light emitting device circuit is not normally coupled to the output voltage;

providing an impedance in the identifiable light emitting device circuit;

setting the output voltage to a predetermined condition by the impedance in the identifiable light emitting device circuit when the identifiable light emitting device circuit changes from being not normally coupled to being normally coupled to the output voltage;

determining whether the identifiable light emitting device circuit changes from being not normally coupled to being normally coupled according to whether the output voltage meets the predetermined condition;

wherein the step of controlling an output voltage at a predetermined level when the identifiable light emitting device circuit is not normally coupled to the output voltage includes;

providing a voltage divider circuit which generates a divided voltage according to a supply voltage, and providing the divided voltage as the output voltage;

wherein when the identifiable light emitting device circuit changes from being not normally coupled to being normally coupled, the impedance in the identifiable light emitting device circuit changes the divided voltage of the voltage divider circuit, such that the output voltage meets the predetermined condition.