Method and apparatus for operating a semiconductor light source

Patent metadata

Field	Value
Publication number	US-11019696-B2
Application number	US-201816185405-A
Country	US
Kind code	B2
Filing date	Nov 9, 2018
Priority date	Feb 8, 2018
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A method and apparatus for operating a semiconductor light source is presented. In particular there is a current regulator for regulating a current flowing through a light emitting diode device. The current regulator includes a first switch for receiving a first current flowing through the semiconductor light source and a control circuit coupled to the first switch and adapted to provide a second current proportional to the first current. The current regulator is adapted to regulate the first current using the second current.

First claim

What is claimed is:

1. A current regulator for use with a semiconductor light source, the current regulator comprising
a first switch for receiving a first current flowing through the semiconductor light source;
a controller circuit coupled to the first switch adapted to provide a second current proportional to the first current;
wherein the controller circuit comprises a comparator coupled to a current mirror circuit via a second switch, the comparator being adapted to compare a feedback value with a control value and to provide a control signal to control the second switch,
wherein the current mirror circuit comprises a first current mirror formed by the first switch and a third switch, and a second current mirror formed by a fourth switch and a fifth switch, wherein the fourth switch is directly connected to the third switch and wherein the second switch has a first terminal to receive the control signal, a second terminal connected to the fifth switch and a third terminal coupled to ground via a resistance, wherein the feedback value comprises a voltage across the resistance; and
a current generator coupled in series with the second switch, the current generator being adapted to provide a setting current;
wherein the current regulator is adapted to regulate the first current using the second current.

2. The current regulator as claimed in claim 1 , wherein the second current is defined by a product of the first current and a constant, wherein the constant is an integer equal or greater than one.

3. The current regulator as claimed in claim 1 , wherein the comparator is an operating amplifier provided with a feedback loop to form a closed-loop amplifier.

4. The current regulator as claimed in claim 1 , wherein the feedback value is a function of the second current.

5. The current regulator as claimed in claim 1 , comprising a voltage source adapted to provide a control voltage.

6. The current regulator as claimed in claim 1 , wherein the setting current is a function of the resistance.

7. A driver for driving a semiconductor light source, the driver comprising
an alternating power source coupled to a rectifier for providing an input voltage to the semiconductor light source, and
a current regulator comprising a first switch for receiving a first current flowing through the semiconductor light source; and a controller circuit coupled to the first switch adapted to provide a second current proportional to the first current; wherein the controller circuit comprises a comparator coupled to a current mirror circuit via a second switch, the comparator being adapted to compare a feedback value with a control value and to provide a control signal to control the second switch, wherein the current mirror circuit comprises a first current mirror formed by the first switch and a third switch, and a second current mirror formed by a fourth switch and a fifth switch, wherein the fourth switch is directly connected to the third switch and wherein the second switch has a first terminal to receive the control signal, a second terminal connected to the fifth switch and a third terminal coupled to ground via a resistance, wherein the feedback value comprises a voltage across the resistance and wherein the current regulator is adapted to regulate the first current using the second current; wherein the current regulator comprises current generator coupled in series with the second switch, the current generator being adapted to provide a setting current.

8. A method of driving a semiconductor light source, the method comprising the steps of:
providing a current regulator comprising a first switch for receiving a first current flowing through the semiconductor light source, and a controller circuit coupled to the first switch adapted to provide a second current proportional to the first current; wherein the controller circuit comprises a comparator coupled to a current mirror circuit via a second switch,
comparing using the comparator a feedback value with a control value to provide a control signal to control the second switch,
wherein the current mirror circuit comprises a first current mirror formed by the first switch and a third switch, and a second current mirror formed by a fourth switch and a fifth switch, wherein the fourth switch is directly connected to the third switch and wherein the second switch has a first terminal to receive the control signal, a second terminal connected to the fifth switch and a third terminal coupled to ground via a resistance, wherein the feedback value comprises a voltage across the resistance;
wherein the current regulator comprises current generator coupled in series with the second switch, the current generator being adapted to provide a setting current, and
regulating the first current using the second current.

9. The method as claimed in claim 8 wherein the second current is defined by a product of the first current and a constant, wherein the constant is an integer equal or greater than one.

10. The method as claimed in claim 8 , wherein the feedback value is function of the second current.

11. The method as claimed in claim 8 , wherein the control value is a control voltage; and wherein the feedback value is a feedback voltage.

12. The method as claimed in claim 8 , wherein the comparator is an operating amplifier provided with a feedback loop to form a closed-loop amplifier.

Assignees

• Dialog Semiconductor Uk Ltd

Inventors

• Sun Junyue
• Zou Yufeng
• Cao Huibin
• Chen Lijie

Classifications

• H05B45/397 Primary

  Current mirror circuits · CPC title

• H05B45/345

  Current stabilisation; Maintaining constant current · CPC title

• Y02B20/30

  Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] · CPC title

• H05B45/10

  Controlling the intensity of the light · CPC title

• H05B45/37 Primary

  Converter circuits · CPC title