Power supply with a feedback circuit relieving spikes

• US 7,852,649 B2
• Filed: 11/15/2007
• Issued: 12/14/2010
• Est. Priority Date: 06/07/2007
• Status: Expired due to Fees

• Current Assignee: Young Green Energy Co. (Coretronic Corporation)
• Original Assignee: Young Green Energy Co. (Coretronic Corporation)
• Inventors: Hsiao, Chien-Chung
• Primary Examiner(s): Sterrett, Jeffrey L
• Application Number:
  US11/941,068
• Publication Number:
  US 20080304294A1
• Time in Patent Office: 1,125 Days
• Field of Search: 363/78, 363/84, 363/89, 363/95, 363/97, 363/98
• US Class Current: 363/97
• 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: 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: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

In a feedback circuit of a power supply, an electrical level of an output voltage is stabilized corresponding to changes of an electrical level of a pulse width modulation signal, and effects, which are caused by spikes, on passive elements are decreased to a lowest degree. The electrical level of the output voltage is stabilized by storing a voltage corresponding to a low-to-high electrical level of the PWM signal with a capacitor, by discharging the stored voltage with a high-to-low electrical level of said PWM signal, and by regulating a discharging path of the stored voltage with a diode, which is not conducted. The abovementioned disposition may be utilized on various power-consuming devices, a duty cycle of each of which is controlled with a PWM signal, for stabilizing output voltages of said power-consuming devices, and for reducing effects, which are caused by spikes, on passive elements inside said power-consuming devices.

Claims

1. A power supply comprising:

a power supplying circuit;

a power controlling circuit having an output terminal coupled to an input terminal of the power supplying circuit;

a first switch;

a pulse width modulation signal source coupled to a first terminal of the first switch; and

a feedback circuit comprising;

a first operational amplifier having a first input terminal coupled to a first reference voltage source, and a second input terminal coupled to a second terminal of the first switch;

a first resistor having a first terminal coupled to an output terminal of the first operational amplifier;

a first diode having a first terminal coupled to a second terminal of the first resistor;

a first capacitor having a first terminal coupled to a second terminal of the first diode, and a second terminal coupled to ground;

a second resistor having a first terminal coupled to the second terminal of the first diode;

a second diode having a first terminal coupled to a second terminal of the second resistor;

a third resistor having a first terminal coupled to a second terminal of the second diode, and a second terminal coupled to the second terminal of the first capacitor;

a second operational amplifier having a first input terminal coupled to a second reference voltage source, a second input terminal coupled to the second terminal of the second diode, and an output terminal coupled to an input terminal of the power controlling circuit; and

a fourth resistor having a first terminal coupled to the output terminal of the second operational amplifier, and a second terminal coupled to the first terminal of the third resistor.

2. The power supply of claim 1 wherein the feedback circuit further comprises:

a fifth resistor having a first terminal coupled to the second terminal of the first switch; and

a second capacitor having a first terminal coupled to a second terminal of the fifth resistor, and a second terminal coupled to the second terminal of the first capacitor.

3. The power supply of claim 1 wherein the power supplying circuit comprises:

a voltage source;

a third capacitor having a first terminal coupled to the voltage source, and a second terminal coupled to ground;

a transformer having a first input terminal coupled to the first terminal of the third capacitor, a second input terminal coupled to the output terminal of the power controlling circuit, and a first output terminal coupled to ground;

a third diode having a first terminal coupled to a second output terminal of the transformer;

a fourth capacitor having a first terminal coupled to the first terminal of the third diode;

a sixth resistor having a first terminal coupled to a second terminal of the fourth capacitor, and a second terminal coupled to a second terminal of the third diode;

a fifth capacitor having a first terminal coupled to the second terminal of the third diode, and a second terminal coupled to the first output terminal of the transformer;

an inductor having a first terminal coupled to the second terminal of the third diode;

a sixth capacitor having a first terminal coupled to a second terminal of the inductor, and a second terminal coupled to the first output terminal of the transformer; and

a seventh resistor having a first terminal coupled to the first output terminal of the transformer, and a second terminal coupled to the second terminal of the first switch.

4. The power supply of claim 1 wherein the power controlling circuit comprises:

a pulse width modulation circuit;

a light coupling circuit having an input terminal coupled to the output terminal of the second operational amplifier, and an output terminal coupled to an input terminal of the pulse width modulation circuit;

a second switch having a first terminal coupled to a first output terminal of the pulse width modulation circuit, a second terminal coupled to an second output terminal of the pulse width modulation circuit, and a third terminal coupled to the input terminal of the power supplying circuit; and

an eighth resistor having a first terminal coupled to the second output terminal of the pulse width modulation circuit, and a second terminal coupled to ground.

5. The power supply of claim 4 wherein the second switch is an N-type metal oxide semiconductor transistor.

6. The power supply of claim 4 wherein the second switch is a P-type metal oxide semiconductor transistor.

7. The power supply of claim 1 wherein the first switch is an N-type metal oxide semiconductor transistor.

8. The power supply of claim 1 wherein the first switch is a P-type metal oxide semiconductor transistor.

9. The power supply of claim 1 wherein a first output terminal of the power supplying circuit is coupled to an input terminal of a light module for supplying power for the light module.

10. The power supply of claim 9 wherein the light module comprises a plurality of light emitting diodes, the plurality of the light emitting diodes including a first light emitting diode coupled to the output terminal of the second operational amplifier, and a second light emitting diode coupled to a third terminal of the first switch.