Charging circuit

Abstract

An exemplary charging circuit (200) includes for charging a load component (210) includes a power supply unit (220), a feedback circuit, and a sampling resistor (230). The power supply unit includes a pulse width modulation circuit (221) and a power output terminal (222) configured to output a direct current supply. The feedback circuit includes an amplifying comparator (241), a constant voltage circuit (242), a transistor (243), and an optoelectrical coupler (244). The constant voltage circuit is configured to generate a reference voltage and apply the reference voltage to a negative input terminal of the amplifier comparator. An output terminal of the amplifier comparator is connected to the pulse width modulation circuit via the transistor and the optoelectrical coupler. The sampling resistor includes a current sampling terminal connected to a positive input terminal of the amplifier comparator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a charging circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram of a charging circuit according to a second embodiment of the present invention.

FIG. 3 is a diagram of a charging circuit of a conventional battery charger.

Claims

1. A charging circuit for charging a load component, the charging circuit comprising: a power supply unit comprising a pulse width modulation circuit and a power output terminal configured to output a direct current supply;a feedback circuit comprising an amplifying comparator, a constant voltage circuit, a transistor, and an optoelectrical coupler, the constant voltage circuit being configured to generate a reference voltage and apply the reference voltage to a negative input terminal of the amplifier comparator, an output terminal of the amplifier comparator being connected to the pulse width modulation circuit via the transistor and the optoelectrical coupler; anda sampling resistor comprising a current sampling terminal connected to a positive input terminal of the amplifier comparator;wherein the charging circuit is configured such that when the load component is coupled to the direct current supply of the charging circuit and a direct current traveling through the load component changes, the amplifier comparator generates a feedback signal and applies the feedback signal to the pulse width modulation circuit via the transistor and the optoelectrical coupler, and the pulse width modulation circuit adjusts the direct current supply output from the power output terminal according the feedback signal to stabilize the current traveling through the load component.

2. The charging circuit as claimed in claim 1, wherein the constant voltage circuit comprises a first resistor and a second resistor connected in series, and a diode connected with the first and second resistors in parallel.

3. The charging circuit as claimed in claim 2, wherein a node between the first resistor and the second resistor is connected to the negative input terminal of the amplifier comparator.

4. The charging circuit as claimed in claim 2, wherein a resistance of the first resistor is 1000Ω.

5. The charging circuit as claimed in claim 2, wherein the second resistor is an adjustable resistor.

6. The charging circuit as claimed in claim 5, wherein the second resistor has an adjustable resistance in the range from 34˜2000Ω.

7. The charging circuit as claimed in claim 1, further comprising a red light emitting diode, wherein the output terminal of the amplifier comparator is grounded via the red light emitting diode.

8. The charging circuit as claimed in claim 7, further comprising a switching transistor and a green light emitting diode connected between a source electrode and a drain electrode of the switching transistor.

9. The charging circuit as claimed in claim 8, wherein a source electrode of the switching transistor is connected to the power output terminal, a gate electrode of the switching transistor is connected to the output terminal of the amplifier comparator, and a drain electrode of the switching transistor is grounded.

10. The charging circuit as claimed in claim 9, further comprising a bias resistor, wherein the source electrode of the switching transistor is connected to the power output terminal via the bias resistor.

11. The charging circuit as claimed in claim 1, further comprising a rectifier-filter circuit for rectifying and filtering the direct current supply output from the power output terminal.

12. The charging circuit as claimed in claim 1, wherein the load component is a rechargeable battery.

13. The charging circuit as claimed in claim 12, wherein the load component is a lithium ion rechargeable battery.

14. The charging circuit as claimed in claim 12, wherein the load component is a nickel-cadmium rechargeable battery.

15. The charging circuit as claimed in claim 1, wherein the pulse width modulation circuit is integrated in the power supply unit by a full bridge rectifier circuit.

16. The charging circuit as claimed in claim 1, wherein the pulse width modulation circuit is integrated in the power supply unit by a half bridge rectifier circuit.

17. The charging circuit as claimed in claim 1, wherein the power supply unit further comprising a grounding terminal connected the ground.

18. The charging circuit as claimed in claim 1, wherein the pulse width modulation circuit is an NCP1203 type pulse width modulation circuit.

19. A charging circuit for charging a load component, the charging circuit comprising: a power supply unit comprising a power output terminal configured to output a direct current supply and a pulse width modulation circuit configured to adjust the direct current supply to stabilize a current traveling through the load component;a feedback circuit comprising an amplifying comparator, a constant voltage circuit, a transistor, and an optoelectrical coupler, the constant voltage circuit being configured for generating a reference voltage and applying the reference voltage to a negative input terminal of the amplifier comparator, an output terminal of the amplifier comparator being connected to the pulse width modulation circuit via the transistor and the optoelectrical coupler; anda sampling resistor comprising a current sampling terminal connected to a positive input terminal of the amplifier comparator.

20. A charging circuit assembly comprising: a load component;a power supply unit comprising a pulse width modulation circuit and a power output terminal configured to output a direct current supply;a feedback circuit comprising an amplifying comparator, a constant voltage circuit, a transistor, and an optoelectrical coupler, the constant voltage circuit being configured to generate a reference voltage and apply the reference voltage to a negative input terminal of the amplifier comparator, an output terminal of the amplifier comparator being connected to the pulse width modulation circuit via the transistor and the optoelectrical coupler; anda sampling resistor comprising a current sampling terminal connected to a positive input terminal of the amplifier comparator;wherein the charging circuit is configured such that when the load component is coupled to the direct current supply of the charging circuit and a direct current traveling through the load component changes, the amplifier comparator generates a feedback signal and applies the feedback signal to the pulse width modulation circuit via the transistor and the optoelectrical coupler, and the pulse width modulation circuit adjusts the direct current supply output from the power output terminal according the feedback signal to stabilize the current traveling through the load component.