CN215897350U - Battery charging circuit and drying box - Google Patents
Battery charging circuit and drying box Download PDFInfo
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- CN215897350U CN215897350U CN202122315475.8U CN202122315475U CN215897350U CN 215897350 U CN215897350 U CN 215897350U CN 202122315475 U CN202122315475 U CN 202122315475U CN 215897350 U CN215897350 U CN 215897350U
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Abstract
The utility model relates to the technical field of drying boxes, in particular to a battery charging circuit and a drying box. The circuit comprises a power supply input circuit, a reference voltage source circuit and at least one group of charging units, wherein each charging unit comprises: the LED driving circuit comprises a voltage comparison circuit, a charging control circuit, a first LED driving circuit and a second LED driving circuit; the voltage comparison circuit is used for comparing the battery voltage with the reference voltage, and the output of the voltage comparison circuit controls the charging control circuit to charge the battery; the first LED driving circuit is used for driving a first indicator light to indicate that the battery is charged, and the second LED driving circuit is used for driving a second indicator light to indicate that the battery is fully charged; the charging control circuit, the first LED drive circuit and the second LED drive circuit adopt discrete semiconductor switches for switching control. The utility model adopts a discrete device for controlling and indicating the charging of the battery, and provides a low-cost battery charging solution.
Description
Technical Field
The utility model relates to the field of drying boxes, in particular to a battery charging circuit and a drying box.
Background
Due to the recent drastic fluctuation of the market price of semiconductor circuits, it is required to develop a battery charging circuit of a dry box using a separate device for charge control to control the cost.
SUMMERY OF THE UTILITY MODEL
In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a battery charging circuit and a drying box to optimize costs.
To achieve the above object, the present invention provides a battery charging circuit, including a power input circuit, a reference voltage source circuit and at least one set of charging unit, the charging unit including: the LED driving circuit comprises a voltage comparison circuit, a charging control circuit, a first LED driving circuit and a second LED driving circuit;
the power supply input circuit is used for outputting a first direct current voltage and supplying power to the reference voltage source circuit, the voltage comparison circuit, the charging control circuit and the LED drive circuit;
the reference voltage source circuit is used for outputting a reference voltage;
the voltage comparison circuit is used for comparing the battery voltage with the reference voltage and outputting a high level when the battery voltage is greater than the reference voltage; outputting a low level when the battery voltage is lower than the reference voltage;
the charging control circuit comprises a first semiconductor switch, the input end of the first semiconductor switch is electrically connected with the output end of the power input circuit, the output end of the first semiconductor switch is electrically connected with the anode of the battery through a resistor, and the control end of the first semiconductor switch is electrically connected with the output end of the voltage comparison circuit;
the first LED driving circuit comprises a first indicator light, the first indicator light is controlled by the output signal of the voltage comparison circuit, and when the output signal of the voltage comparison circuit is at a low level, the first indicator light is turned on;
the second LED driving circuit comprises a second indicator light, the second indicator light is controlled by the battery voltage, and when the battery voltage is larger than a first threshold value, the second indicator light is turned on.
Furthermore, the first LED driving circuit further includes a second semiconductor switching tube and a third semiconductor switching tube, the second semiconductor switching tube is a PNP triode or a PMOS tube, and a control end of the second semiconductor switching tube is electrically connected to an output end of the voltage comparison circuit; the input end of the power supply input circuit is electrically connected with the output end of the power supply input circuit; the output end of the third semiconductor switch tube is electrically connected with the control end of the third semiconductor switch tube through a resistor; the third semiconductor switch tube is an NPN triode or an NMOS tube, the input end of the third semiconductor switch tube is electrically connected with the cathode of the first indicator lamp, and the output end of the third semiconductor switch tube is grounded; and the anode of the first indicator lamp is electrically connected with the output end of the power input circuit.
Furthermore, the second LED driving circuit further includes a fourth semiconductor switching tube and a fifth semiconductor switching tube, the fourth semiconductor switching tube is a PNP triode or a PMOS tube, a control end of the fourth semiconductor switching tube is electrically connected to the positive electrode of the battery, and an input end of the fourth semiconductor switching tube is electrically connected to an output end of the power input circuit; the output end of the first semiconductor switch tube is electrically connected with the input end of the second semiconductor switch tube through a resistor; the fifth semiconductor switch tube is an NPN triode or an NMOS tube, the control end of the fifth semiconductor switch tube is respectively and electrically connected with the output end of the power input circuit and the anode of the battery through resistors, the input end of the fifth semiconductor switch tube is electrically connected with the cathode of the second indicator lamp, and the output end of the fifth semiconductor switch tube is grounded; and the anode of the second indicator light is electrically connected with the output end of the power input circuit.
Furthermore, the voltage comparison circuit comprises a comparator unit, wherein the non-inverting input end of the comparator unit is electrically connected with the output end of the comparator unit through a first resistor, is electrically connected with the output end of the power input circuit through the first resistor and a second resistor, is electrically connected with the positive electrode of the battery through a third resistor and a fourth resistor, and is electrically connected with the output end of the reference voltage source circuit through the third resistor and a first capacitor; and the inverting input end of the comparator unit is electrically connected with the output end of the reference voltage source circuit.
Further, the first indicator light and the second indicator light are two LED units of a double-color indicator light, wherein the two LED units are connected in a common positive mode or are mutually independent.
Further, the first indicator light is a red indicator light; the second indicator light is a green indicator light.
Further, the reference voltage source circuit comprises a reference source and a voltage dividing circuit, and the output of the reference source outputs the reference voltage through the voltage dividing circuit.
Further, the battery is a nickel-metal hydride battery, the reference voltage is 1.41V, and the tolerance is +/-2%.
Further, the input end of the power input circuit is a USB interface; and a power management chip in the power input circuit is a low dropout linear regulator.
A drying box comprising a battery charging circuit as described above, wherein the charging units are two groups; the object of charging is a rechargeable button cell.
The utility model adopts a discrete device for controlling and indicating the charging of the battery, and provides a low-cost battery charging solution.
Drawings
FIG. 1 is a block diagram of a dry box battery charging circuit;
FIG. 2 is a circuit schematic of the dry box battery charging circuit;
fig. 3 is a partially enlarged view of fig. 2.
Detailed Description
To further illustrate the various embodiments, the utility model provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the utility model and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.
The utility model will now be further described with reference to the accompanying drawings and detailed description.
As shown in fig. 1 and fig. 2, the present invention provides a battery charging circuit, which is applied to a low-power drying box, such as a drying box of a hearing aid, and the drying box simultaneously charges two rechargeable button batteries for the hearing aid, and the battery charging circuit includes a power input circuit 10, a reference voltage source circuit 20 and two charging units, each of which includes a voltage comparison circuit 30, a charging control circuit 40 and an LED driving circuit 50. The rechargeable battery used by the hearing aid is a nickel-metal hydride battery A13, and the standard output voltage of the rechargeable battery is 1.45V.
In this embodiment, the power input circuit 10 includes a power management chip IC1, the power input interface is a standard charging interface such as Type C, USB, etc., and the power management chip IC1 outputs 3.3V, identified as VDD, by using an LDO (low dropout linear regulator), and supplies power to the reference voltage source circuit 20, the voltage comparison circuit 30, the charging control circuit 40, and the LED driving circuit 50, respectively.
In the present embodiment, the reference voltage source circuit 20 employs a reference source chip TL431, and the reference source chip TL431 outputs 2.5V at its output terminal (pin 3) by a suitable driving current, and the voltage outputs a reference voltage through a voltage dividing circuit composed of R2 and R30, and in this application, the reference voltage is 1.41V with a tolerance of ± 2%.
In the present embodiment, the voltage comparison circuit 30 is configured to compare the battery voltage with a reference voltage, and output a high level when the battery voltage is greater than the reference voltage; when the battery voltage is lower than the reference voltage, a low level is output. Specifically, the circuit comprises a comparator unit U1A, resistors R5, R10, R20, R21 and a capacitor C2; wherein the non-inverting input terminal of the comparator unit U1A is connected to the output of the comparator unit U1A through R20, to VDD through R20, R21, to the positive electrode of the battery through R10, R5, to the reference voltage (1.41V) through R10, C2; the inverting input of comparator unit U1A is connected to the reference voltage (1.41V).
In this embodiment, the charge control circuit 40 includes a transistor Q1, the transistor Q1 is a PNP transistor whose emitter is connected to VDD, collector is connected to the positive electrode of the battery through a current limiting resistor R22, base is connected to the output terminal of the voltage comparison circuit, the output of the voltage comparison circuit 30 controls, and when Q1 is turned on, the battery BAT1 is charged by the power supply VDD through the current limiting resistor R22.
In the present embodiment, the LED driving circuit 50 includes a first LED driving unit and a second LED driving unit. The first LED driving unit includes a red indicator lamp in a red and green LED indicator lamp LED1, which is controlled by an output signal of the voltage comparison circuit 30 and is turned on when the output signal of the voltage comparison circuit 30 is at a low level, and a triode Q2, Q8. The transistor Q2 is a PNP transistor, and the transistor Q8 is an NPN transistor. The specific circuit connection is as follows: the base of the triode Q2 is connected with the output of the voltage comparison circuit 30; its emitter is connected to VDD; the collector of the transistor is connected with the base of a triode Q8 through a resistor R11; the collector of the triode Q8 is connected with the cathode of the red indicator light, and the emitter of the triode Q8 is grounded; the anode of the red indicator light is connected with VDD.
The second LED driving unit includes a green indicator lamp in a red and green LED indicator lamp LED1, a triode Q3, Q7, the green indicator lamp is controlled by the battery voltage, and the green indicator lamp is turned on when the battery voltage reaches a charging voltage threshold. The triode Q3 is a PNP triode, the base electrode of the triode Q3 is connected with the positive electrode of the battery BAT1, and the emitter electrode of the triode Q3 is connected with VDD; the collector of the transistor is connected with the base of a triode Q7 through a current-limiting resistor R9; the triode Q7 is an NPN triode, and the base electrodes of the triode Q7 are respectively connected with the positive electrode of the battery BAT1 through resistors R32, R8 and VDD; the collector of the green indicator lamp is connected with the cathode of the green indicator lamp, and the emitter of the green indicator lamp is grounded; the anode of the green indicator light is connected with VDD.
In other implementations, the transistors Q1, Q2, Q3 may be PMOS transistors, and the transistors Q7, Q8 may be NMOS transistors. In the present application, it is only necessary that vgs (th) of each MOS is not more than 1V to realize the same function.
In the embodiment, the reference voltage source circuit comprises a reference source and a voltage division circuit, wherein the reference source is TL431, and the reference source outputs 2.5V and outputs a reference voltage (1.41V) through the voltage division circuit.
The working principle of the charging circuit will be described by taking the charging unit where the battery BAT1 is located as an example:
1. when the charging circuit is powered on, the dc voltage VDD is output via the power management chip IC 2.
A reference voltage 1.41V is generated by a reference voltage source circuit and supplied to inverting input terminals of comparators U1A and U1B as a reference voltage.
2. When the battery BAT1 is not charged, the dc voltage VDD is transmitted to the non-inverting input terminal of the comparator U1A through the R32, R8, R5, and R10, at this time, the voltage at the non-inverting input terminal is at a high level (3.3V), and after being compared by the comparator U1A, the high level (3V-3.3V) is output, so that the triodes Q1, Q2, Q3, Q7, and Q8 are turned off, and at this time, the red and green lights of the LED1 indicator light are in an off state, indicating an uncharged state.
3. When the voltage across the battery BAT1 is lower than 1.41V, the voltage across the non-inverting input terminal of the comparator U1A is lower than 1.41V, and the comparator U1A compares the voltage and outputs low level to turn on the Q1, Q2, Q3, Q7 and Q8, and the red indicator light and the green indicator light of the indicator light LED1 are simultaneously on to emit orange light to indicate the charging state.
4. After charging, when the voltage at two ends of the battery BAT1 is greater than 1.41V, the voltage at the non-inverting input end of the comparator U1A is greater than 1.41V, and the comparator U1A compares the voltage and outputs a high level (3.3V), so that the triodes Q1, Q2 and Q8 are cut off, the triodes Q3 and Q7 are turned on, and at this time, the red indicator light of the LED1 is in an off state, and the green indicator light is on, which indicates that the battery is fully charged.
The utility model adopts a discrete device for controlling and indicating the charging of the battery, and provides a low-cost battery charging solution.
It will be understood by those skilled in the art that "connections" between electronic devices in the present embodiment each represent a circuit connection that is in physical contact.
While the utility model has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the utility model as defined by the appended claims.
Claims (10)
1. A battery charging circuit comprising a power input circuit, a reference voltage source circuit and at least one set of charging cells, said charging cells comprising: the LED driving circuit comprises a voltage comparison circuit, a charging control circuit, a first LED driving circuit and a second LED driving circuit;
the power supply input circuit is used for outputting a first direct current voltage and supplying power to the reference voltage source circuit, the voltage comparison circuit, the charging control circuit and the LED drive circuit;
the reference voltage source circuit is used for outputting a reference voltage;
the voltage comparison circuit is used for comparing the battery voltage with the reference voltage and outputting a high level when the battery voltage is greater than the reference voltage; outputting a low level when the battery voltage is lower than the reference voltage;
the charging control circuit comprises a first semiconductor switch, the input end of the first semiconductor switch is electrically connected with the output end of the power input circuit, the output end of the first semiconductor switch is electrically connected with the anode of the battery through a resistor, and the control end of the first semiconductor switch is electrically connected with the output end of the voltage comparison circuit;
the first LED driving circuit comprises a first indicator light, the first indicator light is controlled by the output signal of the voltage comparison circuit, and when the output signal of the voltage comparison circuit is at a low level, the first indicator light is turned on;
the second LED driving circuit comprises a second indicator light, the second indicator light is controlled by the battery voltage, and when the battery voltage is larger than a first threshold value, the second indicator light is turned on.
2. The battery charging circuit of claim 1, wherein the first LED driving circuit further comprises a second semiconductor switch transistor and a third semiconductor switch transistor, the second semiconductor switch transistor is a PNP triode or a PMOS transistor, and a control terminal of the second semiconductor switch transistor is electrically connected to the output terminal of the voltage comparison circuit; the input end of the power supply input circuit is electrically connected with the output end of the power supply input circuit; the output end of the third semiconductor switch tube is electrically connected with the control end of the third semiconductor switch tube through a resistor; the third semiconductor switch tube is an NPN triode or an NMOS tube, the input end of the third semiconductor switch tube is electrically connected with the cathode of the first indicator lamp, and the output end of the third semiconductor switch tube is grounded; and the anode of the first indicator lamp is electrically connected with the output end of the power input circuit.
3. The battery charging circuit of claim 1, wherein the second LED driving circuit further comprises a fourth semiconductor switching tube and a fifth semiconductor switching tube, the fourth semiconductor switching tube is a PNP triode or a PMOS transistor, a control terminal of the fourth semiconductor switching tube is electrically connected to the positive electrode of the battery, and an input terminal of the fourth semiconductor switching tube is electrically connected to the output terminal of the power input circuit; the output end of the first semiconductor switch tube is electrically connected with the input end of the second semiconductor switch tube through a resistor; the fifth semiconductor switch tube is an NPN triode or an NMOS tube, the control end of the fifth semiconductor switch tube is respectively and electrically connected with the output end of the power input circuit and the anode of the battery through resistors, the input end of the fifth semiconductor switch tube is electrically connected with the cathode of the second indicator lamp, and the output end of the fifth semiconductor switch tube is grounded; and the anode of the second indicator light is electrically connected with the output end of the power input circuit.
4. The battery charging circuit according to claim 1, wherein the voltage comparison circuit comprises a comparator unit, a non-inverting input terminal of the comparator unit is electrically connected to an output terminal of the comparator unit through a first resistor, is electrically connected to an output terminal of the power input circuit through the first resistor, a second resistor, is electrically connected to a positive electrode of the battery through a third resistor, a fourth resistor, and is electrically connected to an output terminal of the reference voltage source circuit through the third resistor, a first capacitor; and the inverting input end of the comparator unit is electrically connected with the output end of the reference voltage source circuit.
5. The battery charging circuit of claim 1, wherein the first indicator light and the second indicator light are two LED units of a two-color indicator light, wherein the two LED units are connected in common or independent of each other.
6. The battery charging circuit of claim 1, wherein the first indicator light is a red indicator light; the second indicator light is a green indicator light.
7. The battery charging circuit of claim 1, wherein the reference voltage source circuit comprises a reference source and a voltage divider circuit, an output of the reference source outputting the reference voltage via the voltage divider circuit.
8. The battery charging circuit of claim 1, wherein the battery is a nickel metal hydride battery, the reference voltage is 1.41V, and the tolerance is ± 2%.
9. The battery charging circuit of claim 1, wherein the input of the power input circuit is a USB interface; and a power management chip in the power input circuit is a low dropout linear regulator.
10. A drying box comprising a battery charging circuit according to any of claims 1-9, wherein the charging units are in two groups; the object of charging is a rechargeable button cell.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122315475.8U CN215897350U (en) | 2021-09-24 | 2021-09-24 | Battery charging circuit and drying box |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122315475.8U CN215897350U (en) | 2021-09-24 | 2021-09-24 | Battery charging circuit and drying box |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN215897350U true CN215897350U (en) | 2022-02-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122315475.8U Active CN215897350U (en) | 2021-09-24 | 2021-09-24 | Battery charging circuit and drying box |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN215897350U (en) |
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2021
- 2021-09-24 CN CN202122315475.8U patent/CN215897350U/en active Active
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