CN208142879U - Charging control circuit and charging device - Google Patents

Abstract

The utility model relates to a charging control circuit and a charging device, which belongs to the technical field of battery charging and solves the problem that the battery charging is easy to be overcharged in the prior art. It includes a logic control unit and a switch control unit; the logic control unit includes a voltage comparator U2A and a reference source U1, the positive input terminal of the voltage comparator U2A is used to input the sampling voltage of the rechargeable battery, and the negative input terminal is connected to the reference source U1; the response Based on the high level output by the voltage comparator U2A, the switch control unit shuts off the battery charging main circuit. The charging control circuit realizes that when the battery voltage reaches the set value, the charging circuit is turned off in time to prevent overcharging and improve the service life of the battery.

Description

A charging control circuit and charging device

technical field

The utility model relates to the technical field of charging control, in particular to a charging control circuit and a charging device.

Background technique

Currently, there are many types of rechargeable batteries, and it is necessary to use a charging device to charge the batteries. However, the existing charging device is prone to overcharging when charging the battery, which greatly affects the service life of the battery.

Utility model content

In view of the above analysis, the utility model aims to provide a charging control circuit and a charging device to solve the problem that the existing charging device is easy to overcharge.

The purpose of this utility model is mainly achieved by the following technical solutions:

On the one hand, an embodiment provides a charging control circuit, including a logic control unit and a switch control unit;

The logic control unit includes a voltage comparator U2A and a reference source U1, the positive input terminal of the voltage comparator U2A is used to input the sampling voltage of the rechargeable battery, and the negative input terminal is connected to the reference source U1; the reference source U1 It is a three-terminal adjustable shunt reference source;

A switch control unit, in response to the high level output by the voltage comparator U2A, the switch control unit shuts off the battery charging main circuit.

In another embodiment, the switch control unit includes a switch drive circuit and a switch tube Q2, the switch tube Q2 is arranged in the charging main circuit; in response to the high level output by the logic control unit, the switch drive circuit drives the switch Tube Q2 is turned off.

In another embodiment, the switch drive circuit includes a triode Q1 and resistors R7-R8;

The base of the triode Q1 is electrically connected to the output terminal of the voltage comparator U2A; the collector is electrically connected to one end of the resistor R7, and at the same time is electrically connected to the gate of the switching tube Q2; the emitter is connected to the negative pole of the power supply; the resistor R7 The other end is used to connect to the positive pole of the power supply;

The resistor R8 is connected between the collector and the emitter of the triode Q1;

The drain of the switching tube Q2 is used for connecting with the negative pole of the rechargeable battery, and the source is used for connecting with the negative pole of the power supply.

In another embodiment, it further includes a resistor R6 connected in series between the base of the transistor Q1 and the output terminal of the voltage comparator U2A.

In another embodiment, a resistor R4 is also included, the three-terminal adjustable shunt reference source is TL431, the cathode and reference terminal of the TL431 are respectively connected to the negative input terminal of the voltage comparator U2A, and the cathode of the TL431 is connected to the negative input terminal of the voltage comparator U2A. One end of the resistor R4 is electrically connected, the other end of the resistor R4 is used to connect to the positive pole of the power supply, and the anode of the TL431 is used to connect to the negative pole of the power supply.

In another embodiment, the logic control unit further includes a resistor R5 connected in series between the positive input terminal and the output terminal of the voltage comparator U2A.

In another embodiment, the logic control unit further includes a capacitor C1, one end of the capacitor C1 is connected to the positive input end of the voltage comparator U2A, and the other end of the capacitor C1 is used to connect to the negative pole of the power supply.

In another embodiment, the logic control unit further includes a capacitor C2, one end of the capacitor C2 is connected to the output end of the voltage comparator U2A, and the other end of the capacitor C2 is used to connect to the negative pole of the power supply.

In another embodiment, a voltage sampling unit is also included, the voltage sampling unit is electrically connected to the positive input terminal of the voltage comparator U2A, and is used to input the sampling voltage of the rechargeable battery into the positive input terminal of the voltage comparator U2A. input.

In another embodiment, the voltage sampling unit includes resistors R2 and R3, and the positive input terminal of the voltage comparator U2 is electrically connected to one end of the resistor R2 and one end of the resistor R3 respectively; the other end of the resistor R2 is used to connect with the rechargeable battery The positive pole is connected, and the other end of the resistor R3 is used to connect with the negative pole of the rechargeable battery.

In another embodiment, it further includes a charging state indication unit connected in series in the charging main circuit, for indicating the charging state.

In another embodiment, the charging state indicating unit includes a resistor R1 and a light emitting diode D1; one end of the resistor R1 is used to connect to the positive pole of the power supply, and the other end is connected to the positive pole of the light emitting diode D1, and the light emitting diode D1 The negative pole of the battery is used to connect to the positive pole of the rechargeable battery.

In another embodiment, all the ports used to be connected to the positive pole of the power supply are electrically connected together as the positive pole interface of the power supply; all the ports used to be connected to the negative pole of the power supply are electrically connected together as the negative pole interface of the power supply; The ports connected to the positive poles are electrically connected together as the charging positive pole interface; all the ports for connecting with the negative pole of the rechargeable battery are electrically connected together as the charging negative pole interface.

In another aspect, a charging device including the charging control circuit described in any one of the above embodiments is provided.

The beneficial effect of above-mentioned embodiment scheme is as follows:

1. By comparing the sampling voltage of the rechargeable battery with the reference voltage, the logic control unit controls the shutdown of the main charging circuit when the battery voltage is higher than the reference voltage, that is, when the rechargeable battery is overcharged, which solves the problem of easy overcharging of the rechargeable battery , improve battery life.

2. Since the three-terminal adjustable shunt reference source is used as the reference source, the response rate is improved. The TL431 is selected as the comparison reference, which can ensure the timeliness of the response and stop charging immediately after the battery voltage reaches the preset value. Using precise 431 as the reference, since the voltage comparator and 431 are less affected by temperature, the entire charging control circuit is less affected by temperature, which improves the applicability.

3. Set the resistor R5 between the positive input terminal and the output terminal of the voltage comparator U2A to provide positive feedback for the voltage comparator U2A, so that the battery voltage hysteresis can be set, and the charger will restart only when the battery voltage drops to a certain value. Connect it to charge the battery, and the control circuit will not turn off and on repeatedly.

4. Since the capacitor C1 is set at the rechargeable battery terminal, false triggering caused by clutter voltage interference at the battery terminal can be prevented, and the stability of the charging control circuit is improved.

5. Since the capacitor C2 is set at the output terminal of the voltage comparator U2A, the power supply terminal and other possible clutter interferences are filtered out, false triggering is prevented, and the reliability of the charging control circuit is improved.

6. The ports connected to the positive and negative poles of the power supply and the positive and negative poles of the rechargeable battery are electrically connected together, so that the entire control circuit can be made into a module with double-ended input and double-ended output, which can be directly connected between the charger and the battery, so that The entire control circuit can be modularized, which improves its convenience.

In the present utility model, the above-mentioned technical solutions can also be combined with each other to realize more preferred combination solutions. Other features and advantages of the present utility model will be described in the following description, and some advantages may become apparent from the description, or be understood by implementing the present utility model. The purpose and other advantages of the utility model can be realized and obtained by the contents particularly pointed out in the specification, claims and accompanying drawings.

Description of drawings

The drawings are only for the purpose of illustrating specific embodiments, and are not considered to limit the present utility model. Throughout the drawings, the same reference symbols represent the same components.

Fig. 1 is the structural block diagram of an embodiment of the utility model;

Fig. 2 is the schematic diagram of the principle of an embodiment of the utility model;

FIG. 3 is a schematic diagram of the circuit structure of another embodiment of the present invention.

Detailed ways

The preferred embodiments of the utility model are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the application and are used together with the embodiments of the utility model to explain the principle of the utility model and are not used to limit the scope of the utility model scope.

A specific embodiment of the present invention provides a charging control circuit, as shown in FIG. 1 . The charging control circuit includes a logic control unit and a switch control unit; the logic control unit includes a voltage comparator U2A and a reference source U1, the positive input terminal of the voltage comparator U2A is used to input the sampling voltage of the rechargeable battery, and the negative input terminal is connected to the The reference source U1 is connected; the reference source U1 is a three-terminal adjustable shunt reference source; the switch control unit responds to the high level output by the voltage comparator U2A, and the switch control unit shuts off the battery charging main circuit.

During implementation, as shown in Figure 2, the charging control circuit is connected between the charger and the rechargeable battery, and the logic control unit determines whether the rechargeable battery is fully charged according to the sampled battery voltage. The charger charges the battery; if it is fully charged, it controls to disconnect the charging main circuit and stops charging the battery.

Compared with the prior art, the charging control circuit provided by this embodiment shuts off the charging circuit in time after the battery is fully charged, so as to prevent overcharging and prolong the service life of the rechargeable battery. And the three-terminal adjustable shunt reference source is used as the reference source of the voltage comparator, which improves the real-time performance of the shutdown response and ensures that the battery voltage is turned off in time after reaching the preset value.

Specifically, the switch control unit includes a switch drive circuit and a switch tube Q2, and the switch tube Q2 is arranged in the charging main circuit; in response to the high level output by the logic control unit, the switch drive circuit drives the switch tube Q2 to turn off.

It should be noted that any switch driving circuit that can respond to the high level output by the logic control unit and control the switch to turn off can be applied to the charging control circuit of this embodiment, and can achieve the same effect.

Preferably, the switch drive circuit includes a triode Q1 and resistors R7-R8, the switch tube Q2 is a MOS tube, and the switch drive circuit is connected to the output terminal of the logic control unit, that is, the output terminal of the voltage comparator U2A through the resistor R6, as shown in Figure 3 . Transistor Q1, the base is electrically connected to the output terminal of the voltage comparator U2A through the resistor R6; the collector is electrically connected to one end of the resistor R7, and is electrically connected to the gate of the switching tube Q2; the emitter is connected to the negative pole of the power supply; the resistor The other end of R7 is used to connect to the positive pole of the power supply; resistor R8 is connected between the collector and emitter of the triode Q1; the drain of the switching tube Q2 is used to connect to the negative pole of the rechargeable battery, and the source is used to connect to the negative pole of the power supply connected.

Using the above switch driving circuit can ensure that when the voltage comparison unit outputs a low-level signal, the voltage division of the resistor R6 and the resistor R7 provides a driving voltage for the switch tube Q2, the switch tube Q2 is closed, the entire charging main circuit is turned on, and the rechargeable battery is normal. Charging; when the voltage comparison unit outputs a high-level signal, the triode Q1 is saturated and turned on, and the voltage across R7 is very low, that is, the driving voltage of the switching tube Q2 is low, and the switching tube responds in time to turn off, the entire charging circuit is disconnected, and the charger stops Charging the battery plays a role in preventing the battery from overcharging.

Preferably, the three-terminal adjustable shunt reference source is TL431, the cathode and reference terminals of TL431 are respectively connected to the negative input terminal of the voltage comparator U2A, the cathode of TL431 is electrically connected to one end of the resistor R1, and the other end of the resistor R1 is used for Connect the positive pole of the power supply, and the anode of the TL431 is used to connect the negative pole of the power supply. The TL431 is connected to the positive pole of the power supply through the resistor R1 to provide the reference voltage for the voltage comparator.

Both TL431 and voltage comparator U2A are less affected by temperature, which ensures that the accuracy of the entire control circuit will not be affected by ambient temperature or temperature changes during device use, and improves the reliability of the entire charging control circuit.

Exemplarily, as shown in Figure 3, a 5V charger is used to charge a 3.7V lithium-ion rechargeable battery, the voltage of the 3.7V lithium-ion battery is 4.2V after it is fully charged, and the reference voltage of TL431 is 2.5V. When the battery is fully charged, U2A+ is just higher than 2.5V, U2A outputs a high level, and Q1 is saturated and turned on. The voltage across R7 is only about 0.2V, that is, the driving voltage of the switching tube Q2 is only 0.2V, that is, the driving voltage of the switching tube Q2 is only 0.2V, the switching tube Q2 is turned off, the entire charging circuit is disconnected, and the charger stops charging the battery, which prevents the battery from overcharging.

After overcharging and power-off, due to voltage fluctuations, the switch may be turned on repeatedly. A resistor R5 can be connected in series between the positive input terminal and output terminal of the voltage comparator U2A to prevent repeated opening and improve The stability and reliability of the charging control circuit are improved.

Specifically, when U2A outputs high level, resistor R5 is connected in parallel with resistor R2 to pull up the sampling voltage of the battery, and U2A continues to output high level; when U2A outputs low level, resistor R5 is connected in parallel with resistor R3 to pull down the battery voltage. Sampling voltage, U2A continuously outputs low level; avoid repeated shutdown and startup of the charging main circuit.

Considering that there may be a voltage interference signal at the rechargeable battery terminal, which may cause false triggering; a capacitor C1 can be set in the charging control circuit, one end of the capacitor C1 is connected to the positive input end of the voltage comparator U2A, and the other end of the capacitor C1 is used for Because it is connected to the negative pole of the power supply C, the clutter voltage at the battery terminal is filtered out, preventing false triggering, and improving the stability and reliability of the entire charging control circuit.

At the same time, considering that the power supply terminal and other possible interference signals may affect the charging accuracy; a capacitor C2 can be set in the charging control circuit, one end of the capacitor C2 is connected to the output end of the voltage comparator U2A, and the other end of the capacitor C2 is used Because it is connected to the negative pole of the power supply, it filters out the clutter voltage at the power supply end, prevents false triggering, and improves the stability and reliability of the entire charging control circuit.

Optionally, voltage sampling can be implemented in various ways, and those skilled in the art should be able to understand that any unit capable of collecting the voltage at both ends of the rechargeable battery can be applied to the charging control circuit and achieve the same effect. It is preferably a sampling resistor, for example, resistors R2 and R3 connected in series at both ends of the rechargeable battery are used as a voltage sampling unit (as shown in Figure 3), and the positive input terminal of the voltage comparator U2A is connected to one end of the resistor R2 and one end of the resistor R3 respectively. Electrical connection; the other end of the resistor R2 is used to connect to the positive pole of the rechargeable battery, and the other end of the resistor R3 is used to connect to the negative pole of the rechargeable battery. The voltage sampling unit has simple composition and high sampling precision, which further improves the reliability and control precision of the charging control circuit.

In order to display the charging state of the rechargeable battery, a charging state indicating unit can be connected in series in the charging main circuit. Optionally, when charging normally, the indicator light is on, and the indicator light is off when it is fully charged.

Specifically, the charging state indicating unit includes a resistor R1 and a light emitting diode D1; one end of the resistor R1 is connected to the positive pole of the power supply, the other end is connected to the positive pole of the light emitting diode D1, and the negative pole of the light emitting diode D1 is used to be connected to the positive pole of the rechargeable battery. The light-emitting diode D1 is used as an indicator light, and it is on when it is charged normally; it is off when it is fully charged.

In order to improve the operability and convenience of the charging control circuit, all the ports used to connect to the positive pole of the power supply are electrically connected together as the positive pole interface of the power supply; all the ports used to be connected to the negative pole of the power supply are electrically connected together as the negative pole of the power supply Interface; all ports used to connect to the positive pole of the rechargeable battery are electrically connected together as a positive charging interface; all ports used to connect to the negative pole of the rechargeable battery are electrically connected together as a negative charging interface; thus the entire control circuit is modularized, The entire control circuit can be made into a module with double-terminal input and double-terminal output, and then can be directly connected between the charger and the battery, which greatly improves the applicability and convenience of the charging control circuit.

In another embodiment, a charging device is provided, including the charging control circuit in any one of the above embodiments.

Optionally, the charging control circuit can be integrated with existing charging sources such as chargers to form a charging device, which is directly used to charge the battery, thereby achieving the effect of preventing battery overcharging.

Since the charging device of this embodiment includes the charging control circuit of any of the above embodiments, it can also achieve the effect of any of the above embodiments.

Those skilled in the art should be able to understand that, during specific implementation, the parameters of each component in the circuit, such as the resistance value of each resistor and the capacitance value of each capacitor, can be set and adjusted by those skilled in the art according to actual needs, and are not described here. Specific limits.

Those skilled in the art can understand that the above embodiments do not involve any software improvement. As for the connection manners between hardware devices with corresponding functions, those skilled in the art can use the existing technology to realize, and no detailed description will be given here.

The above is only a preferred embodiment of the utility model, but the scope of protection of the utility model is not limited thereto, and any person familiar with the technical field can easily think of All changes or replacements should fall within the protection scope of the present utility model.

Claims (14)

1. A charging control circuit, characterized in that: comprising a logic control unit and a switch control unit; The logic control unit includes a voltage comparator U2A and a reference source U1, the positive input terminal of the voltage comparator U2A is used to input the sampling voltage of the rechargeable battery, and the negative input terminal is connected to the reference source U1 for inputting the reference voltage ; The reference source U1 is a three-terminal adjustable shunt reference source; A switch control unit, in response to the high level output by the voltage comparator U2A, the switch control unit shuts off the battery charging main circuit. 2. The charging control circuit according to claim 1, characterized in that: the switch control unit includes a switch drive circuit and a switch tube Q2, and the switch tube Q2 is arranged in the charging main circuit; in response to the output of the logic control unit High level, the switch drive circuit drives the switch tube Q2 to turn off. 3. The charging control circuit according to claim 2, characterized in that: the switch driving circuit comprises a triode Q1 and resistors R7-R8; The base of the triode Q1 is electrically connected to the output terminal of the voltage comparator U2A; the collector is electrically connected to one end of the resistor R7, and at the same time is electrically connected to the gate of the switching tube Q2; the emitter is connected to the negative pole of the power supply; the resistor R7 The other end is used to connect to the positive pole of the power supply; The resistor R8 is connected between the collector and the emitter of the triode Q1; The drain of the switching tube Q2 is used for connecting with the negative pole of the rechargeable battery, and the source is used for connecting with the negative pole of the power supply. 4. The charging control circuit according to claim 3, further comprising a resistor R6 connected in series between the base of the transistor Q1 and the output terminal of the voltage comparator U2A. 5. The charging control circuit according to any one of claims 1-4, characterized in that: it also includes a resistor R4, the three-terminal adjustable shunt reference source is TL431, and the cathode and reference terminals of the TL431 are respectively compared with the voltage The negative input terminal of the device U2A is connected, the cathode of the TL431 is electrically connected to one end of the resistor R4, the other end of the resistor R4 is used to connect to the positive pole of the power supply, and the anode of the TL431 is used to connect to the negative pole of the power supply. 6. The charging control circuit according to any one of claims 1-4, wherein the logic control unit further comprises a resistor R5, which is connected in series between the positive input terminal of the voltage comparator U2A and between the output terminals. 7. The charging control circuit according to any one of claims 1-4, wherein the logic control unit further includes a capacitor C1, one end of the capacitor C1 is connected to the positive input end of the voltage comparator U2A, The other end of the capacitor C1 is used to connect to the negative pole of the power supply. 8. The charging control circuit according to any one of claims 1-4, wherein the logic control unit further includes a capacitor C2, one end of the capacitor C2 is connected to the output end of the voltage comparator U2A, and the The other end of the capacitor C2 is used to connect to the negative pole of the power supply. 9. The charging control circuit according to claim 1, further comprising a voltage sampling unit electrically connected to the positive input terminal of the voltage comparator U2A for sampling the rechargeable battery The voltage is input to the positive input terminal of the voltage comparator U2A. 10. The charging control circuit according to claim 9, wherein the voltage sampling unit includes resistors R2 and R3, and the forward input terminal of the voltage comparator U2 is electrically connected to one end of the resistor R2 and one end of the resistor R3 respectively ; The other end of the resistor R2 is used to connect to the positive pole of the rechargeable battery, and the other end of the resistor R3 is used to connect to the negative pole of the rechargeable battery. 11. The charging control circuit according to claim 1, further comprising a charging state indicating unit serially connected in the main charging circuit for indicating the charging state. 12. The charging control circuit according to claim 11, characterized in that: the charging state indicating unit comprises a resistor R1 and a light-emitting diode D1; one end of the resistor R1 is used to connect to the positive pole of the power supply, and the other end is connected to the light-emitting diode D1. The anode of the diode D1 is connected, and the cathode of the light-emitting diode D1 is used to connect with the anode of the rechargeable battery. 13. The charging control circuit according to any one of claims 10-12, characterized in that: all ports for connecting to the positive pole of the power supply are electrically connected together as the positive pole interface of the power supply; all ports for connecting to the negative pole of the power supply are electrically connected to each other. Connect together as the negative interface of the power supply; all the ports used to connect to the positive pole of the rechargeable battery are electrically connected together as the positive interface for charging; all the ports used to connect to the negative pole of the rechargeable battery are electrically connected together as the negative interface for charging. 14. A charging device, comprising the charging control circuit according to any one of claims 1-13.