Lithium battery charging and discharging circuit and circuit board with same

Abstract

The utility model provides a lithium battery charging and discharging circuit and a circuit board with the same. The lithium battery charging and discharging circuit comprises a charging module, a lithium battery, a switch module and a voltage regulating module. The charging module is used for carrying out voltage adjusting operation on the power supply voltage of the external power supply, and the charging module can generate power supply voltage. The lithium battery is connected with the charging module, is used for carrying out energy storage operation on the power supply voltage, and generates battery voltage based on the power supply voltage. One end of the switch module is connected with the lithium battery and the charging module, the other end of the switch module is connected with the voltage regulating module, and the switch module can control power supply voltage or battery voltage to be input into the voltage regulating module. The voltage regulating module is used for carrying out voltage regulating operation on the battery voltage or the power supply voltage, the voltage regulating module generates load voltage, and the load voltage is used for carrying out power supply operation on a load.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, and particularly relates to a lithium battery charging and discharging circuit and a circuit board with the circuit. Background Art

[0002] In modern society, lithium batteries are widely used in electronic devices. In order to better charge and discharge the lithium battery, a charging and discharging circuit is always provided for use with the lithium battery. However, the load voltage of the existing charging and discharging circuit is fixed and cannot be adjusted according to the rated voltage of the load, thus making it inconvenient for users to charge different loads.

[0003] Therefore, it is necessary to provide a lithium battery charging and discharging circuit and a circuit board with the circuit to solve the above technical problems. Summary of the Utility Model

[0004] The utility model provides a lithium battery charging and discharging circuit and a circuit board with the circuit, effectively solving the technical problem that it is inconvenient for users to charge different loads.

[0005] The utility model provides a lithium battery charging and discharging circuit, which comprises:

[0006] A charging module, configured to perform a voltage regulation operation on the power supply voltage of an external power supply to generate a supply voltage;

[0007] A lithium battery, connected to the charging module, configured to perform an energy storage operation on the supply voltage, and the lithium battery generates a battery voltage based on the supply voltage;

[0008] A switch module, one end of which is connected to the lithium battery and the charging module, and the other end is connected to the voltage regulation module, configured to control the supply voltage or the battery voltage to be input to the voltage regulation module;

[0009] The voltage regulation module is configured to perform a voltage regulation operation on the battery voltage or the supply voltage to generate a load voltage, and the load voltage is used to supply power to a load.

[0010] Further, the charging module includes a first voltage regulation chip, the first voltage regulation chip includes an input pin, an output pin and an ISET pin, the charging module further includes a first adjustable potentiometer, the input pin is connected to the external power supply, the output pin is connected to the lithium battery, the first adjustable potentiometer is connected to the ISET pin, the input pin is used to input the power supply voltage, the first adjustable potentiometer is used to cooperate with the first voltage regulation chip to perform a voltage regulation operation on the power supply voltage, and the output pin is used to output the supply voltage.

[0011] Further, the voltage regulation module includes a second voltage regulation chip. The second voltage regulation chip includes a VIN pin, a VOUT pin, and an FB pin. The voltage regulation module further includes a second adjustable potentiometer. The VIN pin is connected to the output pin and the lithium battery. The VOUT pin is connected to the load. The adjustable potentiometer is connected to the FB pin. The input pin is used to input the power supply voltage or the supply voltage. The second adjustable potentiometer is used to cooperate with the second voltage regulation chip to perform a voltage regulation operation on the power supply voltage or the supply voltage. The output pin is used to output the load voltage.

[0012] Further, the switch module includes a first MOS transistor, a second MOS transistor, and a switch. The switch includes a first connection end and a second connection end. The drain of the first MOS transistor is connected to the lithium battery and the output pin. The gate of the first MOS transistor is grounded. The gate of the second MOS transistor is connected to the gate of the first MOS transistor. The source of the first MOS transistor is connected to the source of the second MOS transistor. The drain of the second MOS transistor is connected to the first connection end of the switch. The second connection end of the switch is connected to the VIN pin.

[0013] Further, when the switch is in the conducting state, if the charging module generates the supply voltage, the lithium battery is used to store the supply voltage, and the voltage regulation module is used to perform a voltage regulation operation on the supply voltage to generate the load voltage. When the switch is in the conducting state, if the charging module does not generate the supply voltage and the voltage value of the lithium battery is greater than the set value, the voltage regulation module is used to perform a voltage regulation operation on the battery voltage to generate the load voltage. When the switch is in the cut-off state, if the charging module generates the supply voltage, the lithium battery is used to store the supply voltage.

[0014] Further, the lithium battery charge and discharge circuit further includes a display module. The display module is connected in parallel between the charging module and the lithium battery. The display module is used to display the power of the lithium battery, the charging state of the lithium battery, and whether the charging module outputs the supply voltage to the voltage regulation module.

[0015] Further, the charging module includes a filtering unit. The filtering unit is connected in parallel with the input pin. The filtering unit is used to perform a filtering operation on the supply voltage.

[0016] Further, the filtering unit includes a first filtering capacitor and a second filtering capacitor. One end of the first filtering capacitor is connected to the output pin. The other end of the first filtering capacitor is grounded. The second filtering capacitor is connected to the first filtering capacitor.

[0017] Further, the model of the first voltage regulating chip is ETA9742, and the model of the second voltage regulating chip is MP3429.

[0018] A circuit board includes the lithium battery charging and discharging circuit according to any one of the above.

[0019] Compared with the prior art, the beneficial effects of the present utility model are as follows: The present utility model provides a lithium battery charging and discharging circuit and a circuit board having the circuit. The lithium battery charging and discharging circuit and the circuit board having the circuit include a charging module, a lithium battery, and a voltage regulating module. The charging module can adjust the power supply voltage of an external power supply, and the charging module can generate a supply voltage. The lithium battery can store energy for the supply voltage, and the lithium battery can generate a battery voltage based on the supply voltage. The voltage regulating module can be used to adjust the voltage of the battery voltage or the supply voltage, and the voltage regulating module can generate a load voltage, and the load voltage is used to supply power to a load. Therefore, the user can adjust the load voltage of the lithium battery charging and discharging circuit through the voltage regulating module, so that the load voltage can meet the charging requirements of various loads. If the user needs to charge loads with different rated voltages, the user only needs to use this circuit to charge different loads. The user does not need to design multiple charging and discharging circuits to meet the charging needs of different loads. Therefore, it is more convenient for the user to use this circuit to charge the load, and the cost of circuit design can also be saved. This circuit has high compatibility and effectively solves the technical problem that it is inconvenient for the user to charge different loads.

[0020] Moreover, the charging module can adjust the power supply voltage of the external power supply, and further adjust the charging current of the lithium battery. When the user needs to go out temporarily, the user can appropriately increase the charging current, thereby shortening the charging time and enabling the load or the lithium battery to be quickly fully charged. And, the lithium battery can be used as a temporary mobile power source. Therefore, the design with adjustable charging current can further provide convenience for the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following briefly introduces the drawings required to be used in the embodiments. The drawings described below are only the corresponding drawings of some embodiments of the present utility model.

[0022] Figure 1 It is a block diagram of an embodiment of the lithium battery charging and discharging circuit of the present utility model.

[0023] Figure 2 It is a circuit diagram of an embodiment of the lithium battery charging and discharging circuit of the present utility model.

[0024] In the figure, 10 is the lithium battery charge and discharge circuit; 11 is the charging module; 111 is the input pin; 112 is the output pin; 113 is the filtering unit; 12 is the lithium battery; 13 is the switching module; 131 is the first connection end; 132 is the second connection end; 14 is the voltage regulating module; 15 is the load; 16 is the display module; 17 is the external power supply. Detailed implementation manners

[0025] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present utility model.

[0026] The directional terms mentioned in the present utility model, such as "up", "down", "front", "rear", "left", "right", "inside", "outside", "side", "top" and "bottom", etc., are only references to the orientation of the accompanying drawings. The directional terms used are for explaining and understanding the present utility model, rather than for limiting the present utility model.

[0027] The terms "first", "second", etc. in the present utility model are only for descriptive purposes, and cannot be understood as indicating or implying relative importance, nor as a limitation on the sequence.

[0028] In the figure, units with similar structures are denoted by the same reference numerals.

[0029] Please refer to Figure 1, the present utility model provides a lithium battery charging and discharging circuit and a circuit board having the same. The lithium battery charging and discharging circuit 10 includes a charging module 11, a lithium battery 12, a switching module 13, and a voltage regulating module 14. The lithium battery charging and discharging circuit 10 is applied to a circuit board. The charging module 11 is used to adjust the power supply voltage of the external power supply 17, so that the charging module 11 can generate a supply voltage. The lithium battery 12 is connected to the charging module 11. The lithium battery 12 is used to store energy for the supply voltage. The lithium battery 12 can generate a battery voltage based on the supply voltage. One end of the switching module 13 is connected to the lithium battery 12 and the charging module 11, and the other end of the switching module 13 is connected to the voltage regulating module 14. The switch S1 can control whether the voltage regulating module 14 inputs the supply voltage or the battery voltage. The voltage regulating module 14 can adjust the voltage of the battery voltage or the supply voltage, so that the voltage regulating module 14 can generate a load voltage, and the load voltage is used to supply power to the load 15. Moreover, the lithium battery charging and discharging circuit 10 further includes a display module 16. The display module 16 is connected in parallel between the charging module 11 and the lithium battery 12. The display module 16 is used to display the power of the lithium battery 12, the charging state of the lithium battery 12, and whether the charging module 11 outputs the supply voltage to the voltage regulating module 14.

[0030] Please refer to Figure 2 , the following is a detailed description of the specific structure of the lithium battery charging and discharging circuit 10:

[0031] Please refer to Figure 2 , the charging module 11 includes a first voltage regulating chip U2, and the model of the first voltage regulating chip U2 is ETA9742. The first voltage regulating chip U2 includes an input pin 111, an output pin 112, and an ISET pin. The charging module 11 further includes a first adjustable potentiometer R10. The input pin 111 is connected to the external power supply 17, the output pin 112 is connected to the lithium battery 12, the first adjustable potentiometer R10 is connected to the ISET pin. The input pin 111 is used to input the power supply voltage, the first adjustable potentiometer R10 is used to cooperate with the first voltage regulating chip U2 to adjust the voltage of the power supply voltage, and the output pin 112 is used to output the supply voltage. Based on the operation that the charging module 11 can adjust the voltage of the power supply voltage, the charging module 11 can further adjust the output current. Among them, the charging module 11 further includes a TYPE-C port USB1. The TYPE-C port USB1 is connected to the input pin 111, and the external power supply 17 can transmit the power supply voltage to the charging module 11 through the TYPE-C port USB1. The first voltage regulating chip U2 further includes a BAT pin, and the BAT pin is connected to the lithium battery 12. The BAT pin is the power monitoring pin of the first voltage regulating chip U2, and the BAT pin can be used to detect the power of the lithium battery 12.

[0032] Moreover, the charging module 11 further includes an adjusting resistor R9, and the user can reasonably set the parameters of the adjusting resistor R9 and the first adjustable potentiometer R10. Furthermore, the user can adjust the charging current through the first adjustable potentiometer R10 so that the charging current is 0.5A - 3A. Therefore, when the user needs to go out temporarily, the user can appropriately increase the charging current, thereby shortening the charging time and enabling the load 15 or the lithium battery 12 to be quickly fully charged. In addition, the charging module 11 further includes an inductor L2, a capacitor C6, a resistor C7, and a capacitor C10.

[0033] Please refer to Figure 2 , the voltage regulating module 14 includes a second voltage regulating chip U1, and the model of the second voltage regulating chip U1 is MP3429. The second voltage regulating chip U1 includes a VIN pin, a VOUT pin, and an FB pin. The voltage regulating module 14 further includes a second adjustable potentiometer R11. The VIN pin is connected to the output pin 112 and the lithium battery 12, the VOUT pin is connected to the load 15, and the second adjustable potentiometer R11 is connected to the FB pin. The input pin 111 is used to input the power supply voltage or the supply voltage, the second adjustable potentiometer R11 is used to cooperate with the second voltage regulating chip U1 to perform a voltage regulating operation on the power supply voltage or the supply voltage, and the output pin 112 is used to output the load voltage. Among them, the voltage regulating module 14 further includes an adjustable resistor R1 and an adjustable resistor R2.

[0034] The second voltage regulating chip U1 inputs a voltage of 2.7V - 8.4V, and the load voltage output by the second voltage regulating chip U1 can be adjusted according to the requirements of the load 15. Among them, the voltage value of the load voltage can be converted according to the following formula: vout = verf * (1 + r1 / (r2 + r11)), verf = 1V, r1 is the resistance value of the adjustable resistor R1, r2 is the resistance value of the adjustable resistor R2, r11 is the resistance value of the second adjustable potentiometer R11, and vout is the voltage value of the load voltage. The user reasonably sets the resistance parameters of the adjustable resistor R1 and the adjustable resistor R2, and the user adjusts the resistance value of the second adjustable potentiometer R11. Therefore, the user can adjust the voltage value of the load voltage. The second voltage regulating chip U1 can output a load voltage of 5V - 12V, and the lithium battery charge and discharge circuit 10 is applicable to single - section or multi - section lithium battery 12 power supply scenarios. The load voltage can meet the charging requirements of various loads 15. The user does not need to design multiple charge and discharge circuits to meet the charging needs of different loads 15. Therefore, it is more convenient for the user to use this circuit to charge the load 15, and the cost of circuit design can also be saved. In addition, the voltage regulating module 14 further includes a resistor R3, a resistor R4, and an inductor L1. The voltage regulating module 14 further includes a capacitor CIN1, a capacitor CIN2, a capacitor CIN3, a capacitor CO1, a capacitor CO2, a capacitor CO3, a capacitor C1, a capacitor C2, and a capacitor C3, and a capacitor C4.

[0035] Please refer to Figure 2, the switch module 13 includes a first MOS transistor Q1, a second MOS transistor Q2, and a switch S1. The switch S1 includes a first connection end 131 and a second connection end 132. Both the first MOS transistor Q1 and the second MOS transistor Q2 are P-channel MOS transistors. The drain of the first MOS transistor Q1 is connected to the lithium battery 12 and the output pin 112, and the gate of the first MOS transistor Q1 is grounded. The gate of the second MOS transistor Q2 is connected to the gate of the first MOS transistor Q1, and the source of the first MOS transistor Q1 is connected to the source of the second MOS transistor Q2. The drain of the second MOS transistor Q2 is connected to the first connection end 131 of the switch S1, and the second connection end 132 of the switch S1 is connected to the VIN pin. Moreover, the switch module 13 further includes a resistor R5.

[0036] Please refer to Figure 2 , when the switch S1 is in the conducting state, if the charging module 11 generates a supply voltage, the lithium battery 12 is used to store the supply voltage, and the voltage regulating module 14 is used to regulate the supply voltage. The voltage regulating module 14 can generate a load voltage. When the switch S1 is in the conducting state, if the charging module 11 does not generate a supply voltage and the voltage value of the lithium battery 12 is greater than a set value, the set value is 2.7V, the voltage regulating module 14 is used to regulate the battery voltage. The voltage regulating module 14 can generate a load voltage. When the switch S1 is in the cut-off state, if the charging module 11 generates a supply voltage, the lithium battery 12 is used to store the supply voltage.

[0037] Please refer to Figure 2 , when the charging module 11 does not charge the lithium battery 12 and the switch S1 is open, the first MOS transistor Q1 and the second MOS transistor Q2 can conduct normally. At this time, as long as the power of the lithium battery 12 is not lower than its own over-discharge voltage, the protection board built in the lithium battery 12 is in the normally open state. The over-discharge voltage is 2.7V. Subsequently, the lithium battery 12 can output a battery voltage. Then, the enable pin EN of the second voltage regulating chip U1 is raised, and the enable pin EN can become a high level. Then, the second voltage regulating chip U1 can work normally, and the second voltage regulating chip U1 can perform a voltage regulating operation on the battery voltage. Thus, the second voltage regulating chip U1 can transmit a preset load voltage to the load 15.

[0038] Please refer to Figure 2, when the battery level of the lithium battery 12 is low (the blue LED light of the display module 16 can display the battery level in real time), the external power supply 17 can input the power supply voltage through the TYPE-C port USB1. The first voltage regulating chip U2 can perform voltage regulation operation on this power supply voltage, so that the first voltage regulating chip U2 can generate a power supply voltage, and this power supply voltage can charge the lithium battery 12. At this time, the first MOS transistor Q1 and the second MOS transistor Q2 are also normally conducted, and this power supply voltage can be transmitted to the voltage regulating module 14. The second voltage regulating chip U1 can perform voltage regulation operation on this power supply voltage. Thus, the second voltage regulating chip U1 can transmit a preset load voltage to the load 15. Therefore, the lithium battery charge and discharge circuit 10 can supply power to both the lithium battery 12 and the load 15 at the same time. At this time, the output end of the voltage regulating module 14 is not affected, and the load 15 can also work normally, and the lithium battery charge and discharge circuit 10 can achieve synchronous charge and discharge.

[0039] When the charge and discharge are carried out synchronously, the charging time may be affected by the load 15, which may extend the time required for the lithium battery 12 to be fully charged. At this time, the user can appropriately adjust the resistance value of the first adjustable potentiometer R10, so as to adjust the charging current, increase the charging current, and then shorten the charging time. Moreover, the user can also completely turn off the output of the lithium battery charge and discharge circuit 10 by turning off the switch S1. At this time, the lithium battery charge and discharge circuit 10 can only charge the lithium battery 12 and does not discharge the load 15, which can further shorten the charging time of the lithium battery 12.

[0040] Please refer to Figure 2 , the display module 16 includes a yellow LED lamp D1, a red LED lamp D2, a green LED lamp D3, and a blue LED lamp D4. The blue LED lamp D4 can display the battery status in real time, and the blue LED lamp D4 can perform single-LED heartbeat-style power display. When the battery level of the lithium battery 12 is 0-25%, the blue LED lamp flashes once. When the battery level of the lithium battery 12 is 25-50%, the blue LED lamp flashes twice. When the battery level of the lithium battery 12 is 50-75%: the blue LED lamp flashes three times. When the battery level of the lithium battery 12 is 75-100%, the blue LED lamp flashes four times. When the battery level of the lithium battery 12 is 100%, the blue LED lamp is constantly on. And, the red LED lamp D2 and the green LED lamp D3 can indicate the charging status of the lithium battery 12. If the lithium battery 12 is not fully charged or the connection is accidentally disconnected during the charging of the lithium battery 12, the red LED lamp D2 lights up. If the lithium battery 12 is fully charged, the green LED lamp D3 lights up. The yellow LED lamp D1 is a discharge indicator light. If the charging module 11 outputs a power supply voltage to the voltage regulating module 14, the yellow LED lamp D1 lights up. That is, when the charging module 11 outputs a power supply voltage and the switch S1 is turned on, the yellow LED lamp D1 lights up.

[0041] Please refer to Figure 2 The charging module 11 includes a filtering unit 113. The filtering unit 113 is connected in parallel with the input pin 111, and the filtering unit 113 is used to perform a filtering operation on the supply voltage. The filtering unit 113 includes a first filtering capacitor C8 and a second filtering capacitor C9. One end of the first filtering capacitor C8 is connected to the output pin 112, the other end of the first filtering capacitor C8 is grounded, and the second filtering capacitor C9 is connected to the first filtering capacitor C8. The first filtering capacitor C8 and the second filtering capacitor C9 can filter out interference components such as clutter and noise in the load voltage. Therefore, the second voltage regulating chip U1 can stably output the load voltage to the load 15.

[0042] The working principle of the present invention is as follows: When the lithium battery charging and discharging circuit 10 works, first, an external power supply 17 inputs a power supply voltage. Then, the first voltage regulating chip U2 of the charging module 11 can receive the power supply voltage through the input pin 111. The first voltage regulating chip U2 can perform a voltage regulating operation on the power supply voltage, so that the first voltage regulating chip U2 can output a supply voltage through the output pin 112. Subsequently, the lithium battery 12 can perform an energy storage operation on the supply voltage. Moreover, the user can reasonably set the parameters of the adjusting resistor R9 and the first adjustable potentiometer R10. The first adjustable potentiometer R10 is used to cooperate with the first voltage regulating chip U2 to perform a voltage regulating operation on the power supply voltage. Furthermore, the user can adjust the charging current of the lithium battery 12, so that the charging time of the lithium battery 12 can be flexibly adjusted. At this time, if the switch S1 of the voltage regulating module 14 is in the off state, the lithium battery charging and discharging circuit 10 only charges the lithium battery 12. If the switch S1 of the voltage regulating module 14 is in the on state, the second voltage regulating chip U1 can receive the supply voltage through the VIN pin. The second voltage regulating chip U1 can perform a voltage regulating operation on the supply voltage, and the VOUT pin of the second voltage regulating chip U1 can output the load voltage to the load 15, and the load voltage can be used to supply power to the load 15. And the user reasonably sets the resistance parameters of the adjustable resistor R1 and the adjustable resistor R2, and adjusts the resistance value of the second adjustable potentiometer R11, so that the user can adjust the load voltage.

[0043] When the external power supply 17 does not input a power supply voltage, the lithium battery charging and discharging circuit 10 can only perform a discharging operation. At this time, if the switch S1 of the voltage regulating module 14 is in the on state, the lithium battery 12 can output the battery voltage to the VIN pin of the second voltage regulating chip U1. The second voltage regulating chip U1 can perform a voltage regulating operation on the battery voltage, and then the VOUT pin of the second voltage regulating chip U1 can output the load voltage, and the load voltage is used to supply power to the load 15. And the user reasonably sets the resistance parameters of the adjustable resistor R1 and the adjustable resistor R2, and adjusts the resistance value of the second adjustable potentiometer R11, so that the user can adjust the load voltage.

[0044] The present utility model provides a lithium battery charging and discharging circuit and a circuit board having the same. The lithium battery charging and discharging circuit and the circuit board having the same include a charging module, a lithium battery, and a voltage regulating module. The charging module can perform a voltage regulating operation on the power supply voltage of an external power supply, and the charging module can generate a power supply voltage. The lithium battery can perform an energy storage operation on the power supply voltage, and the lithium battery can generate a battery voltage based on the power supply voltage. The voltage regulating module can be used to perform a voltage regulating operation on the battery voltage or the power supply voltage, and the voltage regulating module can generate a load voltage, and the load voltage is used to perform a power supply operation on a load. Therefore, a user can adjust the load voltage of the lithium battery charging and discharging circuit through the voltage regulating module, so that the load voltage can meet the charging requirements of various loads. If the user needs to charge loads with different rated voltages, the user only needs to use this circuit to charge different loads. The user does not need to design multiple charging and discharging circuits to meet the charging needs of different loads. Therefore, it is more convenient for the user to use this circuit to charge the load, and the cost of circuit design can also be saved. This circuit has high compatibility and effectively solves the technical problem that it is inconvenient for the user to charge different loads.

[0045] Moreover, the charging module can perform a voltage regulating operation on the power supply voltage of the external power supply, and thus can adjust the charging current of the lithium battery. When the user needs to go out temporarily, the user can appropriately increase the charging current, thereby shortening the charging time and enabling the load or the lithium battery to be quickly fully charged. And, the lithium battery can be used as a temporary mobile power supply. Therefore, the design of adjustable charging current can further provide convenience for the user.

[0046] In summary, although the present utility model has been disclosed above with preferred embodiments, the above preferred embodiments are not intended to limit the present utility model. Those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model is subject to the scope defined by the claims.

Claims

1. A lithium battery charging and discharging circuit, characterized in that, It includes a charging module for adjusting the power supply voltage of an external power supply to generate a power supply voltage; a lithium battery connected to the charging module for storing energy of the power supply voltage, and the lithium battery generates a battery voltage based on the power supply voltage; a switching module with one end connected to the lithium battery and the charging module and the other end connected to a voltage regulating module for controlling the input of the power supply voltage or the battery voltage to the voltage regulating module; the voltage regulating module for adjusting the battery voltage or the power supply voltage to generate a load voltage for powering a load.

2. The lithium battery charging and discharging circuit according to claim 1, wherein The charging module includes a first voltage regulating chip which includes an input pin, an output pin and an ISET pin. The charging module further includes a first adjustable potentiometer. The input pin is connected to the external power supply, the output pin is connected to the lithium battery, the first adjustable potentiometer is connected to the ISET pin. The input pin is used for inputting the power supply voltage, the first adjustable potentiometer is used to cooperate with the first voltage regulating chip to adjust the power supply voltage, and the output pin is used for outputting the power supply voltage.

3. The lithium battery charging and discharging circuit according to claim 2, wherein, The voltage regulating module includes a second voltage regulating chip which includes a VIN pin, a VOUT pin and an FB pin. The voltage regulating module further includes a second adjustable potentiometer. The VIN pin is connected to the output pin and the lithium battery, the VOUT pin is connected to the load, the adjustable potentiometer is connected to the FB pin. The input pin is used for inputting the power supply voltage or the power supply voltage, the second adjustable potentiometer is used to cooperate with the second voltage regulating chip to adjust the power supply voltage or the power supply voltage, and the output pin is used for outputting the load voltage.

4. The lithium battery charging and discharging circuit according to claim 3, characterized in that, The switching module includes a first MOS transistor, a second MOS transistor and a switch. The switch includes a first connection end and a second connection end. The drain of the first MOS transistor is connected to the lithium battery and the output pin, the gate of the first MOS transistor is grounded, the gate of the second MOS transistor is connected to the gate of the first MOS transistor, the source of the first MOS transistor is connected to the source of the second MOS transistor, the drain of the second MOS transistor is connected to the first connection end of the switch, and the second connection end of the switch is connected to the VIN pin.

5. The lithium battery charging and discharging circuit according to claim 4, characterized in that, When the switch is in the on state, if the charging module generates the power supply voltage, the lithium battery is used for storing energy of the power supply voltage, and the voltage regulating module is used for adjusting the power supply voltage to generate a load voltage; when the switch is in the on state, if the charging module does not generate the power supply voltage and the voltage value of the lithium battery is greater than a set value, the voltage regulating module is used for adjusting the battery voltage to generate a load voltage; when the switch is in the off state, if the charging module generates the power supply voltage, the lithium battery is used for storing energy of the power supply voltage.

6. The lithium battery charging and discharging circuit according to claim 1, characterized in that The lithium battery charging and discharging circuit further includes a display module, which is connected in parallel between the charging module and the lithium battery. The display module is used to display the power of the lithium battery, the charging state of the lithium battery, and whether the charging module outputs a power supply voltage to the voltage regulating module.

7. The lithium battery charging and discharging circuit according to claim 2, characterized in that, The charging module includes a filtering unit, which is connected in parallel with the input pin. The filtering unit is used to perform a filtering operation on the power supply voltage.

8. The lithium battery charging and discharging circuit according to claim 7, characterized in that The filtering unit includes a first filtering capacitor and a second filtering capacitor. One end of the first filtering capacitor is connected to the output pin, the other end of the first filtering capacitor is grounded, and the second filtering capacitor is connected to the first filtering capacitor.

9. The lithium battery charging and discharging circuit according to claim 3, wherein, The model of the first voltage regulating chip is ETA9742, and the model of the second voltage regulating chip is MP3429.

10. A circuit board, characterized in that, It includes the lithium battery charging and discharging circuit according to any one of claims 1-9.

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