A lithium battery charging circuit

Abstract

The utility model discloses a lithium battery charging circuit, including external circuit and control chip, and external circuit includes positive power input module, lithium battery module, battery voltage sampling module, temperature detection module, overcurrent detection module, discharge switch module, charging switch module, equalizing module and drive enhancement module, and one end of positive power input module is electrically connected with lithium battery module and equalizing module one end, and the other end of lithium battery module is electrically connected with the other end of equalizing module, battery voltage sampling module, temperature detection module and overcurrent detection module one end respectively, and the other end of battery voltage sampling module, temperature detection module and overcurrent detection module is electrically connected with control chip one end. The utility model can solve the technical problem that the existing lithium battery charging circuit is in the application scene of the charging of larger current or the driving of multiple chips, and the charging speed is limited and the battery life is shortened due to the insufficient driving capacity and the decline of charging efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of lithium battery charging management technology, and more specifically, relates to a lithium battery charging circuit. Background Technology

[0002] Existing lithium battery charging circuits mostly adopt linear charging or switching charging structures. In application scenarios with large current charging or driving multiple chips, they often suffer from insufficient driving capability and reduced efficiency, which leads to limited charging speed and shortened battery life. Utility Model Content

[0003] In view of the above-mentioned defects or improvement needs of the existing technology, this utility model provides a lithium battery charging circuit. Its purpose is to solve the technical problems of limited charging speed and shortened battery life caused by insufficient driving capability and reduced charging efficiency in application scenarios where existing lithium battery charging circuits are used for charging with large current or driving multiple chips.

[0004] To achieve the above objectives, according to one aspect of this utility model, a lithium battery charging circuit is provided, including an external circuit and a control chip. The external circuit includes a positive power input module, a lithium battery module, a battery voltage sampling module, a temperature detection module, an overcurrent detection module, a discharge switch module, a charging switch module, an equalization module, and a drive enhancement module. One end of the positive power input module is electrically connected to one end of the lithium battery module and one end of the equalization module, and the other end of the lithium battery module is electrically connected to one end of the equalization module, one end of the battery voltage sampling module, one end of the temperature detection module, and one end of the overcurrent detection module.

[0005] The other end of the battery voltage sampling module, temperature detection module, and overcurrent detection module is electrically connected to one end of the control chip;

[0006] The other end of the control chip is electrically connected to one end of the discharge switch module and one end of the charging switch module;

[0007] The other end of the charging switch module is electrically connected to the drive enhancement module, and the other end of the discharging switch module and the drive enhancement module are electrically connected to the positive power input module.

[0008] Preferably, the positive power input module includes a first resistor, a first capacitor, and a first diode;

[0009] One end of the first resistor is electrically connected to one end of the first capacitor and the VCC pin of the control chip;

[0010] The other end of the first capacitor is connected to the ground wire.

[0011] The other end of the first resistor is electrically connected to the cathode of the first diode;

[0012] The anode of the first diode D1 is electrically connected to the charging input terminal of the control chip.

[0013] The resistance of the first resistor is 1 kΩ, the capacitance of the first capacitor C1 is 1 μF, the rectified current of the first diode is 150 mA, and the DC reverse withstand voltage is 100 V.

[0014] Preferably, the lithium battery module includes a first lithium battery, a second lithium battery, a third lithium battery, and a fourth lithium battery;

[0015] The positive terminal of the first lithium battery is electrically connected to the anode of the first diode, and the negative terminal of the first lithium battery is electrically connected to the positive terminal of the second lithium battery.

[0016] The negative terminal of the second lithium battery is electrically connected to the positive terminal of the third lithium battery;

[0017] The negative terminal of the third lithium battery is electrically connected to the positive terminal of the fourth lithium battery;

[0018] The negative terminal of the fourth lithium battery is electrically connected to ground.

[0019] The nominal voltage of the first, second, third, and fourth lithium batteries is 3.7V.

[0020] Preferably, the battery voltage sampling module includes a second resistor, a third resistor, a fourth resistor, a fifth resistor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor;

[0021] One end of the second resistor is electrically connected to the positive terminal of the first lithium battery, the other end of the second resistor is electrically connected to one end of the second capacitor and the VC1 pin of the control chip, and the other end of the second capacitor is electrically connected to the ground wire.

[0022] One end of the third resistor is electrically connected to the positive terminal of the second lithium battery, the other end of the third resistor is electrically connected to one end of the third capacitor and the VC2 pin of the control chip, and the other end of the third capacitor is electrically connected to the ground wire.

[0023] One end of the fourth resistor is electrically connected to the positive terminal of the third lithium battery, the other end of the fourth resistor is electrically connected to one end of the fourth capacitor and the VC3 pin of the control chip, and the other end of the fourth capacitor is electrically connected to the ground wire.

[0024] One end of the fifth resistor is electrically connected to the positive terminal of the fourth lithium battery, the other end of the fifth resistor is electrically connected to one end of the fifth capacitor and the VC4 pin of the control chip, and the other end of the fifth capacitor is electrically connected to the ground wire.

[0025] The resistance values ​​of the second, third, fourth, and fifth resistors are all 1 kΩ;

[0026] The capacitance values ​​of the second, third, fourth, and fifth capacitors are all 0.1 microfarads.

[0027] Preferably, the discharge switch module includes a sixth resistor, a seventh resistor, a twenty-seventh resistor, a second diode, a seventh transistor, a first MOSFET, a second MOSFET, a third MOSFET, and a fourth MOSFET.

[0028] One end of the sixth resistor is electrically connected to the output control pin DO of the control chip, and the other end of the sixth resistor is electrically connected to the anode of the second diode and the base of the seventh transistor, respectively. The cathode of the second diode is electrically connected to the emitter of the seventh transistor, as well as the gate terminals of the first MOSFET, the second MOSFET, the third MOSFET, and the fourth MOSFET.

[0029] The sources of the first, second, third, and fourth MOSFETs are electrically connected to one end of the eleventh resistor, and the drains of the first, second, third, and fourth MOSFETs are electrically connected to one end of the twenty-seventh resistor. The other end of the twenty-seventh resistor is electrically connected to the ground wire.

[0030] The collector of the seventh transistor is electrically connected to one end of the seventh resistor, and the other end of the seventh resistor is electrically connected to ground.

[0031] The sixth and seventh resistors both have a resistance of 100 ohms, and the twenty-seventh resistor has a resistance of 1 megohm.

[0032] The second diode has a rectified current of 150mA and a DC reverse withstand voltage of 100V.

[0033] The seventh transistor is a PNP transistor with a voltage of 160V;

[0034] The four MOSFETs connected in parallel are N-channel MOSFETs.

[0035] Preferably, the temperature detection module includes an eighth resistor and a ninth resistor;

[0036] One end of the eighth resistor is electrically connected to the RTV pin of the control chip, the other end of the eighth resistor is electrically connected to one end of the ninth resistor and the RTS pin of the control chip, and the other end of the ninth resistor is electrically connected to the ground wire.

[0037] The resistance of the eighth resistor is 300 kilohms;

[0038] The resistance of the ninth resistor is 100 kilohms.

[0039] Preferably, the overcurrent detection module includes a tenth resistor, an eleventh resistor, and a sixth capacitor;

[0040] One end of the tenth resistor is electrically connected to the VINI pin of the control chip and one end of the sixth capacitor. The other end of the tenth resistor is electrically connected to one end of the eleventh resistor. The other ends of the sixth capacitor and the eleventh resistor are electrically connected to the ground wire.

[0041] The resistance of the tenth resistor is 1 kiloohm;

[0042] The resistance of the eleventh resistor is 4 milliohms;

[0043] The sixth capacitor has a capacitance of 0.1 microfarads and a rated voltage of 25V;

[0044] The charging detection terminal module is the twelfth resistor;

[0045] One end of the twelfth resistor is electrically connected to the VM pin of the control chip, and the other end of the twelfth resistor is electrically connected to the charging output terminal of the control chip.

[0046] The resistance of the twelfth resistor is 20 kilohms.

[0047] Preferably, the equalization module includes a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a first transistor, a second transistor, a third transistor, and a fourth transistor.

[0048] The emitter of the first transistor is electrically connected to the positive terminal of the first lithium battery, the base of the first transistor is electrically connected to one end of the thirteenth resistor, the other end of the thirteenth resistor is electrically connected to the VC1 pin of the control chip, and the collector of the first transistor is electrically connected to one end of the fourteenth and fifteenth resistors.

[0049] The other ends of the fourteenth and fifteenth resistors are electrically connected to the positive terminal of the second lithium battery and the emitter of the second transistor. The base of the second transistor is electrically connected to one end of the sixteenth resistor. The other end of the sixteenth resistor is electrically connected to the VC2 pin of the control chip. The collector of the second transistor is electrically connected to one end of the seventeenth and eighteenth resistors.

[0050] The other ends of the seventeenth and eighteenth resistors are electrically connected to the positive terminal of the third lithium battery and the emitter of the third transistor. The base of the third transistor is electrically connected to one end of the nineteenth resistor. The other end of the nineteenth resistor is electrically connected to the VC3 pin of the control chip. The collector of the third transistor is electrically connected to one end of the twentieth and twenty-first resistors.

[0051] The other ends of the 20th and 21st resistors are electrically connected to the positive terminal of the fourth lithium battery and the emitter of the fourth transistor. The base of the fourth transistor is electrically connected to one end of the 22nd resistor. The other end of the 22nd resistor is electrically connected to the VC4 pin of the chip. The collector of the fourth transistor is electrically connected to one end of the 23rd and 24th resistors. The other ends of the 23rd and 24th resistors are electrically connected to the ground wire.

[0052] The resistance values ​​of the thirteenth, sixteenth, nineteenth, and twenty-second resistors are all 51 ohms;

[0053] The resistance values ​​of the fourteenth, fifteenth, seventeenth, eighteenth, twentieth, twenty-first, twenty-third, and twenty-fourth resistors are all 200 ohms;

[0054] The first, second, third, and fourth transistors are all PNP type transistors.

[0055] Preferably, the drive enhancement module includes a twenty-fifth resistor, a twenty-sixth resistor, a third diode, a fourth diode, a fifth transistor, and a sixth transistor;

[0056] The anode of the third diode is electrically connected to the charging input terminal of the control chip, and the cathode of the third diode is electrically connected to the collector of the fifth transistor.

[0057] The base of the fifth transistor is electrically connected to the cathode of the fourth diode D4, the base of the sixth transistor, and one end of the twenty-fifth resistor. The emitter of the fifth transistor is electrically connected to the emitter of the sixth transistor and one end of the twenty-sixth resistor.

[0058] The other ends of the 25th and 26th resistors, as well as the collector of the 6th transistor, are electrically connected to the charging output terminal of the control chip.

[0059] The emitter of the sixth transistor is electrically connected to the gate terminals of the four parallel MOSFETs in the charging switch module;

[0060] The resistance values ​​of the twenty-fifth and twenty-sixth resistors are both 4.7 megohms;

[0061] The rectified current of the third and fourth diodes is 150mA, and the DC reverse withstand voltage is 100V.

[0062] The fifth transistor is an NPN transistor with a voltage of 160V;

[0063] The sixth transistor is a PNP type transistor with a voltage of 160V.

[0064] Preferably, the charging switch module includes four parallel-connected fifth MOSFETs, sixth MOSFETs, seventh MOSFETs, and eighth MOSFETs;

[0065] The gate electrical connections of the fifth, sixth, seventh, and eighth MOSFETs;

[0066] The sources of the fifth, sixth, seventh, and eighth MOSFETs are electrically connected to the charging output terminal of the control chip.

[0067] The drain electrical connections of the fifth, sixth, seventh, and eighth MOSFETs;

[0068] The four MOSFETs are N-channel MOSFETs.

[0069] In summary, compared with the prior art, the above-described technical solution conceived by this utility model can achieve the following beneficial effects:

[0070] (1) Since the present invention adds a drive enhancement module, the weak control signal output by the control chip enters the complementary symmetrical push-pull amplification structure of the drive enhancement module to amplify and enhance the drive current. It can provide sufficient and stable output current when charging with a large current or driving multiple back-end chips at the same time, thereby improving charging efficiency, shortening charging time, and effectively extending battery cycle life.

[0071] (2) The lithium battery module, battery voltage sampling module, charging switch module and drive enhancement module used in this utility model have good compatibility and are suitable for charging management of different types of lithium batteries, which improves the coverage and practical value of the technology application.

[0072] (3) This utility model adds a drive enhancement module. The weak control signal output by the control chip enters the complementary symmetrical push-pull amplification structure of the drive enhancement module. The power is amplified by the amplification circuit composed of the fifth transistor Q5 and the sixth transistor Q6, and the drive current is amplified and enhanced, which enhances the driving capability of the CM1341 chip. It can cope with systems with different currents and power, and expands the application range of the chip. Attached Figure Description

[0073] Figure 1 This is a circuit diagram showing the external circuit connection in the lithium battery charging circuit of this utility model;

[0074] Figure 2 This is a circuit diagram of the discharge switch module in the lithium battery charging circuit of this utility model;

[0075] Figure 3 This is a circuit diagram of the equalization module in the lithium battery charging circuit of this utility model;

[0076] Figure 4 This is a circuit diagram of the drive enhancement module in the lithium battery charging circuit of this utility model;

[0077] Figure 5 This is a circuit diagram of the charging switch module in the lithium battery charging circuit of this utility model;

[0078] Figure 6 This is a schematic block diagram of the overall lithium battery charging circuit of this utility model. Detailed Implementation

[0079] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. Furthermore, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0080] like Figure 6 As shown, this utility model provides a lithium battery charging circuit, including an external circuit 1 and a control chip 2. The external circuit 1 includes a positive power input module 3, a lithium battery module 4, a battery voltage sampling module 5, a temperature detection module 6, an overcurrent detection module 7, a discharge switch module 8, a charging switch module 9, an equalization module 10, and a drive enhancement module 11.

[0081] One end of the positive power input module 3 is electrically connected to one end of the lithium battery module 4 and the equalization module 10. The other end of the lithium battery module 4 is electrically connected to the other end of the equalization module 10, the battery voltage sampling module 5, the temperature detection module 6, and one end of the overcurrent detection module 7. The other end of the battery voltage sampling module 5, the temperature detection module 6, and the overcurrent detection module 7 is electrically connected to one end of the control chip 2. The other end of the control chip 2 is electrically connected to one end of the discharge switch module 8 and the charging switch module 9. The other end of the charging switch module 9 is electrically connected to the drive enhancement module 11. The other end of the discharge switch module 8 and the drive enhancement module 11 is electrically connected to the positive power input module 3.

[0082] like Figure 1 As shown, the control chip 2 is a CM1341-BAT chip manufactured by Shenzhen Chuangxin Microelectronics Co., Ltd. (depending on the characteristics of the required rechargeable lithium battery, other main control chips of the same type can be replaced according to the actual situation).

[0083] The positive power input module 3 includes a first resistor R1, a first capacitor C1, and a first diode D1.

[0084] One end of the first resistor R1 is electrically connected to one end of the first capacitor C1 and the VCC pin of the control chip 2. The other end of the first capacitor C1 is electrically connected to the ground wire. The other end of the first resistor R1 is electrically connected to the cathode of the first diode D1. The anode of the first diode D1 is electrically connected to the charging input terminal P+ of the control chip 2.

[0085] The first resistor R1 has a resistance of 1 kΩ and is a surface mount resistor of model 0402WGF1001TCE manufactured by Kunshan Housheng Electronics Industry Co., Ltd.; the first capacitor C1 has a capacitance of 1 μF and is a capacitor of model 0402WGF1001TCE manufactured by Jiangsu Xinsheng Microelectronics Technology Co., Ltd., with a rated voltage of 25V; the first diode D1 is a diode of model 1N4148WS manufactured by Zhuhai Hongjiacheng Technology Co., Ltd., with a rectified current of 150mA and a DC reverse withstand voltage (Vr) of 100V.

[0086] The lithium battery module 4 includes a first lithium battery B1, a second lithium battery B2, a third lithium battery B3, and a fourth lithium battery B4.

[0087] The positive terminal of the first lithium battery B1 is electrically connected to the anode of the first diode D1, the negative terminal of the first lithium battery B1 is electrically connected to the positive terminal of the second lithium battery B2, the negative terminal of the second lithium battery B2 is electrically connected to the positive terminal of the third lithium battery B3, the negative terminal of the third lithium battery B3 is electrically connected to the positive terminal of the fourth lithium battery B4, and the negative terminal of the fourth lithium battery B4 is electrically connected to the ground wire.

[0088] The nominal voltage of the first lithium battery B1, the second lithium battery B2, the third lithium battery B3, and the fourth lithium battery B4 is all 3.7V. They are all lithium batteries manufactured by Dongguan Yuanyang Electronics Co., Ltd., with the model number FLY.18650.2200.

[0089] The battery voltage sampling module 5 includes a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5.

[0090] One end of the second resistor R2 is electrically connected to the positive terminal of the first lithium battery B1. The other end of the second resistor R2 is electrically connected to one end of the second capacitor C2 and the VC1 pin of the control chip 2. The other end of the second capacitor C2 is electrically connected to ground. One end of the third resistor R3 is electrically connected to the positive terminal of the second lithium battery B2. The other end of the third resistor R3 is electrically connected to one end of the third capacitor C3 and the VC2 pin of the control chip 2. The other end of the third capacitor C3 is electrically connected to ground. One end of the fourth resistor R4 is electrically connected to the positive terminal of the third lithium battery B3. The other end of the fourth resistor R4 is electrically connected to one end of the fourth capacitor C4 and the VC3 pin of the control chip 2. The other end of the fourth capacitor C4 is electrically connected to ground. One end of the fifth resistor R5 is electrically connected to the positive terminal of the fourth lithium battery B4. The other end of the fifth resistor R5 is electrically connected to one end of the fifth capacitor C5 and the VC4 pin of the control chip 2. The other end of the fifth capacitor C5 is electrically connected to ground.

[0091] The resistance values ​​of the second resistor R2, the third resistor R3, the fourth resistor R4, and the fifth resistor R5 are all 1 kΩ, and they are resistors manufactured by Kunshan Housheng Electronics Industry Co., Ltd. with the model number 0402WGF1001TCE. The capacitance values ​​of the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5 are all 0.1 μF, and they are capacitors manufactured by Jiangsu Xinsheng Microelectronics Technology Co., Ltd. with the model number CGA0402X7R104K250GT and the rated voltage of 25V.

[0092] like Figure 2 As shown, the discharge switch module 8 includes a sixth resistor R6, a seventh resistor R7, a twenty-seventh resistor R27, a second diode D2, a seventh transistor Q7, a first MOSFET Q11, a second MOSFET Q12, a third MOSFET Q13, and a fourth MOSFET Q14.

[0093] One end of the sixth resistor R6 is electrically connected to the output control pin DO of the control chip 2. The other end of the sixth resistor R6 is electrically connected to the anode of the second diode D2 and the base of the seventh transistor Q7. The cathode of the second diode D2 is electrically connected to the emitter of the seventh transistor Q7 and the gates of the first MOSFET Q11, the second MOSFET Q12, the third MOSFET Q13, and the fourth MOSFET Q14. The sources of the first MOSFET Q11, the second MOSFET Q12, the third MOSFET Q13, and the fourth MOSFET Q14 are electrically connected to one end of the eleventh resistor R11. The drains of the first MOSFET Q11, the second MOSFET Q12, the third MOSFET Q13, and the fourth MOSFET Q14 are electrically connected to one end of the twenty-seventh resistor R27. The other end of the twenty-seventh resistor R27 is electrically connected to the ground. The collector of the seventh transistor Q7 is electrically connected to one end of the seventh resistor R7. The other end of the seventh resistor R7 is electrically connected to the ground.

[0094] The sixth resistor R6 and the seventh resistor R7 are both 100 ohms, and are 0402WGF1000TCE resistors manufactured by Kunshan Housheng Electronics Industry Co., Ltd. The twenty-seventh resistor R27 is 1 megohm, and is 0402WGF1004TCE resistor manufactured by Kunshan Housheng Electronics Industry Co., Ltd. The second diode D2 is an N4148WS diode manufactured by Zhuhai Hongjiacheng Technology Co., Ltd., with a rectified current of 150mA and a DC reverse withstand voltage Vr of 100V. The seventh transistor Q7 is an MMBT5401 transistor manufactured by Zhuhai Hongjiacheng Technology Co., Ltd., a PNP transistor with a voltage of 160V. The four parallel MOSFETs are N-channel MOSFETs AP30H150G manufactured by Shenzhen Quanli Semiconductor Co., Ltd.

[0095] Temperature detection module 6 includes an eighth resistor R8 and a ninth resistor R9.

[0096] One end of the eighth resistor R8 is electrically connected to the RTV pin of the control chip 2, and the other end of the eighth resistor R8 is electrically connected to one end of the ninth resistor R9 and the RTS pin of the control chip 2. The other end of the ninth resistor R9 is electrically connected to the ground wire.

[0097] The eighth resistor R8 has a resistance of 300 kΩ and is a 0402WGF3003TCE resistor manufactured by Kunshan Housheng Electronics Industry Co., Ltd. The ninth resistor R9 has a resistance of 100 kΩ and is a SDNT1608X104F3950FTF thermistor manufactured by Shenzhen Shunluo Electronics Co., Ltd.

[0098] The overcurrent detection module 7 includes a tenth resistor R10, an eleventh resistor R11, and a sixth capacitor C6.

[0099] One end of the tenth resistor R10 is electrically connected to the VINI pin of the control chip 2 and one end of the sixth capacitor C6. The other end of the tenth resistor R10 is electrically connected to one end of the eleventh resistor R11. The other ends of the sixth capacitor C6 and the eleventh resistor R11 are electrically connected to the ground wire.

[0100] The tenth resistor, R10, has a resistance of 1 kΩ and is a 0402WGF1001TCE resistor manufactured by Kunshan Housheng Electronics Industry Co., Ltd. The eleventh resistor, R11, has a resistance of 4 mΩ and is a sampling resistor LR123WF400NT4E manufactured by Kunshan Housheng Electronics Industry Co., Ltd. The sixth capacitor, C6, has a capacitance of 0.1 μF and is a CGA0402X7R104K250GT capacitor manufactured by Jiangsu Xinsheng Microelectronics Technology Co., Ltd., with a rated voltage of 25V.

[0101] The charging detection terminal module includes a twelfth resistor, R12.

[0102] One end of the twelfth resistor R12 is electrically connected to the VM pin of the control chip 2, and the other end of the twelfth resistor R12 is electrically connected to the charging output terminal P- of the control chip 2.

[0103] The twelfth resistor, R12, has a resistance of 20 kΩ and is a 0402WGF2002TCE resistor manufactured by Kunshan Housheng Electronics Industry Co., Ltd.

[0104] like Figure 3 As shown, the equalization module of the lithium battery charging circuit of this utility model includes a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a first transistor Q1, a second transistor Q2, a third transistor Q3, and a fourth transistor Q4.

[0105] The emitter of the first transistor Q1 is electrically connected to the positive terminal of the first lithium battery B1. The base of the first transistor Q1 is electrically connected to one end of the thirteenth resistor R13. The other end of the thirteenth resistor R13 is electrically connected to the VC1 pin of the control chip 2. The collector of the first transistor Q1 is electrically connected to one end of two parallel resistors (the fourteenth resistor R14 and the fifteenth resistor R15). The other end of the parallel resistors is electrically connected to the positive terminal of the second lithium battery B2 and the emitter of the second transistor Q2. The base of the second transistor Q2 is electrically connected to one end of the sixteenth resistor R16. The other end of the sixteenth resistor R16 is electrically connected to the VC2 pin of the control chip 2. The collector of the second transistor Q2 is electrically connected to one end of two parallel resistors (the seventeenth resistor R17 and the eighteenth resistor R18). The other end of the parallel resistors is electrically connected to the third... The positive terminal of lithium battery B3 is electrically connected to the emitter of the third transistor Q3. The base of the third transistor Q3 is electrically connected to one end of the nineteenth resistor R19. The other end of the nineteenth resistor R19 is electrically connected to the VC3 pin of the control chip 2. The collector of the third transistor Q3 is electrically connected to one end of two parallel resistors (the twentieth resistor R20 and the twenty-first resistor R21). The other end of the parallel resistors is electrically connected to the positive terminal of the fourth lithium battery B4 and the emitter of the fourth transistor Q4. The base of the fourth transistor Q4 is electrically connected to one end of the twenty-second resistor R22. The other end of the twenty-second resistor R22 is electrically connected to the VC4 pin of the chip. The collector of the fourth transistor Q4 is electrically connected to one end of two parallel resistors (the twenty-third resistor R23 and the twenty-fourth resistor R24). The other end of the parallel resistors is electrically connected to the ground wire.

[0106] The resistance values ​​of resistors R13 (13th), R16 (16th), R19 (19th), and R22 (22nd) are all 51 ohms. They are resistors manufactured by Kunshan Housheng Electronics Industry Co., Ltd., model 0402WGF510JTCE. The resistance values ​​of resistors R14 (14th), R15 (15th), R17 (17th), R18 (18th), R20 (20th), R21 (21st), R23 (23rd), and R24 (24th) are all 200 ohms. They are resistors manufactured by Kunshan Housheng Electronics Industry Co., Ltd., model 0603WAF2000T5E. Transistors Q1 (1st), Q2 (2nd), Q3 (3rd), and Q4 (4th) are PNP transistors manufactured by Zhuhai Hongjiacheng Technology Co., Ltd., model S8550.

[0107] like Figure 4 As shown, the drive enhancement module of the lithium battery charging circuit of this utility model includes a 25th resistor R25, a 26th resistor R26, a 3rd diode D3, a 4th diode D4, a 5th transistor Q5, and a 6th transistor Q6.

[0108] The anode of the third diode D3 is electrically connected to the charging input terminal P+ of the control chip 2. The cathode of the third diode D3 is electrically connected to the collector of the fifth transistor Q5. The base of the fifth transistor Q5 is electrically connected to the cathode of the fourth diode D4, the base of the sixth transistor Q6, and one end of the twenty-fifth resistor R25. The emitter of the fifth transistor Q5 is electrically connected to the emitter of the sixth transistor Q6 and one end of the twenty-sixth resistor R26. The other ends of the twenty-fifth and twenty-sixth resistors R25 and the collector of the sixth transistor Q6 are electrically connected to the charging output terminal P- of the control chip 2. The emitter of the sixth transistor Q6 is electrically connected to... Figure 5 The gates of the four parallel MOSFETs in the charging switch module are electrically connected.

[0109] The resistance values ​​of resistors R25 (25th) and R26 (26th) are both 4.7 megohms. They are 0402WGF4704TCE resistors manufactured by Kunshan Housheng Electronics Industry Co., Ltd. The resistance values ​​of diodes D3 (3rd) and D4 (4th) are 1N4148WS diodes manufactured by Zhuhai Hongjiacheng Technology Co., Ltd., with a rectified current of 150mA and a DC reverse withstand voltage (Vr) of 100V. The resistance value of diode Q5 (5th) is MMBT5551, an NPN transistor manufactured by Zhuhai Hongjiacheng Technology Co., Ltd., with a voltage of 160V. The resistance value of diode Q6 (6th) is MMBT5401, a PNP transistor manufactured by Zhuhai Hongjiacheng Technology Co., Ltd., with a voltage of 160V.

[0110] like Figure 5 As shown, the charging switch module 9 of this utility model includes a fifth MOSFET Q21, a sixth MOSFET Q22, a seventh MOSFET Q23, and an eighth MOSFET Q24.

[0111] The gates of the fifth MOSFET Q21, the sixth MOSFET Q22, the seventh MOSFET Q23, and the eighth MOSFET Q24 are electrically connected. The sources of the fifth MOSFET Q21, the sixth MOSFET Q22, the seventh MOSFET Q23, and the eighth MOSFET Q24 are electrically connected to the charging output terminal P- of the control chip 2. The drains of the fifth MOSFET Q21, the sixth MOSFET Q22, the seventh MOSFET Q23, and the eighth MOSFET Q24 are electrically connected.

[0112] The four parallel MOSFETs are N-channel MOSFETs, model AP30H150G, manufactured by Shenzhen Quanli Semiconductor Co., Ltd.

[0113] The working principle of this utility model is as follows:

[0114] A lithium battery is connected in series in the lithium battery charging circuit of this invention. The voltage signal of the lithium battery is acquired in real time by the battery voltage sampling module. After sampling, the voltage signal is filtered and transmitted to the control chip 2 via pins VC1, VC2, VC3, and VC4. The control chip analyzes and processes the voltage signal and outputs a corresponding charging control signal according to the battery status. Under normal charging conditions, if the lithium battery voltage is less than the overcharge protection voltage of the control chip, the control chip controls the CO pin to output a high level, controlling the MOSFET of the charging circuit switch to turn on, thereby charging the four lithium batteries B1, B2, B3, and B4. The charging current flows out from the charging input terminal P+ of the control chip, flows through the four series-connected lithium batteries B1, B2, B3, and B4, and charges them. Finally, the current returns to the charging output terminal P- of the control chip through the charging switch MOSFET circuit. When the sampling circuit detects that any lithium battery exceeds the charging protection voltage of the control chip, the chip controls the CO pin terminal to reverse the output level, thereby controlling the charging switch MOSFET to turn off, and the charging current in the circuit is cut off.

[0115] This utility model's lithium battery charging circuit includes an equalization module. When the battery voltage sampling module detects that the voltage of any lithium battery (such as the first lithium battery B1) exceeds the equalization detection voltage, the first transistor Q1 connected to lithium battery B1 is switched on. The charging current can be shunted through the parallel resistors (the fourteenth resistor R14 and the fifteenth resistor R15), which reduces the charging current of the high-voltage lithium battery B1 and increases the charging current of the other low-voltage lithium batteries, thereby achieving equalization of the lithium battery charging voltage.

[0116] Because the control chip's own output drive current is relatively small, its original drive capability is insufficient to drive multiple power chips or larger power devices. At this point, the drive enhancement circuit comes into play. The weak control signal output by the control chip first enters the complementary symmetrical push-pull amplification structure of the drive enhancement circuit. It is then amplified by the amplifier circuit composed of transistors Q5 and Q6, increasing the drive current. When the CO pin of the control chip outputs a high-level charging control signal, the base of the NPN transistor Q5 receives a positive bias voltage and enters the conducting state. The collector current, from the charging input terminal P+ of the control chip, flows through the third diode D3 to the gate of the charging switch MOSFET, thus achieving a larger current output drive. When the CO pin of the control chip outputs a low-level control signal, the base of the PNP transistor Q6 receives a negative bias voltage and enters the conducting state. The emitter and collector of the transistor Q6 are connected, and the emitter receives a low level, turning off the four MOSFETs of the charging switch module. The push-pull circuit controls the collector current through the base current, achieving a small current boost to a large current drive. The enhanced drive signal is sent to the charging switch control circuit, which can reliably drive multiple parallel-connected charging switch MOSFETs or external power chips. During charging, the amplified charging control signal can effectively control the charging switch module to conduct, achieving high-current charging.

[0117] The lithium battery charging circuit of this invention allows the control chip, which originally drove low-power devices, to adapt to a wider range of current output after the addition of a drive enhancement circuit. This enables it to match lithium battery packs of different capacities and diverse power demand scenarios, significantly expanding the chip's application range. Simultaneously, the enhanced drive capability improves the switching speed of the power devices, reduces switching losses, and increases the overall efficiency of the charging circuit.

[0118] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A lithium battery charging circuit, comprising an external circuit and a control chip, wherein the external circuit includes a positive power input module, a lithium battery module, a battery voltage sampling module, a temperature detection module, an overcurrent detection module, a discharge switch module, a charging switch module, an equalization module, and a drive enhancement module, characterized in that, One end of the positive power input module is electrically connected to one end of the lithium battery module and one end of the equalization module, and the other end of the lithium battery module is electrically connected to one end of the equalization module, the battery voltage sampling module, the temperature detection module, and the overcurrent detection module, respectively. The other end of the battery voltage sampling module, temperature detection module, and overcurrent detection module is electrically connected to one end of the control chip; The other end of the control chip is electrically connected to one end of the discharge switch module and one end of the charging switch module; The other end of the charging switch module is electrically connected to the drive enhancement module, and the other end of the discharging switch module and the drive enhancement module are electrically connected to the positive power input module.

2. The lithium battery charging circuit according to claim 1, characterized in that, The positive power input module includes a first resistor, a first capacitor, and a first diode; One end of the first resistor is electrically connected to one end of the first capacitor and the VCC pin of the control chip; The other end of the first capacitor is connected to the ground wire. The other end of the first resistor is electrically connected to the cathode of the first diode; The anode of the first diode D1 is electrically connected to the charging input terminal of the control chip; The resistance of the first resistor is 1 kΩ, the capacitance of the first capacitor C1 is 1 μF, the rectified current of the first diode is 150 mA, and the DC reverse withstand voltage is 100 V.

3. The lithium battery charging circuit according to claim 2, characterized in that, The lithium battery module includes a first lithium battery, a second lithium battery, a third lithium battery, and a fourth lithium battery; The positive terminal of the first lithium battery is electrically connected to the anode of the first diode, and the negative terminal of the first lithium battery is electrically connected to the positive terminal of the second lithium battery. The negative terminal of the second lithium battery is electrically connected to the positive terminal of the third lithium battery; The negative terminal of the third lithium battery is electrically connected to the positive terminal of the fourth lithium battery; The negative terminal of the fourth lithium battery is electrically connected to ground. The nominal voltage of the first, second, third, and fourth lithium batteries is 3.7V.

4. The lithium battery charging circuit according to claim 3, characterized in that, The battery voltage sampling module includes a second resistor, a third resistor, a fourth resistor, a fifth resistor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor; One end of the second resistor is electrically connected to the positive terminal of the first lithium battery, the other end of the second resistor is electrically connected to one end of the second capacitor and the VC1 pin of the control chip, and the other end of the second capacitor is electrically connected to the ground wire. One end of the third resistor is electrically connected to the positive terminal of the second lithium battery, the other end of the third resistor is electrically connected to one end of the third capacitor and the VC2 pin of the control chip, and the other end of the third capacitor is electrically connected to the ground wire. One end of the fourth resistor is electrically connected to the positive terminal of the third lithium battery, the other end of the fourth resistor is electrically connected to one end of the fourth capacitor and the VC3 pin of the control chip, and the other end of the fourth capacitor is electrically connected to the ground wire. One end of the fifth resistor is electrically connected to the positive terminal of the fourth lithium battery, the other end of the fifth resistor is electrically connected to one end of the fifth capacitor and the VC4 pin of the control chip, and the other end of the fifth capacitor is electrically connected to the ground wire. The resistance values ​​of the second, third, fourth, and fifth resistors are all 1 kΩ; The capacitance values ​​of the second, third, fourth, and fifth capacitors are all 0.1 microfarads.

5. The lithium battery charging circuit according to claim 4, characterized in that, The discharge switch module includes a sixth resistor, a seventh resistor, a twenty-seventh resistor, a second diode, a seventh transistor, a first MOSFET, a second MOSFET, a third MOSFET, and a fourth MOSFET. One end of the sixth resistor is electrically connected to the output control pin DO of the control chip, and the other end of the sixth resistor is electrically connected to the anode of the second diode and the base of the seventh transistor, respectively. The cathode of the second diode is electrically connected to the emitter of the seventh transistor, as well as the gate terminals of the first MOSFET, the second MOSFET, the third MOSFET, and the fourth MOSFET. The sources of the first, second, third, and fourth MOSFETs are electrically connected to one end of the eleventh resistor, and the drains of the first, second, third, and fourth MOSFETs are electrically connected to one end of the twenty-seventh resistor. The other end of the twenty-seventh resistor is electrically connected to the ground wire. The collector of the seventh transistor is electrically connected to one end of the seventh resistor, and the other end of the seventh resistor is electrically connected to ground. The sixth and seventh resistors both have a resistance of 100 ohms, and the twenty-seventh resistor has a resistance of 1 megohm. The second diode has a rectified current of 150mA and a DC reverse withstand voltage of 100V. The seventh transistor is a PNP transistor with a voltage of 160V; The four MOSFETs connected in parallel are N-channel MOSFETs.

6. The lithium battery charging circuit according to claim 5, characterized in that, The temperature detection module includes an eighth resistor and a ninth resistor; One end of the eighth resistor is electrically connected to the RTV pin of the control chip, the other end of the eighth resistor is electrically connected to one end of the ninth resistor and the RTS pin of the control chip, and the other end of the ninth resistor is electrically connected to the ground wire. The resistance of the eighth resistor is 300 kilohms; The resistance of the ninth resistor is 100 kilohms.

7. The lithium battery charging circuit according to claim 6, characterized in that, The overcurrent detection module includes a tenth resistor, an eleventh resistor, and a sixth capacitor; One end of the tenth resistor is electrically connected to the VINI pin of the control chip and one end of the sixth capacitor. The other end of the tenth resistor is electrically connected to one end of the eleventh resistor. The other ends of the sixth capacitor and the eleventh resistor are electrically connected to the ground wire. The resistance of the tenth resistor is 1 kiloohm; The resistance of the eleventh resistor is 4 milliohms; The sixth capacitor has a capacitance of 0.1 microfarads and a rated voltage of 25V. The charging detection terminal module is the twelfth resistor; One end of the twelfth resistor is electrically connected to the VM pin of the control chip, and the other end of the twelfth resistor is electrically connected to the charging output terminal of the control chip. The resistance of the twelfth resistor is 20 kilohms.

8. The lithium battery charging circuit according to claim 7, characterized in that, The equalization module includes resistors numbered thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, twentieth, twenty-first, twenty-second, twenty-third, and twenty-fourth, as well as transistors one, two, three, and four. The emitter of the first transistor is electrically connected to the positive terminal of the first lithium battery, the base of the first transistor is electrically connected to one end of the thirteenth resistor, the other end of the thirteenth resistor is electrically connected to the VC1 pin of the control chip, and the collector of the first transistor is electrically connected to one end of the fourteenth and fifteenth resistors. The other ends of the fourteenth and fifteenth resistors are electrically connected to the positive terminal of the second lithium battery and the emitter of the second transistor. The base of the second transistor is electrically connected to one end of the sixteenth resistor. The other end of the sixteenth resistor is electrically connected to the VC2 pin of the control chip. The collector of the second transistor is electrically connected to one end of the seventeenth and eighteenth resistors. The other ends of the seventeenth and eighteenth resistors are electrically connected to the positive terminal of the third lithium battery and the emitter of the third transistor. The base of the third transistor is electrically connected to one end of the nineteenth resistor. The other end of the nineteenth resistor is electrically connected to the VC3 pin of the control chip. The collector of the third transistor is electrically connected to one end of the twentieth and twenty-first resistors. The other ends of the 20th and 21st resistors are electrically connected to the positive terminal of the fourth lithium battery and the emitter of the fourth transistor. The base of the fourth transistor is electrically connected to one end of the 22nd resistor. The other end of the 22nd resistor is electrically connected to the VC4 pin of the chip. The collector of the fourth transistor is electrically connected to one end of the 23rd and 24th resistors. The other ends of the 23rd and 24th resistors are electrically connected to the ground wire. The resistance values ​​of the thirteenth, sixteenth, nineteenth, and twenty-second resistors are all 51 ohms; The resistance values ​​of the fourteenth, fifteenth, seventeenth, eighteenth, twentieth, twenty-first, twenty-third, and twenty-fourth resistors are all 200 ohms; The first, second, third, and fourth transistors are all PNP type transistors.

9. The lithium battery charging circuit according to claim 8, characterized in that, The drive enhancement module includes a 25th resistor, a 26th resistor, a 3rd diode, a 4th diode, a 5th transistor, and a 6th transistor; The anode of the third diode is electrically connected to the charging input terminal of the control chip, and the cathode of the third diode is electrically connected to the collector of the fifth transistor. The base of the fifth transistor is electrically connected to the cathode of the fourth diode D4, the base of the sixth transistor, and one end of the twenty-fifth resistor. The emitter of the fifth transistor is electrically connected to the emitter of the sixth transistor and one end of the twenty-sixth resistor. The other ends of the 25th and 26th resistors, as well as the collector of the 6th transistor, are electrically connected to the charging output terminal of the control chip. The emitter of the sixth transistor is electrically connected to the gate terminals of the four parallel MOSFETs in the charging switch module; The resistance values ​​of the twenty-fifth and twenty-sixth resistors are both 4.7 megohms; The rectified current of the third and fourth diodes is 150mA, and the DC reverse withstand voltage is 100V. The fifth transistor is an NPN transistor with a voltage of 160V; The sixth transistor is a PNP type transistor with a voltage of 160V.

10. The lithium battery charging circuit according to claim 9, characterized in that, The charging switch module includes four parallel-connected fifth MOSFETs, sixth MOSFETs, seventh MOSFETs, and eighth MOSFETs; The gate electrical connections of the fifth, sixth, seventh, and eighth MOSFETs; The sources of the fifth, sixth, seventh, and eighth MOSFETs are electrically connected to the charging output terminal of the control chip. The drain electrical connections of the fifth, sixth, seventh, and eighth MOSFETs; The four MOSFETs are N-channel MOSFETs.

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