Battery charging circuit and system

Abstract

The utility model discloses a battery charging circuit and system, and relates to the technical field of battery charging, the battery charging circuit comprises a power supply control chip, a comparator, an OR gate, an over-current sampling circuit and an over-temperature sampling circuit; the input end and the output end of the power supply control chip are respectively connected with a power supply and a battery; the overcurrent sampling circuit outputs a first sampling signal to a first input end of the OR gate according to the output end current of the power supply control chip; the over-temperature sampling circuit outputs a second sampling signal to the second input end of the OR gate according to the temperature; the output end of the OR gate is connected with the first input end of the comparator, the second input end of the comparator is connected with the reference voltage, the output end of the comparator is connected with the enabling end of the power supply control chip, and when the voltage value of the first sampling signal or the second sampling signal is not lower than the voltage value of the reference voltage, the OR gate is matched with the comparator to turn off the power supply control chip. According to the utility model, over-current or over-temperature protection is realized through hardware, the action time is shorter, and the protection performance is better.

Description

Technical Field

[0001] The utility model relates to the technical field of battery charging, and in particular to a battery charging circuit and system. Background Art

[0002] At present, the low-current charging function is generally used in the scenario of feeding power to small batteries. When the voltage of the small battery is low, if a high voltage is used directly for power supply, the instantaneous current will be large, which will damage the small battery and affect the working life of the small battery. Therefore, in the scenario of low battery voltage or low temperature environment, the small battery is first charged with a small current. When the voltage of the small battery reaches a certain level, it is switched to the main circuit, and the DCDC of the main circuit charges the battery with a large current, so as to ensure that the small battery has a longer service life.

[0003] BMS (battery management system) products with low current charging all use built-in DCDC chips to charge small batteries, generally including output overcurrent protection and over-temperature protection functions. The specific implementation logic is as follows:

[0004] Over-temperature protection: Use NTC to convert the temperature signal into a voltage signal, and sample it through the ADC port of the MCU. When the temperature exceeds the temperature threshold set by the MCU software, the protection logic is triggered, and the built-in DCDC chip is disconnected through communication to stop charging.

[0005] Overcurrent protection: Use a sampling circuit to sample the real-time current of the shunt resistor, and use the MCU to judge the current value. When the current exceeds the current threshold set by the MCU software, the protection logic is triggered, and the built-in DCDC chip is disconnected through communication to stop charging.

[0006] Although the above solution can realize the output over-current protection and over-temperature protection functions, when the over-current and over-temperature protection are realized by the MCU-based software, the software response time is slightly long, and it is difficult to quickly cut off the charging circuit, which poses certain safety hazards. Utility Model Content

[0007] The embodiment of the utility model provides a battery charging circuit and system to solve the technical problems in the related art that the existing battery charging circuit implements over-current and over-temperature protection based on MCU software control, the software response time is long, and it is difficult to quickly cut off the charging circuit.

[0008] In a first aspect, a battery charging circuit is provided, comprising: a power control chip, a comparator, an OR gate, an overcurrent sampling circuit and an overtemperature sampling circuit;

[0009] The input end and the output end of the power control chip are used to connect to the power source and the battery respectively;

[0010] The overcurrent sampling circuit is connected to the OR gate and the output end of the power control chip, and outputs a first sampling signal to the first input end of the OR gate according to the output end current of the power control chip;

[0011] The over-temperature sampling circuit is connected to the OR gate, and outputs a second sampling signal to the second input terminal of the OR gate according to the temperature;

[0012] The output end of the OR gate is connected to the first input end of the comparator, the second input end of the comparator is connected to the reference voltage, and the output end of the comparator is connected to the enable end of the power control chip. When the voltage value of the first sampling signal or the second sampling signal is not lower than the voltage value of the reference voltage, the OR gate cooperates with the comparator to shut down the power control chip.

[0013] In some embodiments, the overcurrent sampling circuit includes a sampling shunt, a first resistor, a second resistor, a third resistor and an operational amplifier, the sampling shunt is arranged between the output end of the power control chip and the battery, the first end of the first resistor is connected to the first end of the sampling shunt, the second end of the first resistor is connected to the non-inverting input end of the operational amplifier, the first end of the second resistor is connected to the second end of the sampling shunt, the second end of the second resistor is connected to the inverting input end of the operational amplifier, the first end of the third resistor is connected to the inverting input end of the operational amplifier, and the second end of the third resistor is connected to the output end of the operational amplifier and the first input end of the OR gate.

[0014] In some embodiments, the over-temperature sampling circuit includes a temperature sampling resistor and a fourth resistor, the first end of the temperature sampling resistor is connected to a power supply, the second end of the temperature sampling resistor is connected to the first end of the fourth resistor, the second end of the fourth resistor is grounded, and the common end of the temperature sampling resistor and the fourth resistor is connected to the second input end of the OR gate.

[0015] In some embodiments, the battery charging circuit further comprises:

[0016] An output overvoltage sampling circuit is connected to the OR gate and the output end of the power control chip, and outputs a third sampling signal to the third input end of the OR gate according to the output end voltage of the power control chip.

[0017] In some embodiments, the battery charging circuit further comprises:

[0018] The output overvoltage sampling circuit includes a fifth resistor and a sixth resistor, the first end of the fifth resistor is connected to the output end of the power control chip, the second end of the fifth resistor is connected to the first end of the sixth resistor, the second end of the sixth resistor is grounded, and the common end of the fifth resistor and the sixth resistor is connected to the third input end of the OR gate.

[0019] In some embodiments, the battery charging circuit further comprises:

[0020] An input undervoltage sampling circuit is connected to the OR gate and the input end of the power control chip, and outputs a fourth sampling signal to the fourth input end of the OR gate according to the input end voltage of the power control chip.

[0021] In some embodiments, the input undervoltage sampling circuit includes a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor and a transistor, the first end of the seventh resistor is connected to the input end of the power control chip, the second end of the seventh resistor is connected to the first end of the eighth resistor, the second end of the eighth resistor is grounded, the common end of the seventh resistor and the eighth resistor is connected to the first end of the ninth resistor, the second end of the ninth resistor is connected to the base of the transistor, the first end of the tenth resistor is connected to the input end of the power control chip, the second end of the tenth resistor is connected to the collector of the transistor and the fourth input end of the OR gate, the first end of the eleventh resistor is connected to the base of the transistor, and the second end of the eleventh resistor is connected to the emitter of the transistor and grounded.

[0022] In some embodiments, the battery charging circuit further comprises:

[0023] An output reverse protection module is provided between the output end of the power control chip and the battery.

[0024] In some embodiments, the output reverse protection module is a diode, the anode of the diode is connected to the output end of the power control chip, and the cathode of the diode is connected to the battery.

[0025] In a second aspect, a battery charging system is provided, comprising the aforementioned battery charging circuit.

[0026] The beneficial effects brought by the technical solution provided by the utility model include:

[0027] The embodiment of the utility model provides a battery charging circuit and system, wherein the battery charging circuit is provided with a power control chip, a comparator, an OR gate, an overcurrent sampling circuit and an overtemperature sampling circuit, wherein the overcurrent sampling circuit outputs a first sampling signal to a first input terminal of the OR gate according to the output current of the power control chip, and the overtemperature sampling circuit outputs a second sampling signal to a second input terminal of the OR gate according to the temperature, and when the voltage value of the first sampling signal or the second sampling signal is not lower than the voltage value of the reference voltage, the OR gate cooperates with the comparator to turn off the power control chip, that is, the utility model directly implements overcurrent or overtemperature protection through hardware, with a shorter action time and better protection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic diagram of a battery charging circuit provided by an embodiment of the utility model;

[0030] Figure 2 A schematic diagram of an overcurrent sampling circuit provided by an embodiment of the utility model;

[0031] Figure 3 A schematic diagram of an over-temperature sampling circuit provided by an embodiment of the utility model;

[0032] Figure 4 A schematic diagram of an output overvoltage sampling circuit provided by an embodiment of the utility model;

[0033] Figure 5 A schematic diagram of an input undervoltage sampling circuit provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] The embodiment of the utility model provides a battery charging circuit, which can solve the technical problems that the existing battery charging circuit realizes over-current and over-temperature protection based on MCU software control, the software response time is long, and it is difficult to quickly cut off the charging circuit.

[0036] See also Figure 1 As shown, an embodiment of the utility model provides a battery charging circuit, including: a power control chip U1, a comparator U2, an OR gate G1, an overcurrent sampling circuit and an overtemperature sampling circuit.

[0037] The input end and the output end of the power control chip U1 are respectively used to connect to the power supply and the battery. The overcurrent sampling circuit is connected to the OR gate G1 and the output end of the power control chip U1, and outputs a first sampling signal to the first input end of the OR gate G1 according to the output end current of the power control chip U1. The overtemperature sampling circuit is connected to the OR gate G1, and outputs a second sampling signal to the second input end of the OR gate G1 according to the temperature. Optionally, the power control chip U1 is a Buck power control chip.

[0038] The output end of the OR gate G1 is connected to the first input end of the comparator U2, the second input end of the comparator U2 is connected to the reference voltage Vref, and the output end of the comparator U2 is connected to the enable end of the power control chip U1. When the voltage value of the first sampling signal or the second sampling signal is not lower than the voltage value of the reference voltage Vref, the OR gate G1 cooperates with the comparator U2 to turn off the power control chip U1.

[0039] Specifically, when the voltage value of the first sampling signal or the second sampling signal is not lower than the voltage value of the reference voltage Vref, the comparator U2 outputs a low level, the enable end of the power control chip U1 inputs a low level, and the output of the power control chip U1 is turned off to achieve over-current or over-temperature protection.

[0040] The battery charging circuit in the embodiment of the utility model is provided with a power control chip, a comparator, an OR gate, an overcurrent sampling circuit and an overtemperature sampling circuit. The overcurrent sampling circuit outputs a first sampling signal to the first input terminal of the OR gate according to the output current of the power control chip, and the overtemperature sampling circuit outputs a second sampling signal to the second input terminal of the OR gate according to the temperature, and when the voltage value of the first sampling signal or the second sampling signal is not lower than the voltage value of the reference voltage, the OR gate cooperates with the comparator to turn off the power control chip, that is, the utility model directly realizes overcurrent or overtemperature protection through hardware, with shorter action time and better protection performance.

[0041] As an optional implementation, in a utility model embodiment, see Figure 1 and Figure 2 As shown, the overcurrent sampling circuit includes a sampling shunt Ra, a first resistor R1, a second resistor R2, a third resistor R3 and an operational amplifier U3. The sampling shunt Ra is arranged between the output end of the power control chip U1 and the battery. The first end of the first resistor R1 is connected to the first end of the sampling shunt Ra, the second end of the first resistor R1 is connected to the non-inverting input end of the operational amplifier U3, the first end of the second resistor R2 is connected to the second end of the sampling shunt Ra, the second end of the second resistor R2 is connected to the inverting input end of the operational amplifier U3, the first end of the third resistor R3 is connected to the inverting input end of the operational amplifier U3, and the second end of the third resistor R3 is connected to the output end of the operational amplifier U3 and the first input end of the OR gate G1.

[0042] For example, assuming that the voltage value of the reference voltage is 2.5V, the limiting voltage of the overcurrent protection is 10A (greater than or equal to 10A is considered unsafe), a 10mΩ sampling shunt can be selected. When the output current of the power control chip is 10A, the voltage value on the sampling shunt is 0.1V. This voltage signal is input into the first end Cin of the first resistor R1, and the resistance ratio of the third resistor R3 and the second resistor R2 is set to 24. After 0.1V is amplified, the output end Cout of the operational amplifier U3 outputs 2.5V. When the output end voltage of the OR gate G1 is not less than 2.5V, the comparator U2 outputs a low level, and the enable end of the power control chip U1 inputs a low level, turning off the output of the power control chip U1 to achieve the purpose of overcurrent protection.

[0043] As an optional implementation, in a utility model embodiment, see Figure 1 and Figure 3 As shown, the over-temperature sampling circuit includes a temperature sampling resistor NTC and a fourth resistor R4, the first end of the temperature sampling resistor NTC is connected to the power supply VCC, the second end of the temperature sampling resistor NTC is connected to the first end of the fourth resistor R4, the second end of the fourth resistor R4 is grounded, and the common end of the temperature sampling resistor NTC and the fourth resistor R4 is connected to the second input end of the OR gate G1. By using NTC and the fourth resistor R4 for voltage division, the over-temperature threshold can be set to 85°C. When the temperature reaches 85°C, the NTC_IN end outputs 2.5V to the OR gate G1, and then the comparator U2 outputs a low level, and the enable end of the power control chip U1 inputs a low level, turning off the output of the power control chip U1, thereby achieving the purpose of over-temperature protection.

[0044] As an optional implementation, in a utility model embodiment, see Figure 1 and Figure 4As shown, the battery charging circuit also includes: an output overvoltage sampling circuit, which is connected to the OR gate G1 and the output end of the power control chip U1, and outputs a third sampling signal to the third input end of the OR gate G1 according to the output end voltage of the power control chip U1.

[0045] Furthermore, the output overvoltage sampling circuit includes a fifth resistor R5 and a sixth resistor R6, the first end of the fifth resistor R5 is connected to the output end of the power control chip U1, the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6, the second end of the sixth resistor R6 is grounded, and the common end of the fifth resistor R5 and the sixth resistor R6 is connected to the third input end of the OR gate G1. The overvoltage threshold can be set to 12.8V. When the voltage Vout reaches 12.8V, the ratio of R5 / R6 is configured, and the UVout end outputs 2.5V to the OR gate G1, and then the comparator U2 outputs a low level, and the enable end of the power control chip U1 inputs a low level, turning off the output of the power control chip U1, thereby achieving the purpose of output overvoltage protection.

[0046] As an optional implementation, in a utility model embodiment, see Figure 1 and Figure 5 As shown, the battery charging circuit also includes: an input undervoltage sampling circuit, which is connected to the OR gate G1 and the input end of the power control chip U1, and outputs a fourth sampling signal to the fourth input end of the OR gate G1 according to the input end voltage of the power control chip U1.

[0047] Further, the input undervoltage sampling circuit includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a transistor Q1, the first end of the seventh resistor R7 is connected to the input end of the power control chip U1, the second end of the seventh resistor R7 is connected to the first end of the eighth resistor R8, the second end of the eighth resistor R8 is grounded, the common end of the seventh resistor R7 and the eighth resistor R8 is connected to the first end of the ninth resistor R9, the second end of the ninth resistor R9 is connected to the base of the transistor Q1, the first end of the tenth resistor R10 is connected to the input end of the power control chip, the second end of the tenth resistor R10 is connected to the collector of the transistor and the fourth input end of the OR gate, the first end of the eleventh resistor is connected to the base of the transistor, and the second end of the eleventh resistor is connected to the emitter of the transistor and grounded. The undervoltage threshold can be set to 10V, and the resistance values ​​of the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, and the eleventh resistor R11 are configured. When the voltage Vin is less than or equal to 10V, the transistor Q1 is cut off, UVIN outputs a high level (generally greater than 2.5V) to the OR gate G1, and then the comparator U2 outputs a low level, and the enable end of the power control chip U1 inputs a low level, turning off the output of the power control chip U1, thereby achieving the purpose of input undervoltage protection.

[0048] As an optional implementation, in a utility model embodiment, see Figure 1 As shown, the battery charging circuit also includes: an output reverse protection module, which is arranged between the output end of the power control chip and the battery. Optionally, the output reverse protection module is a diode D1, the anode of the diode D1 is connected to the output end of the power control chip U1, and the cathode of the diode D1 is connected to the battery. The diode D1 can prevent the internal voltage of the battery from being higher than the input voltage of the power control chip U1, that is, to prevent the battery current from backflowing and burning the power control chip U1.

[0049] An embodiment of the utility model further provides a battery charging system, comprising the aforementioned battery charging circuit.

[0050] In the description of the present utility model, it should be noted that the terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present utility model. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to the specific circumstances.

[0051] It should be noted that, in the present utility model, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0052] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features of the present invention.

Claims

1. A battery charging circuit, characterized in that: include: Power control chip, comparator, OR gate, over-current sampling circuit and over-temperature sampling circuit; The input end and the output end of the power control chip are used to connect to the power source and the battery respectively; The overcurrent sampling circuit is connected to the OR gate and the output end of the power control chip, and outputs a first sampling signal to the first input end of the OR gate according to the output end current of the power control chip; The over-temperature sampling circuit is connected to the OR gate, and outputs a second sampling signal to the second input terminal of the OR gate according to the temperature; The output end of the OR gate is connected to the first input end of the comparator, the second input end of the comparator is connected to the reference voltage, and the output end of the comparator is connected to the enable end of the power control chip. When the voltage value of the first sampling signal or the second sampling signal is not lower than the voltage value of the reference voltage, the OR gate cooperates with the comparator to shut down the power control chip.

2. The battery charging circuit according to claim 1, characterized in that: The overcurrent sampling circuit includes a sampling shunt, a first resistor, a second resistor, a third resistor and an operational amplifier. The sampling shunt is arranged between the output end of the power control chip and the battery, the first end of the first resistor is connected to the first end of the sampling shunt, the second end of the first resistor is connected to the non-inverting input end of the operational amplifier, the first end of the second resistor is connected to the second end of the sampling shunt, the second end of the second resistor is connected to the inverting input end of the operational amplifier, the first end of the third resistor is connected to the inverting input end of the operational amplifier, and the second end of the third resistor is connected to the output end of the operational amplifier and the first input end of the OR gate.

3. The battery charging circuit according to claim 1, characterized in that: The over-temperature sampling circuit includes a temperature sampling resistor and a fourth resistor, wherein a first end of the temperature sampling resistor is connected to a power supply, a second end of the temperature sampling resistor is connected to a first end of the fourth resistor, a second end of the fourth resistor is grounded, and a common end of the temperature sampling resistor and the fourth resistor is connected to a second input end of the OR gate.

4. The battery charging circuit according to claim 1, characterized in that: Also includes: An output overvoltage sampling circuit is connected to the OR gate and the output end of the power control chip, and outputs a third sampling signal to the third input end of the OR gate according to the output end voltage of the power control chip.

5. The battery charging circuit according to claim 4, characterized in that: The output overvoltage sampling circuit includes a fifth resistor and a sixth resistor, the first end of the fifth resistor is connected to the output end of the power control chip, the second end of the fifth resistor is connected to the first end of the sixth resistor, the second end of the sixth resistor is grounded, and the common end of the fifth resistor and the sixth resistor is connected to the third input end of the OR gate.

6. The battery charging circuit according to claim 1, characterized in that: Also includes: An input undervoltage sampling circuit is connected to the OR gate and the input end of the power control chip, and outputs a fourth sampling signal to the fourth input end of the OR gate according to the input end voltage of the power control chip.

7. The battery charging circuit according to claim 6, characterized in that: The input undervoltage sampling circuit includes a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor and a transistor, wherein the first end of the seventh resistor is connected to the input end of the power control chip, the second end of the seventh resistor is connected to the first end of the eighth resistor, the second end of the eighth resistor is grounded, the common end of the seventh resistor and the eighth resistor is connected to the first end of the ninth resistor, the second end of the ninth resistor is connected to the base of the transistor, the first end of the tenth resistor is connected to the input end of the power control chip, the second end of the tenth resistor is connected to the collector of the transistor and the fourth input end of the OR gate, the first end of the eleventh resistor is connected to the base of the transistor, and the second end of the eleventh resistor is connected to the emitter of the transistor and grounded.

8. The battery charging circuit according to claim 1, characterized in that: Also includes: An output reverse protection module is provided between the output end of the power control chip and the battery.

9. The battery charging circuit according to claim 8, characterized in that: The output anti-reverse module is a diode, the anode of the diode is connected to the output end of the power control chip, and the cathode of the diode is connected to the battery.

10. A battery charging system, characterized in that: A battery charging circuit comprising the battery charging circuit according to any one of claims 1 to 9.

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