Battery discharge protection circuit and power supply system

Abstract

The invention provides a battery discharge temperature protection circuit and a power supply system, and relates to the field of power supply. The battery discharge temperature protection circuit comprises a battery management circuit electrically connected with a battery; the operational amplifier circuit is electrically connected with the battery management circuit; the power supply enable signal control circuit is electrically connected with the operational amplifier circuit; the DC-DC converter is electrically connected with the power supply enable signal control circuit, the battery management circuit and the electric equipment; wherein the battery management circuit is used for detecting the real-time temperature of a battery in real time through a thermistor and outputting a temperature signal; the operational amplifier circuit is used for receiving a temperature signal of the battery management circuit and converting the temperature signal into a level signal to be output; the power supply enable signal control circuit is used for outputting a corresponding enable signal according to the received level signal; and the DC-DC converter is used for controlling power supply to the electric equipment according to the high and low levels of the received enable signal. According to the scheme, discharge temperature protection of the battery is achieved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The invention relates to the field of power supply, and in particular to a battery discharge protection circuit and a power supply system. Background Art

[0002] Due to the characteristics of lithium batteries, the discharge process of lithium batteries needs to be carried out within a certain temperature range. However, many battery charging management integrated circuits on the market do not have high and low temperature discharge temperature protection functions, which causes the battery to be discharged at too high or too low temperatures, damaging the battery life and posing safety risks. Summary of the invention

[0003] The present invention provides a battery discharge protection circuit and a power supply system, which solves the problem that the existing power supply system cannot perform temperature protection on the discharge battery during the power supply process, resulting in damage to the battery life and safety risks.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] An embodiment of the present invention provides a battery discharge temperature protection circuit, comprising:

[0006] a battery management circuit electrically connected to the battery;

[0007] an operational amplifier circuit electrically connected to the battery management circuit;

[0008] A power enable signal control circuit electrically connected to the operational amplifier circuit;

[0009] A DC-to-DC converter electrically connected to the power enable signal control circuit, the battery management circuit, and the power-consuming device;

[0010] Among them, the battery management circuit is used to detect the real-time temperature of the battery through a thermistor and output a temperature signal; the operational amplifier circuit is used to receive the temperature signal of the battery management circuit and convert the temperature signal into a level signal for output; the power enable signal control circuit is used to receive the level signal sent by the operational amplifier circuit and output the corresponding enable signal according to the received level signal; the DC to DC converter is used to receive the enable signal and control the power supply to the electrical equipment according to the high and low levels of the received enable signal.

[0011] Optionally, the battery management circuit includes:

[0012] An external power supply combining circuit electrically connected to the battery;

[0013] A battery charging chip electrically connected to the external power supply combining circuit;

[0014] A voltage stabilizing circuit, wherein the input end of the voltage stabilizing circuit is electrically connected to the output end of the external power supply combining circuit, and the output end of the voltage stabilizing circuit is electrically connected to the operational amplifier circuit.

[0015] Optionally, the external power supply combining circuit includes:

[0016] A power adapter electrically connected to an external power source and a battery interface connected to a battery;

[0017] Wherein, the first pin of the battery interface is grounded;

[0018] The second pin of the battery interface is electrically connected to the thermistor inside the battery and is electrically connected to the battery charging chip;

[0019] The fourth pin of the battery interface is electrically connected to the battery and to the third pin of the first field effect transistor;

[0020] The second pin of the first field effect transistor is electrically connected to the battery charging chip;

[0021] The first pin of the first field effect transistor is electrically connected to the fourth pin of the power adapter through the second resistor;

[0022] The second pin of the power adapter is electrically connected to the third pin of the power adapter, the third pin of the power adapter is electrically connected to the fourth pin of the power adapter through the first resistor, and is grounded;

[0023] The fourth pin of the power adapter is electrically connected to the external power source and is electrically connected to the battery charging chip through the first diode.

[0024] Optionally, the first pin of the battery charging chip is electrically connected to the tenth pin of the battery charging chip through an inductor coil, and the tenth pin of the battery charging chip is electrically connected to the fourth pin of the battery interface through a nineteenth resistor;

[0025] The fifteenth pin of the battery charging chip is electrically connected to the first pin of the battery charging chip through the first capacitor;

[0026] The ninth pin of the battery charging chip is electrically connected to the fourth pin of the battery interface;

[0027] The second pin of the battery charging chip is electrically connected to the second pin of the first field effect transistor, the cathode of the first diode and the voltage stabilizing circuit;

[0028] The third pin of the battery charging chip electrically outputs a 4.5V power supply and is electrically connected to the thirteenth pin of the battery charging chip through the twentieth resistor;

[0029] The thirteenth pin of the battery charging chip is electrically connected to the second pin of the battery interface;

[0030] The sixth pin of the battery charging chip is electrically connected to the eighth pin of the battery charging chip through a twenty-first resistor, and the eighth pin of the battery charging chip is grounded.

[0031] Optionally, the voltage stabilizing circuit includes:

[0032] The second transistor and shunt regulator;

[0033] Wherein, the third pin of the second transistor is electrically connected to the output end of the external power supply combining circuit;

[0034] The second pin of the second triode is electrically connected to the operational amplifier circuit;

[0035] The first pin of the second triode is electrically connected to the third pin of the second triode through a fifth resistor, and is grounded through the fifth resistor and a third capacitor;

[0036] The second pin of the shunt regulator is electrically connected to the first pin of the second transistor;

[0037] The first pin of the shunt regulator is electrically connected to the second pin of the second transistor through a sixth resistor, and is grounded through an eighth resistor;

[0038] The third pin of the parallel regulator is grounded and electrically connected to the second pin of the second transistor through a second capacitor.

[0039] Optionally, the operational amplifier circuit includes:

[0040] A first operational amplifier hysteresis comparison circuit and a second operational amplifier hysteresis comparison circuit;

[0041] Among them, the positive power supply pin of the first op amp hysteresis comparison circuit and the positive power supply pin of the second op amp hysteresis comparison circuit are both electrically connected to the output end of the voltage stabilizing circuit, and the output end of the first op amp hysteresis comparison circuit and the output end of the second op amp hysteresis comparison circuit are both electrically connected to the power enable signal control circuit.

[0042] Optionally, the first operational amplifier hysteresis comparison circuit includes:

[0043] a first operational amplifier, wherein a first pin of the first operational amplifier is electrically connected to a power enable signal control circuit through a second diode, and is electrically connected to a third pin of the first operational amplifier through an eleventh resistor;

[0044] The third pin of the first operational amplifier is electrically connected to the output end of the voltage stabilizing circuit through the twelfth resistor and the ninth resistor, and is grounded through the tenth resistor;

[0045] The second pin of the first operational amplifier is electrically connected to the battery charging chip;

[0046] The eighth pin of the first operational amplifier is electrically connected to the output end of the voltage stabilizing circuit, and the fourth pin of the first operational amplifier is grounded.

[0047] Optionally, the second operational amplifier hysteresis comparison circuit includes:

[0048] a second operational amplifier, wherein a seventh pin of the second operational amplifier is electrically connected to the power enable signal control circuit through a fifth diode, and is electrically connected to the fifth pin of the second operational amplifier through a sixteenth resistor;

[0049] The fifth pin of the second operational amplifier is electrically connected to the battery charging chip through an eighteenth resistor;

[0050] The sixth pin of the second operational amplifier is electrically connected to the output end of the voltage stabilizing circuit through the third resistor, and is grounded through the fourth resistor;

[0051] The eighth pin of the second operational amplifier is electrically connected to the output end of the voltage stabilizing circuit, and the fourth pin of the second operational amplifier is grounded.

[0052] Optionally, the power enable signal control circuit includes:

[0053] a third triode, wherein a first pin of the third triode is electrically connected to the operational amplifier circuit through a fifteenth resistor and is grounded through a seventeenth resistor;

[0054] The second pin of the third triode is grounded;

[0055] The third pin of the third triode is electrically connected to the output end of the voltage stabilizing circuit through the thirteenth resistor, and is electrically connected to the DC to DC converter through the fourth diode;

[0056] A third diode, wherein an anode of the third diode is electrically connected to the fourth pin of the power adapter through a fourteenth resistor, and a cathode of the third diode is electrically connected to the DC to DC converter.

[0057] An embodiment of the present invention further provides a power supply system, comprising: a battery, an external power supply and an electrical device, wherein the electrical device is electrically connected to the battery and the external power supply via a battery discharge temperature protection circuit, and the battery discharge temperature protection circuit is any one of the battery discharge temperature protection circuits described above.

[0058] The above solution of the present invention includes at least the following beneficial effects:

[0059] The battery discharge temperature protection circuit of the present invention comprises: a battery management circuit electrically connected to the battery; an operational amplifier circuit electrically connected to the battery management circuit; a power enable signal control circuit electrically connected to the operational amplifier circuit; a DC to DC converter electrically connected to the power enable signal control circuit, the battery management circuit and the electrical equipment; wherein the battery management circuit is used to detect the real-time temperature of the battery in real time through a thermistor and output a temperature signal; the operational amplifier circuit is used to receive the temperature signal of the battery management circuit and convert the temperature signal into a level signal for output; the power enable signal control circuit is used to receive the level signal sent by the operational amplifier circuit and output a corresponding enable signal according to the received level signal; the DC to DC converter is used to receive the enable signal and control the power supply to the electrical equipment according to the high and low levels of the received enable signal. The temperature protection of the discharge battery during the battery discharge process is realized, the battery life is extended, and the safety of the battery during use is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a structural schematic diagram of an external power supply combining circuit of a battery discharge temperature protection circuit of the present invention;

[0061] Figure 2 It is a structural schematic diagram of a battery charging chip of a battery discharge temperature protection circuit of the present invention;

[0062] Figure 3 It is a structural schematic diagram of a voltage stabilizing circuit of a battery discharge temperature protection circuit of the present invention;

[0063] Figure 4 It is a structural schematic diagram of an operational amplifier circuit and a power supply enable signal control circuit of a battery discharge temperature protection circuit of the present invention. DETAILED DESCRIPTION

[0064] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0065] like Figures 1 to 4 As shown, an embodiment of the present invention provides a battery discharge temperature protection circuit, comprising:

[0066] a battery management circuit electrically connected to the battery;

[0067] an operational amplifier circuit electrically connected to the battery management circuit;

[0068] A power enable signal control circuit electrically connected to the operational amplifier circuit;

[0069] A DC-to-DC converter electrically connected to the power enable signal control circuit, the battery management circuit, and the power-consuming device;

[0070] Among them, the battery management circuit is used to detect the real-time temperature of the battery through a thermistor and output a temperature signal; the operational amplifier circuit is used to receive the temperature signal of the battery management circuit and convert the temperature signal into a level signal for output; the power enable signal control circuit is used to receive the level signal sent by the operational amplifier circuit and output the corresponding enable signal according to the received level signal; the DC to DC converter is used to receive the enable signal and control the power supply to the electrical equipment according to the high and low levels of the received enable signal.

[0071] In this embodiment, the design of the DC-to-DC converter is not unique, as long as it can be realized that whether to power the electrical device is determined according to the high and low levels of the received enable signal; the battery management circuit is also used to provide real-time power to the operational amplifier circuit, and is used to ensure the normal operation of the operational amplifier circuit when the power enable signal control circuit disconnects the electrical device; the battery discharge temperature protection circuit uses a thermistor to detect the real-time temperature of the current battery during the battery discharge process in real time, and transmits the temperature signal to the power enable signal control circuit after conversion through the operational amplifier circuit, and outputs the corresponding enable signal through the power enable signal control circuit. The DC-to-DC converter receives the enable signal and determines whether to power the electrical device according to the high and low levels of the received enable signal; by controlling whether the power supply end of the electrical device is powered, the discharge of the battery is controlled in real time according to the current discharge temperature of the battery, thereby improving the service life of the battery (power supply device) and the safety of the battery during power supply.

[0072] In an optional embodiment of the present invention, the battery management circuit includes:

[0073] An external power supply combining circuit electrically connected to the battery;

[0074] A battery charging chip UP1 electrically connected to the external power supply combining circuit;

[0075] A voltage stabilizing circuit, wherein the input end of the voltage stabilizing circuit is electrically connected to the output end of the external power supply combining circuit, and the output end of the voltage stabilizing circuit is electrically connected to the operational amplifier circuit.

[0076] In an optional embodiment of the present invention, the external power supply combining circuit includes:

[0077] A power adapter DC1 electrically connected to an external power source Vin and a battery interface J1 connected to a battery;

[0078] Wherein, the first pin of the battery interface J1 is grounded;

[0079] The second pin of the battery interface J1 is electrically connected to the thermistor inside the battery and is electrically connected to the battery charging chip UP1;

[0080] The fourth pin of the battery interface J1 is electrically connected to the battery and is electrically connected to the third pin of the first field effect transistor Q1;

[0081] The second pin of the first field effect transistor Q1 is electrically connected to the battery charging chip UP1;

[0082] The first pin of the first field effect transistor Q1 is electrically connected to the fourth pin of the power adapter DC1 through the second resistor R2;

[0083] The second pin of the power adapter DC1 is electrically connected to the third pin of the power adapter DC1, and the third pin of the power adapter DC1 is electrically connected to the fourth pin of the power adapter DC1 through the first resistor R1 and is grounded;

[0084] The fourth pin of the power adapter DC1 is electrically connected to the external power source Vin, and is electrically connected to the battery charging chip UP1 through the first diode D1.

[0085] In this embodiment, the external power supply combining circuit is mainly used to connect the power supply battery and the external power supply Vin, wherein the battery is used to act as a power supply to supply power when the external power supply stops supplying power;

[0086] In an optional embodiment of the present invention, the first pin of the battery charging chip UP1 is electrically connected to the tenth pin of the battery charging chip UP1 through the inductor LP1, and the tenth pin of the battery charging chip UP1 is electrically connected to the fourth pin of the battery interface J1 through the nineteenth resistor RPS1;

[0087] The fifteenth pin of the battery charging chip UP1 is electrically connected to the first pin of the battery charging chip UP1 through the first capacitor C1;

[0088] The ninth pin of the battery charging chip UP1 is electrically connected to the fourth pin of the battery interface J1;

[0089] The second pin of the battery charging chip UP1 is electrically connected to the second pin of the first field effect transistor Q1, the cathode of the first diode D1 and the voltage stabilizing circuit;

[0090] The third pin of the battery charging chip UP1 electrically outputs a 4.5V power supply and is electrically connected to the thirteenth pin of the battery charging chip UP1 through the twentieth resistor RP3;

[0091] The thirteenth pin of the battery charging chip UP1 is electrically connected to the second pin of the battery interface J1;

[0092] The sixth pin of the battery charging chip UP1 is electrically connected to the eighth pin of the battery charging chip UP1 through a twenty-first resistor RP4, and the eighth pin of the battery charging chip UP1 is grounded.

[0093] In this embodiment, the fourteenth pin, the fifth pin and the fourth pin of the battery charging chip UP1 are grounded through the fourth capacitor C4, the twenty-third resistor RP6 and the twenty-second resistor RP5 respectively; the sixteenth pin of the battery charging chip UP1 is grounded;

[0094] In this embodiment, the battery discharge temperature protection circuit uses the battery charging chip UP1 as the battery charging management IC, and the external power supply and the battery power supply are combined to obtain a VDC power supply, and the DC to DC converter is electrically connected to the VDC power supply of the battery management circuit; the VDC supplies power to the battery charging chip UP1; the 4.5V power supply generated inside the battery charging chip UP1 is divided by a resistor to obtain an NTC voltage (the NTC is connected to the VCC pin for external power supply of 4.5V through a pull-up resistor, and is connected to GND through the NTC thermistor in the battery pack); the VDC generates a 5V power supply through a voltage stabilizing circuit, which is mainly used to supply power to the operational amplifier circuit separately when the battery discharge temperature protection takes effect (the system is powered off and in sleep mode), to ensure the normal operation of the protection mechanism;

[0095] In this embodiment, the discharge protection threshold temperature of the battery is first determined, for example, the threshold temperatures of the high and low temperature discharge protection of the battery are Temp_H and Temp_L, where Temp_H=63°C and Temp_L=6°C; then, according to the temperature characteristics of the thermistor, the resistance values ​​of the thermistor at the threshold temperature are determined to be R_HighTemp and R_LowTemp (R_HighTemp=2.8kΩ, Temp_L=21.7kΩ), respectively, and the voltage of the NTC at this time is determined according to the resistance value of the thermistor, where the voltage of the NTC thermistor at the high temperature threshold temperature is V_NTC_H=4.5V÷(R_HighTemp+RP3)×R_HighTemp; where R_ HighTemp represents the resistance of the thermistor at a temperature of Temp_H degrees; RP3 represents the resistance of the twentieth resistor, and 4.5v represents the 4.5V power supply generated inside the battery charging chip UP1; similarly, the NTC voltage V_NTC_L at the low temperature threshold temperature is V_NTC_L=4.5V÷(R_LowTemp+RP3)×R_LowTemp; wherein R_LowTemp represents the resistance of the thermistor at a temperature of Temp_L degrees; based on V_NTC_L, the resistance of the fourth resistor R4 and the third resistor R3 are adjusted to make V_REF_L equal to V_NTC_L, and the resistance of the ninth resistor R19 and the tenth resistor R20 are adjusted to make V_REF_H equal to V_NTC_H.

[0096] In an optional embodiment of the present invention, the voltage stabilizing circuit includes:

[0097] The second transistor Q2 and the shunt regulator QM1;

[0098] Wherein, the third pin of the second transistor Q2 is electrically connected to the output end of the external power supply combining circuit;

[0099] The second pin of the second transistor Q2 is electrically connected to the operational amplifier circuit;

[0100] The first pin of the second transistor Q2 is electrically connected to the third pin of the second transistor Q2 through the fifth resistor R5, and is grounded through the fifth resistor R5 and the third capacitor C3;

[0101] The second pin of the shunt regulator QM1 is electrically connected to the first pin of the second transistor Q2;

[0102] The first pin of the shunt regulator QM1 is electrically connected to the second pin of the second transistor Q2 through the sixth resistor R6, and is grounded through the eighth resistor R8;

[0103] The third pin of the shunt regulator QM1 is grounded, and is electrically connected to the second pin of the second transistor Q2 via the second capacitor C2.

[0104] In an optional embodiment of the present invention, the operational amplifier circuit includes:

[0105] A first operational amplifier hysteresis comparison circuit and a second operational amplifier hysteresis comparison circuit;

[0106] Among them, the positive power supply pin of the first op amp hysteresis comparison circuit and the positive power supply pin of the second op amp hysteresis comparison circuit are both electrically connected to the output end of the voltage stabilizing circuit, and the output end of the first op amp hysteresis comparison circuit and the output end of the second op amp hysteresis comparison circuit are both electrically connected to the power enable signal control circuit.

[0107] In an optional embodiment of the present invention, the first operational amplifier hysteresis comparison circuit includes:

[0108] a first operational amplifier U1A, wherein a first pin of the first operational amplifier U1A is electrically connected to a power enable signal control circuit via a second diode D2, and is electrically connected to a third pin of the first operational amplifier U1A via an eleventh resistor R11;

[0109] The third pin of the first operational amplifier U1A is electrically connected to the output end of the voltage stabilizing circuit through the twelfth resistor R12 and the ninth resistor R19, and is grounded through the tenth resistor R20;

[0110] The second pin of the first operational amplifier U1A is electrically connected to the battery charging chip UP1;

[0111] The eighth pin of the first operational amplifier U1A is electrically connected to the output end of the voltage stabilizing circuit, and the fourth pin of the first operational amplifier U1A is grounded.

[0112] In an optional embodiment of the present invention, the second operational amplifier hysteresis comparison circuit includes:

[0113] a second operational amplifier U1B, wherein a seventh pin of the second operational amplifier U1B is electrically connected to the power enable signal control circuit via a fifth diode D5, and is electrically connected to a fifth pin of the second operational amplifier U1B via a sixteenth resistor R16;

[0114] The fifth pin of the second operational amplifier U1B is electrically connected to the battery charging chip UP1 through the eighteenth resistor R18;

[0115] The sixth pin of the second operational amplifier U1B is electrically connected to the output end of the voltage stabilizing circuit through the third resistor R3 and is grounded through the fourth resistor R4;

[0116] The eighth pin of the second operational amplifier U1B is electrically connected to the output end of the voltage stabilizing circuit, and the fourth pin of the second operational amplifier U1B is grounded.

[0117] In this embodiment, when in use, after the operational amplifier circuit is electrically connected to the output end of the voltage stabilizing circuit, the 5V power supply at the output end of the voltage stabilizing circuit passes through two groups of voltage regulators to generate V_REF_H and V_REF_L voltages respectively, wherein V_REF_H and NTC are respectively connected to the in-phase and inverting input ends of the first operational amplifier U1A, and NTC and V_REF_L are respectively connected to the in-phase and inverting input ends of the second operational amplifier U1B, forming two groups of operational amplifier hysteresis comparators.

[0118] In an optional embodiment of the present invention, the power enable signal control circuit includes:

[0119] A third transistor Q3, wherein a first pin of the third transistor Q3 is electrically connected to the operational amplifier circuit through a fifteenth resistor R15, and is grounded through a seventeenth resistor R17;

[0120] The second pin of the third transistor Q3 is grounded;

[0121] The third pin of the third triode Q3 is electrically connected to the output end of the voltage stabilizing circuit through the thirteenth resistor R13, and is electrically connected to the DC to DC converter through the fourth diode D4;

[0122] A third diode D3, wherein an anode of the third diode D3 is electrically connected to the fourth pin of the power adapter DC1 through a fourteenth resistor R14, and a cathode of the third diode D3 is electrically connected to the DC to DC converter.

[0123] In this embodiment, when in use, the outputs of the first operational amplifier U1A and the second operational amplifier U1B pass through diodes respectively to control a triode common emitter amplifier, and the triode collector and the external power supply Vin pass through diodes respectively to output a "post-stage power enable signal" PWR_EN; the high and low levels of the PWR_EN signal are used to control whether all the post-stage power supplies of the system are working. When the level is high, the DC-to-DC converter outputs voltage and the system works normally; when the level is low, the DC-to-DC converter no longer outputs voltage, the system powers off and goes into sleep mode, and only the voltage stabilizing circuit and the operational amplifier circuit are still working.

[0124] In this embodiment, when the battery is within the discharge temperature range, according to the NTC resistance characteristics, the NTC resistance is greater than R_HighTemp and less than R_LowTemp. At this time, the NTC voltage is greater than V_REF_H and less than V_REF_L; the 2-way op amp hysteresis comparison circuits both output a low level of 0V, and the transistor Q3 is in the cut-off region. At this time, the 5V power supply of the power enable signal control circuit pulls up PWR_EN to a high level, and the DC to DC converter allows the system to work normally.

[0125] The specific working principle of the battery discharge temperature protection circuit described in the present invention is as follows:

[0126] When the external power supply Vin is powered off, the battery starts to discharge externally. If the temperature of the battery pack rises from the normal operating temperature to a temperature higher than Temp_H at this time, according to the NTC resistance characteristics, the NTC resistance value will be less than R_HighTemp, and the NTC voltage will be less than V_REF_H, then the first operational amplifier U1A outputs a high level, and the third transistor Q3 enters the amplification area, pulling the anode of the fourth diode D4 down to a low level; since there is no external power supply Vin input at this time, PWR_EN is a low level, the DC to DC converter is not enabled, the system is powered off and hibernated, and the battery stops discharging to the electrical equipment; at this time, the battery discharge is only for the battery charging chip UP1 and the operational amplifier circuit to work, and the discharge current is small enough to be ignored, and the circuit plays the role of low-temperature discharge protection of the lithium battery;

[0127] Since the output end of the operational amplifier circuit is connected to the non-inverting input end of the operational amplifier circuit through a MΩ-level resistor, there is positive feedback to the operational amplifier circuit. Therefore, the battery temperature needs to be reduced to a temperature lower than Temp_H, and the first operational amplifier U1A will output a low level, thereby enabling the DC-to-DC converter, restoring the system to normal operation, and the battery discharging normally;

[0128] Similarly, when the external power supply Vin is powered off and the battery is discharged, if the battery pack temperature drops from the normal operating temperature to a temperature lower than Temp_L, the NTC resistor value will be greater than R_LowTemp, the NTC voltage will be greater than V_REF_L, the second operational amplifier U1B outputs a high level, and the third transistor Q3 pulls the anode of the fourth diode D4 down to a low level. Since there is no Vin input at this time, PWR_EN is a low level, the DC to DC converter is not enabled, the system is powered off and goes into hibernation, and the circuit plays the role of protecting the lithium battery from high-temperature discharge. When the battery pack temperature rises again to a temperature higher than Temp_L, the second operational amplifier U1B will output a low level to enable the system power supply, the system resumes normal operation, and the battery discharges normally.

[0129] The battery discharge temperature protection circuit of the present invention is constructed by using the characteristics of diodes, transistors, and operational amplifiers. After the discharge temperature protection takes effect, the battery discharge current is reduced to a negligible level, thereby protecting the battery. The circuit also has the following advantages: when the temperature returns to the battery discharge temperature range again, the circuit can restore the battery to normal discharge without manual intervention; the high-temperature and low-temperature discharge temperature protection thresholds of the lithium battery can be accurately set by adjusting the resistance of the voltage divider resistor; the hysteresis generated by the positive feedback of the operational amplifier circuit can prevent the battery discharge protection circuit from repeatedly switching the protection state at the high and low temperature protection critical values, thereby ensuring stable operation of the system; the entire circuit only needs diodes, transistors, and operational amplifiers to achieve lithium battery discharge temperature protection, and does not require a special battery protection IC, thereby having a low-cost advantage.

[0130] An embodiment of the present invention further provides a power supply system, comprising: a battery, an external power supply and an electrical device, wherein the electrical device is electrically connected to the battery and the external power supply via a battery discharge temperature protection circuit, and the battery discharge temperature protection circuit is the battery discharge temperature protection circuit described in the above embodiment.

[0131] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A battery discharge temperature protection circuit, characterized in that: include: a battery management circuit electrically connected to the battery; an operational amplifier circuit electrically connected to the battery management circuit; A power enable signal control circuit electrically connected to the operational amplifier circuit; A DC-to-DC converter electrically connected to the power enable signal control circuit, the battery management circuit, and the power-consuming device; Among them, the battery management circuit is used to detect the real-time temperature of the battery through a thermistor and output a temperature signal; the operational amplifier circuit is used to receive the temperature signal of the battery management circuit and convert the temperature signal into a level signal for output; the power enable signal control circuit is used to receive the level signal sent by the operational amplifier circuit and output the corresponding enable signal according to the received level signal; the DC to DC converter is used to receive the enable signal and control the power supply to the electrical equipment according to the high and low levels of the received enable signal.

2. The battery discharge temperature protection circuit according to claim 1, characterized in that: The battery management circuit comprises: An external power supply combining circuit electrically connected to the battery; a battery charging chip (UP1) electrically connected to the external power supply combining circuit; A voltage stabilizing circuit, wherein the input end of the voltage stabilizing circuit is electrically connected to the output end of the external power supply combining circuit, and the output end of the voltage stabilizing circuit is electrically connected to the operational amplifier circuit.

3. The battery discharge temperature protection circuit according to claim 2, characterized in that: The external power supply combining circuit comprises: A power adapter (DC1) electrically connected to an external power source (Vin) and a battery interface (J1) connected to a battery; Wherein, the first pin of the battery interface (J1) is grounded; The second pin of the battery interface (J1) is electrically connected to the thermistor inside the battery and is also electrically connected to the battery charging chip (UP1); The fourth pin of the battery interface (J1) is electrically connected to the battery and is electrically connected to the third pin of the first field effect transistor (Q1); The second pin of the first field effect transistor (Q1) is electrically connected to the battery charging chip (UP1); The first pin of the first field effect tube (Q1) is electrically connected to the fourth pin of the power adapter (DC1) through the second resistor (R2); The second pin of the power adapter (DC1) is electrically connected to the third pin of the power adapter (DC1), and the third pin of the power adapter (DC1) is electrically connected to the fourth pin of the power adapter (DC1) via the first resistor (R1) and is grounded; The fourth pin of the power adapter (DC1) is electrically connected to the external power source (Vin), and is electrically connected to the battery charging chip (UP1) through the first diode (D1).

4. The battery discharge temperature protection circuit according to claim 3, characterized in that: The first pin of the battery charging chip (UP1) is electrically connected to the tenth pin of the battery charging chip (UP1) through the inductor (LP1), and the tenth pin of the battery charging chip (UP1) is electrically connected to the fourth pin of the battery interface (J1) through the nineteenth resistor (RPS1); The fifteenth pin of the battery charging chip (UP1) is electrically connected to the first pin of the battery charging chip (UP1) via the first capacitor (C1); The ninth pin of the battery charging chip (UP1) is electrically connected to the fourth pin of the battery interface (J1); The second pin of the battery charging chip (UP1) is electrically connected to the second pin of the first field effect transistor (Q1), the cathode of the first diode (D1) and the voltage stabilizing circuit; The third pin of the battery charging chip (UP1) electrically outputs a 4.5V power supply and is electrically connected to the thirteenth pin of the battery charging chip (UP1) through the twentieth resistor (RP3); The thirteenth pin of the battery charging chip (UP1) is electrically connected to the second pin of the battery interface (J1); The sixth pin of the battery charging chip (UP1) is electrically connected to the eighth pin of the battery charging chip (UP1) through a twenty-first resistor (RP4), and the eighth pin of the battery charging chip (UP1) is grounded.

5. The battery discharge temperature protection circuit according to claim 4, characterized in that: The voltage stabilizing circuit comprises: The second transistor (Q2) and the shunt regulator (QM1); Wherein, the third pin of the second transistor (Q2) is electrically connected to the output end of the external power supply combining circuit; The second pin of the second transistor (Q2) is electrically connected to the operational amplifier circuit; The first pin of the second triode (Q2) is electrically connected to the third pin of the second triode (Q2) through a fifth resistor (R5), and is grounded through the fifth resistor (R5) and a third capacitor (C3); The second pin of the shunt regulator (QM1) is electrically connected to the first pin of the second transistor (Q2); The first pin of the shunt regulator (QM1) is electrically connected to the second pin of the second transistor (Q2) through a sixth resistor (R6), and is grounded through an eighth resistor (R8); The third pin of the parallel regulator (QM1) is grounded and electrically connected to the second pin of the second transistor (Q2) via the second capacitor (C2).

6. The battery discharge temperature protection circuit according to claim 2, characterized in that: The operational amplifier circuit comprises: A first operational amplifier hysteresis comparison circuit and a second operational amplifier hysteresis comparison circuit; Among them, the positive power supply pin of the first op amp hysteresis comparison circuit and the positive power supply pin of the second op amp hysteresis comparison circuit are both electrically connected to the output end of the voltage stabilizing circuit, and the output end of the first op amp hysteresis comparison circuit and the output end of the second op amp hysteresis comparison circuit are both electrically connected to the power enable signal control circuit.

7. The battery discharge temperature protection circuit according to claim 6, characterized in that: The first operational amplifier hysteresis comparison circuit comprises: a first operational amplifier (U1A), wherein a first pin of the first operational amplifier (U1A) is electrically connected to a power enable signal control circuit via a second diode (D2), and is electrically connected to a third pin of the first operational amplifier (U1A) via an eleventh resistor (R11); The third pin of the first operational amplifier (U1A) is electrically connected to the output end of the voltage stabilizing circuit through a twelfth resistor (R12) and a ninth resistor (R19), and is grounded through a tenth resistor (R20); The second pin of the first operational amplifier (U1A) is electrically connected to the battery charging chip (UP1); The eighth pin of the first operational amplifier (U1A) is electrically connected to the output end of the voltage stabilizing circuit, and the fourth pin of the first operational amplifier (U1A) is grounded.

8. The battery discharge temperature protection circuit according to claim 6, characterized in that: The second operational amplifier hysteresis comparison circuit comprises: a second operational amplifier (U1B), wherein a seventh pin of the second operational amplifier (U1B) is electrically connected to the power enable signal control circuit via a fifth diode (D5), and is electrically connected to a fifth pin of the second operational amplifier (U1B) via a sixteenth resistor (R16); The fifth pin of the second operational amplifier (U1B) is electrically connected to the battery charging chip (UP1) through an eighteenth resistor (R18); The sixth pin of the second operational amplifier (U1B) is electrically connected to the output end of the voltage stabilizing circuit through a third resistor (R3) and is grounded through a fourth resistor (R4); The eighth pin of the second operational amplifier (U1B) is electrically connected to the output end of the voltage stabilizing circuit, and the fourth pin of the second operational amplifier (U1B) is grounded.

9. The battery discharge temperature protection circuit according to claim 3, characterized in that: The power enable signal control circuit comprises: a third triode (Q3), wherein a first pin of the third triode (Q3) is electrically connected to the operational amplifier circuit via a fifteenth resistor (R15), and is grounded via a seventeenth resistor (R17); The second pin of the third transistor (Q3) is grounded; The third pin of the third triode (Q3) is electrically connected to the output end of the voltage stabilizing circuit through a thirteenth resistor (R13), and is electrically connected to the DC to DC converter through a fourth diode (D4); A third diode (D3), wherein an anode of the third diode (D3) is electrically connected to a fourth pin of the power adapter (DC1) via a fourteenth resistor (R14), and a cathode of the third diode (D3) is electrically connected to a DC to DC converter.

10. A power supply system, characterized in that: include: A battery, an external power supply and an electrical device, wherein the electrical device is electrically connected to the battery and the external power supply via a battery discharge temperature protection circuit, and the battery discharge temperature protection circuit is the battery discharge temperature protection circuit as claimed in any one of claims 1 to 9.

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