Battery overdischarge protection circuit and control method thereof

Abstract

The invention relates to the technical field of circuits, in particular to a battery overdischarge protection circuit and a control method thereof.The battery overdischarge protection circuit comprises a voltage detection module, a voltage comparison module and a switch module which are connected in sequence; the voltage detection module is used for dividing the battery voltage and then outputting the battery divided voltage; the voltage comparison module is used for outputting a low level when the battery voltage is not lower than the minimum working voltage of the voltage comparison module and if the battery voltage is reduced to be lower than a drop voltage threshold value and the battery partial voltage is lower than the reference voltage accessed by the voltage comparison module, so as to control the switch module to disconnect a power supply loop of the battery to the load; if the voltage of the battery rises to be higher than the rising voltage threshold value and the divided voltage of the battery is higher than the reference voltage, outputting a high-resistance state to control the switch module to conduct a power supply loop of the battery to the load; according to the invention, over-discharge of the battery can be avoided, the battery is effectively protected, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a battery over-discharge protection circuit and a control method thereof. Background Art

[0002] Battery overdischarge will cause battery capacity to decrease, accelerate the aging process, shorten battery life, and charge the battery in an overdischarged state, which will also damage the charging equipment. Therefore, it is necessary to provide a battery overdischarge protection circuit to cut off the discharge circuit before the battery voltage drops to the protection value, stop powering the load, and avoid battery overdischarge. Summary of the invention

[0003] To solve the above problems, the present invention provides a battery over-discharge protection circuit and a control method thereof to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0004] In order to achieve the above object, the present invention provides the following technical solutions: A battery over-discharge protection circuit, the battery over-discharge protection circuit comprises a voltage detection module, a voltage comparison module and a switch module connected in sequence; the voltage detection module and the switch module are connected to the battery; the switch module is also connected to a load; The voltage detection module is used to detect the battery voltage of the battery, divide the battery voltage and output the battery divided voltage; The voltage comparison module is used to output a low level to control the switch module to disconnect the power supply circuit from the battery to the load if the battery voltage drops below a falling voltage threshold so that the battery voltage is lower than a reference voltage connected to the voltage comparison module when the battery voltage is not lower than the lowest operating voltage of the voltage comparison module; if the battery voltage rises above a rising voltage threshold so that the battery voltage is higher than the reference voltage, then the voltage comparison module outputs a high impedance state to control the switch module to connect the power supply circuit from the battery to the load; wherein the rising voltage threshold is higher than the falling voltage threshold.

[0005] Preferably, the voltage detection module comprises a voltage divider circuit, an input end of the voltage divider circuit is connected to a battery, a voltage divider end of the voltage divider circuit is connected to an input end of the voltage comparison module, and a ground end of the voltage divider circuit is grounded.

[0006] Preferably, the voltage divider circuit includes a second resistor and a third resistor, one end of the second resistor and one end of the third resistor together serve as the voltage divider end of the voltage comparison module, the other end of the second resistor serves as the input end of the voltage comparison module, and the other end of the third resistor serves as the ground end of the voltage comparison module.

[0007] Preferably, the voltage detection module also includes a first resistor and a fourth resistor, both of which are jumper resistors, the first resistor is connected between the input end of the voltage divider circuit and the battery, and one end of the fourth resistor is connected to the ground end of the voltage divider circuit and the other end is grounded.

[0008] Preferably, the voltage comparison module includes an uplink hysteresis comparator, a fifth resistor, a sixth resistor and a first diode, the non-phase input terminal of the uplink hysteresis comparator is respectively connected to one end of the second resistor, one end of the third resistor and one end of the fifth resistor, the inverting input terminal of the uplink hysteresis comparator is connected to an external reference voltage, the other end of the fifth resistor is connected to the anode of the first diode, the output terminal of the uplink hysteresis comparator is respectively connected to the cathode of the first diode and one end of the sixth resistor, and the other end of the sixth resistor is connected to the input terminal of the voltage clamping module.

[0009] Preferably, the battery over-discharge protection circuit further includes a voltage clamping module, the voltage clamping module includes a diode clamping circuit, the input end of the diode clamping circuit is respectively connected to the output end of the uplink hysteresis comparator and the battery, the output end of the diode clamping circuit is connected to the input end of the switch module, and the clamping voltage of the diode clamping circuit is higher than the lowest operating voltage of the uplink hysteresis comparator.

[0010] Preferably, the voltage clamping module further includes a seventh resistor, and the seventh resistor is connected between the input end of the diode clamping circuit and the battery.

[0011] Preferably, the switch module includes a triode, a first MOS tube and a second MOS tube, the base of the triode is connected to the output end of the diode clamping circuit, the collector is respectively connected to the gate of the first MOS tube and the gate of the second MOS tube, and the emitter is grounded; the source of the first MOS tube is connected to the source of the second MOS tube, the drain of the first MOS tube is connected to the battery, and the drain of the second MOS tube is connected to the load.

[0012] Preferably, the switch module further includes an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor and a capacitor, one end of the eighth resistor and one end of the ninth resistor are commonly connected to the base of the transistor, the other end of the eighth resistor is connected to the output end of the diode clamping circuit, the other end of the ninth resistor is grounded, one end of the eleventh resistor is connected to the collector of the transistor, and the other end is respectively connected to the gate of the first MOS tube, the gate of the second MOS tube, one end of the tenth resistor and one end of the capacitor, and the other end of the tenth resistor and the other end of the capacitor are commonly connected between the source of the first MOS tube and the source of the second MOS tube.

[0013] A control method for a battery over-discharge protection circuit is applied to any of the above-mentioned battery over-discharge protection circuits, and the method comprises the following steps: S100, a voltage detection module detects a battery voltage of a battery, divides the battery voltage and outputs the battery divided voltage; S200, when the battery voltage is not lower than the lowest operating voltage of the voltage comparison module, if the battery voltage drops below the falling voltage threshold, so that the battery voltage division is lower than the reference voltage connected to the voltage comparison module, the voltage comparison module outputs a low level to control the switch module to disconnect the power supply circuit of the battery to the load; if the battery voltage rises to above the rising voltage threshold, so that the battery voltage division is higher than the reference voltage, the voltage comparison module outputs a high impedance state to control the switch module to turn on the power supply circuit of the battery to the load; wherein the rising voltage threshold is higher than the falling voltage threshold.

[0014] The beneficial effects of the present invention are as follows: the present invention provides a battery over-discharge protection circuit and a control method thereof, when the battery voltage is not lower than the lowest working voltage of the voltage comparison module, the battery voltage division is compared with the reference voltage, an on-off level is output according to the magnitude of the battery voltage division and the reference voltage, and the on-off of the battery and the load is controlled by a switch module; when the battery voltage drops below a falling voltage threshold, the battery voltage division is lower than the reference voltage connected to the voltage comparison module; when the battery voltage rises above a rising voltage threshold, the battery voltage division is higher than the reference voltage; by setting different falling voltage thresholds and rising voltage thresholds for the battery voltage, over-discharge of the battery can be avoided, the battery is effectively protected, and the service life of the battery is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in 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 paying creative labor.

[0016] Figure 1 is a circuit block diagram of a battery over-discharge protection circuit in an embodiment of the present invention; Figure 2 is an output transfer characteristic curve diagram of a voltage comparison module in an embodiment of the present invention; Figure 3 The invention discloses a circuit diagram of a battery over-discharge protection circuit. DETAILED DESCRIPTION

[0017] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0018] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0019] In the description of the present invention, if there are words such as "several", it means one or more, "more" means more than two, greater than, less than, exceed, etc. are understood as not including the number, and above, below, within, etc. are understood as including the number.

[0020] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0021] In a single-limit comparator, even a slight jitter of the input voltage near the threshold voltage will cause frequent jumps in the output level. Therefore, if a single-limit comparator is used, after the battery is disconnected from the load, it may quickly rise to the set value again, and the battery is reconnected. The continuous on and off of the battery will reduce the battery life. Although most comparators have a hysteresis function, the internal hysteresis voltage is small. If the external signal jitter is too large, the internal hysteresis will not work. Therefore, an external hysteresis circuit needs to be added to slow down the output jump caused by jitter.

[0022] Based on this, the present invention provides a battery over-discharge protection circuit with hysteresis function, which sets different falling voltage thresholds Vd and rising voltage thresholds Vr according to the changing state of the battery voltage to realize the on-off of the battery and the load, effectively protect the battery and extend the battery life.

[0023] Reference Figure 1 and Figure 2 , Figure 1 : is a circuit block diagram of a battery over-discharge protection circuit of the present invention, wherein the battery over-discharge protection circuit comprises a voltage detection module 100, a voltage comparison module 200 and a switch module 400 which are connected in sequence; the voltage detection module 100 and the switch module 400 are connected to a battery together; the switch module 400 is also connected to a load; The voltage detection module 100 is used to detect the battery voltage Vbat of the battery, and divide the battery voltage Vbat to output the battery divided voltage Vin; The voltage comparison module 200 is used to output a low level VL to control the switch module 400 to disconnect the battery power supply circuit to the load if the battery voltage Vbat drops below a falling voltage threshold Vd, so that the battery divided voltage Vin is lower than the reference voltage Vref connected to the voltage comparison module 200, when the battery voltage Vbat is not lower than the lowest operating voltage VCC of the voltage comparison module 200; if the battery voltage Vbat rises to be higher than a rising voltage threshold Vr, so that the battery divided voltage Vin is higher than the reference voltage Vref, then the high impedance VH is output to control the switch module 400 to turn on the battery power supply circuit to the load; wherein the rising voltage threshold Vr is higher than the falling voltage threshold Vd.

[0024] The battery over-discharge protection circuit provided by the present invention comprises a voltage detection module 100 for detecting a battery voltage Vbat, a voltage comparison module 200 for comparing a voltage outputted by the voltage detection module 100 with a reference voltage Vref, a voltage clamping module 300 for clamping the battery voltage Vbat, and a switch module 400 for controlling the connection between the battery and the load. When the battery voltage Vin is lower than the reference voltage Vref, a low level VL is outputted, and the switch module 400 disconnects the power supply circuit of the battery to the load; when the battery starts to charge, if the battery voltage Vin is higher than the reference voltage Vref after the battery voltage rises, a high impedance state VH is outputted, and the power supply circuit of the battery to the load is turned on; since the rising voltage threshold Vr is higher than the falling voltage threshold Vd, frequent charging and discharging of the battery can be avoided; the battery over-discharge protection circuit provided by the present invention has a hysteresis function, and by setting different falling voltage thresholds Vd and rising voltage thresholds Vr, the battery voltage Vbat automatically disconnects the circuit when it drops to the falling voltage threshold Vd, and reconnects the circuit when it rises to higher than the rising voltage threshold Vr, effectively protecting the battery and extending the battery life.

[0025] In some embodiments, the voltage detection module 100 includes a voltage divider circuit 110, the input end of the voltage divider circuit 110 is connected to a battery, the voltage divider end of the voltage divider circuit 110 is connected to an input end of the voltage comparison module 200, and the ground end of the voltage divider circuit 110 is grounded.

[0026] Specifically, the battery voltage Vbat is divided by the voltage divider circuit 110 and then output to the voltage comparison module 200 .

[0027] In some embodiments, the voltage divider circuit 110 includes a second resistor R2 and a third resistor R3, one end of the second resistor R2 and one end of the third resistor R3 together serve as a voltage divider end of the voltage comparison module 200, the other end of the second resistor R2 serves as an input end of the voltage comparison module 200, and the other end of the third resistor R3 serves as a ground end of the voltage comparison module 200.

[0028] Specifically, the second resistor R2 and the third resistor R3 divide the battery voltage Vbat. The voltage division value of the second resistor R2 and the third resistor R3 is the positive input of the upward hysteresis comparator U1.

[0029] In some embodiments, the voltage detection module 100 also includes a first resistor R1 and a fourth resistor R4, wherein the first resistor R1 and the fourth resistor R4 are both jumper resistors, the first resistor R1 is connected between the input end of the voltage divider circuit 110 and the battery, and one end of the fourth resistor R4 is connected to the ground end of the voltage divider circuit 110 and the other end is grounded.

[0030] Specifically, the first resistor R1 is connected between the second resistor R2 and the battery, and the third resistor R3 is grounded through the fourth resistor R4. The first resistor R1 and the fourth resistor R4 are used to fine-tune the resistance value of the voltage divider when adjusting the circuit.

[0031] In some embodiments, the voltage comparison module 200 includes an up hysteresis comparator U1, a fifth resistor R5, a sixth resistor R6 and a first diode D1, the non-inverting input terminal of the up hysteresis comparator U1 is respectively connected to one end of the second resistor R2, one end of the third resistor R3 and one end of the fifth resistor R5, the inverting input terminal of the up hysteresis comparator U1 is connected to an external reference voltage Vref, the other end of the fifth resistor R5 is connected to the anode of the first diode D1, the output terminal of the up hysteresis comparator U1 is respectively connected to the cathode of the first diode D1 and one end of the sixth resistor R6, and the other end of the sixth resistor R6 is connected to the input terminal of the voltage clamping module 300.

[0032] Specifically, the voltage comparison module 200 is connected to the battery divided voltage Vin and the reference voltage Vref respectively. When the battery divided voltage Vin decreases from a voltage value above the reference voltage Vref connected to the voltage comparison module 200, if the battery divided voltage Vin decreases to below the reference voltage Vref, the voltage comparison module 200 outputs a low level VL to control the switch module 400 to disconnect the battery-to-load power supply circuit; when the battery divided voltage Vin increases from a voltage value below the reference voltage Vref to a high value, if the battery divided voltage Vin increases to above the reference voltage Vref, the voltage comparison module 200 outputs a high impedance VH to control the switch module 400 to turn on the battery-to-load power supply circuit.

[0033] The uplink hysteresis comparator U1 prevents the output from continuously jumping and generating glitches when the battery divided voltage Vin is close to the reference voltage Vref. The first diode D1 separates the output pull-up voltage from the output of the uplink hysteresis comparator U1 to prevent the hysteresis value from being affected by the output pull-up resistor.

[0034] Exemplarily, the working process of the hysteresis up hysteresis comparator U1 is calculated using actual values: The battery is a lead-acid battery with a voltage of 12V. The resistance of the second resistor R2 is 510KΩ, and the resistance of the third resistor R3 is 30KΩ. The first resistor R1 and the fourth resistor R4 are 0Ω, with an accuracy of 1%, and are used to fine-tune the resistance of the second resistor R2 and the third resistor R3. The reference voltage Vref of the inverting input terminal of the uplink hysteresis comparator U1 is 0.6V.

[0035] When the battery voltage Vbat changes from high to low from 12V: Since when the battery voltage Vbat is equal to 10.8V, the battery voltage Vin is 10.8V×30KΩ / (510KΩ+30KΩ)=0.6V, the falling voltage threshold Vd=10.8V can be set. When the battery voltage Vbat is greater than 10.8V, the voltage of the positive input terminal of the uplink hysteresis comparator U1 is higher than that of the inverting input terminal, and the output terminal of the uplink hysteresis comparator U1 is high level, the first diode D1 is cut off, and the output pull-up does not affect the hysteresis value. When the battery voltage Vbat is lower than 10.8V, the uplink hysteresis comparator U1 will output a low level VL.

[0036] When the battery voltage Vbat changes from low to high below 10.8V: After the battery is charged, the battery voltage Vbat will rise again. When the battery voltage Vbat rises to 10.8V, due to the conduction of the first diode D1, the fifth resistor R5 will also participate in the battery voltage division. The resistance value of the fifth resistor R5 is 510KΩ. Therefore, when the voltage is 10.8V, the battery divided voltage Vin is about 0.57V. At this time, the output of the upward hysteresis comparator U1 is still a low level VL. The fifth resistor and the third resistor are connected in parallel. In order to meet the battery divided voltage Vin reaching 0.6V, the formula Vbat×(510KΩ / 30KΩ) / (510KΩ+510KΩ / 30KΩ)=0.6V can be established, and Vbat=11.4V is obtained. The rising voltage threshold Vr=11.4V is set. Only when the battery voltage Vbat rises to 11.4V, the output of the upward hysteresis comparator U1 will flip to a high impedance state VH.

[0037] In some embodiments, the battery over-discharge protection circuit further includes a voltage clamping module 300, the voltage clamping module 300 includes a diode clamping circuit 310, the input end of the diode clamping circuit 310 is respectively connected to the output end of the uplink hysteresis comparator U1 and the battery, the output end of the diode clamping circuit 310 is connected to the input end of the switch module 400, and the clamping voltage of the diode clamping circuit 310 is higher than the lowest operating voltage VCC of the uplink hysteresis comparator U1.

[0038] Specifically, the voltage clamping module 300 is used to clamp the battery voltage Vbat when the battery voltage Vbat drops below the minimum operating voltage VCC of the voltage comparison module 200; wherein, the clamping voltage of the voltage clamping module 300 is higher than the minimum operating voltage VCC of the voltage comparison module 200; the diode clamping circuit 310 prevents the switch module 400 from being mistakenly turned on when the battery voltage Vbat is too low and the upstream hysteresis comparator U1 does not work; the diode clamping circuit 310 includes a second diode, a third diode, a fourth diode and a fifth diode connected in sequence; the anode of the second diode is connected to the output end of the upstream hysteresis comparator U1, and the cathode of the fifth diode is connected to the input end of the switch module 400. Exemplarily, the minimum operating voltage VCC of the uplink hysteresis comparator U1 is 1.8V. When the battery voltage Vbat drops below 1.8V, the uplink hysteresis comparator U1 no longer works. At this time, due to the clamping of the diode clamping circuit 310, the transistor Q1 will not be turned on, ensuring that the battery will not be mistakenly turned on when the voltage is too low.

[0039] In some embodiments, the voltage clamping module 300 further includes a seventh resistor R7, and the seventh resistor R7 is connected between the input end of the diode clamping circuit 310 and the battery.

[0040] Specifically, one end of the seventh resistor R7 is connected to the anode of the second diode, and the other end is connected to the battery.

[0041] When the battery voltage Vbat drops below the minimum operating voltage VCC of the uplink hysteresis comparator U1, the uplink hysteresis comparator U1 does not work. If there is no voltage clamping, the switch device of the switch module 400 will be turned on. In other words, when the battery voltage Vbat is high, the on-off of the battery and the load is controlled by the uplink hysteresis comparator U1; when the battery voltage Vbat is very low, the uplink hysteresis comparator U1 does not work, and the on-off of the battery and the load is controlled by the voltage clamping module 300. The voltage clamping module 300 includes 5 diodes, and the clamping voltage of the 5 diodes is about 4.0V. When the temperature rises, the clamping voltage will decrease, but it will not be lower than the minimum operating voltage VCC of the uplink hysteresis comparator U1, ensuring that the switch device of the switch module 400 will not be turned on at low voltage.

[0042] In some embodiments, the switch module 400 includes a transistor Q1, a first MOS transistor Q2, and a second MOS transistor Q3. The base of the transistor Q1 is connected to the output end of the diode clamp circuit 310, the collector is respectively connected to the gate of the first MOS transistor Q2 and the gate of the second MOS transistor Q3, and the emitter is grounded; the source of the first MOS transistor Q2 is connected to the source of the second MOS transistor Q3, the drain of the first MOS transistor Q2 is connected to the battery, and the drain of the second MOS transistor Q3 is connected to the load.

[0043] It should be noted that the base voltage of the transistor Q1 can control the on / off of the first MOS transistor Q2 and the second MOS transistor Q3, thereby realizing the on / off of the battery and the load. Compared with the ordinary single PMOS switch, the first MOS transistor Q2 and the second MOS transistor Q3 are used in combination to avoid output backflow. Specifically, when the battery voltage Vin is higher than the reference voltage Vref, the positive input of the uplink hysteresis comparator U1 is higher than the negative input, the uplink hysteresis comparator U1 outputs a high impedance state VH, the transistor Q1 is turned on, and the gate voltage of the first MOS transistor Q2 is pulled down, so that the gate-source voltage of the first MOS transistor Q2 meets the on-condition of the first MOS transistor Q2, and the first MOS transistor Q2 is turned on; the on-condition of the first MOS transistor Q2 will also make the gate-source voltage of the second MOS transistor Q3 meet the on-condition, and the second MOS transistor Q3 is also turned on, and the battery supplies power to the load. When the battery voltage Vin is lower than the reference voltage Vref, the uplink hysteresis comparator U1 outputs a low level VL, the switch device transistor Q1 is not turned on, the gate voltage of the first MOS transistor Q2 is 0.7V lower than the source voltage, the first MOS transistor Q2 does not meet the conduction condition, and the battery is not connected to the load. When the voltage continues to drop below the working step-down voltage of the uplink hysteresis comparator U1, the diode step-down makes the transistor Q1 unable to turn on.

[0044] In some embodiments, the switch module 400 further includes an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a capacitor C1, one end of the eighth resistor R8 and one end of the ninth resistor R9 are commonly connected to the base of the transistor Q1, the other end of the eighth resistor R8 is connected to the output end of the diode clamping circuit 310, the other end of the ninth resistor R9 is grounded, one end of the eleventh resistor R11 is connected to the collector of the transistor Q1, and the other end is respectively connected to the gate of the first MOS transistor Q2, the gate of the second MOS transistor Q3, one end of the tenth resistor R10 and one end of the capacitor C1, the other end of the tenth resistor R10 and the other end of the capacitor C1 are commonly connected between the source of the first MOS transistor Q2 and the source of the second MOS transistor Q3.

[0045] Specifically, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11 and the capacitor C1 can play a role in current limiting or filtering to protect the first MOS transistor Q2 and the second MOS transistor Q3.

[0046] In addition, an embodiment of the present invention provides a control method for a battery over-discharge protection circuit, which is applied to the battery over-discharge protection circuit described in any of the above embodiments, and the method comprises the following steps: S100, the voltage detection module 100 detects a battery voltage Vbat of a battery, divides the battery voltage Vbat and outputs a battery divided voltage Vin; S200, when the battery voltage Vbat is not lower than the lowest operating voltage VCC of the voltage comparison module 200, if the battery voltage Vbat drops below the falling voltage threshold Vd, so that the battery divided voltage Vin is lower than the reference voltage Vref connected to the voltage comparison module 200, the voltage comparison module 200 outputs a low level VL to control the switch module 400 to disconnect the battery power supply circuit to the load; if the battery voltage Vbat rises to be higher than the rising voltage threshold Vr, so that the battery divided voltage Vin is higher than the reference voltage Vref, the voltage comparison module 200 outputs a high impedance VH to control the switch module 400 to turn on the battery power supply circuit to the load; wherein the rising voltage threshold Vr is higher than the falling voltage threshold Vd.

[0047] The embodiments described in the embodiments of the present invention are intended to more clearly illustrate the technical solutions of the embodiments of the present invention, and do not constitute a limitation on the technical solutions provided by the embodiments of the present invention. Those skilled in the art can appreciate that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of the present invention are also applicable to similar technical problems.

[0048] Those skilled in the art will appreciate that the technical solutions shown in the figures do not limit the embodiments of the present invention and may include more or fewer steps than shown in the figures, or a combination of certain steps, or different steps.

[0049] The device embodiments described above are merely illustrative, and the circuits described as separate components may or may not be physically separated, that is, they may be located in one place, or they may be distributed over multiple network circuits. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0050] Those skilled in the art will appreciate that all or some of the steps in the methods disclosed above, and the functional modules / circuits in the systems and devices may be implemented as software, firmware, hardware, or a suitable combination thereof.

[0051] The terms "first", "second", "third", "fourth", etc. (if any) in the description of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or circuits is not necessarily limited to those steps or circuits clearly listed, but may include other steps or circuits that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] It should be understood that in the present invention, "at least one (item)" refers to one or more, and "plurality" refers to two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can represent: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0053] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the above circuits is only a logical function division. There may be other division methods in actual implementation, such as multiple circuits or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or circuits, which can be electrical, mechanical or other forms.

[0054] The circuits described as separate components may or may not be physically separated, and the components shown as circuits may or may not be physical circuits, that is, they may be located in one place or distributed over multiple network circuits. Some or all of the circuits may be selected according to actual needs to achieve the purpose of the present embodiment.

[0055] In addition, each functional circuit in each embodiment of the present invention may be integrated into one processing circuit, or each circuit may exist physically separately, or two or more circuits may be integrated into one circuit. The above integrated circuit may be implemented in the form of hardware or in the form of software functional circuit.

[0056] The preferred embodiments of the embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of rights of the embodiments of the present invention is not limited thereby. Any modifications, equivalent substitutions and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of the present invention should be within the scope of rights of the embodiments of the present invention. Although the description disclosed in the present invention has been quite detailed and several of the embodiments are described in particular, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation of these claims by reference to the attached claims, taking into account the prior art, so as to effectively cover the intended scope disclosed by the present invention. In addition, the above describes the present invention with the foreseeable embodiments of the inventor, the purpose of which is to provide a useful description, and those non-substantial changes to the present invention that have not yet been foreseen may still represent equivalent changes to the present disclosure.

Claims

1. A battery over-discharge protection circuit, characterized in that: The battery over-discharge protection circuit comprises a voltage detection module, a voltage comparison module and a switch module connected in sequence; the voltage detection module and the switch module are connected to the battery; the switch module is also connected to a load; The voltage detection module is used to detect the battery voltage of the battery, divide the battery voltage and output the battery divided voltage; The voltage comparison module is used to output a low level to control the switch module to disconnect the power supply circuit from the battery to the load if the battery voltage drops below a falling voltage threshold so that the battery voltage is lower than a reference voltage connected to the voltage comparison module when the battery voltage is not lower than the lowest operating voltage of the voltage comparison module; if the battery voltage rises above a rising voltage threshold so that the battery voltage is higher than the reference voltage, then the voltage comparison module outputs a high impedance state to control the switch module to connect the power supply circuit from the battery to the load; wherein the rising voltage threshold is higher than the falling voltage threshold.

2. The battery over-discharge protection circuit according to claim 1, characterized in that: The voltage detection module comprises a voltage divider circuit, an input end of the voltage divider circuit is connected to a battery, a voltage divider end of the voltage divider circuit is connected to an input end of the voltage comparison module, and a ground end of the voltage divider circuit is grounded.

3. The battery over-discharge protection circuit according to claim 2, characterized in that: The voltage divider circuit includes a second resistor and a third resistor, one end of the second resistor and one end of the third resistor together serve as the voltage divider end of the voltage comparison module, the other end of the second resistor serves as the input end of the voltage comparison module, and the other end of the third resistor serves as the ground end of the voltage comparison module.

4. The battery over-discharge protection circuit according to claim 3, characterized in that: The voltage detection module also includes a first resistor and a fourth resistor, both of which are jumper resistors. The first resistor is connected between the input end of the voltage divider circuit and the battery, and one end of the fourth resistor is connected to the ground end of the voltage divider circuit and the other end is grounded.

5. The battery over-discharge protection circuit according to claim 3, characterized in that: The voltage comparison module includes an upward hysteresis comparator, a fifth resistor, a sixth resistor and a first diode. The positive input end of the upward hysteresis comparator is respectively connected to one end of the second resistor, one end of the third resistor and one end of the fifth resistor. The inverting input end of the upward hysteresis comparator is connected to an external reference voltage. The other end of the fifth resistor is connected to the anode of the first diode. The output end of the upward hysteresis comparator is respectively connected to the cathode of the first diode and one end of the sixth resistor. The other end of the sixth resistor is connected to the input end of the voltage clamping module.

6. The battery over-discharge protection circuit according to claim 5, characterized in that: The battery over-discharge protection circuit also includes a voltage clamping module, which includes a diode clamping circuit, wherein the input end of the diode clamping circuit is respectively connected to the output end of the uplink hysteresis comparator and the battery, the output end of the diode clamping circuit is connected to the input end of the switch module, and the clamping voltage of the diode clamping circuit is higher than the lowest operating voltage of the uplink hysteresis comparator.

7. The battery over-discharge protection circuit according to claim 6, characterized in that: The voltage clamping module further includes a seventh resistor, and the seventh resistor is connected between the input end of the diode clamping circuit and the battery.

8. The battery over-discharge protection circuit according to claim 6, characterized in that: The switch module includes a triode, a first MOS tube and a second MOS tube, wherein the base of the triode is connected to the output end of the diode clamp circuit, the collector is respectively connected to the gate of the first MOS tube and the gate of the second MOS tube, and the emitter is grounded; the source of the first MOS tube is connected to the source of the second MOS tube, the drain of the first MOS tube is connected to a battery, and the drain of the second MOS tube is connected to a load.

9. The battery over-discharge protection circuit according to claim 8, characterized in that: The switch module also includes an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor and a capacitor, one end of the eighth resistor and one end of the ninth resistor are commonly connected to the base of the transistor, the other end of the eighth resistor is connected to the output end of the diode clamping circuit, the other end of the ninth resistor is grounded, one end of the eleventh resistor is connected to the collector of the transistor, and the other end is respectively connected to the gate of the first MOS tube, the gate of the second MOS tube, one end of the tenth resistor and one end of the capacitor, and the other end of the tenth resistor and the other end of the capacitor are commonly connected between the source of the first MOS tube and the source of the second MOS tube.

10. A control method for a battery over-discharge protection circuit, characterized in that: The battery over-discharge protection circuit according to any one of claims 1 to 9 is characterized in that the method comprises the following steps: S100, a voltage detection module detects a battery voltage of a battery, divides the battery voltage and outputs the battery divided voltage; S200, when the battery voltage is not lower than the lowest operating voltage of the voltage comparison module, if the battery voltage drops below the falling voltage threshold, so that the battery voltage division is lower than the reference voltage connected to the voltage comparison module, the voltage comparison module outputs a low level to control the switch module to disconnect the power supply circuit of the battery to the load; if the battery voltage rises to above the rising voltage threshold, so that the battery voltage division is higher than the reference voltage, the voltage comparison module outputs a high impedance state to control the switch module to turn on the power supply circuit of the battery to the load; wherein the rising voltage threshold is higher than the falling voltage threshold.

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