Overcurrent detection module, battery protection circuit and system

Abstract

The application provides an overcurrent detection module, a battery protection circuit and a system. The overcurrent detection module comprises: a reference voltage generation circuit, which is used to obtain a temperature value of a charge-discharge switch, obtain a corresponding reference voltage VR based on the obtained temperature value of the charge-discharge switch, and output the reference voltage VR through an output end of the reference voltage generation circuit. The reference voltage VR changes with the temperature in a manner consistent with the change of the on-resistance of the charge-discharge switch with the temperature. A comparator has a first input end receiving the reference voltage VR output by the reference voltage generation circuit and a second input end obtaining a voltage of a second detection end VM. The comparator is used to compare the reference voltage VR and the voltage of the second detection end VM, and output a corresponding current detection signal through an output end of the comparator based on the comparison result. Compared with the prior art, the application can not only realize high-precision charge-discharge overcurrent detection, but also save the occupied printed circuit board area and reduce energy consumption.

Description

[Technical Field]

[0001] This invention relates to the field of circuit design, and in particular to an overcurrent detection module, a battery protection circuit, and a system. [Background Technology]

[0002] In existing technologies, to achieve high-precision discharge overcurrent detection, a current sampling resistor R1 is generally used to obtain current detection information. Please refer to [reference needed]. Figure 1 As shown, it is a circuit diagram of a battery protection system in the prior art. Figure 1 The battery protection system shown includes cell BAT1, battery protection circuit (or battery protection chip) 110, charging power switch (or charging power transistor) FET2, discharging power switch (or discharging power transistor) FET1, and resistor R1. Generally, the voltage at the detection terminal VSS is defined as 0V. The voltage at the detection terminal VL relative to VSS, i.e., the voltage across resistor R1, reflects the discharge current. The voltage across resistor R1 (i.e., the voltage at the detection terminal VL) is proportional to the discharge current. This scheme requires a high-precision resistor R1, which is costly, occupies printed circuit board space, consumes energy, and generates heat, among other problems. If the voltage at the detection terminal VM is directly used as the current sampling information, the current detection will be inaccurate.

[0003] Therefore, it is necessary to propose an improved technical solution to overcome the above problems. [Summary of the Invention]

[0004] One of the objectives of this invention is to provide an overcurrent detection module, a battery protection circuit, and a system that can achieve high-precision overcurrent detection during discharge or charging, thereby improving battery safety.

[0005] According to one aspect of the present invention, an overcurrent detection module is provided, comprising: a reference voltage generating circuit, configured to acquire the temperature value of a charge / discharge switch, and obtain a corresponding reference voltage VR based on the acquired temperature value of the charge / discharge switch, and output the reference voltage VR through its output terminal, wherein the change of the reference voltage VR with temperature is consistent with the change of the on-resistance of the charge / discharge switch with temperature; a comparator, wherein its first input terminal receives the reference voltage VR output by the reference voltage generating circuit, and its second input terminal acquires the voltage of a second detection terminal VM, the comparator being configured to compare the magnitude of the reference voltage VR and the voltage of the second detection terminal VM, and output a corresponding current detection signal through its output terminal based on the comparison result.

[0006] Furthermore, the reference voltage VR = K1.V1 + K2.V2, where K1 is a fixed coefficient, K2 is a fixed coefficient, V1 is a positive temperature coefficient voltage, and V2 is a zero temperature coefficient voltage.

[0007] Furthermore, the reference voltage generation circuit includes a temperature sensing module T_Sens, a positive temperature coefficient voltage generator VPTC, a zero temperature coefficient voltage generator VZTC, multipliers M1 and M2, and an adder Add. The temperature sensing module T_Sens is used to conduct heat from the charge / discharge switch to the positive temperature coefficient voltage generator VPTC, ensuring that the temperature of the positive temperature coefficient voltage generator VPTC matches the temperature of the charge / discharge switch. The positive temperature coefficient voltage generator VPTC generates a positive temperature coefficient voltage V1 based on its own temperature and outputs it. The positive temperature coefficient voltage V1 is output from the terminal; the zero temperature coefficient voltage generator VZTC is used to generate a zero temperature coefficient voltage V2 and outputs the zero temperature coefficient voltage V2 through its output terminal; the multiplier M1 is used to multiply the positive temperature coefficient voltage V1 by a fixed coefficient K1 to obtain a positive temperature coefficient voltage V3; the multiplier M2 is used to multiply the zero temperature coefficient voltage V2 by a fixed coefficient K2 to obtain a zero temperature coefficient voltage V4; the adder Add is used to add the positive temperature coefficient voltage V3 and the zero temperature coefficient voltage V4 to generate the reference voltage VR.

[0008] Furthermore, based on the characteristics of the on-resistance of the charge-discharge switch, the coefficients K1 and K2 are modified so that the change of the reference voltage VR with temperature is consistent with the change of the on-resistance of the charge-discharge switch with temperature; or the positive temperature coefficient voltage V1 is proportional to the temperature of the charge-discharge switch.

[0009] Furthermore, the positive temperature coefficient voltage generator (VPTC) includes MOSFETs MP1, MP2, and MP3, resistors R1 and R2, operational amplifier OP, and bipolar transistors Q1 and Q2. The first connection terminal of MOSFET MP1 is connected to the power supply terminal, and its second connection terminal is connected to node A. The first connection terminal of bipolar transistor Q1 is connected to node A, and its second connection terminal and control terminal are both grounded. The first connection terminal of MOSFET MP2 is connected to the power supply terminal, its control terminal is connected to the control terminal of MOSFET MP1, and its second connection terminal is connected to node B. The second connection terminal of bipolar transistor Q2... One connection terminal is connected to node B via resistor R1, and its second connection terminal and its control terminal are both grounded; the first input terminal of the operational amplifier OP is connected to node A, its second input terminal is connected to node B, and its output terminal is connected to the control terminal of MOS transistor MP1; the first connection terminal of MOS transistor MP3 is connected to the power supply terminal, and its control terminal is connected to the control terminal of MOS transistor MP2, and its second connection terminal is connected to the output terminal V1 of the positive temperature coefficient voltage generator VPTC; one end of resistor R2 is connected to the output terminal V1 of the positive temperature coefficient voltage generator VPTC, and the other end is grounded.

[0010] Furthermore, the MOS transistors MP1, MP2, and MP3 are all PMOS transistors, and the first connection terminal, the second connection terminal, and the control terminal of the MOS transistors MP1, MP2, and MP3 are the source, drain, and gate of the PMOS transistors, respectively; the bipolar transistors Q1 and Q2 are both PNP bipolar transistors, and the first connection terminal, the second connection terminal, and the control terminal of the bipolar transistors Q1 and Q2 are the emitter, collector, and base of the PNP bipolar transistors, respectively; the resistors R1 and R2 are resistors of the same type.

[0011] Furthermore, the multipliers M1 and M2 are implemented using analog multipliers, and the coefficients K1 and K2 are implemented using analog voltage signals; or the multipliers M1 and M2 are implemented using digital multipliers, and the coefficients K1 and K2 are implemented using digital voltage signals.

[0012] According to another aspect of the present invention, a battery protection circuit is provided, comprising a second detection terminal connected to the negative terminal of the battery, a third detection terminal connected to the negative terminal of the battery cell, a first detection terminal connected to the positive terminal of the battery cell, a discharge control terminal connected to the control terminal of a discharge power switch, and a charging control terminal connected to the control terminal of a charging power switch, wherein the discharge power switch and the charging power switch are connected between the third detection terminal and the second detection terminal, and the discharge power switch and the charging power switch are collectively referred to as a charge-discharge switch, and further comprising: an overcurrent detection module as described above; a logic module that generates a charging control signal and a discharging control signal based on the current detection signal output by the overcurrent detection module; and a first driving circuit for controlling the charging and discharging of the battery cell. The electrical control signal is driven and processed, and the processed charging control signal is provided to the charging control terminal; the second driving circuit is used to drive and process the discharge control signal and provide the processed discharge control signal to the discharge control terminal; the power supply pre-adjustment module has its input terminal connected to the first detection terminal, and its output terminal connected to the power supply terminal of the first driving circuit and the power supply terminal of the second driving circuit. When the voltage of the first detection terminal is less than the overvoltage detection voltage threshold, the output terminal of the power supply pre-adjustment module outputs the voltage of the first detection terminal; when the voltage of the first detection terminal is greater than the overvoltage detection voltage threshold, the output terminal of the power supply pre-adjustment module outputs a constant voltage.

[0013] Furthermore, the power pre-adjustment module includes an adaptive charge pump and a low-dropout regulator. The input terminal of the adaptive charge pump is connected to the first detection terminal, and the input terminal of the low-dropout regulator is connected to the output terminal of the adaptive charge pump. The output terminal of the low-dropout regulator serves as the output terminal of the power pre-adjustment module. When the voltage at the first detection terminal is less than the overvoltage detection voltage threshold, the output voltage of the charge pump is equal to the voltage at the first detection terminal, and the output voltage of the low-dropout regulator is equal to the output voltage of the adaptive charge pump. When the voltage at the first detection terminal is greater than the overvoltage detection voltage threshold, the adaptive charge pump boosts the voltage at the first detection terminal and outputs a voltage greater than the voltage at the first detection terminal. The low-dropout regulator performs low-dropout regulation on the output voltage of the adaptive charge pump. The boost factor of the adaptive charge pump changes with the voltage at the first detection terminal.

[0014] Furthermore, the adaptive charge pump is provided with multiple boost factors corresponding to multiple segmented sections of the voltage value at the first detection terminal, with each segmented section of the voltage value at the first detection terminal corresponding to a boost factor; as the voltage value of the segmented section of the voltage value at the first detection terminal decreases, the corresponding boost factor decreases.

[0015] According to another aspect of the present invention, the present invention provides a battery protection system comprising: a battery cell; a charging power switch and a discharging power switch, the discharging power switch and the charging power switch being collectively referred to as a charge-discharge switch; and a battery protection circuit as described above.

[0016] Furthermore, heat can be conducted through the metal sheet on the underside of the chip package to import the temperature information of the charge / discharge switch into the temperature sensing module T_Sens inside the chip; or a metal sheet can be added to the printed circuit board, and then the temperature information of the charge / discharge switch can be imported into the temperature sensing module T_Sens inside the chip through the pins of the package.

[0017] Furthermore, the charge / discharge switch and the battery protection circuit are packaged in the same package.

[0018] Furthermore, the battery protection circuit is placed close together with the charge / discharge switch; and / or the battery protection circuit and the charge / discharge switch are in close contact with the same metal plate.

[0019] Compared with the prior art, the present invention does not require the use of a current sampling resistor R1 to obtain current detection information (or current sampling information). Instead, it uses the voltage of the detection terminal VM as the current detection information. This not only enables high-precision charging and discharging overcurrent detection, but also saves the area occupied by the printed circuit board and reduces energy consumption. [Attached Image Description]

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used 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 those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0021] Figure 1 This is a circuit diagram of a battery protection system in the prior art;

[0022] Figure 2 This is a circuit diagram of the battery protection system in one embodiment of the present invention;

[0023] Figure 3 This is a circuit diagram of the discharge overcurrent detection module in the battery protection circuit of the present invention in one embodiment;

[0024] Figure 4 For the purposes of this invention Figure 3 The circuit diagram shown is of a positive temperature coefficient voltage generator (VPTC) in one embodiment.

[0025] Figure 5 This is a circuit diagram of a battery protection circuit in one embodiment of the present invention;

[0026] Figure 6 For the purposes of this invention Figure 5 The diagram shows a circuit diagram of the Pre-REG power supply module in one embodiment.

Detailed Implementation Methods

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms "connected," "linked," and "connected" used herein to indicate electrical connection refer to direct or indirect electrical connection.

[0029] As mentioned in the background section, directly using the voltage at the detection terminal VM as the current sampling information leads to inaccurate current detection. This is because the voltage at the detection terminal VM reflects the voltage drop across the discharge power switch FET1 and the charging power switch FET2. During normal discharge, the voltage at the detection terminal VM is equal to I * Ron, where I is the discharge current and Ron is the sum of the on-resistances of the discharge power switch FET1 and the charging power switch FET2. Generally, the gate voltages of the discharge power switch FET1 and the charging power switch FET2 are the cell voltages. When cell BAT1 discharges, the cell voltage gradually decreases; when cell BAT1 charges, the cell voltage gradually increases. Therefore, the cell voltage may change. When the cell voltage changes, the gate voltages of the discharge power switch FET1 and the charging power switch FET2 also change accordingly, and the on-resistances of the discharge power switch FET1 and the charging power switch FET2 change with their gate voltages. When a constant voltage VR is used as the voltage threshold for discharge overcurrent detection (i.e., a constant reference voltage VR is compared with the voltage at the detection terminal VM; when the voltage at the detection terminal VM exceeds this constant reference voltage VR, it is considered that a discharge overcurrent has been detected, and a corresponding discharge prohibition operation is performed), the actual corresponding discharge overcurrent detection current threshold is Ith = VR / Ron, where VR is the aforementioned constant reference voltage, and Ron is the sum of the on-resistances of the discharge power switch FET1 and the charging power switch FET2. Ron changes with the gate voltages of the discharge power switch FET1 and the charging power switch FET2. Generally, the gate voltages of the discharge power switch FET1 and the charging power switch FET2 are driven by the cell voltage. As cell BAT1 discharges, its cell voltage decreases; as cell BAT1 is charged, its cell voltage increases. In addition, as the temperature of the discharge power switch FET1 and the charging power switch FET2 changes, their on-resistance Ron also changes. When Ron changes, the discharge overcurrent detection current threshold Ith changes accordingly. In practical applications, it is best to keep the discharge overcurrent detection current threshold Ith constant.

[0030] Therefore, the present invention provides an overcurrent detection module, a battery protection circuit, and a system that do not require the use of Figure 1 The current sampling resistor R1 is used to obtain current detection information, which can also save a chip pin VL (such as...). Figure 1(As shown in the diagram); instead, the voltage at the detection terminal VM is used as the current detection information, and the overcurrent detection voltage threshold VR mimics the characteristic that the sum of the on-resistances of the discharge power switch FET1 and the charge power switch FET2 changes with their temperature; during normal charging and discharging, the gate voltages of the discharge power switch FET1 and the charge power switch FET2 are kept constant, thereby achieving a precise overcurrent detection current threshold Ith, which does not change with cell voltage or with temperature changes of the discharge power switch FET1 and the charge power switch FET2. This not only achieves high-precision overcurrent detection but also saves printed circuit board area and reduces energy consumption.

[0031] Please refer to Figure 2 As shown, it is a circuit diagram of the battery protection system in one embodiment of the present invention. Figure 2 The battery protection system shown includes battery cell BAT1, battery protection circuit (or battery protection chip) 110, charging power switch (or charging power transistor) FET2, and discharging power switch (or discharging power transistor) FET1. Discharging power switch FET1 and charging power switch FET2 are connected in series between the negative terminal B- of battery cell BAT1 and the negative terminal P- of the battery, and the positive terminal B+ of battery cell BAT1 is directly connected to the positive terminal P+ of the battery.

[0032] The charging power switch (or charging power transistor) FET2 includes a diode (not shown) parasitic within it. In one embodiment of the invention, the charging power switch (or charging power transistor) FET2 is an NMOS (N-channel Metal-Oxide Semiconductor) field-effect transistor. The discharging power switch FET1 includes a diode (not shown) parasitic within it. In one embodiment of the invention, the discharging power switch FET1 is an NMOS field-effect transistor. The drains of NMOS transistor FET1 and NMOS transistor FET2 are connected. The source of NMOS transistor FET1 is connected to the negative terminal B- of the battery cell, and the source of NMOS transistor FET2 is connected to the negative terminal P- of the battery.

[0033] The battery protection circuit 110 includes three detection terminals (or connection terminals) and two control terminals. The three detection terminals are the first detection terminal VDD, the second detection terminal VM, and the third detection terminal G. The two control terminals are the charging control terminal CO and the discharging control terminal DO. Specifically, the first detection terminal VDD is connected to the positive terminal B+ of battery cell BAT1, the third detection terminal G is connected to the negative terminal B- of battery cell BAT1, the second detection terminal VM is connected to the negative terminal P- of the battery, the charging control terminal CO is connected to the control terminal of the charging power switch FET2 (i.e., the gate of the NMOS transistor FET2), and the discharging control terminal DO is connected to the control terminal of the discharging power switch FET1 (i.e., the gate of the NMOS transistor FET1).

[0034] The battery protection circuit 110 can provide charging and discharging protection for the battery cell BAT1 by controlling the on and off states of the discharge power switch FET1 and the charging power switch FET2. Under normal conditions, the battery protection circuit 110 controls both the discharge power switch FET1 and the charging power switch FET2 to be on simultaneously, allowing both charging and discharging. If an abnormality occurs during charging, the battery protection circuit 110 controls the charging power switch FET2 to be off, thus cutting off the charging circuit, but discharging is still possible. If an abnormality occurs during discharging, the battery protection circuit 110 controls the discharge power switch FET1 to be off, thus cutting off the discharging circuit, but charging is still possible.

[0035] The battery protection circuit 110 performs discharge overcurrent detection or charging overcurrent detection by sampling the voltage of the detection terminal VM; and the battery protection circuit 110 internally generates a reference voltage VR (i.e., the voltage threshold VR for overcurrent detection), which mimics the characteristic that the sum of the on-resistances of the discharge power switch FET1 and the charging power switch FET2 changes with their temperature (i.e., the change of the reference voltage VR with temperature is consistent with the change of the on-resistance of the charge and discharge switches with temperature); during normal charging and discharging, the battery protection circuit 110 keeps the gate voltages of the discharge power switch FET1 and the charging power switch FET2 constant.

[0036] Please refer to Figure 3 As shown, it is a circuit diagram of the discharge overcurrent detection module in the battery protection circuit of the present invention in one embodiment.

[0037] like Figure 3 As shown, the discharge overcurrent detection module in the battery protection circuit of the present invention includes a reference voltage generation circuit 310 and a comparator Comp. Figure 3The discharge overcurrent detection module shown performs discharge overcurrent detection by sampling the voltage at the second detection terminal VM. For ease of description, the charging power switch FET2 and the discharging power switch FET1 are collectively referred to as the charge-discharge switch in the following text; the sum of the on-resistances of the charging power switch FET2 and the discharging power switch FET1 is called the on-resistance of the charge-discharge switch.

[0038] The reference voltage generation circuit 310 is used to acquire the temperature values ​​of the charge / discharge switches (i.e., charging power switch FET2 and discharging power switch FET1), and based on the acquired temperature values, obtains the corresponding reference voltage VR, which is then output through its output terminal. The reference voltage VR only mimics the change in the on-resistance of the charge / discharge switches (i.e., the sum of the on-resistances of charging power switch FET2 and discharging power switch FET1) with temperature. In other words, the change in reference voltage VR with temperature is consistent with the change in the on-resistance of the charge / discharge switches with temperature. For example, if the on-resistance of the charge / discharge switches increases with increasing temperature, then the resistance value of the reference voltage VR increases with increasing temperature; conversely, if the on-resistance of the charge / discharge switches decreases with decreasing temperature, then the resistance value of the reference voltage VR decreases with decreasing temperature. The reference voltage VR can also be referred to as the voltage threshold VR for discharge overcurrent detection.

[0039] The first input terminal of comparator Comp is connected to the output terminal of reference voltage generation circuit 310 to receive the reference voltage VR output by reference voltage generation circuit 310, and its second input terminal is connected to the second detection terminal VM to obtain the voltage of the second detection terminal VM. Comparator Comp is used to compare the magnitude of the reference voltage VR output by reference voltage generation circuit 310 and the voltage of the second detection terminal VM, and outputs a corresponding current detection signal (or discharge overcurrent detection signal) EDI through its output terminal based on the comparison result. Figure 3 In the specific embodiment shown, the first input terminal and the second input terminal of the comparator Comp are its negative input terminal and its positive input terminal, respectively.

[0040] exist Figure 3 In the specific embodiment shown, the reference voltage generation circuit 310 includes a temperature sensing module T_Sens 312, a positive temperature coefficient voltage generator VPTC 314, a zero temperature coefficient voltage generator VZTC 316, a multiplier M1, a multiplier M2, and an adder Add.

[0041] The temperature sensing module T_Sens312 is used to conduct heat from the charge and discharge switches (i.e., the charging power switch FET2 and the discharging power switch FET1) to the positive temperature coefficient voltage generator VPTC314, so that the temperature of the positive temperature coefficient voltage generator VPTC314 is the same as the temperature of the charge and discharge switches.

[0042] The positive temperature coefficient voltage generator VPTC314 generates a positive temperature coefficient voltage V1 based on its own temperature (i.e., the positive temperature coefficient voltage V1 increases with increasing temperature) and outputs the positive temperature coefficient voltage V1 through its output terminal. In a preferred embodiment, the positive temperature coefficient voltage V1 is proportional to the temperature of the charge and discharge switches (i.e., the charging power switch FET2 and the discharging power switch FET1).

[0043] The zero-temperature coefficient voltage generator VZTC316 generates a zero-temperature coefficient voltage V2 (i.e., the zero-temperature coefficient voltage V2 does not change with temperature) and outputs this zero-temperature coefficient voltage V2. Multiplier M1 multiplies the positive temperature coefficient voltage V1 by a fixed coefficient K1 to obtain a positive temperature coefficient voltage V3. Multiplier M2 multiplies the zero-temperature coefficient voltage V2 by a fixed coefficient K2 to obtain a zero-temperature coefficient voltage V4. Adder Adds the positive temperature coefficient voltage V3 and the zero-temperature coefficient voltage V4 to generate a reference voltage VR.

[0044] Alternatively, VR can be expressed as K1.V1 + K2.V2, where K1 is a fixed coefficient, K2 is a fixed coefficient, V1 is the positive temperature coefficient voltage, and V2 is the zero temperature coefficient voltage.

[0045] For different charging power switches FET2 and discharging power switches FET1, their on-resistance characteristics may be different. The corresponding reference voltage VR can be generated by modifying the coefficients K1 and K2 so that the change of the reference voltage VR with temperature is consistent with the change of the on-resistance of the charging and discharging switches (i.e., the sum of the on-resistances of charging power switch FET2 and discharging power switch FET1) with temperature. In other words, the reference voltage VR imitates the change of the on-resistance of the charging and discharging switches with temperature.

[0046] Figure 3 The zero-temperature coefficient voltage generator VZTC316 shown can be implemented using various bandgap reference circuits or other zero-temperature coefficient reference voltage generation circuits in the prior art. In one implementation, coefficients K1 and K2 can be implemented using analog voltage signals (which can be an adjustable reference voltage), and the corresponding multipliers M1 and M2 can also be implemented using analog multipliers; in another implementation, coefficients K1 and K2 can be implemented using digital signals, and the corresponding multipliers M1 and M2 can also be implemented using digital multipliers.

[0047] In one embodiment, heat can be conducted through a metal sheet on the underside of the chip package, or by adding a metal sheet on the printed circuit board, and then importing the temperature information of the discharge power switch FET1 and the charging power switch FET2 (i.e., the charge and discharge switch) into the temperature sensing module T_Sens inside the chip through the pins of the package.

[0048] In one implementation, the chips of the discharge power switch FET1 and the charge power switch FET2 (i.e., the charge / discharge switch) can be integrated with... Figure 2 The battery protection circuit 110 is packaged in the same package, which makes it easier for the battery protection circuit 110 to sense the temperature of the discharge power switch FET1 and the charging power switch FET2 (i.e., the charge / discharge switch), thus keeping the temperature of the battery protection circuit 110 the same as that of the discharge power switch FET1 and the charging power switch FET2 (i.e., the charge / discharge switch). Further improvements can be made to the package by placing the battery protection circuit 110 chip tightly together with the discharge power switch FET1 and the charging power switch FET2 (i.e., the charge / discharge switch) chips, or by attaching all three to the same metal sheet, allowing the metal sheet to aid in heat conduction.

[0049] Please refer to Figure 4 As shown, it is the present invention as follows. Figure 3 The diagram shows a circuit diagram of a positive temperature coefficient voltage generator (VPTC) in one embodiment. Figure 4 The positive temperature coefficient voltage generator VPTC shown includes MOSFETs MP1, MP2 and MP3, resistors R1 and R2, operational amplifier OP, and bipolar transistors Q1 and Q2.

[0050] In this configuration, the first terminal of MOSFET MP1 is connected to the power supply, and its second terminal is connected to node A; the first terminal of bipolar transistor Q1 is connected to node A, and its second terminal and control terminal are both grounded; the first terminal of MOSFET MP2 is connected to the power supply, its control terminal is connected to the control terminal of MOSFET MP1, and its second terminal is connected to node B; the first terminal of bipolar transistor Q2 is connected to node B via resistor R1, and its second terminal and control terminal are both grounded; the first input terminal of operational amplifier OP is connected to node A, its second input terminal is connected to node B, and its output terminal is connected to the control terminal of MOSFET MP1; the first terminal of MOSFET MP3 is connected to the power supply, its control terminal is connected to the control terminal of MOSFET MP2, and its second terminal is connected to the output terminal V1 of positive temperature coefficient voltage generator VPTC314; one end of resistor R2 is connected to the output terminal V1 of positive temperature coefficient voltage generator VPTC314, and the other end is grounded.

[0051] exist Figure 4In the specific embodiment shown, MOS transistors MP1, MP2, and MP3 are all PMOS transistors. The first connection terminal, the second connection terminal, and the control terminal of MOS transistors MP1, MP2, and MP3 are the source, drain, and gate of the PMOS transistors, respectively. Bipolar transistors Q1 and Q2 are both PNP bipolar transistors. The first connection terminal, the second connection terminal, and the control terminal of bipolar transistors Q1 and Q2 are the emitter, collector, and base of the PNP bipolar transistors, respectively. Resistors R1 and R2 are resistors of the same type. The first input terminal and the second input terminal of operational amplifier OP are its negative input terminal and its positive input terminal, respectively.

[0052] In other embodiments, bipolar transistors Q1 and Q2 can also be NPN bipolar transistors; the specific connection relationship will not be described again to avoid repetition.

[0053] exist Figure 4 In the illustrated embodiment, the operational amplifier OP is adjusted so that its positive and negative inputs are equal. Therefore, the voltage across resistor R1 is equal to Vbe1 - Vbe2, where Vbe1 is the base-emitter voltage of bipolar transistor Q1, and Vbe2 is the base-emitter voltage of bipolar transistor Q2. The voltage across resistor R1 is a positive temperature coefficient voltage. MOSFETs MP3, MP2, and MP1 form a current mirror, with MOSFET MP3 replicating the current of MOSFET MP2. The current across resistor R1 is equal to (Vbe1 - Vbe2) / R1, which is also equal to the current of MOSFET MP2 and MP3. The voltage across resistor R2 is equal to (Vbe1 - Vbe2)R2 / R1, where R1 and R2 are the resistance values ​​of resistors R1 and R2, respectively. Resistors R1 and R2 are of the same type, so their temperature coefficients cancel each other out. Therefore, the voltage across resistor R2 (i.e., the voltage at the output V1 of the positive temperature coefficient voltage generator VPTC) is also a positive temperature coefficient voltage.

[0054] The preceding text describes the circuit structure and operation of the discharge overcurrent detection module in the battery protection circuit of this invention. It should be noted that the charging overcurrent detection module in the battery protection circuit of this invention has a similar structure and operating principle to the discharge overcurrent detection module; therefore, a detailed description of the charging overcurrent detection module in the battery protection circuit of this invention will not be provided here.

[0055] Please refer to Figure 5 As shown, it is a circuit diagram of the battery protection circuit in one embodiment of the present invention. Figure 5 The battery protection circuit shown includes an overvoltage detection module VDet510, an overcurrent detection module IDet520, a logic module Logic530, a power pre-adjustment module Pre-REG560, a first drive circuit DRV1540, and a second drive circuit DRV2550.

[0056] The IDet520 overcurrent detection module includes a charging overcurrent detection module and, for example, a charging overcurrent detection module and, Figure 3 The discharge overcurrent detection module is shown. The overvoltage detection module VDet510 detects the charging and discharging circuit of cell BAT1 based on the connection terminal VDD to output a corresponding voltage detection signal. The overvoltage detection module VDet510 can be implemented using existing technologies.

[0057] If the current detection signal EDI output by the overcurrent detection module IDet520 goes high, the logic module Logic530 can time it. If the discharge overcurrent protection delay time is exceeded, the discharge control terminal DO goes low, turning off the discharge power switch FET1 and preventing discharge. If the charging overcurrent protection delay time is exceeded, the charging control terminal CO goes low, turning off the charging power switch FET2 and preventing charging. In other words, the logic module Logic530 generates charging or discharging control signals based on the current detection signal EDI output by the overcurrent detection module IDet520.

[0058] The first drive circuit, DRV1 540, processes the charging control signal and provides the processed signal to the charging control terminal CO. The second drive circuit, DRV2 550, processes the discharging control signal and provides the processed signal to the discharging control terminal DO. Figure 5 In the specific embodiment shown, the ground terminal of the first driving circuit DRV1 540 is connected to the second detection terminal VM, and the ground terminal of the second driving circuit DRV2 550 is connected to the third detection terminal G.

[0059] The input terminal of the power pre-adjustment module Pre-REG560 is connected to the first detection terminal VDD, and its output terminal is connected to the power supply terminal of the first drive circuit DRV1 540 and the power supply terminal of the second drive circuit DRV2 550. When the voltage of the first detection terminal VDD is less than the overvoltage discharge voltage threshold, the output terminal of the power pre-adjustment module Pre-REG560 outputs the voltage of the first detection terminal VDD; when the voltage of the first detection terminal VDD is greater than the overvoltage discharge voltage threshold, the output terminal of the power pre-adjustment module Pre-REG560 outputs a constant voltage.

[0060] Please refer to Figure 6 As shown, it is the present invention as follows. Figure 5 The diagram shows a circuit diagram of the Pre-REG power supply module in one embodiment. Figure 6The power pre-regulation module Pre-REG shown includes an adaptive charge pump ChargePump610 and a low dropout regulator LDO620.

[0061] The input terminal of the adaptive charge pump ChargePump610 is connected to the first detection terminal VDD. It is used to boost the voltage of the first detection terminal VDD and output an output voltage VCHP that is larger than the voltage of the first detection terminal VDD. The boost factor of the adaptive charge pump ChargePump610 changes with the voltage of the first detection terminal VDD.

[0062] The input of the low-dropout regulator LDO620 is connected to the output of the adaptive charge pump ChargePump610, and its output serves as the output VLO of the power supply pre-regulation module Pre-REG. The LDO620 is used to regulate the output voltage VCHP of the adaptive charge pump ChargePump610 with low dropout.

[0063] In one embodiment, when 2V ≤ VDD < 2.3V, the ChargePump610 uses a 3x boost ratio to boost the voltage, meaning the generated output voltage VCHP satisfies 6V ≤ VCHP < 6.9V. After passing through the low-dropout regulator LDO620, it produces a constant voltage of 4.5V (i.e., the output voltage VLO of the power supply pre-regulation module Pre-REG is 4.5V). When 2.3V ≤ VDD < 3V, the ChargePump610 uses a 2x boost ratio to boost the voltage, meaning the generated output voltage VCHP satisfies 4.6V ≤ VCHP < 6V. After passing through the low-dropout regulator LDO620, it produces a constant voltage of 4.5V (i.e., the output voltage VLO of the power supply pre-regulation module Pre-REG is 4.5V). When VDD < 2V (for example, the overvoltage discharge voltage threshold is 2V), there is no need to boost the voltage, and the charge pump 610 can stop working. This is because lithium batteries generally enter an overvoltage discharge state when the voltage is below 2V, and discharge should be prohibited. At this time, the output voltage VCHP of the charge pump 610 can be equal to the voltage of the first detection terminal VDD, and the low dropout regulator LDO620 also outputs a voltage close to the voltage of the first detection terminal VDD (because the low dropout regulator LDO620 can no longer output 4.5V, its output voltage VLO behaves as if it follows the input voltage).

[0064] Alternatively, the input of the adaptive charge pump ChargePump610 is connected to the first detection terminal VDD, and the input of the low-dropout regulator LDO620 is connected to the output of the adaptive charge pump ChargePump610. The output of the low-dropout regulator LDO620 serves as the output VLO of the power supply pre-regulation module Pre-REG. When the voltage at the first detection terminal VDD is less than the overvoltage discharge voltage threshold (or the overvoltage detection voltage threshold), the output voltage VCHP of the charge pump ChargePump610 is equal to the voltage at the first detection terminal VDD, and the output voltage VLO of the low-dropout regulator LDO620 is equal to the output voltage VCHP of the charge pump ChargePump610. When the voltage at the first detection terminal VDD is greater than the overvoltage discharge voltage threshold (or the overvoltage detection voltage threshold), the adaptive charge pump ChargePump610 is used to boost the voltage at the first detection terminal VDD and output an output voltage VCHP that is greater than the voltage at the first detection terminal VDD. The low-dropout regulator LDO620 performs low-dropout regulation on the output voltage VCHP of the adaptive charge pump ChargePump610. The boost factor of the adaptive charge pump ChargePump610 changes with the voltage at the first detection terminal VDD.

[0065] In one embodiment, the charge pump 610 is provided with multiple boost factors corresponding to multiple segmented sections of the voltage value of the first detection terminal VDD. Each segment of the voltage value of the first detection terminal VDD corresponds to one boost factor, and the boost factor decreases as the voltage value of the segmented section of the voltage value of the first detection terminal VDD decreases. For example, when 2V≤VDD<2.3V, the charge pump 610 uses a boost factor of 3; when 2.3V≤VDD<3V, the charge pump 610 uses a boost factor of 2.

[0066] In summary, this invention provides an overcurrent detection module, a battery protection circuit, and a system that do not require the use of Figure 1 The current sampling resistor R1 is used to obtain current detection information, which can also save a chip pin VL (such as...). Figure 1As shown in the diagram; the battery protection circuit performs discharge overcurrent detection or charging overcurrent detection by sampling the voltage at the detection terminal VM; and the battery protection circuit internally generates a reference voltage VR (i.e., the overcurrent detection voltage threshold VR), which only mimics the characteristic that the sum of the on-resistances of the discharge power switch FET1 and the charging power switch FET2 changes with their temperature (i.e., the change of the reference voltage VR with temperature is consistent with the change of the on-resistance of the charge and discharge switches with temperature); during normal charging and discharging, the battery protection circuit keeps the gate voltages of the discharge power switch FET1 and the charging power switch FET2 constant. This achieves a precise overcurrent detection current threshold Ith, which does not change with cell voltage or with temperature changes of the discharge power switch FET1 and the charging power switch FET2. In this way, not only can high-precision charging and discharging overcurrent detection be achieved, but also the printed circuit board area can be saved, and energy consumption can be reduced.

[0067] In this invention, terms such as “connection,” “linked,” “connected,” and “joined” that indicate electrical connection, unless otherwise specified, indicate direct or indirect electrical connection.

[0068] It should be noted that any modifications made by those skilled in the art to the specific embodiments of the present invention do not depart from the scope of the claims. Accordingly, the scope of the claims is not limited to the foregoing specific embodiments.

Claims

1. An overcurrent detection module, characterized in that, It includes: A reference voltage generation circuit is used to obtain the temperature value of the charge-discharge switch, and obtain a corresponding reference voltage VR based on the obtained temperature value of the charge-discharge switch, and output the reference voltage VR through its output terminal. The change of the reference voltage VR with temperature is consistent with the change of the on-resistance of the charge-discharge switch with temperature. The comparator receives the reference voltage VR output by the reference voltage generation circuit at its first input terminal and acquires the voltage of the second detection terminal VM at its second input terminal. The comparator compares the magnitudes of the reference voltage VR and the voltage of the second detection terminal VM, and outputs a corresponding current detection signal based on the comparison result. The reference voltage VR = K1×V1 + K2×V2, Where K1 is a fixed coefficient, K2 is another fixed coefficient, V1 is the positive temperature coefficient voltage, and V2 is the zero temperature coefficient voltage. The reference voltage generation circuit includes a temperature sensing module T_Sens, a positive temperature coefficient voltage generator VPTC, a zero temperature coefficient voltage generator VZTC, multipliers M1 and M2, and an adder Add. The temperature sensing module T_Sens is used to conduct the temperature of the charge / discharge switch to the positive temperature coefficient voltage generator VPTC, so that the temperature of the positive temperature coefficient voltage generator VPTC is the same as the temperature of the charge / discharge switch. The positive temperature coefficient voltage generator VPTC generates the positive temperature coefficient voltage V1 based on its own temperature and outputs the positive temperature coefficient voltage V1 through its output terminal; The zero temperature coefficient voltage generator VZTC is used to generate the zero temperature coefficient voltage V2 and outputs the zero temperature coefficient voltage V2 through its output terminal. The multiplier M1 is used to multiply the positive temperature coefficient voltage V1 by a fixed coefficient K1 to obtain the positive temperature coefficient voltage V3. The multiplier M2 is used to multiply the zero temperature coefficient voltage V2 by another fixed coefficient K2 to obtain the zero temperature coefficient voltage V4. The adder Add is used to add the positive temperature coefficient voltage V3 and the zero temperature coefficient voltage V4 to generate the reference voltage VR.

2. The overcurrent detection module according to claim 1, characterized in that, Based on the characteristics of the on-resistance of the charge-discharge switch, the coefficients K1 and K2 are modified so that the change of the reference voltage VR with temperature is consistent with the change of the on-resistance of the charge-discharge switch with temperature. or The positive temperature coefficient voltage V1 is proportional to the temperature of the charge / discharge switch.

3. The overcurrent detection module according to claim 1, characterized in that, The positive temperature coefficient voltage generator (VPTC) includes MOSFETs MP1, MP2, and MP3, resistors R1 and R2, an operational amplifier OP, and bipolar transistors Q1 and Q2. The first terminal of the MOS transistor MP1 is connected to the power supply, and its second terminal is connected to node A. The first terminal of the bipolar transistor Q1 is connected to node A, and its second terminal and control terminal are both grounded. The first terminal of the MOS transistor MP2 is connected to the power supply, its control terminal is connected to the control terminal of the MOS transistor MP1, and its second terminal is connected to node B. The first terminal of the bipolar transistor Q2 is connected to node B via resistor R1, and its second terminal and control terminal are both grounded. The first input terminal of the operational amplifier OP is connected to node A, its second input terminal is connected to node B, and its output terminal is connected to the control terminal of the MOS transistor MP1. The first terminal of the MOS transistor MP3 is connected to the power supply, and its control terminal is connected to the control terminal of the MOS transistor MP2. Its second terminal is connected to the output terminal V1 of the positive temperature coefficient voltage generator VPTC. One end of resistor R2 is connected to the output terminal V1 of the positive temperature coefficient voltage generator VPTC, and the other end is grounded.

4. The overcurrent detection module according to claim 3, characterized in that, The MOS transistors MP1, MP2 and MP3 are all PMOS transistors, and the first connection terminal, the second connection terminal and the control terminal of the MOS transistors MP1, MP2 and MP3 are the source, drain and gate of the PMOS transistors, respectively. Both bipolar transistors Q1 and Q2 are PNP bipolar transistors. The first connection terminal, the second connection terminal, and the control terminal of bipolar transistors Q1 and Q2 are the emitter, collector, and base of the PNP bipolar transistor, respectively. The resistors R1 and R2 are of the same type.

5. The overcurrent detection module according to claim 1, characterized in that, The multipliers M1 and M2 are implemented using analog multipliers, and the coefficients K1 and K2 are implemented using analog voltage signals; or The multipliers M1 and M2 are implemented using digital multipliers, and the coefficients K1 and K2 are implemented using digital voltage signals.

6. A battery protection circuit, comprising a second detection terminal connected to the negative terminal of the battery, a third detection terminal connected to the negative terminal of the battery cell, a first detection terminal connected to the positive terminal of the battery cell, a discharge control terminal connected to the control terminal of a discharge power switch, and a charging control terminal connected to the control terminal of a charging power switch, wherein, The discharge power switch and the charging power switch are connected between the third detection terminal and the second detection terminal. The discharge power switch and the charging power switch are collectively referred to as the charge-discharge switch. Its characteristic is that it further includes: The overcurrent detection module as described in any one of claims 1-5; The logic module generates charging control signals and discharging control signals based on the current detection signal output by the overcurrent detection module. The first driving circuit is used to drive the charging control signal and provide the driven and processed charging control signal to the charging control terminal. The second driving circuit is used to drive the discharge control signal and provide the processed discharge control signal to the discharge control terminal. The power supply pre-adjustment module has its input terminal connected to the first detection terminal and its output terminal connected to the power supply terminal of the first driving circuit and the power supply terminal of the second driving circuit. When the voltage of the first detection terminal is less than the overvoltage detection voltage threshold, the output terminal of the power supply pre-adjustment module outputs the voltage of the first detection terminal; when the voltage of the first detection terminal is greater than the overvoltage detection voltage threshold, the output terminal of the power supply pre-adjustment module outputs a constant voltage.

7. The battery protection circuit according to claim 6, characterized in that, The power supply pre-adjustment module includes an adaptive charge pump and a low-dropout regulator. The input terminal of the adaptive charge pump is connected to the first detection terminal, and the input terminal of the low-dropout regulator is connected to the output terminal of the adaptive charge pump. The output terminal of the low-dropout regulator serves as the output terminal of the power supply pre-adjustment module. When the voltage at the first detection terminal is less than the overvoltage detection voltage threshold, the output voltage of the charge pump is equal to the voltage at the first detection terminal, and the output voltage of the low-dropout regulator is equal to the output voltage of the adaptive charge pump. When the voltage at the first detection terminal is greater than the overvoltage detection voltage threshold, the adaptive charge pump boosts the voltage at the first detection terminal and outputs an output voltage greater than the voltage at the first detection terminal. The low-dropout regulator regulates the output voltage of the adaptive charge pump with low-dropout adjustment. The boost factor of the adaptive charge pump changes with the voltage at the first detection terminal.

8. The battery protection circuit according to claim 7, characterized in that, The adaptive charge pump is provided with multiple boost factors corresponding to multiple segmented sections of the voltage value at the first detection terminal, and each segmented section of the voltage value at the first detection terminal corresponds to a boost factor. As the voltage value of the segmented section of the voltage value at the first detection terminal decreases, the relative boost factor also decreases.

9. A battery protection system, characterized in that, It includes: Battery cell; The charging power switch and the discharging power switch are collectively referred to as a charging and discharging switch; The battery protection circuit as described in any one of claims 6-8.

10. The battery protection system according to claim 9, characterized in that, Heat is conducted through a metal plate on the underside of the chip package to transmit the temperature information of the charge / discharge switch to the temperature sensing module T_Sens inside the chip; or A metal sheet is added to the printed circuit board, and then the temperature information of the charge / discharge switch is imported into the temperature sensing module T_Sens inside the chip through the package pins.

11. The battery protection system according to claim 9, characterized in that, The charge / discharge switch and the battery protection circuit are packaged in the same package.

12. The battery protection system according to claim 11, characterized in that, The battery protection circuit is placed close together with the charge / discharge switch; and / or The battery protection circuit and the charge / discharge switch are attached to the same metal plate.

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