Battery protection chip test circuit, battery protection chip test device and method

Abstract

The present application relates to a battery protection chip and a test circuit thereof, a battery protection chip test device and method, including a test voltage divider circuit, a test signal generating circuit and a test signal input circuit. The test voltage divider circuit divides the voltage according to the power supply voltage of the external power supply terminal to obtain an overcharge test voltage divider. When the overcharge test voltage divider is greater than or equal to a preset reference voltage, the test signal generating circuit outputs an overcharge test signal which is transmitted to the overcharge output circuit through the test signal input circuit, so that the overcharge output circuit outputs an overcharge signal according to the overcharge test signal and the overcharge comparison signal. The test voltage divider circuit is powered by the existing external power supply terminal of the chip, and then the test signal generating circuit is controlled to output an overcharge test signal to replace the delay signal of the overcharge protection action, so that the overcharge output circuit of the chip directly outputs an overcharge signal according to the overcharge test signal and the overcharge comparison signal, thereby shortening the triggering time of the overcharge protection action of the chip and improving the test efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of battery protection chip testing, and in particular to a battery protection chip and a testing circuit thereof, and a battery protection chip testing device and method. Background Art

[0002] With the development of electronic technology, lithium batteries have entered a large-scale practical stage and have become an essential power source for various smart devices. At the same time, battery protection chips are usually added to monitor and protect the charging and discharging process of lithium batteries, and to promptly cut off the connection between the battery and external devices when abnormal charging and discharging occurs. Among them, the battery protection chip can realize many monitoring and protection functions, such as open short circuit protection, overcharge protection, overcharge recovery, over-discharge protection, over-discharge recovery, overcurrent protection and temperature protection, etc. Correspondingly, the battery protection chip also needs to be repeatedly tested for various functions before leaving the factory to ensure the quality of the chip.

[0003] In order to prevent false operation caused by noise, existing battery protection chips usually delay the output of protection signals from the protection action circuit. The delay of overcharge protection action can reach hundreds of milliseconds or even seconds. For the overcharge protection action of the traditional normal trigger chip, the test method is to wait for the delay and then observe the level state of the charging control terminal CO for testing. Too long a delay will lead to a long test time for the battery protection chip, which has the disadvantage of low test efficiency. Summary of the invention

[0004] Based on this, it is necessary to provide a battery protection chip and its test circuit, a battery protection chip test device and method to address the problems of long test time and low test efficiency in traditional battery protection chip test solutions.

[0005] A test circuit for a battery protection chip, comprising: a test voltage-dividing circuit, a test signal generating circuit and a test signal input circuit, wherein the test voltage-dividing circuit is connected to an external power supply terminal through an overcharge voltage circuit of the battery protection chip, the test voltage-dividing circuit is also connected to the test signal generating circuit, the test signal generating circuit is connected to the test signal input circuit, and the test signal input circuit is connected to an overcharge output circuit of the battery protection chip;

[0006] The test voltage divider circuit is used to divide the voltage according to the power supply voltage of the external power supply terminal to obtain an overcharge test voltage divider; the overcharge test voltage divider is smaller than the overcharge detection voltage divider, and the overcharge detection voltage divider is output by the overcharge voltage divider circuit;

[0007] The test signal generating circuit outputs an overcharge test signal to the test signal input circuit when the overcharge test divided voltage is greater than or equal to a preset reference voltage;

[0008] The test signal input circuit is used to output the received overcharge test signal to the overcharge output circuit, so that the overcharge output circuit outputs an overcharge signal according to the overcharge test signal and the overcharge comparison signal; wherein the overcharge comparison signal is obtained by the overcharge comparison circuit of the battery protection chip according to the overcharge detection voltage divider and the preset reference voltage.

[0009] In one embodiment, the test signal generating circuit includes a test comparison circuit, a noise suppression circuit and a pulse generating circuit, the test comparison circuit is connected to the test voltage divider circuit and the noise suppression circuit, the noise suppression circuit is connected to the pulse generating circuit, and the pulse generating circuit is connected to the test signal input circuit.

[0010] In one embodiment, the test comparison circuit includes a comparator, and the comparator is connected to the test voltage divider circuit and the noise suppression circuit.

[0011] In one of the embodiments, the test voltage-dividing circuit includes a voltage-dividing component, and the voltage-dividing component is connected to the overvoltage circuit and the test comparison circuit.

[0012] In one embodiment, the voltage divider component includes three resistors connected in series, and one end of the resistors connected in series is connected to the overvoltage circuit, and the other end is grounded;

[0013] The test comparison circuit also includes a data selector, a first input end of the data selector is connected to a first common end of three resistors in series, a second input end of the data selector is connected to a second common end of three resistors in series, an output end of the data selector is connected to the first input end of the comparator, and a control end of the data selector is connected to the noise suppression circuit.

[0014] In one embodiment, the test signal input circuit is an NOR logic gate, a first input end of the NOR logic gate is connected to the test signal generating circuit, a second input end of the NOR logic gate is connected to the overcharge delay circuit of the battery protection chip, and an output end of the NOR logic gate is connected to the overcharge output circuit.

[0015] In one of the embodiments, the test circuit of the battery protection chip further includes a mid-test circuit, and the mid-test circuit is connected to the overcharge comparison circuit.

[0016] In one embodiment, a battery protection chip is provided, including a control chip, a load detection circuit, a reference circuit, an over-full voltage circuit, an overcharge comparison circuit, an overcharge delay circuit, an overcharge output circuit, a charging control switch and the above-mentioned test circuit, the test circuit is connected to the reference circuit, the over-full voltage circuit and the overcharge output circuit, the load detection circuit is connected to the external detection terminal, the overcharge comparison circuit and the reference circuit, the over-full voltage circuit is connected to the external power supply terminal and the overcharge comparison circuit, the overcharge comparison circuit is connected to the reference circuit, the overcharge delay circuit and the overcharge output circuit, the overcharge delay circuit is connected to the overcharge output circuit, the overcharge output circuit is connected to the control chip, the control chip is connected to the charging control switch, and the charging control is connected to the external detection terminal and the external ground terminal.

[0017] In one embodiment, a battery protection chip testing device is provided, which performs an overcharge protection test on the battery protection chip based on the above-mentioned test circuit, including a main controller, a test pin, a first power supply, a second power supply and a parameter detection module, wherein the main controller is connected to the test pin, the first power supply, the second power supply and the parameter detection module, the test pin is connected to the middle test circuit of the test circuit, the first power supply is connected to the external power supply terminal and the external grounding terminal of the battery protection chip, the second power supply is connected to the external detection terminal and the external grounding terminal of the battery protection chip, and the parameter detection module is connected to the external detection terminal;

[0018] The first power supply is used to output a supply voltage to the battery protection chip;

[0019] The second power supply is used to output a load detection voltage to the battery protection chip;

[0020] The test pin is used to detect a first level state output by the intermediate test circuit; the first level state is determined according to an overcharge comparison signal output by the overcharge comparison circuit of the battery protection chip;

[0021] The parameter detection module is used to detect the second level state of the external detection terminal; the second level state is determined according to the overcharge signal output by the overcharge output circuit of the battery protection chip;

[0022] The main controller is used for analyzing the first level state and the second level state to obtain a test result.

[0023] In one embodiment, a method for testing a battery protection chip is provided, which is implemented based on the main controller of the battery protection chip testing device described above, and includes:

[0024] Controlling the supply voltage output by the first power supply to increase according to a preset step length to obtain a first level state returned by the test pin;

[0025] Controlling the supply voltage output by the first power supply to be a preset overcharge voltage, and controlling the load detection voltage output by the second power supply to be a preset load voltage;

[0026] When the battery protection chip is judged to be in an overcharge state according to the second level state returned by the parameter detection module, the supply voltage output by the first power supply is controlled to be a first preset test voltage and a second preset test voltage in sequence, and a second level state corresponding to the first preset test voltage and a second level state corresponding to the second preset test voltage are obtained;

[0027] The test result of the battery protection chip is obtained by analyzing the first level state, the second level state corresponding to the first preset test voltage, and the second level state corresponding to the second preset test voltage.

[0028] The battery protection chip and its test circuit, battery protection chip test device and method above power the test voltage divider circuit through the existing external power supply terminal of the chip, and then control the test signal generating circuit to output an overcharge test signal to replace the delay signal of the overcharge protection action, so that the overcharge output circuit of the chip directly outputs the overcharge signal according to the overcharge test signal and the overcharge comparison signal, shortening the triggering time of the overcharge protection action of the chip and improving the test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A system block diagram of a part of the circuits in a battery protection chip in one embodiment;

[0030] Figure 2 is a circuit diagram of a test signal generating circuit in an embodiment;

[0031] Figure 3 A circuit diagram of a portion of a circuit in a battery protection chip in an embodiment;

[0032] Figure 4 A connection diagram of a test circuit in an embodiment;

[0033] Figure 5 is a system block diagram of a battery protection chip testing device in one embodiment;

[0034] Figure 6 is a flow chart of a battery protection chip testing method in one embodiment;

[0035] Figure 7 FIG. 4 is a flow chart of an overcharge protection FT test method in one embodiment. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0039] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0040] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0041] The battery protection chip is used to monitor and protect the charging and discharging process of the lithium battery, and to promptly cut off the connection between the battery and external devices when abnormal charging and discharging occurs. Among them, the battery protection chip can realize a lot of monitoring and protection functions, such as open short circuit protection, overcharge protection, overcharge recovery, overdischarge protection, overdischarge recovery, overcurrent protection and temperature protection, etc. Correspondingly, the battery protection chip also needs to be repeatedly tested for various functions before leaving the factory to ensure the quality of the chip. In order to prevent false operation caused by noise, the existing battery protection chip usually delays the output of the protection action circuit protection signal. Among them, the delay of the overcharge protection action can reach hundreds of milliseconds or even seconds. For the overcharge protection action of the traditional normal trigger chip, the method of waiting for the delay and then observing the level state of the charging control terminal CO for testing, the long delay will cause the test time of the battery protection chip to be long, and there is a disadvantage of low test efficiency.

[0042] Based on this, the present application proposes a battery protection chip and its test circuit, a battery protection chip test device and method, which power the test voltage divider circuit through the existing external power supply terminal of the chip, and then control the test signal generating circuit to output an overcharge test signal to replace the delay signal of the overcharge protection action, so that the chip's overcharge output circuit directly outputs an overcharge signal based on the overcharge test signal and the overcharge comparison signal, shortening the triggering time of the chip's overcharge protection action and improving the test efficiency.

[0043] In one embodiment, Figure 1 As shown, a test circuit 110 of a battery protection chip 100 is provided, including a test voltage divider circuit 111, a test signal generating circuit 112 and a test signal input circuit 113. The test voltage divider circuit 111 is connected to an external power supply terminal VDD through an over-voltage circuit 150 of the battery protection chip 100. The test voltage divider circuit 111 is also connected to a test signal generating circuit 112. The test signal generating circuit 112 is connected to a test signal input circuit 113. The test signal input circuit 113 is connected to an overcharge output circuit 180 of the battery protection chip 100. The test voltage divider circuit 111 is used to perform a test according to the power supply voltage of the external power supply terminal VDD. The overcharge test divided voltage is obtained by dividing the voltage by the overcharge test signal and obtaining the overcharge test divided voltage; the overcharge test divided voltage is less than the overcharge detection divided voltage, and the overcharge detection divided voltage is output by the overcharge voltage circuit 150; when the overcharge test divided voltage is greater than or equal to the preset reference voltage, the test signal generating circuit 112 outputs the overcharge test signal to the test signal input circuit 113; the test signal input circuit 113 is used to output the received overcharge test signal to the overcharge output circuit 180, so that the overcharge output circuit 180 outputs the overcharge signal according to the overcharge test signal and the overcharge comparison signal; wherein the overcharge comparison signal is obtained by the overcharge comparison circuit 160 of the battery protection chip 100 according to the overcharge detection divided voltage and the preset reference voltage.

[0044] Among them, when the battery protection chip 100 is connected to the lithium battery to realize the overcharge protection function, it is connected to the external power supply terminal VDD and collects the power supply voltage of the lithium battery to determine whether there is an overcharge situation. Specifically, during the normal protection process of the chip, the over-voltage circuit 150 divides the power supply voltage of the external power supply terminal VDD and outputs the overcharge detection voltage VDD_DIV_OV, so that the overcharge comparison circuit 160 outputs the overcharge comparison signal OV when the overcharge detection voltage VDD_DIV_OV is greater than or equal to the preset reference voltage VREF. Further, based on the need to test the overcharge protection function of the battery protection chip 100, after the over-voltage circuit 150 divides the power supply voltage of the external power supply terminal VDD, a test voltage divider circuit 111 is added to further divide the voltage and output the overcharge test voltage VDD_DIV_TEST, so that the test signal generating circuit 112 outputs the overcharge test signal Test_Pulse when the overcharge test voltage VDD_DIV_TEST is greater than or equal to the preset reference voltage VREF.

[0045] It can be understood that, since the test voltage divider circuit 111 further divides the voltage based on the voltage output by the overcharge voltage divider circuit 150, for the same amplitude of the supply voltage, the overcharge test voltage divider VDD_DIV_TEST must be smaller than the overcharge detection voltage divider VDD_DIV_OV. Correspondingly, when the overcharge test voltage divider VDD_DIV_TEST is greater than or equal to the preset reference voltage VREF, so that the test signal generating circuit 112 outputs the overcharge test signal Test_Pulse, the overcharge comparison circuit 160 must have output the overcharge comparison signal OV according to the overcharge detection voltage divider VDD_DIV_OV and the preset reference voltage VREF.

[0046] Furthermore, after the overcharge comparison circuit 160 triggers the overcharge protection action, the overcharge comparison signal OV is synchronously transmitted to the overcharge delay circuit 170 and the overcharge output circuit 180. The overcharge delay circuit 170 starts the timer when receiving the overcharge comparison signal OV, and generates an overcharge trigger signal Tov_Pulse to the overcharge output circuit 180 after the timing reaches the overcharge protection delay Tov. The overcharge output circuit 180 outputs the overcharge signal OV_Dealy only after receiving the overcharge comparison signal OV and the overcharge trigger signal Tov_Pulse. When the overcharge protection function of the battery protection chip 100 is tested, the overcharge test signal Test_Pulse output by the test signal generating circuit 112 is used to be directly transmitted to the overcharge output circuit 180 through the test signal input circuit 113 without delay, so that the overcharge output circuit 180 directly outputs the overcharge signal OV_Dealy when receiving the overcharge test signal Test_Pulse and the overcharge comparison signal OV.

[0047] The test circuit of the above-mentioned battery protection chip supplies power to the test voltage divider circuit through the existing external power supply terminal of the chip, and then controls the test signal generating circuit to output an overcharge test signal to replace the delay signal of the overcharge protection action, so that the overcharge output circuit of the chip directly outputs the overcharge signal according to the overcharge test signal and the overcharge comparison signal, shortening the triggering time of the overcharge protection action of the chip and improving the test efficiency.

[0048] In one embodiment, the test voltage divider circuit 111 includes a voltage divider component, and the voltage divider component connects the overcharge voltage circuit 150 and the test signal generating circuit 112. It can be understood that the type of voltage divider component is not unique, and it can be a voltage divider component composed of a resistor device, a capacitor device, or a transistor device, without limitation. As long as the voltage can be divided and outputted, the overcharge test divided voltage VDD_DIV_TEST, the overcharge detection divided voltage VDD_DIV_OV and other voltages in the embodiment of the present application can be output, and the overcharge test signal Test_Pulse and the overcharge comparison signal OV can be output accordingly. In this embodiment, the voltage divider component is composed of a resistor device as an example for explanation.

[0049] In addition, the number and resistance value of the resistors included in the test voltage divider circuit 111 are not limited and can be selected according to actual needs. For example, when the test voltage divider circuit 111 is composed of one resistor, one end of the resistor is connected to the over-voltage circuit 150, and the other end is grounded. The end connected to the over-voltage circuit 150 is also used to output the overcharge test voltage divider VDD_DIV_TEST to the test signal generating circuit 112. When the test voltage divider circuit 111 is composed of two resistors connected in series, one end of the resistor connected in series is connected to the over-voltage circuit 150, and the other end is grounded. The common end of the resistors connected in series outputs the overcharge test voltage divider VDD_DIV_TEST to the test signal generating circuit 112. When the test voltage divider circuit 111 is composed of three or more resistors connected in series, one end of the resistor connected in series is connected to the over-voltage circuit 150, and the other end is grounded. Any common end of the resistors connected in series outputs the overcharge test voltage divider VDD_DIV_TEST to the test signal generating circuit 112. It can be understood that the number and resistance values ​​of the resistors selected by the test voltage divider circuit 111 and the common terminal from which the overcharge test divided voltage VDD_DIV_TEST is output need to be set according to the protection threshold of the battery pack protected by the actual battery protection chip, and this application will not elaborate on them.

[0050] In one embodiment, Figure 2As shown, the test signal generating circuit 112 includes a test comparison circuit 210, a noise suppression circuit 220 and a pulse generating circuit 230. The test comparison circuit 210 is connected to the test voltage divider circuit 111 and the noise suppression circuit 220. The noise suppression circuit 220 is connected to the pulse generating circuit 230. The pulse generating circuit 230 is connected to the test signal input circuit 113.

[0051] Specifically, the test comparison circuit 210 is used to output a test enable signal when the overcharge test voltage VDD_DIV_TEST is greater than or equal to the preset reference voltage VREF. The noise suppression circuit 220 is used to screen whether the test enable signal output by the test comparison circuit 210 is generated by noise interference, etc. If not, the noise suppression circuit 220 transmits the test enable signal to the pulse generation circuit 230. The pulse generation circuit 230 is used to output an overcharge test signal Test_Pulse with a preset test pulse width after receiving the test enable signal.

[0052] The noise suppression circuit 220 is a capacitor device, and the test enable signal output by the test comparison circuit 210 charges the capacitor of the noise suppression circuit 220. When the capacitor is fully charged, the test enable signal can be transmitted to the pulse generating circuit 230. In this way, the purpose of preventing the test enable signal from being mistakenly generated by noise interference is achieved. In addition, the pulse generating circuit 230 can be implemented by a pulse generator or a square wave generator.

[0053] In one embodiment, Figure 2 As shown, the test comparison circuit 210 includes a comparator U2, and the comparator U2 is connected to the test voltage divider circuit 111 and the noise suppression circuit 220. Specifically, the non-inverting end of the comparator U2 is the first input end, which is connected to the test voltage divider circuit 111 to obtain the overcharge test voltage divider VDD_DIV_TEST. The inverting end of the comparator U2 is the second input end, which is connected to the preset reference voltage VREF. The output end of the comparator U2 is connected to the noise suppression circuit 220 to output a test enable signal.

[0054] In order to avoid the fluctuation of the amplitude of the overcharge test voltage divider VDD_DIV_TEST output by the test voltage divider circuit 111 affecting the stable output of the test enable signal, thereby affecting the test of the battery protection chip. In one embodiment, the test voltage divider circuit 111 is also used to divide the voltage according to the power supply voltage of the external power supply terminal to obtain the overcharge hysteresis test voltage divider VDD_DIV_TESThys. Among them, the overcharge hysteresis test voltage divider VDD_DIV_TESThys is greater than the overcharge test voltage divider VDD_DIV_TEST. Correspondingly, the voltage divider component includes three resistors connected in series, and one end of the series connection is connected to the overcharge voltage circuit 150, and the other end is grounded, and the two common ends of the three resistors in series are connected to the comparator U2.

[0055] Correspondingly, in one embodiment, the test comparison circuit 210 also includes a data selector U1, a first input terminal of the data selector U1 is connected to a first common terminal of three resistors connected in series, a second input terminal of the data selector U1 is connected to a second common terminal of the three resistors connected in series, an output terminal of the data selector U1 is connected to a first input terminal of the comparator U2, and a control terminal of the data selector U1 is connected to the noise suppression circuit 220.

[0056] Among them, when the control terminal input of the data selector U1 is a low level, channel 1 is selected to obtain the overcharge test voltage divider VDD_DIV_TEST and output it to the in-phase terminal of the comparator U2; when the control terminal input of the data selector U1 is a high level, channel 2 is selected to obtain the overcharge hysteresis test voltage divider VDD_DIV_TESThys and output it to the in-phase terminal of the comparator U2.

[0057] Specifically, when the overcharge test voltage VDD_DIV_TEST is less than the preset reference voltage VREF, the test enable signal output by the comparator U2 is continuously at a low level. Then, the noise suppression circuit 220 continuously outputs a low level to the control end of the data selector U1, so that the data selector U1 continuously selects channel 1 to obtain the overcharge test voltage VDD_DIV_TEST and outputs it to the in-phase end of the comparator U2. By adjusting the supply voltage to the preset overcharge voltage, when the overcharge test voltage VDD_DIV_TEST received by the comparator U2 is greater than or equal to the preset reference voltage VREF, the output test enable signal is flipped to a high level. When the pulse generating circuit 230 receives the test enable signal and outputs the overcharge test signal Test_Pulse, the high-level test enable signal is input to the control end of the data selector U1, so that the data selector U1 switches to select channel 2 to obtain the overcharge hysteresis test voltage VDD_DIV_TESThys and outputs it to the in-phase end of the comparator U2. Since the overcharge hysteresis test voltage divider VDD_DIV_TESThys is greater than the overcharge test voltage divider VDD_DIV_TEST, it can be ensured that the overcharge hysteresis test voltage divider VDD_DIV_TESThys is necessarily greater than the preset reference voltage VREF, further ensuring the stable output of the test enable signal.

[0058] In the battery protection chip 100 corresponding to the embodiment of the present application, the overcharge output circuit 180 includes a reset / set trigger, that is, an RS latch. The overcharge output circuit 180 can be composed of two NOR gates or two NAND gates. In this embodiment, Figure 3As shown, an RS latch composed of two NAND gates is used as an example for explanation. The specific working principle of the RS latch is not repeated here. Correspondingly, in this application, the S input terminal of the RS latch is connected to the overcharge delay circuit 170, and the overcharge delay circuit 170 inputs the overcharge trigger signal Tov_Pulse to the S input terminal of the RS latch after passing through a logic NOT gate. The R input terminal of the RS latch is connected to the overcharge comparison circuit 160 to receive the overcharge comparison signal OV.

[0059] Correspondingly, based on the need to test the overcharge protection function of the battery protection chip 100, the test signal input circuit 113 needs to be connected to the S input terminal of the RS latch to input the overcharge test signal Test_Pulse to replace the overcharge trigger signal Tov_Pulse output by the overcharge delay circuit 170, so that the overcharge output circuit directly outputs the overcharge signal OV_Delay according to the overcharge test signal Test_Pulse and the overcharge comparison signal OV, thereby shortening the trigger time of the chip's overcharge protection action and achieving the purpose of improving test efficiency.

[0060] Specifically, the structure of the test signal input circuit 113 is not unique, and can be consistent with the overcharge delay circuit 170, and can be implemented by a logic NOT gate. The overcharge test signal Test_Pulse generated by the test signal generating circuit 112 is transmitted to the S input terminal of the RS latch through a logic NOT gate. In addition, in one embodiment, Figure 3 As shown, the test signal input circuit 113 is a NOR logic gate NOR1, the first input end of the NOR logic gate NOR1 is connected to the test signal generating circuit 112, the second input end of the NOR logic gate NOR1 is connected to the overcharge delay circuit 170 of the battery protection chip 100, and the output end of the NOR logic gate NOR1 is connected to the overcharge output circuit 180. In this embodiment, the overcharge trigger signal Tov_Pulse of the overcharge delay circuit 170 and the overcharge test signal Test_Pulse of the test signal generating circuit 112 are input to the overcharge output circuit 180 through an NOR logic gate NOR1. The overcharge protection test function can be added without affecting the triggering of the original overcharge protection function of the battery protection chip 100, which can reduce the number of devices on the chip and is conducive to chip miniaturization and integration.

[0061] In one embodiment, Figure 4 As shown, the test circuit of the battery protection chip further includes a middle test circuit, and the middle test circuit is connected to the overcharge comparison circuit 160 .

[0062] Specifically, the intermediate test circuit is used for pre-packaging testing of the battery protection chip, and the chip parameters can be adjusted according to the test results so that the chip parameters are adjusted to the specification range. Among them, the intermediate test circuit includes an OR gate OR1, a resistor R1 and a detection gasket TEST. The first input end of the OR gate OR1 is connected to the output end of the overcharge comparison circuit 160, the second input end of the OR gate OR1 is connected to the output end of the over-discharge comparison circuit of the battery protection chip, and the output end of the OR gate OR1 is connected to the detection gasket TEST through the resistor R1. Furthermore, when performing pre-packaging testing, the output signals of the overcharge comparison circuit 160 and the over-discharge comparison circuit can be obtained by connecting the detection gasket TEST through the detection needle.

[0063] It can be understood that the test circuit 110 in any of the above embodiments can be applied to test the overcharge protection function of the battery protection chip 100. Among them, the test of the overcharge protection function of the battery protection chip 100 can be divided into the CP (Chip Probe) test in the pre-packaging stage and the FT (Final Test) test after packaging. The CP test can detect the parameters of the chip and adjust them to the specification range. The FT test can be used to eliminate chips whose parameters are out of range due to packaging. Correspondingly, the intermediate test circuit is applied to the CP test stage, and can be removed from the battery protection chip after the test is completed, saving space for the battery protection chip. The test voltage divider circuit 111, the test signal generating circuit 112 and the test signal input circuit 113 are applied to the FT test stage, and need to be packaged in the finished product of the battery protection chip 100 together with other circuits in the chip to ensure that the FT test is completed.

[0064] In one embodiment, Figure 1 As shown, a battery protection chip 100 is provided, including a control chip 120, a load detection circuit 130, a reference circuit 140, an over-voltage circuit 150, an overcharge comparison circuit 160, an overcharge delay circuit 170, an overcharge output circuit 180, a charging control switch 190 and the above-mentioned test circuit 110, the test circuit 110 is connected to the reference circuit 140, the over-voltage circuit 150 and the overcharge output circuit 180, the load detection circuit 130 is connected to the external detection terminal VM, the overcharge comparison circuit 160, the overcharge delay circuit 170, the overcharge output circuit 180, the charging control switch 190 and the above-mentioned test circuit 110, 60 and the reference circuit 140, the overcharge voltage circuit 150 is connected to the external power supply terminal VDD and the overcharge comparison circuit 160, the overcharge comparison circuit 160 is connected to the reference circuit 140, the overcharge delay circuit 170 and the overcharge output circuit 180, the overcharge delay circuit 170 is connected to the overcharge output circuit 180, the overcharge output circuit 180 is connected to the control chip 120, the control chip 120 is connected to the charging control switch 190, and the charging control switch 190 is connected to the external detection terminal VM and the external ground terminal GND.

[0065] The control end of the charging control switch 190 is connected to the control chip 120, one end of the charging control switch 190 is connected to the positive end of the external load through the external detection terminal VM, and the other end of the charging control switch 190 is connected to the negative end of the lithium battery through the external ground terminal GND. The charging control switch 190 is connected in series in the charging circuit of the lithium battery protected by the battery protection chip, and is controlled by the control chip 120 to turn on or off the charging circuit of the lithium battery.

[0066] The reference circuit 140 is used to output reference signals used by various circuits in the battery protection chip 100, for example, it can output the preset reference voltage VREF required in the overcharge comparison circuit 160 and the test circuit 110, and can also output the preset load reference voltage VREF_Loader required in the load detection circuit 130. The input source of its power supply is not unique, and it can be obtained by connecting to the external power supply terminal VDD or by connecting to the control chip 120.

[0067] In addition, since the battery protection chip 100 can determine when to return to a normal state based on whether a load is connected when in an overvoltage state. It can be understood that when no load is connected, the lithium battery protected by the battery protection chip needs to reduce the voltage to a normal state by self-discharge, and the corresponding recovery threshold is the overcharge detection recovery voltage VDD_DIV_OVhys. When a load is connected, the voltage can be reduced to a normal state by load discharge, and the corresponding recovery threshold is the overcharge detection voltage VDD_DIV_OV. Among them, the overcharge detection voltage VDD_DIV_OV is greater than the overcharge detection recovery voltage VDD_DIV_OVhys.

[0068] Therefore, the load detection circuit 130 can be connected to the data selector U3 of the overcharge comparison circuit 160 to control the selection of the recovery threshold from the overcharge state to the normal state. Among them, the load detection circuit 130 is a comparator U5, the in-phase end of the comparator U5 is connected to the external detection terminal VM, the inverting end of the comparator U5 is connected to the reference circuit 140, and the output end of the comparator U5 is connected to the control end of the data selector U3 of the overcharge comparison circuit 160. Specifically, according to the comparison between the load detection voltage of the external detection terminal VM and the preset load reference voltage VREF_Loader, the principle of correspondingly controlling the selection of the data selector U3 is similar to that of selecting the data selector U1 in the above-mentioned test circuit, and will not be repeated.

[0069] Specifically, after receiving the overcharge test signal Test_Pulse and the overcharge comparison signal OV, the overcharge output circuit 180 directly outputs the overcharge signal OV_Dealy to the control chip 120. The control chip 120 can output a shutdown signal to the control end of the charging control switch 190 according to the overcharge signal OV_Dealy, and control the charging control switch 190 to cut off the connection between the external detection terminal VM and the external ground terminal GND. Furthermore, in actual applications, the charging circuit of the lithium battery is cut off, so that the entire battery system enters an overcharge state.

[0070] The specific definition in the battery protection chip embodiment can refer to the definition of the test circuit of the battery protection chip above, which will not be repeated here.

[0071] In this embodiment, the test circuit is powered by the existing external power supply terminal of the battery protection chip, and then the test circuit is controlled to output an overcharge test signal to replace the delay signal of the overcharge protection action, so that the overcharge output circuit of the chip directly outputs an overcharge signal according to the overcharge test signal and the overcharge comparison signal, shortening the triggering time of the chip's overcharge protection action and improving the test efficiency. At the same time, there is no need to add a special test PIN pin to the battery protection chip, saving the chip packaging cost and facilitating product miniaturization.

[0072] In one embodiment, Figure 5 As shown, a battery protection chip testing device is provided, which performs an overcharge protection test on the battery protection chip 100 based on the test circuit 110, including a main controller 310, a test pin (not shown), a first power supply V1, a second power supply V2 and a parameter detection module 320, the main controller 310 connects the test pin, the first power supply V1, the second power supply V2 and the parameter detection module 320, the test pin is connected to the middle test circuit of the test circuit 110, the first power supply V1 is connected to the external power supply terminal VDD and the external ground terminal GND of the battery protection chip 100, the second power supply V2 is connected to the external detection terminal VM and the external ground terminal GND of the battery protection chip 100, and the parameter detection module Block 320 is connected to the external detection terminal VM; the first power supply V1 is used to output the power supply voltage to the battery protection chip 100; the second power supply V2 is used to output the load detection voltage to the battery protection chip 100; the test pin is used to detect the first level state output by the intermediate test circuit; the first level state is determined according to the overcharge comparison signal output by the overcharge comparison circuit 160 of the battery protection chip 100; the parameter detection module 320 is used to detect the second level state of the external detection terminal VM; the second level state is determined according to the overcharge signal output by the overcharge output circuit 180 of the battery protection chip 100; the main controller 310 is used to analyze and obtain the test result according to the first level state and the second level state.

[0073] It can be understood that the overcharge protection test performed on the battery protection chip to be tested by the battery protection chip testing device of this embodiment and the above-mentioned test circuit 110 may include an overcharge protection CP test and an overcharge protection FT test in sequence.

[0074] Specifically, during the overcharge protection CP test, the main controller 310 controls the supply voltage output by the first power supply V1 to increase according to a preset step length starting from the overcharge voltage lower limit threshold. Synchronously, the overcharge test voltage VDD_DIV_TEST output by the overcharge voltage circuit 150 also increases accordingly. The test needle continuously detects the first level state output by the detection pad TEST of the test circuit, and feeds back the first level state to the main controller 310 in real time. It can be understood that when the overcharge test voltage VDD_DIV_TEST increases to a value greater than the preset reference voltage VREF, the first level state is flipped from a low level to a high level. The main controller 310 can determine the voltage value of the supply voltage output by the first power supply V1 when the first level state is flipped to a high level as the overcharge protection detection threshold of the battery protection chip to be tested. Further, if this overcharge protection detection threshold does not meet the parameter specifications, corresponding adjustments can be made until the parameter specifications are met after detection. Among them, the overcharge voltage lower limit threshold is the lower limit value of the overcharge protection threshold corresponding to the actual product parameter specifications. The value of the preset step size is not fixed and can be set according to actual test requirements.

[0075] Furthermore, before the overcharge protection FT test, the battery protection chip to be tested must be in an overcharge state and the load connection must be detected, so that its overcharge recovery voltage threshold is equal to the overcharge protection voltage threshold, without hysteresis voltage, further shortening the overcharge protection test time.

[0076] It can be understood that the present application encapsulates the charging control switch 190 and its control terminal inside the battery protection chip. During the FT test phase, it is impossible to detect the level change of the control signal to determine whether the battery protection chip is in an overcharge state, but it is achieved by detecting the second level state of the external detection terminal VM through the parameter detection module 320. Among them, the second power supply V2 is a voltage source with current limiting. Specifically, when the charging control switch 190 is switched to the disconnected state by the control signal of the control chip 120, the voltage of the external detection terminal VM connected to it is the voltage applied by the second power supply V2. When the charging control switch 190 is switched to the on state by the control signal of the control chip 120, due to the on-resistance on the charging control switch 190, the current value flowing through will be much greater than the current limiting value of the second power supply V2, so the voltage of the second power supply V2 will be pulled down to close to 0V, that is, the voltage tested to the external detection terminal VM is also close to 0V. Correspondingly, when the second level state detected by the parameter detection module is the voltage applied by the second power supply V2, the battery protection chip to be tested is in an overcharged state; when the second level state detected by the parameter detection module is 0V, the battery protection chip to be tested is not in an overcharged state. In addition, the current limit value of the second power supply V2 is not limited and can be selected according to the actual battery protection chip and the protected lithium battery. For example, in this embodiment, the current limit value of the second power supply V2 is 10mA to 50mA.

[0077] Specifically, the main controller 310 controls the first power supply V1 to output a power supply voltage to the external power supply terminal VDD as a preset overcharge voltage, so that the battery protection chip to be tested quickly enters an overcharge state. Among them, the preset overcharge voltage is a voltage value that is much higher than the overcharge protection detection threshold of the protection chip to be tested. Taking the lithium battery with a protection specification of 4.2V as an example, the overcharge protection threshold can be 4.3V, and the preset overcharge voltage can be set to 6V accordingly to ensure that the battery protection chip to be tested is in an overcharge state. It can be understood that after the first power supply V1 outputs a power supply voltage with a preset overcharge voltage to the external power supply terminal VDD, the preset overcharge voltage is divided by the test voltage divider circuit 111 in the test circuit 110, and the overcharge test divided voltage VDD_DIV_TEST is output to its test signal generating circuit 112. Then, the test signal generating circuit 112 outputs the overcharge test signal Test_Pulse which is directly transmitted to the overcharge output circuit 180 through the test signal input circuit 113 without delay, so that when the overcharge output circuit 180 receives the overcharge test signal Test_Pulse and the overcharge comparison signal OV, it directly outputs the overcharge signal OV_Dealy, and the battery protection chip is in an overcharge state.

[0078] In addition, the main controller 310 controls the load detection voltage output by the second power supply V2 to be a preset load voltage, so that the load detection circuit 130 inside the battery protection chip to be tested outputs a high level and detects that the load is connected. Then the data selector U3 of the overcharge comparison circuit 160 is controlled to select the overcharge detection voltage divider VDD_DIV_OV to enter the in-phase end of its comparator U5. Since the overcharge detection voltage divider VDD_DIV_OV is greater than the overcharge detection recovery voltage divider VDD_DIV_OVhys, the recovery voltage drop during the test can be smaller, and the test time can also be saved. Among them, the preset load voltage is a voltage value greater than the preset load reference voltage VREF_Loader, and the specific value can be selected according to the actual test situation.

[0079] When the main controller 310 converts the second level state from 0V to the voltage applied by the second power supply V2 according to the parameter detection module 320, it can be determined that the battery protection chip is in an overcharge state and can enter the overcharge protection FT test.

[0080] In the overcharge protection FT test, the supply voltage input to the external power supply terminal VDD needs to be adjusted to the upper and lower limits of the overcharge protection threshold corresponding to the parameter specifications of the battery protection chip to be tested. Then, when the upper limit is reached, the battery protection chip to be tested is in an overcharge state, and when the lower limit is reached, the battery protection chip to be tested is in a normal state. In this case, the FT test result of the protection chip to be tested is qualified, and the parameters are not out of range due to packaging.

[0081] Correspondingly, the main controller 310 controls the supply voltage output by the first power supply V1 to be the first preset test voltage and the second preset test voltage in sequence. The parameter acquisition module 320 acquires the second level state corresponding to the first preset test voltage and the second level state corresponding to the second preset test voltage, and feeds back the above two second level states to the main controller 310. Further, the main controller 310 obtains the FT test result of the battery protection chip to be tested according to whether the second level state corresponding to the first preset test voltage and the second level state corresponding to the second preset test voltage meet the qualified level state. In this embodiment, taking the first preset test voltage as the upper limit value of the overcharge protection threshold of the battery protection chip to be tested and the second preset test voltage as the lower limit value of the overcharge protection threshold of the battery protection chip to be tested as an example, when the second level state corresponding to the first preset test voltage is the voltage applied by the second power supply V2, and the second level state corresponding to the second preset test voltage is 0V, the FT test result of the battery protection chip to be tested is qualified.

[0082] The specific definition in the embodiment of the battery protection chip testing device can refer to the definition of the test circuit of the battery protection chip in the above text, which will not be repeated here.

[0083] In this embodiment, by increasing the power supply to the existing external power supply terminal of the battery protection chip to be tested, the test circuit therein outputs an overcharge test signal to replace the delay signal of the overcharge protection action, so that the overcharge output circuit of the chip directly outputs an overcharge signal according to the overcharge test signal and the overcharge comparison signal, thereby shortening the triggering time of the overcharge protection action of the chip and improving the test efficiency.

[0084] In one embodiment, Figure 6 As shown, a method for testing a battery protection chip is provided, which is implemented based on the main controller of the battery protection chip testing device mentioned above, and includes:

[0085] Step 602: Control the supply voltage output by the first power supply to increase according to a preset step length, so as to obtain a first level state returned by the test pin.

[0086] Specifically, during the overcharge protection CP test, the main controller controls the supply voltage output by the first power supply V1 to increase according to a preset step length starting from the overcharge voltage lower limit threshold. Synchronously, the overcharge test voltage divider VDD_DIV_TEST output by the overcharge voltage circuit also increases accordingly. The test needle continuously detects the first level state output by the detection pad TEST of the test circuit, and feeds back the first level state to the main controller in real time. It can be understood that when the overcharge test voltage divider VDD_DIV_TEST increases to be greater than the preset reference voltage VREF, the first level state is flipped from a low level to a high level.

[0087] Step 604: Control the supply voltage output by the first power supply to be a preset overcharge voltage, and control the load detection voltage output by the second power supply to be a preset load voltage.

[0088] Before the overcharge protection FT test, the battery protection chip to be tested must be in an overcharge state and the load connection must be detected, so that its overcharge recovery voltage threshold is equal to the overcharge protection voltage threshold, without hysteresis voltage, further shortening the overcharge protection test time.

[0089] Specifically, the main controller controls the first power supply V1 to output a power supply voltage to the external power supply terminal VDD as a preset overcharge voltage, so that the battery protection chip to be tested quickly enters an overcharge state. Among them, the preset overcharge voltage is a voltage value that is much higher than the overcharge protection detection threshold of the protection chip to be tested. It can be understood that after the first power supply V1 outputs a power supply voltage of the preset overcharge voltage to the external power supply terminal VDD, the preset overcharge voltage is divided by the test voltage divider circuit in the test circuit, and the overcharge test divided voltage VDD_DIV_TEST is output to its test signal generating circuit. Then, the test signal generating circuit outputs an overcharge test signal Test_Pulse, which is directly transmitted to the overcharge output circuit through the test signal input circuit without delay, so that when the overcharge output circuit receives the overcharge test signal Test_Pulse and the overcharge comparison signal OV, it directly outputs the overcharge signal OV_Dealy, and the battery protection chip is in an overcharge state.

[0090] Furthermore, the main controller controls the load detection voltage output by the second power supply V2 to be a preset load voltage, so that the load detection circuit 130 inside the battery protection chip to be tested outputs a high level and detects that the load is connected. Then the data selector U3 of the overcharge comparison circuit is controlled to select the overcharge detection voltage VDD_DIV_OV to enter the in-phase end of its comparator U5. Since the overcharge detection voltage VDD_DIV_OV is greater than the overcharge detection recovery voltage VDD_DIV_OVhys, the recovery voltage drop during the test can be reduced, which can also save test time.

[0091] Step 606: When the battery protection chip is judged to be in an overcharge state according to the second level state returned by the parameter detection module, the supply voltage output by the first power supply is controlled to be the first preset test voltage and the second preset test voltage in sequence to obtain the second level state corresponding to the first preset test voltage and the second level state corresponding to the second preset test voltage.

[0092] When the main controller converts the second level state from 0V to the voltage applied by the second power supply V2 according to the parameter detection module, it can be determined that the battery protection chip is in an overcharge state and can enter the overcharge protection FT test. In the overcharge protection FT test, the power supply voltage input to the external power supply terminal VDD must be adjusted to the upper and lower limits of the overcharge protection threshold corresponding to the parameter specifications of the battery protection chip to be tested. Then, when the upper limit is reached, the battery protection chip to be tested is in an overcharge state, and when the lower limit is reached, the battery protection chip to be tested is in a normal state. It can be determined that the FT test result of the protection chip to be tested is qualified, and the parameters are not out of range due to packaging.

[0093] Correspondingly, the main controller controls the supply voltage output by the first power supply V1 to be the first preset test voltage and the second preset test voltage in turn. The parameter acquisition module acquires the second level state corresponding to the first preset test voltage and the second level state corresponding to the second preset test voltage, and feeds the above two second level states back to the main controller.

[0094] Step 608: Analyze and obtain the test result of the battery protection chip according to the first level state, the second level state corresponding to the first preset test voltage, and the second level state corresponding to the second preset test voltage.

[0095] Specifically, the main controller can determine the voltage value of the supply voltage output by the first power supply V1 corresponding to the first level state when the first level state is flipped to a high level as the overcharge protection detection threshold of the battery protection chip to be tested. If this overcharge protection detection threshold does not meet the parameter specifications, corresponding adjustments can be made until the parameter specifications are met after detection. Among them, the lower limit threshold of the overcharge voltage is the lower limit value of the overcharge protection threshold corresponding to the actual product parameter specifications. The value of the preset step size is not fixed and can be set according to the actual test requirements. It can be understood that only when the overcharge protection detection threshold of the battery protection chip to be tested is adjusted until the parameter specifications are met after detection, packaging is performed, and the FT stage test is performed after packaging.

[0096] Further, the main controller obtains the FT test result of the battery protection chip to be tested according to whether the second level state corresponding to the first preset test voltage and the second level state corresponding to the second preset test voltage meet the qualified level state. In this embodiment, taking the first preset test voltage as the upper limit value of the overcharge protection threshold of the battery protection chip to be tested and the second preset test voltage as the lower limit value of the overcharge protection threshold of the battery protection chip to be tested as an example, when the second level state corresponding to the first preset test voltage is the voltage applied by the second power supply V2 and the second level state corresponding to the second preset test voltage is 0V, the FT test result of the battery protection chip to be tested is qualified.

[0097] The following Figure 7The overcharge protection FT test flow chart shown in the figure is used as an example for explanation. First, the power supply voltage output by the first power supply V1 is powered on to 3.6V, which is within the normal working range. After the test starts, the power supply voltage output by the first power supply V1 is jumped to the preset overcharge voltage, so that the battery protection chip to be tested is in an overcharge state. Then the second power supply V2 is controlled to output a preset load voltage higher than the load detection reference voltage to the external detection terminal VM, so that the battery protection chip to be tested detects the load connection, so that its overcharge recovery voltage threshold is equal to the overcharge protection voltage threshold, and there is no hysteresis voltage. It is judged whether it has entered the overcharge state at this time. If not, the FT test result of the protection chip to be tested is judged to be unqualified. If it has entered the overcharge state, the power supply voltage output by the first power supply V1 is adjusted down to the upper limit of the overcharge protection voltage threshold, and it is judged whether the protection chip to be tested is still in the overcharge state at this time. If not, the FT test result of the protection chip to be tested is judged to be unqualified. If it is still in the overcharge state, the power supply voltage output by the first power supply V1 is adjusted down to the lower limit of the overcharge protection voltage threshold, and it is judged whether the protection chip to be tested has recovered to the normal state at this time. If it is not restored, the FT test result of the protection chip to be tested is judged to be unqualified. If it is restored, the FT test result of the protection chip to be tested is judged to be qualified.

[0098] The specific definition in the embodiment of the battery protection chip testing method can refer to the definition of the battery protection chip testing circuit mentioned above, which will not be repeated here.

[0099] In this embodiment, by increasing the power supply to the existing external power supply terminal of the battery protection chip to be tested, the test circuit therein outputs an overcharge test signal to replace the delay signal of the overcharge protection action, so that the overcharge output circuit of the chip directly outputs an overcharge signal according to the overcharge test signal and the overcharge comparison signal, thereby shortening the triggering time of the overcharge protection action of the chip and improving the test efficiency.

[0100] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A test circuit for a battery protection chip, characterized in that: include: A test voltage-dividing circuit, a test signal generating circuit and a test signal input circuit, wherein the test voltage-dividing circuit is connected to the external power supply terminal through the overcharge voltage circuit of the battery protection chip, the test voltage-dividing circuit is also connected to the test signal generating circuit, the test signal generating circuit is connected to the test signal input circuit, and the test signal input circuit is connected to the overcharge output circuit of the battery protection chip; The test voltage divider circuit is used to divide the voltage according to the power supply voltage of the external power supply terminal to obtain an overcharge test voltage divider; the overcharge test voltage divider is smaller than the overcharge detection voltage divider, and the overcharge detection voltage divider is output by the overcharge voltage divider circuit; The test signal generating circuit outputs an overcharge test signal to the test signal input circuit when the overcharge test divided voltage is greater than or equal to a preset reference voltage; The test signal input circuit is used to output the received overcharge test signal to the overcharge output circuit, so that the overcharge output circuit outputs an overcharge signal according to the overcharge test signal and the overcharge comparison signal; wherein the overcharge comparison signal is obtained by the overcharge comparison circuit of the battery protection chip according to the overcharge detection voltage division and the preset reference voltage; The test signal generating circuit comprises a test comparison circuit, a noise suppression circuit and a pulse generating circuit, wherein the test comparison circuit is connected to the test voltage divider circuit and the noise suppression circuit, the noise suppression circuit is connected to the pulse generating circuit, and the pulse generating circuit is connected to the test signal input circuit; The test comparison circuit comprises a comparator, and the comparator is connected to the test voltage divider circuit and the noise suppression circuit; The test voltage-dividing circuit comprises a voltage-dividing component, and the voltage-dividing component is connected to the overvoltage circuit and the test comparison circuit; The voltage divider component includes three resistors connected in series, one end of which is connected to the overvoltage circuit and the other end is grounded; The test comparison circuit also includes a data selector, a first input end of the data selector is connected to a first common end of three resistors in series, a second input end of the data selector is connected to a second common end of three resistors in series, an output end of the data selector is connected to the first input end of the comparator, and a control end of the data selector is connected to the noise suppression circuit.

2. The test circuit of the battery protection chip according to claim 1, characterized in that: The noise suppression circuit is a capacitor device.

3. The test circuit of the battery protection chip according to claim 2, characterized in that: The pulse generating circuit is a pulse generator.

4. The test circuit of the battery protection chip according to claim 2, characterized in that: The pulse generating circuit is a square wave generator.

5. The test circuit of the battery protection chip according to claim 1, characterized in that: The test signal input circuit is an NOR logic gate, a first input end of the NOR logic gate is connected to the test signal generating circuit, a second input end of the NOR logic gate is connected to the overcharge delay circuit of the battery protection chip, and an output end of the NOR logic gate is connected to the overcharge output circuit.

6. The test circuit of the battery protection chip according to any one of claims 1 to 5, characterized in that: It also includes a mid-test circuit, which is connected to the overcharge comparison circuit.

7. The test circuit of the battery protection chip according to claim 6, characterized in that: The intermediate test circuit includes an OR gate OR1, a resistor R1 and a detection pad, a first input end of the OR gate OR1 is connected to the overcharge comparison circuit, a second input end of the OR gate OR1 is connected to the over-discharge comparison circuit of the battery protection chip, and an output end of the OR gate OR1 is connected to the detection pad through the resistor R1.

8. A battery protection chip, characterized in that: It includes a control chip, a load detection circuit, a reference circuit, an over-full voltage circuit, an overcharge comparison circuit, an overcharge delay circuit, an overcharge output circuit, a charging control switch and a test circuit according to any one of claims 1 to 7, wherein the test circuit is connected to the reference circuit, the over-full voltage circuit and the overcharge output circuit, the load detection circuit is connected to the external detection terminal, the overcharge comparison circuit and the reference circuit, the over-full voltage circuit is connected to the external power supply terminal and the overcharge comparison circuit, the overcharge comparison circuit is connected to the reference circuit, the overcharge delay circuit and the overcharge output circuit, the overcharge delay circuit is connected to the overcharge output circuit, the overcharge output circuit is connected to the control chip, the control chip is connected to the charging control switch, and the charging control is connected to the external detection terminal and the external ground terminal.

9. A battery protection chip testing device, which performs an overcharge protection test on the battery protection chip according to claim 8 based on the test circuit according to any one of claims 1 to 7, characterized in that: It includes a main controller, a test pin, a first power supply, a second power supply and a parameter detection module, the main controller is connected to the test pin, the first power supply, the second power supply and the parameter detection module, the test pin is connected to the intermediate test circuit of the test circuit, the first power supply is connected to the external power supply terminal and the external grounding terminal of the battery protection chip, the second power supply is connected to the external detection terminal and the external grounding terminal of the battery protection chip, and the parameter detection module is connected to the external detection terminal; The first power supply is used to output a supply voltage to the battery protection chip; The second power supply is used to output a load detection voltage to the battery protection chip; The test pin is used to detect a first level state output by the intermediate test circuit; the first level state is determined according to an overcharge comparison signal output by the overcharge comparison circuit of the battery protection chip; The parameter detection module is used to detect the second level state of the external detection terminal; The second level state is determined according to an overcharge signal output by an overcharge output circuit of the battery protection chip; The main controller is used for analyzing the first level state and the second level state to obtain a test result.

10. A method for testing a battery protection chip, implemented based on the main controller of the battery protection chip testing device according to claim 9, characterized in that: include: Controlling the supply voltage output by the first power supply to increase according to a preset step length to obtain a first level state returned by the test pin; Controlling the supply voltage output by the first power supply to be a preset overcharge voltage, and controlling the load detection voltage output by the second power supply to be a preset load voltage; When the battery protection chip is judged to be in an overcharge state according to the second level state returned by the parameter detection module, the supply voltage output by the first power supply is controlled to be a first preset test voltage and a second preset test voltage in sequence, and a second level state corresponding to the first preset test voltage and a second level state corresponding to the second preset test voltage are obtained; The test result of the battery protection chip is obtained by analyzing the first level state, the second level state corresponding to the first preset test voltage, and the second level state corresponding to the second preset test voltage.

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