A broken line detection circuit, a battery management chip and a broken line detection method

Abstract

A broken line detection method, comprising the following steps: the chip battery pin and the ground terminal pin are divided into N groups of battery pins, and the detection method of each group of battery pins is as follows: step 1. The on-off switch in the group is closed, and after a closing time, the on-off switch in the group is opened, and the voltage detection device detects the voltage difference between the battery pins in the group at this time; step 2. The upper adjacent on-off switch is closed, and after a closing time, it is opened, and after a set opening time, the voltage difference between the battery pins in the group at this time is detected; step 3. Detect the difference, if the difference exceeds the set difference threshold, it is judged that the battery connected between the current group of battery pins is broken; when both are less than the lower threshold, it is judged that the current group of battery pins is short-circuited; step 4. Repeat steps 1 to 3 to detect each group of battery pins. The application does not need to additionally set the configuration pin, and can realize the broken line detection by using the switch array and the voltage detection circuit, thereby saving the pin resources.

Description

Technical Field

[0001] This invention belongs to the field of integrated circuit technology, and relates to battery management chip technology, specifically to a disconnection detection circuit, a battery management chip, and a disconnection detection method. Background Technology

[0002] Lithium-ion battery management chips commonly support applications with different numbers of lithium-ion battery cells per chip model. Currently, the common solution for pure hardware protection chips is to use one or more pins to configure the number of lithium-ion battery cells. The reason for configuring the number of lithium-ion battery cells is that different numbers of lithium-ion battery cells require different control logic within the chip for features such as disconnection protection, overvoltage protection during charging, and undervoltage protection during discharging. If the chip lacks disconnection protection, it may lead to overcharging or over-discharging of the lithium-ion battery, posing a safety hazard.

[0003] like Figure 2 The diagram shows the pins used by existing lithium battery management chips during battery configuration. Multiple battery pins VC1 to VC6 are connected in series to form a battery. For unused battery pins such as VC6, they are shorted to VC5. At the same time, different voltage signals need to be input through the configuration pins SEL0 and SEL1. The lithium battery management chip detects the voltage on these two configuration pins to determine how many batteries are currently connected and how many battery pins are short-circuited.

[0004] Because current technology requires a separate configuration pin for configuring the number of lithium batteries, if the chip package has a limited number of pins and cannot provide a configuration pin, the chip will not have a disconnection protection function. If the chip does not have a disconnection protection function, it may lead to the risk of overcharging or over-discharging of lithium batteries, posing a safety hazard. Using a separate configuration pin for configuring the number of lithium battery strings requires occupying the chip's pin resources. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention discloses a wire breakage detection circuit, a battery management chip, and a wire breakage detection method.

[0006] The wire breakage detection method of the present invention includes the following steps: Based on the connection relationship of the battery strings, all N battery pins and one ground pin of the chip are divided into N groups of battery pins. The first group consists of the first battery pin and the ground pin, the second group consists of the second battery pin and the first battery pin, the third group consists of the third battery pin and the second battery pin, and so on. The switch connecting two battery pins within the current group is defined as the switch within the group. The adjacent switches of the switch within the group include the upper adjacent switch and the lower adjacent switch. The switch within the group of the next battery pin of the current group according to the group number is defined as the upper adjacent switch of the current group, and the switch within the group of the previous battery pin of the current group according to the group number is defined as the lower adjacent switch of the current group. Set the difference threshold ΔVT, lower limit threshold LVT, closing time TON, and opening time TOFF; the detection method for each group of battery pins is as follows. Step 1. The switch within the group is closed. After a closing time TON, the switch within the group is opened. After a set opening time, the voltage detection device detects the voltage difference between the battery pins of the group at this time, which is recorded as VT1L. The adjacent switches in Step 1 remain open. Step 2. Close the adjacent upper switch. After the closing time TON, open the adjacent upper switch. After the set opening time TOFF, detect the voltage difference between the battery pins of this group at this time and record it as VT1H; in Step 2, switch K1 in the group remains open. In steps 1 and 2, when the switch is closed, the adjacent switches remain open; Step 3. Detect the difference between VT1L and VT1H. If the difference exceeds the set difference threshold ΔVT, it is determined that the battery connection between the current group of battery pins is broken. When both VT1H and VT1L are less than the lower threshold LVT, it is determined that the current group of battery pins is short-circuited. Step 4. Repeat steps 1 to 3 in the order of group 1, group 2, group 3, etc. to test the battery pins of each group.

[0007] Preferably, step 4 is replaced by: The battery pins are divided into odd and even groups according to their serial numbers. The odd and even groups are tested separately. During the test, the battery pins in the odd or even group are tested simultaneously in steps 1 to 3.

[0008] Preferably, in step 4, the detection of subsequent groups is terminated as soon as a broken wire is detected.

[0009] A disconnection detection circuit includes switches connected between adjacent battery pins and a switch connected between a ground pin and one of the battery pins, wherein the switches are connected in series. The circuit also includes a voltage detection device connected between each battery pin and the ground pin, the detection device being used to detect the voltage value on any one of the switches. The disconnection detection circuit further includes a control circuit for implementing the detection method.

[0010] Preferably, the voltage detection device is a comparator or an analog-to-digital converter.

[0011] A battery management chip includes multiple battery pins and the aforementioned disconnection detection circuit.

[0012] The battery management chip disconnection detection circuit and detection method described in this invention do not require additional configuration pins. Battery disconnection detection can be achieved using a switch array and voltage detection circuit, thus saving pin resources.

[0013] Meanwhile, since existing lithium battery management chips typically come with a switch array and voltage detection circuit to achieve voltage balance among the batteries, this invention can utilize the existing switch array and voltage detection circuit to detect pin disconnection during the brief period after normal power-on. Once it determines that there is no disconnection, it can release the relevant circuit module to resume normal operation. Therefore, there is no need to significantly add additional circuitry internally; only a small amount of logic circuitry is required. Attached Figure Description

[0014] Figure 1 is a schematic diagram of a specific embodiment of the wire breakage detection circuit of the present invention; Figure 2 This is a schematic diagram illustrating a specific implementation of an existing battery management chip. The labels in the diagram are as follows: VC1. First battery pin, VC2. Second battery pin, VC3. Third battery pin, VC4. Fourth battery pin, VC5. Fifth battery pin, VC6. Sixth battery pin, K1. First switch, K2. Second switch, K3. Third switch, K4. Fourth switch, K5. Fifth switch, K6. Sixth switch, CP1. First battery, CP2. Second battery, CP3. Third battery, CP4. Fourth battery, CP5. Fifth battery, CP6. Sixth battery, R1. First resistor, R2. Second resistor, R3. Third resistor, R4. Fourth resistor, R5. Fifth resistor, R6. Sixth resistor, C1. First capacitor, C2. Second capacitor, C3. Third capacitor, C4. Fourth capacitor, C5. Fifth capacitor, C6. Sixth capacitor, VSS. Ground pin, VCC. Power supply pin, ADC. Analog-to-digital converter. Detailed Implementation

[0015] The specific embodiments of the present invention will be described in further detail below.

[0016] like Figure 1As shown, the battery management chip includes a first battery pin VC1, a second battery pin VC2, a third battery pin VC3, a fourth battery pin VC4, a fifth battery pin VC5, a sixth battery pin VC6, a ground pin VSS, and a chip power supply pin VCC. All six battery pins are connected to a voltage detection device. The internal disconnection detection circuit of the chip includes: a first switch K1 connected between the first battery pin and the ground pin; a second switch K2 connected between the first and second battery pins; a third switch K3 connected between the second and third battery pins; a fourth switch K4 connected between the third and fourth battery pins; a fifth switch K5 connected between the fourth and fifth battery pins; and a sixth switch K6 connected between the fifth and sixth battery pins. The control terminals of each switch are connected to a control circuit.

[0017] The specific implementation of each switch can be a MOSFET, a transistor, or a transmission gate circuit.

[0018] Typical circuits for battery management chip applications include Figure 1 As shown, for each unshort-circuited online battery pin, a capacitor is connected between the first battery pin and the ground pin, and between two adjacent battery pins. Each online battery pin is also connected to a resistor, the other end of which is connected to the positive terminal of the battery to which that online battery pin is connected, such as... Figure 1 and 2 As shown, all batteries are connected in series, meaning the positive and negative terminals of adjacent batteries are connected. The negative terminal of the bottommost battery is connected to the ground pin VSS, and the topmost battery is also connected to the chip's power supply pin VCC.

[0019] With the above connection method, the batteries of each battery power supply circuit are connected in series to power the battery management chip.

[0020] For usage scenarios where the battery is not fully loaded, according to existing battery management chip usage specifications, when the battery is not fully loaded, some adjacent battery pins are not connected and are directly short-circuited, such as... Figure 1 As shown, the fifth and sixth battery pins, being the second and highest battery pins respectively, are directly short-circuited without any battery power supply circuit between them. Since at least one battery must be connected for the chip to function properly (otherwise, the chip will have zero power supply), this invention does not discuss the scenario where all battery pins and the ground pin VSS are short-circuited.

[0021] The typical circuit used in the above-mentioned battery management chip application is a conventional prior art in this field. This application improves the internal circuit of the chip based on this typical circuit.

[0022] During testing, the battery pins are grouped. The first battery pin VC1 and the ground pin VSS are the first group. Every two adjacent battery pins are grouped for testing. That is, the first battery pin VC1 and the second battery pin VC2 are the second group, the second battery pin VC2 and the third battery pin VC3 are the third group, and so on.

[0023] In this invention, the voltage detection device detects the intra-group voltage difference between two pins in the same group.

[0024] observe Figure 1 As can be seen, if one battery in the battery string fails and disconnects, the chip cannot detect the actual battery voltage, and the entire battery string will not conduct, preventing the chip from working properly. Therefore, the disconnection mentioned in this application does not refer to a break in the battery itself, but rather to a situation where the battery is working normally, but the positive terminal of the battery fails to connect to the battery detection pin due to reasons such as a broken connection wire or a broken circuit. At the same time, if the negative terminal of the first battery is not connected to the ground pin VSS, or the positive terminal of the last battery is not connected to the power supply pin VCC of the chip, the chip will also fail to work properly. Therefore, the disconnection described in this invention does not consider this situation.

[0025] When testing the first group of battery pins, the switch in the group is the first switch K1, and the switch adjacent to it above is the second switch K2. The testing is performed as follows: Step 1. The first switch K1 is closed. After the set closing time TON, the first switch K1 is opened. After the set opening time TOFF, the voltage detection device detects the voltage difference between the first battery pin VC1 and the ground pin VSS at this time, which is the intra-group voltage difference of the first group, denoted as VT1L; the second switch remains open in Step 1. Step 2. The second switch K2 is closed. After the set closing time TON, the second switch K2 is opened. After the set opening time TOFF, the pressure difference within the group is detected and recorded as VT1H. In Step 2, the first switch K1 and the third switch K3 remain open. The closing time TON needs to be set to ensure that the capacitor connected between the first group of battery pins is fully discharged to near zero, and the opening time TOFF needs to be set to ensure that the capacitor connected to the first group of battery pins is fully charged to its maximum value. The specific values ​​of closing time TON and opening time TOFF are determined based on the selected capacitor value, battery voltage, and internal switch on-resistance, etc.

[0026] Step 3. Detect the difference between VT1L and VT1H. If the difference exceeds the set difference threshold ΔVT, it is determined that the first battery CP1 is disconnected.

[0027] The specific analysis is as follows: Figure 1As shown, it is first assumed that the first battery is not disconnected and the grounding pin VSS is grounded; In step 1, K2 remains open, K1 closes first, the first capacitor C1 is short-circuited and discharged to zero, then K1 opens, the first battery CP1 charges the first capacitor to the positive terminal output voltage VCP1P of the first battery CP1, that is, VT1L=VCP1P; In step 2, K1 remains open, K2 closes first, and the first capacitor C1 is charged by both the first and second batteries. Subsequently, K2 is disconnected. Since K1 is also disconnected, regardless of the voltage of the first capacitor before K2 is disconnected, the first capacitor will be charged to the positive output voltage VCP1P of the first battery CP1 after K2 is disconnected, that is, VT1H=VCP1P. That is, in the case of no disconnection, VT1H=VT1L=VCP1P; Then assume the first battery is disconnected; In step 1, K2 remains open, K1 closes first, the first capacitor C1 is short-circuited and discharged to zero, then K1 opens, and since the first battery CP1 is disconnected, K2 also opens, the first capacitor cannot be charged, that is, VT1L=0; Assuming the second battery is not disconnected, in step 2, K1 remains open and K2 closes first. Since the first battery is disconnected, the first capacitor C1 is charged by the second battery through R2, VC2, and VC1; the charging voltage is the positive voltage VCP2P of the second battery. Subsequently, K2 disconnects. Since K1 also disconnects, the first battery is disconnected. After K2 disconnects, the first capacitor will maintain the voltage before K2 disconnects, i.e., VT1H=VCP2P. That is, when the first battery is disconnected and the second battery is not disconnected, VT1H=VCP2P, VT1L=0; VT1H - VT1L = VCP2P. Assuming the output voltages of the first and second batteries are VCP1 and VCP2 respectively, then VCP2P = VCP1 + VCP2. When the first battery is not disconnected, the difference between the two is theoretically zero. ΔVT can be set to a small value, such as 0.1V. As long as the difference is greater than 0.1V, the first battery can be considered disconnected.

[0028] The above analysis does not consider the case where the second battery is disconnected at the same time. If the second battery is disconnected at the same time, the first capacitor cannot be charged by the second battery when K2 is closed in step 2, so VT1H=0. At this time, it is impossible to conclude whether the first battery is disconnected when detecting the first group of battery pins. However, in the subsequent detection process, since the chip can work normally, at least one battery is normally connected to the battery pin, and a disconnection of a certain battery will inevitably be detected.

[0029] This application can detect whether a battery in a battery string is disconnected. When only one battery is disconnected, it can also detect which battery is disconnected. For the low-probability event of two or more batteries disconnecting at the same time, it can also detect the disconnection and remind the user. In reality, whenever a disconnection occurs, the entire battery power supply system needs to be inspected and replaced.

[0030] Assuming the first group of battery pins are shorted, since the grounding pin VSS is grounded, the voltage on the first battery pin VC1 is always zero, i.e., VT1H=VT1L=0.

[0031] Set a suitable lower limit threshold LVT, such as 0.1V. When both VT1H and VT1L are less than the lower limit threshold LVT, it is determined that the current group of battery pins is short-circuited.

[0032] When both short circuit and open circuit are detected simultaneously, the chip needs to be stopped, the circuit break point needs to be checked, and repaired.

[0033] If a broken wire has been detected in the first group of battery pins, no further detection will be performed. The system will be shut down and the detected broken wire fault will be processed. In this invention, the detection of each subsequent group of battery pins is assumed to be based on the assumption that no broken wire fault was detected before the detection of that group of battery pins.

[0034] When testing the second group of battery pins, the switch within the group is the second switch K2, the switch above switch K2 is the second switch K3, and the switch below switch K2 is the first switch K1. The process is as follows: Step 1. The second switch K2 is closed. After the set closing time TON, the second switch K2 is opened. After the set opening time TOFF, the voltage difference between the second battery pin VC2 and the first battery pin VC1 is detected and recorded as VT2L. In Step 1, the first switch K1 and the third switch K3 remain open. Step 2. The third switch K3 is closed. After the set closing time TON, the third switch K3 is opened. After the set opening time TOFF, the voltage difference between the second battery pin VC2 and the first battery pin VC1 is detected and recorded as VT2H. In Step 2, the second switch K2 and the fourth switch K4 remain open. The closing time TON needs to be set to ensure that the capacitor connected between the pins of the second set of batteries is fully discharged to near zero, and the opening time TOFF needs to be set to ensure that the capacitor connected between the pins of the second set of batteries is fully charged to its maximum value. The specific values ​​of closing time TON and opening time TOFF are determined based on the selected capacitor value, battery voltage, and internal switch on-resistance, etc.

[0035] Step 3. Detect the difference between VT2L and VT2H. If the difference exceeds the set threshold difference ΔVT, it is determined that the second battery CP2 is disconnected.

[0036] like Figure 1 As shown, it is first assumed that the second battery is not disconnected; the first switch K1 remains open. In step 1, K3 remains open, K2 closes first, and the second capacitor C2 is short-circuited and discharged until the voltage of the first battery pin VC1 is equal. Then K2 is opened, and the second battery CP2 charges the second capacitor C2. The voltage difference between the pins of the second group of batteries is the voltage VCP2 of the second battery, that is, VT2L=VCP2. In step 2, K2 remains open, and K3 closes first. When the third battery is disconnected, the second capacitor C2 will be charged by the second battery until the voltage difference between the pins of the second battery group is equal to the voltage VCP2 of the second battery. When the third battery is connected, the second capacitor C2 will be charged by both the third battery and the second battery. Subsequently, K3 is disconnected. Since the second battery is the power source, regardless of the voltage difference between the pins of the second battery group before K3 is disconnected, the second capacitor will be charged to the voltage difference between the pins of the second battery group equal to the voltage VCP2 of the second battery, i.e., VT2H=VCP2. That is, if the second battery is not disconnected, VT2H=VT2L=VCP2; During the detection process from step 1 to step 2, whether the first battery CP1 is online or the first group of battery pins is short-circuited, it only affects the absolute value of the voltage of the first battery pin VC1, and does not affect the voltage difference VCP2 between the second group of battery pins.

[0037] Then assume the second battery is disconnected; In step 1, K3 remains open, K2 closes first, the second capacitor C2 is short-circuited and discharged to the same voltage as the first battery pin VC1, the voltage difference between the pins of the second group of batteries is zero, then K2 is opened, since the second battery is disconnected and cannot supply power, the second battery CP2 cannot charge the second capacitor, the voltage difference between the pins of the second group of batteries remains the original voltage, that is, VT2L=0 at this time. In step 1, when the second switch is closed, the adjacent switches K1 and K3 remain open; In step 2, K2 remains open, and K3 closes first; When both the third and second batteries are disconnected, the voltage difference between the pins of the second battery group remains at its original value of 0. When the third battery is online, the positive terminal of the second capacitor C2 will be charged by the third battery through R3, VC3, K3, and VC2 to the output voltage VCP3P of the positive terminal of the third battery; the negative terminal of the second capacitor C2 maintains the output voltage VCP1P of the positive terminal of the first battery. Subsequently, K3 disconnects. Since the second battery is disconnected and K2 is also disconnected, the voltage between the positive and negative terminals of the second capacitor will remain at its original value; that is, VT2H = VCP3P - VCP1P. Therefore, when the third battery is connected and the second battery is disconnected, the difference between VT2H and VT2L is VT2H-VT2L=VCP3P-VCP1P. Since the positive voltage of the third battery, VCP3P, is equal to the sum of the output voltages of the first, second, and third batteries, and the positive voltage of the first battery, VCP1P, is equal to the output voltage of the first battery; that is, VT2H-VT2L=(VCP3+VCP2+VCP1)-VCP1=VCP3+VCP2, where VCP1, VCP2, and VCP3 are the output voltages of the first, second, and third batteries, respectively.

[0038] When the second battery is online, the difference between the two is zero. By setting ΔVT to a small value greater than zero, such as 0.1V, it can be determined whether the second battery is disconnected.

[0039] Similar to the analysis of the first group of battery pins, the voltage of the second capacitor C2 remains unchanged in step 2 when both the third and second batteries are disconnected. At this time, it is impossible to determine whether the second battery is disconnected, but in subsequent judgment, it will be found that there is a disconnection in the entire battery string, reminding the user to check the circuit.

[0040] In step 2, when the third switch is closed, the adjacent switches K2 and K4 remain open. Assume that the first battery pin VC1 and the second battery pin VC2 are shorted together; In step 1, K3 remains open. Since the first battery pin VC1 and the second battery pin VC2 are shorted, whether K2 is closed or not does not affect the short-circuit state of the first battery pin VC1 and the second battery pin VC2. The positive and negative voltages of the second capacitor are equal and equal to the positive voltage of the first capacitor, that is, VT2L=0. Because the first battery pin VC1 and the second battery pin VC2 are shorted, in step 2, regardless of the states of internal switches K2 and K3, or whether the third battery is shorted, the voltages at the positive and negative terminals of the second capacitor are always equal, i.e., VT2H = 0. It can be seen that when the first battery pin VC1 and the second battery pin VC2 are shorted, VT2H=VT2L=0, which are significantly smaller than when the battery is connected. When both VT2H and VT2L are less than the lower threshold LVT, it is considered that the first battery pin VC1 and the second battery pin VC2 are short-circuited.

[0041] The analysis of the second group of battery pins covers all possible scenarios, including disconnection, short circuit, and whether the battery connected to the next group of battery pins is online. Similar analysis methods can be used for subsequent groups of battery pins to arrive at similar conclusions.

[0042] Step 4. Repeat steps 1 to 3 in the order of group 1, group 2, group 3, etc., to detect the voltage of each group of battery pins. The voltage detection device can use a comparator or a single-channel analog-to-digital converter, and use time-division multiplexing to switch the input terminal to detect the voltage of different groups of battery pins at different times.

[0043] To save testing time, step 4 can be replaced by: dividing each group of battery pins into odd and even groups according to their serial numbers, and testing the odd and even groups separately. During testing, each group of battery pins in the odd or even group is tested simultaneously using steps 1 to 3.

[0044] For example, first test all odd-numbered groups of battery pins, i.e., the first group, the third group, the fifth group, etc. After all the tests are completed, test all even-numbered groups of battery pins, i.e., the second group, the fourth group, the sixth group, etc. At this time, the voltage detection device can use a multi-channel ADC to simultaneously input the voltage of multiple groups of battery pins for voltage difference detection and judgment.

[0045] After all battery pins are tested, if no open circuit is detected, the chip begins normal operation. The switches and voltage detection devices can then be used to perform other functions, such as battery balancing, while the chip is operating normally. If an open circuit is detected, the battery connection is checked after power is cut off, and repairs or replacements are performed. Power is then restored to perform the open circuit test again until no open circuit is detected, at which point the chip resumes normal operation.

[0046] The foregoing descriptions are preferred embodiments of the present invention. Unless there is a clear contradiction between the preferred embodiments or a premise based on a particular preferred embodiment, the preferred embodiments can be arbitrarily combined and used. The embodiments and specific parameters described are only for clearly illustrating the inventor's invention verification process and are not intended to limit the scope of patent protection of the present invention. The scope of patent protection of the present invention shall still be determined by its claims. Similarly, any equivalent structural changes made based on the content of the specification of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A method for detecting broken wires, characterized in that, Includes the following steps: Based on the connection relationship of the battery strings, all N battery pins and one ground pin of the chip are divided into N groups of battery pins. The first group is the first battery pin and the ground pin, the second group is the second battery pin and the first battery pin, the third group is the third battery pin and the second battery pin, ... the Nth group is the Nth battery pin and the (N-1)th battery pin, and so on. The switch connecting two battery pins within the current group is defined as the switch within the group. The adjacent switches of the switch within the group include the upper adjacent switch and the lower adjacent switch. The switch within the group of the next battery pin of the current group according to the group number is defined as the upper adjacent switch of the current group, and the switch within the group of the previous battery pin of the current group according to the group number is defined as the lower adjacent switch of the current group. Set the difference threshold ΔVT, lower limit threshold LVT, closing time TON, and opening time TOFF; the detection method for each group of battery pins is as follows. Step 1. The switch within the group is closed. After a closing time TON, the switch within the group is opened. After a set opening time, the voltage detection device detects the voltage difference between the battery pins of the group at this time, which is recorded as VT1L. The adjacent switches in Step 1 remain open. Step 2. Close the adjacent upper switch. After the closing time TON, open the adjacent upper switch. After the set opening time TOFF, detect the voltage difference between the battery pins of this group at this time and record it as VT1H; in Step 2, switch K1 in the group remains open. In steps 1 and 2, when the switch is closed, the adjacent switches remain open; Step 3. Detect the difference between VT1L and VT1H. If the difference exceeds the set difference threshold ΔVT, it is determined that the battery connection between the current group of battery pins is broken. When both VT1H and VT1L are less than the lower threshold LVT, it is determined that the current group of battery pins is short-circuited. Step 4. Repeat steps 1 to 3 to test the battery pins of each group in the order of the first group, the second group, the third group... the Nth group.

2. The wire breakage detection method as described in claim 1, characterized in that, Step 4 is replaced with: The battery pins are divided into odd and even groups according to their serial numbers. The odd and even groups are tested separately. During the test, the battery pins in the odd or even group are tested simultaneously in steps 1 to 3.

3. The wire breakage detection method as described in claim 1, characterized in that, In step 4, if a broken wire is detected, the detection of subsequent groups will be terminated.

4. A wire breakage detection circuit, characterized in that, The circuit includes switches connected between adjacent battery pins and a switch connected between a ground pin and one of the battery pins, wherein the switches are connected in series. It also includes a voltage detection device connected between each battery pin and the ground pin, the detection device being used to detect the voltage value on any one of the switches. The open circuit detection circuit further includes a control circuit for implementing the detection method as described in any one of claims 1 to 3.

5. The open circuit detection circuit as described in claim 4, characterized in that, The voltage detection device is a comparator or an analog-to-digital converter.

6. A battery management chip, comprising a plurality of battery pins, characterized in that, It also includes the wire breakage detection circuit as described in claim 4.

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