Battery protection chip

Abstract

This invention discloses a battery protection chip with a positive input terminal, a negative input terminal, a positive output terminal, and a negative output terminal. The chip includes a power switch module, a basic function module, and a battery voltage acquisition and processing unit. The power switch module is connected between the negative input terminal and the negative output terminal. The basic function module performs overcharge and over-discharge detection based on the voltage difference between the positive and negative input terminals, and performs overcurrent and short-circuit detection based on the voltage difference across the power switch module. The battery voltage acquisition and processing unit uses the negative input terminal as the input reference ground and the negative output terminal as the output reference ground, scales the battery voltage proportionally, and outputs a voltage detection signal common to the external ground from the positive output terminal. This invention can eliminate the sampling deviation caused by the parasitic diode voltage drop of the MOSFET in the power switch module during overcharge protection, achieving accurate battery voltage acquisition.

Description

Technical Field

[0001] This invention belongs to the field of battery protection technology, and in particular relates to a battery protection chip. Background Technology

[0002] Lithium-ion batteries, with their high energy density and long cycle life, are widely used in power banks, portable digital products, and small energy storage devices. Current mainstream lithium battery safety management solutions typically employ a hardware protection circuit composed of a lithium battery protection IC and a charge / discharge control MOSFET. This circuit monitors the battery cell voltage in real time and quickly cuts off the circuit when the voltage exceeds the limit, preventing safety hazards such as bulging and thermal runaway caused by overcharging, over-discharging, and overcurrent. However, the officially implemented national standard "Technical Specification for Safety of Mobile Batteries GB 47372-2026" (hereinafter referred to as the "New National Standard") explicitly requires in Chapter 6.8, the intelligent management clause, that after overcharging is triggered, the system must accurately collect and record real-time data on the voltage exceeding the upper limit of the charging voltage for a single battery cell, and must store the most unfavorable voltage value at one-hour intervals during overcharging. This imposes mandatory requirements on the accuracy of voltage collection under overcharging conditions.

[0003] While existing lithium battery protection architectures generally yield results consistent with battery voltage under normal operating conditions, overcharge protection triggers a parasitic diode voltage drop in the MOSFETs within the power switching module. This causes the sampled signal to deviate from the battery voltage, failing to meet the data recording requirements of the new national standard. Therefore, there is an urgent need to develop a novel circuit solution that, while retaining the basic overcharge and over-discharge hardware protection functions of the original protection IC, can effectively avoid interference from the parasitic diode voltage drop of the MOSFETs and achieve accurate battery voltage acquisition under overcharge conditions. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a battery protection chip.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A battery protection chip, the chip having a positive input terminal, a negative input terminal, a positive output terminal, and a negative output terminal, the chip comprising: The power switching transistor module has its first connection terminal connected to the negative input terminal of the chip, and its second connection terminal connected to the negative output terminal of the chip. The basic functional module has a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a drive output terminal. The first and second detection terminals are respectively connected to the positive and negative input terminals of the chip. The third and fourth detection terminals are respectively connected to the first and second connection terminals of the power switch module. The drive output terminal is connected to the controlled terminal of the power switch module. The basic functional module is used to detect overcharge and over-discharge of the battery based on the voltage difference between the positive and negative input terminals, to detect overcurrent and short circuit of the battery based on the voltage difference across the power switch module, and to control the power switch module to turn off when an abnormality is detected through the drive output terminal. A battery voltage acquisition and processing unit has its positive detection terminal connected to the positive input terminal of a chip, its negative detection terminal connected to the negative input terminal of a chip, its ground terminal connected to the negative output terminal of a chip, and its detection output terminal connected to the positive output terminal of a chip. It is used to scale the voltage between the positive and negative input terminals using the potential at the negative input terminal as the input reference ground and the potential at the negative output terminal as the output reference ground, and then output a voltage detection signal with the negative output terminal as the reference ground from the positive output terminal.

[0006] Furthermore, the power switch module includes one or more NMOS transistors connected in series, and the gate of each NMOS transistor serves as a controlled terminal of the power switch module.

[0007] A battery protection chip, the chip having a positive input terminal, a negative input terminal, a positive output terminal, a negative output terminal, and a power supply output terminal, the chip comprising: The power switching transistor module has its first connection terminal connected to the positive input terminal of the chip, and its second connection terminal connected to the power supply output terminal of the chip. The basic functional module has a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a drive output terminal. The first and second detection terminals are respectively connected to the positive and negative input terminals of the chip. The third and fourth detection terminals are respectively connected to the first and second connection terminals of the power switch module. The drive output terminal is connected to the controlled terminal of the power switch module. The basic functional module is used to detect overcharge and over-discharge of the battery based on the voltage difference between the positive and negative input terminals, to detect overcurrent and short circuit of the battery based on the voltage difference across the power switch module, and to control the power switch module to turn off when an abnormality is detected through the drive output terminal. A battery voltage acquisition and processing unit has its positive detection terminal connected to the positive input terminal of a chip, its negative detection terminal connected to the negative input terminal of a chip, its ground terminal connected to the negative output terminal of a chip, and its detection output terminal connected to the positive output terminal of a chip. It is used to scale the voltage between the positive and negative input terminals using the potential at the negative input terminal as the input reference ground and the potential at the negative output terminal as the output reference ground, and then output a voltage detection signal with the negative output terminal as the reference ground from the positive output terminal.

[0008] Furthermore, the power switch module includes one or more PMOS transistors connected in series, and the gate of each PMOS transistor serves as a controlled terminal of the power switch module.

[0009] Furthermore, the basic functional module includes an overcharge and over-discharge detection circuit, an overcurrent and short-circuit detection circuit, and a logic processing drive circuit. The two detection terminals of the overcharge and over-discharge detection circuit are respectively connected to the positive and negative input terminals of the chip, and its output terminal is connected to the first input terminal of the logic processing drive circuit, used to send a first protection signal to the logic processing drive circuit when an overcharge or over-discharge phenomenon is detected. The two detection terminals of the overcurrent and short-circuit detection circuit are respectively connected to the first and second connection terminals of the power switch module, and its output terminal is connected to the second input terminal of the logic processing drive circuit, used to send a second protection signal to the logic processing drive circuit when an overcurrent or short-circuit phenomenon is detected. The output terminal of the logic processing drive circuit is connected to the controlled terminal of the power switch module, used to turn off the power switch module when the first protection signal or the second protection signal is received.

[0010] Furthermore, the overcharge and over-discharge detection circuit, the overcurrent and short-circuit detection circuit, and the logic processing drive circuit in the basic functional module all use the potential at the negative input terminal as the internal reference ground.

[0011] Furthermore, the battery voltage acquisition and processing unit includes an operational amplifier OP1, resistors R1, R2, R3, and R4; the positive power supply terminal of the operational amplifier OP1 is electrically connected to the power supply terminal VCC; the non-inverting input terminal of the operational amplifier OP1 is electrically connected to the positive detection terminal VBAT+ through resistor R3, and the non-inverting input terminal of the operational amplifier OP1 is also electrically connected to its negative power supply terminal through resistor R4; the negative power supply terminal of the operational amplifier OP1 is electrically connected to the ground terminal Vneg; the inverting input terminal of the operational amplifier OP1 is electrically connected to the negative detection terminal VBAT- through resistor R1, and the inverting input terminal of the operational amplifier OP1 is also electrically connected to its output terminal through resistor R2; the output terminal of the operational amplifier OP1 is electrically connected to the detection output terminal VOUT.

[0012] Furthermore, the resistance values ​​of resistors R1 and R3 are equal, and the resistance values ​​of resistors R2 and R4 are equal.

[0013] Furthermore, when used in a multi-cell lithium battery protection circuit, the output voltage of operational amplifier OP1 can be kept within a predetermined voltage range by adjusting the ratio of the resistance of resistor R2 to that of resistor R4.

[0014] Furthermore, the power switching module includes two switching MOS transistors, which are connected back-to-back in a source-to-source manner.

[0015] In this invention, the battery voltage acquisition and processing unit uses the negative input terminal of the chip as the input reference ground and the negative output terminal of the chip as the output reference ground, realizing the separation and conversion of the input and output reference grounds. After overcharge protection is triggered, regardless of whether the negative output terminal of the chip is pulled down to negative voltage by the charger under the negative terminal protection architecture, or the voltage of the chip's power supply output terminal is raised by the charger under the positive terminal protection architecture, the parasitic diode of the MOSFET in the power switching module will generate a voltage drop due to current freewheeling. At this time, the battery voltage acquisition and processing unit anchors the output reference ground to the negative output terminal of the chip by differential detection and scaling of the acquired battery voltage, thereby effectively eliminating the interference of negative voltage offset or positive voltage offset and MOSFET parasitic diode voltage drop on the sampling signal. At the same time, with the help of a differential amplifier structure with symmetrical resistor matching and a high-gain operational amplifier, high-precision voltage scaling is achieved while adjusting the battery high voltage to the sampling range of the external MCU unit. This allows the external MCU unit to accurately restore the battery voltage based on the voltage detection signal output from the positive output terminal of the chip, meeting the specification requirements of the new national standard for overcharge voltage acquisition and timing storage of the most unfavorable value. Furthermore, the circuit architecture of this invention does not require any modification to the hardware protection circuit of the original protection IC, and can be widely used in various positive and negative protection products such as single-string discrete and multi-string discrete, with strong compatibility and low modification cost. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a structural block diagram of a battery negative terminal protection system in the prior art.

[0017] Figure 2 This is a structural block diagram of a battery positive terminal protection system in the prior art.

[0018] Figure 3 This is a structural block diagram of an embodiment of the battery protection chip of the present invention.

[0019] Figure 4 This is the circuit diagram of the battery voltage acquisition and processing unit.

[0020] Figure 5 This is a structural block diagram of a battery negative terminal protection system obtained using the battery protection chip of Example 1.

[0021] Figure 6 This is a structural block diagram of another embodiment of the battery protection chip of the present invention.

[0022] Figure 7 This is a structural block diagram of the battery positive terminal protection system obtained by using the battery protection chip of Example 2. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] Please see Figure 1 Currently, mainstream lithium battery negative terminal protection solutions on the market can be divided into single-string discrete protection IC solutions, single-string two-in-one lithium battery negative terminal protection IC solutions, and multi-string discrete protection IC solutions according to their architecture. Under normal battery charging and discharging conditions, the NMOS transistor remains in the conducting state, and the MCU unit directly samples the voltage across the battery cell via P+ and P-. The voltage acquisition result is basically consistent with the battery voltage, which can meet the normal voltage sampling requirements. However, under overcharge protection triggering scenarios, all existing protection architectures have inherent circuit defects and cannot achieve accurate battery voltage acquisition, making it difficult to meet the mandatory requirements of the new national standard for intelligent management.

[0025] In the application scenario of single-string discrete lithium battery negative terminal protection IC, the upper limit voltage of the battery cell for normal charging is generally 4.2V, and the output voltage of the matching charger is usually 5V. When the battery charging voltage exceeds the limit and triggers overcharge protection, the control pin output level of the protection IC jumps, driving the controlled NMOS transistor to turn off to cut off the main charging circuit. After the charging circuit is disconnected, the charger side voltage continues to act on the P- pin of the protection board, directly pulling the P- potential down to a negative voltage. Under typical operating conditions, the negative voltage can reach -0.8V. At this time, the NMOS transistor itself has a parasitic diode to maintain the potential conduction path of the circuit. During the process of the MCU unit collecting voltage through P+ and P-, the sampling circuit will superimpose the fixed voltage drop of the parasitic diode. Finally, the sampling voltage obtained by the MCU unit is the difference between the battery voltage and the voltage drop of the parasitic diode. The sampling value deviates from the battery voltage and cannot accurately capture the over-limit voltage of the battery at the moment of overcharging. It cannot accurately store the overcharge voltage data as required by the new national standard.

[0026] For a single-string dual-cell lithium battery negative terminal protection IC, due to overcharge protection, the P- terminal is also pulled down to a negative voltage by the charger, and the parasitic diode is switched to the charging-disabled direction. Therefore, a parasitic diode voltage still exists, causing the MCU to be unable to accurately read the battery voltage.

[0027] The multi-string discrete lithium battery negative terminal protection IC is composed of multiple sets of single-string discrete protection units cascaded together. The protection branch circuit topology, overcharge protection action logic, and sampling error mechanism caused by NMOS parasitic diodes for a single battery cell are exactly the same as those of the single-string discrete scheme. The technical drawbacks of the corresponding branch P- negative voltage and parasitic diode voltage drop interference sampling after overcharge triggering also exist simultaneously.

[0028] Therefore, the current industry-used single-string discrete and multi-string discrete lithium battery negative terminal protection IC architectures are all affected by the P-negative voltage and NMOS parasitic diode voltage drop after overcharge protection takes effect. This results in distorted MCU voltage sampling data, making it impossible to accurately obtain the battery overcharge voltage parameters and failing to meet the mandatory specifications for overcharge voltage recording and extreme value storage in the new national standard.

[0029] Please see Figure 2 In current mainstream lithium battery positive terminal protection schemes, the power switch module is placed in the connection path between the battery's positive terminal and the MCU unit's power input terminal. The protection IC's power output terminal V+ is electrically connected to the MCU unit's power input terminal P+. Under normal charging and discharging conditions, the PMOS transistor remains in the conducting state, and the MCU unit directly samples the voltage across the battery cell via P+ and P-, with the sampled value being basically consistent with the battery voltage. However, in overcharge protection trigger scenarios, the protection IC controls the PMOS transistor to turn off to cut off the main charging circuit, causing a voltage drop in the parasitic diode of the PMOS transistor. When the MCU unit samples the voltage via P+ and P-, this parasitic diode voltage drop is superimposed, resulting in a sampled value that deviates from the battery voltage. Consequently, it is impossible to accurately obtain the battery's over-limit voltage at the moment of overcharging.

[0030] Example 1 Please see Figure 3 , Figure 3 This is a structural block diagram of an embodiment of the battery protection chip of the present invention. The battery protection chip in this embodiment is a negative-terminal protection architecture battery protection chip, which has a positive input terminal VDD, a negative input terminal VSS, a positive output terminal AOUT+, and a negative output terminal AOUT- (the negative output terminal AOUT- is also the detection terminal VM of the battery negative-terminal protection IC). The chip includes a power switch module, a basic function module, and a battery voltage acquisition and processing unit.

[0031] The first connection terminal of the power switch module is connected to the negative input terminal VSS of the chip, and the second connection terminal is connected to the negative output terminal AOUT- of the chip. The power switch module can be a single NMOS transistor or multiple NMOS transistors connected in series. For example, when the power switch module uses two NMOS transistors, the two NMOS transistors can be connected in series back-to-back with their source terminals connected. The drains of the two NMOS transistors serve as the first connection terminal and the second connection terminal of the power switch module, respectively, and the gates of the two NMOS transistors serve as the controlled terminals of the power switch module, connected to the basic functional module. Thus, the charging circuit and the discharging circuit can be controlled separately by the two NMOS transistors.

[0032] The basic functional module is used to implement the basic protection functions of the battery protection chip. The basic functional module has a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a drive output terminal. The first and second detection terminals of the basic functional module are respectively connected to the positive input terminal VDD and the negative input terminal VSS of the chip, used to detect overcharge and over-discharge of the battery. The third and fourth detection terminals of the basic functional module are respectively connected to the first and second connection terminals of the power switch module (i.e., the negative input terminal VSS and the negative output terminal AOUT- of the chip), used to detect overcurrent and short circuit of the battery. The drive output terminal of the basic functional module is connected to the controlled terminal of the power switch module, used to control the power switch module to shut down when an abnormality is detected.

[0033] Specifically, the basic functional module includes an overcharge and over-discharge detection circuit, an overcurrent and short-circuit detection circuit, and a logic processing drive circuit. The two detection terminals of the overcharge and over-discharge detection circuit (i.e., the first detection terminal and the second detection terminal of the basic functional module) are respectively connected to the positive input terminal VDD and the negative input terminal VSS of the chip, and its output terminal is connected to the first input terminal of the logic processing drive circuit, which is used to send a first protection signal to the logic processing drive circuit when an overcharge or over-discharge phenomenon is detected.

[0034] The two detection terminals of the overcurrent and short-circuit detection circuit (i.e., the third and fourth detection terminals of the basic functional module) are respectively connected to the first and second connection terminals of the power switch module (i.e., the negative input terminal VSS and the negative output terminal AOUT- of the chip). Its output terminal is connected to the second input terminal of the logic processing driver circuit, used to send a second protection signal to the logic processing driver circuit when an overcurrent or short circuit is detected. The output terminal of the logic processing driver circuit is connected to the controlled terminal of the power switch module, used to turn off the power switch module upon receiving either the first or second protection signal.

[0035] Since the overcharge and over-discharge detection circuit, the overcurrent and short-circuit detection circuit, and the logic processing drive circuit all use the potential at the negative input terminal VSS of the chip as the internal reference ground, the overcurrent and short-circuit detection circuit can also be connected to the negative input terminal VSS of the chip by connecting the internal reference ground, so the third detection terminal can be omitted.

[0036] The battery voltage acquisition and processing unit has a power supply terminal VCC, a positive detection terminal VBAT+, a negative detection terminal VBAT-, a ground terminal Vneg, and a detection output terminal VOUT. The positive detection terminal VBAT+ is connected to the positive input terminal VDD of the chip, the negative detection terminal VBAT- is connected to the negative input terminal VSS of the chip, the ground terminal Vneg is connected to the negative output terminal AOUT- of the chip, and the detection output terminal VOUT is connected to the positive output terminal AOUT+ of the chip. The battery voltage acquisition and processing unit uses the potential at the negative input terminal VSS of the chip as the input reference ground and the potential at the negative output terminal AOUT- of the chip as the output reference ground. It then scales the voltage between the positive input terminal VDD and the negative input terminal VSS and outputs the voltage detection signal from the positive output terminal AOUT+. The power supply terminal VCC of the battery voltage acquisition and processing unit is used to connect to an external power supply voltage, which can be provided internally by the chip.

[0037] Please see Figure 4 The battery voltage acquisition and processing unit can use a differential operational amplifier structure to acquire the battery voltage, and then scale down the battery voltage value proportionally to adapt to the sampling range of the external MCU unit. The battery voltage acquisition and processing unit includes an operational amplifier OP1, resistors R1, R2, R3, and R4. The positive power supply terminal of operational amplifier OP1 is electrically connected to the power supply terminal VCC; the non-inverting input terminal of operational amplifier OP1 is electrically connected to the positive detection terminal VBAT+ through resistor R3, and is also electrically connected to its negative power supply terminal through resistor R4. The negative power supply terminal of operational amplifier OP1 is electrically connected to the ground terminal Vneg. The inverting input terminal of operational amplifier OP1 is electrically connected to the negative detection terminal VBAT- through resistor R1, and is also electrically connected to its output terminal through resistor R2. The output terminal of operational amplifier OP1 is electrically connected to the detection output terminal VOUT. Figure 4 The capacitor C1 in the circuit is an NC floating capacitor, which is a reserved design position and does not function in the current circuit.

[0038] The resistance values ​​of resistors R1 and R3 are equal, and the resistance values ​​of resistors R2 and R4 are equal. Assuming the resistance value of resistors R1 and R3 is x, and the resistance value of resistors R2 and R4 is y, through symmetrical resistor matching, common-mode interference and ground noise on the positive detection terminal VBAT+ and the negative detection terminal VBAT- can be perfectly suppressed, extracting only the difference between the two (i.e., the battery voltage). By adjusting the ratio (x:y), the output voltage of operational amplifier OP1 can be proportionally reduced relative to the detection voltage, ensuring that the output voltage is within a predetermined voltage range (i.e., the voltage range of the external MCU unit). For example, by adjusting the values ​​of resistance x and resistance y, the output voltage of operational amplifier OP1 can be made no greater than 3.0V, ensuring that the output voltage of operational amplifier OP1 is less than the maximum voltage range of the MCU unit, 3.3V. This embodiment can be used for both single-string lithium battery protection circuits and multi-string lithium battery protection circuits. When used for multi-string lithium battery protection, it is only necessary to adjust the values ​​of resistance x and resistance y according to the output voltage of the multi-string lithium batteries so that the output voltage of operational amplifier OP1 is not greater than 3.0V.

[0039] In addition, the input resistance of operational amplifier OP1 needs to be large enough (e.g., 10 ohms). 12 (Ω level) so that the input of operational amplifier OP1 draws almost no current, thus avoiding shunting the current of voltage divider resistors R1 / R3, ensuring a precise and constant voltage divider value and error-free sampling voltage. The open-loop gain needs to be sufficiently large (e.g., reaching 10). 5 ~10 7 This enables virtual short-circuit characteristics and allows for deep negative feedback to achieve precise compression and amplification.

[0040] Please see Figure 5 When using the battery protection chip of this embodiment to obtain a battery negative terminal protection system, the connection relationship between the battery protection chip, the external battery, and the MCU unit is as follows: the positive input terminal VDD of the chip is electrically connected to the positive terminal of the battery; the negative input terminal VSS of the chip is electrically connected to the negative terminal of the battery; the positive output terminal AOUT+ of the chip is electrically connected to the first input / output terminal I / O1 of the MCU unit; the negative output terminal AOUT- of the chip is electrically connected to the ground terminal GND of the MCU unit; the power supply input terminal P+ of the MCU unit is electrically connected to the positive terminal of the battery; and the second input / output terminal I / O2 of the MCU unit is used to connect a charger or load. The power switch module of the chip is connected in series in the connection path between the negative terminal of the battery and the ground terminal GND of the MCU unit, and the power supply input terminal P+ of the MCU unit is electrically connected to the positive terminal of the battery. The working principle of this embodiment is as follows: The positive detection terminal VBAT+ and negative detection terminal VBAT- of the battery voltage acquisition and processing unit are connected to the positive and negative terminals of the battery through the positive input terminal VDD and negative input terminal VSS of the chip, respectively, to detect the voltage across the battery terminals in real time. The battery voltage acquisition and processing unit uses the negative input terminal VSS (i.e., the negative terminal of the battery) as the input reference ground and the negative output terminal AOUT- as the output reference ground. After scaling the acquired battery voltage using a differential operational amplifier structure, the corresponding voltage detection signal is output from the detection output terminal VOUT. This signal is then output to the external MCU unit via the positive output terminal AOUT+. Since the voltage reference ground of the positive output terminal AOUT+ is the negative output terminal AOUT-, and the negative output terminal AOUT- is directly connected to the ground terminal GND of the MCU unit, the voltage detection signal output from the positive output terminal AOUT+ shares a common ground with the MCU unit. The MCU unit can accurately sample this signal and calculate the battery voltage.

[0041] For example, assuming that resistors R1 and R3 have equal values ​​and resistors R2 and R4 have equal values, when x:y = 2:1, the potential at the non-inverting input terminal of operational amplifier OP1 is: V + =(V BAT+ -V neg )×[R4 / (R3+R4)]+V neg The inverting input potential of operational amplifier OP1 is: V - =(V OUT -V BAT- )×[R1 / (R1+R2)]+V BAT- Because the open-loop gain of operational amplifier OP1 is large enough, V + =V - Calculations show that: V OUT -V neg =1 / 2×(V BAT+ -V BAT- ) In the formula, V + V represents the voltage at the non-inverting input terminal of operational amplifier OP1; BAT+ This indicates the potential of the positive detection terminal VBAT+ (connected to the positive terminal of the battery during use); V neg This represents the potential of the ground terminal Vneg (i.e., the potential of the MCU unit's ground terminal); V - V represents the voltage at the inverting input terminal of operational amplifier OP1; BAT- This indicates the potential of the negative terminal VBAT- (connected to the negative terminal of the battery during use); V OUTThis represents the output voltage of operational amplifier OP1; R1, R2, R3, and R4 represent the resistance values ​​of resistors R1, R2, R3, and R4, respectively.

[0042] From the above equation, it can be seen that the output signal V of operational amplifier OP1 is... OUT The voltage between the MCU unit's ground terminal and the MCU unit's ground terminal is equal to half the battery voltage, that is: the output signal V of operational amplifier OP1. OUT The voltage is referenced to the ground terminal of the MCU unit. Therefore, the differential operational amplifier circuit described above can accurately convert and output the acquired battery voltage, which is then sent to the subsequent MCU unit to record the battery voltage, and the output signal V... OUT The ground terminal GND of the MCU unit is used as the reference ground, so it can accurately reflect the battery voltage and meet the requirements of the new national standard.

[0043] V was read from the MCU unit. OUT After obtaining the voltage, the battery voltage can be calculated using the formula. Once an overvoltage is detected, the MCU unit controls the controlled switch S1 to cut off the charging and discharging circuit, thus prohibiting charging and discharging. For example, in an overcharge protection trigger scenario, when the battery charging voltage exceeds the limit and triggers overcharge protection, the basic function module controls the NMOS transistor in the power switch module to turn off to cut off the main charging circuit. At this time, the parasitic diode of the NMOS transistor generates a voltage drop. Since the ground terminal Vneg of the battery voltage acquisition and calculation unit is directly connected to the negative output terminal AOUT- of the chip, its output voltage detection signal uses AOUT- as the reference ground, rather than the negative terminal of the battery as the reference ground. Therefore, this signal does not contain negative voltage offset and parasitic diode voltage drop, and can accurately reflect the battery voltage. Based on this voltage detection signal, the MCU unit can accurately calculate the battery voltage, completing the accurate acquisition and storage of the overcharge voltage.

[0044] In this embodiment, the battery voltage acquisition and processing unit uses the negative input terminal VSS of the chip as the input reference ground and the negative output terminal AOUT- of the chip as the output reference ground to complete the potential conversion. Under the condition that the overcharge protection action causes the negative output terminal AOUT- of the chip to be pulled to a negative voltage by the charger and the NMOS transistor in the power switching module generates a voltage drop, it can eliminate the sampling deviation caused by the negative voltage and the diode voltage drop. With the help of the symmetrical resistor differential structure and high-performance operational amplifier, it can achieve high-precision voltage scaling and adjust the battery high voltage to within the 3.3V sampling range allowed by the MCU unit, so that the external MCU unit can accurately calculate the battery voltage and successfully complete the overcharge voltage acquisition and storage in accordance with the new national standard. Moreover, the circuit does not require modification of the original protection IC hardware protection circuit. It is compatible with various negative terminal protection products such as single-string discrete and multi-string discrete, and has strong versatility and low modification cost.

[0045] Example 2 Please see Figure 6 , Figure 6 This is a structural block diagram of another embodiment of the battery protection chip of the present invention. The battery protection chip in this embodiment is a positive terminal protection architecture battery protection chip, which has a positive input terminal VDD, a negative input terminal VSS, a positive output terminal AOUT+, a negative output terminal AOUT-, and a power supply output terminal V+ (the power supply output terminal V+ is also the detection terminal VM of the battery positive terminal protection IC). The chip includes a power switch module, a basic function module, and a battery voltage acquisition and processing unit.

[0046] The first connection terminal of the power switch module is connected to the positive input terminal VDD of the chip, and the second connection terminal is connected to the power output terminal V+ of the chip. The power switch module can be a single PMOS transistor or multiple PMOS transistors connected in series. When two PMOS transistors are used, they are connected back-to-back in a source-to-source configuration. The drains of the two PMOS transistors serve as the first and second connection terminals of the power switch module, respectively, and the gates of the two PMOS transistors serve as the controlled terminals of the power switch module, connected to the basic functional module. The charging circuit and the discharging circuit are controlled by the two PMOS transistors respectively.

[0047] The basic functional module has a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a drive output terminal. The first and second detection terminals of the basic functional module are connected to the positive input terminal VDD and the negative input terminal VSS of the chip, respectively, for detecting battery overcharge and over-discharge. The third and fourth detection terminals of the basic functional module are connected to the first and second connection terminals of the power switch module (i.e., the positive input terminal VDD and the power output terminal V+ of the chip), respectively, for detecting battery overcurrent and short circuit. Of course, since the first and third detection terminals are both connected to the positive input terminal VDD of the chip, they can also be combined into a single detection terminal. The drive output terminal of the basic functional module is connected to the controlled terminal of the power switch module, for controlling the power switch module to shut down when an abnormality is detected.

[0048] Specifically, the basic functional module includes an overcharge and over-discharge detection circuit, an overcurrent and short-circuit detection circuit, and a logic processing drive circuit. The two detection terminals of the overcharge and over-discharge detection circuit (i.e., the first detection terminal and the second detection terminal of the basic functional module) are respectively connected to the positive input terminal VDD and the negative input terminal VSS of the chip, and its output terminal is connected to the first input terminal of the logic processing drive circuit, which is used to send a first protection signal to the logic processing drive circuit when an overcharge or over-discharge phenomenon is detected.

[0049] The two detection terminals of the overcurrent and short-circuit detection circuit (i.e., the third and fourth detection terminals of the basic functional module) are respectively connected to the first and second connection terminals of the power switch module (i.e., the positive input terminal VDD and the power supply output terminal V+ of the chip). Its output terminal is connected to the second input terminal of the logic processing driver circuit, used to send a second protection signal to the logic processing driver circuit when an overcurrent or short circuit is detected. The output terminal of the logic processing driver circuit is connected to the controlled terminal of the power switch module, used to turn off the power switch module upon receiving the first or second protection signal. The overcharge and over-discharge detection circuit, the overcurrent and short-circuit detection circuit, and the logic processing driver circuit all use the potential at the negative input terminal VSS of the chip as their internal reference ground.

[0050] The structure and principle of the battery voltage acquisition and processing unit are the same as those in Embodiment 1, and will not be repeated here.

[0051] Please see Figure 7 When using the battery protection chip of this embodiment to obtain a battery positive terminal protection system, the connection relationship between the battery protection chip, the external battery, and the MCU unit is as follows: the positive input terminal VDD of the chip is electrically connected to the positive terminal of the battery; the negative input terminal VSS of the chip is electrically connected to the negative terminal of the battery; the positive output terminal AOUT+ of the chip is electrically connected to the first input / output terminal I / O1 of the MCU unit; the negative output terminal AOUT- of the chip is electrically connected to the ground terminal GND of the MCU unit; the power output terminal V+ of the chip is electrically connected to the power input terminal P+ of the MCU unit; the ground terminal GND of the MCU unit is electrically connected to the negative terminal of the battery; and the second input / output terminal I / O2 of the MCU unit is used to connect a charger or load. The power switching transistor module of the chip is connected in series in the connection path between the positive terminal of the battery and the power input terminal P+ of the MCU unit.

[0052] The detection principle in this embodiment is the same as in Embodiment 1. The voltage detection signal is still output to the external MCU unit via the positive output terminal AOUT+ of the chip, thus avoiding the influence of the parasitic diode voltage drop of the PMOS transistor in the power switch module when protection occurs. Since the voltage reference ground of the positive output terminal AOUT+ is the negative output terminal AOUT-, and the negative output terminal AOUT- is directly connected to the ground terminal GND of the MCU unit, the voltage detection signal output from the positive output terminal AOUT+ shares a common ground with the MCU unit. The MCU unit can accurately sample this signal and calculate the battery voltage.

[0053] For example, in an overcharge protection trigger scenario, when the battery charging voltage exceeds the limit and triggers overcharge protection, the basic function module controls the PMOS transistor in the power switching module to turn off to cut off the main charging circuit. At this time, the parasitic diode of the PMOS transistor generates a voltage drop. Since the voltage detection signal output by the battery voltage acquisition and calculation unit detects the voltage at the positive input terminal VDD and the negative input terminal VSS of the chip, and these voltages are the voltage directly output by the battery, they are not affected by the parasitic diode of the PMOS transistor in the power switching module. Therefore, this signal does not contain the parasitic diode voltage drop of the PMOS transistor and can accurately reflect the battery voltage. The MCU unit can accurately calculate the battery voltage based on this voltage detection signal, completing the accurate acquisition and storage of the overcharge voltage.

[0054] In this embodiment, the battery voltage acquisition and processing unit can isolate the interference of the parasitic diode of the PMOS transistor in the power switching module on the sampling accuracy. Regardless of normal charging and discharging or after overcharge protection action, the MCU unit can accurately and stably obtain the battery voltage to meet the new national standard data recording requirements. Moreover, the circuit does not require modification of the original protection IC hardware protection circuit. It is compatible with various positive terminal protection products such as single-string discrete and multi-string discrete, and has strong versatility and low modification cost.

[0055] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A battery protection chip, characterized in that: The chip has a positive input terminal, a negative input terminal, a positive output terminal, and a negative output terminal. The chip includes: The power switching transistor module has its first connection terminal connected to the negative input terminal of the chip, and its second connection terminal connected to the negative output terminal of the chip. The basic functional module has a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a drive output terminal. The first and second detection terminals are respectively connected to the positive and negative input terminals of the chip. The third and fourth detection terminals are respectively connected to the first and second connection terminals of the power switch module. The drive output terminal is connected to the controlled terminal of the power switch module. The basic functional module is used to detect overcharge and over-discharge of the battery based on the voltage difference between the positive and negative input terminals, to detect overcurrent and short circuit of the battery based on the voltage difference across the power switch module, and to control the power switch module to turn off when an abnormality is detected through the drive output terminal. A battery voltage acquisition and processing unit has its positive detection terminal connected to the positive input terminal of a chip, its negative detection terminal connected to the negative input terminal of a chip, its ground terminal connected to the negative output terminal of a chip, and its detection output terminal connected to the positive output terminal of a chip. It is used to scale the voltage between the positive and negative input terminals using the potential at the negative input terminal as the input reference ground and the potential at the negative output terminal as the output reference ground, and then output a voltage detection signal with the negative output terminal as the reference ground from the positive output terminal.

2. The battery protection chip as described in claim 1, characterized in that: The power switch module includes one or more NMOS transistors connected in series, and the gate of each NMOS transistor serves as a controlled terminal of the power switch module.

3. A battery protection chip, characterized in that: The chip has a positive input terminal, a negative input terminal, a positive output terminal, a negative output terminal, and a power supply output terminal. The chip includes: The power switching transistor module has its first connection terminal connected to the positive input terminal of the chip, and its second connection terminal connected to the power supply output terminal of the chip. The basic functional module has a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a drive output terminal. The first and second detection terminals are respectively connected to the positive and negative input terminals of the chip. The third and fourth detection terminals are respectively connected to the first and second connection terminals of the power switch module. The drive output terminal is connected to the controlled terminal of the power switch module. The basic functional module is used to detect overcharge and over-discharge of the battery based on the voltage difference between the positive and negative input terminals, to detect overcurrent and short circuit of the battery based on the voltage difference across the power switch module, and to control the power switch module to turn off when an abnormality is detected through the drive output terminal. A battery voltage acquisition and processing unit has its positive detection terminal connected to the positive input terminal of a chip, its negative detection terminal connected to the negative input terminal of a chip, its ground terminal connected to the negative output terminal of a chip, and its detection output terminal connected to the positive output terminal of a chip. It is used to scale the voltage between the positive and negative input terminals using the potential at the negative input terminal as the input reference ground and the potential at the negative output terminal as the output reference ground, and then output a voltage detection signal with the negative output terminal as the reference ground from the positive output terminal.

4. The battery protection chip as described in claim 3, characterized in that: The power switch module includes one or more PMOS transistors connected in series, and the gate of each PMOS transistor serves as a controlled terminal of the power switch module.

5. The battery protection chip according to any one of claims 1 to 4, characterized in that: The basic functional module includes an overcharge and over-discharge detection circuit, an overcurrent and short-circuit detection circuit, and a logic processing drive circuit. The two detection terminals of the overcharge and over-discharge detection circuit are respectively connected to the positive and negative input terminals of the chip, and its output terminal is connected to the first input terminal of the logic processing drive circuit. This circuit sends a first protection signal to the logic processing drive circuit when overcharge or over-discharge is detected. The two detection terminals of the overcurrent and short-circuit detection circuit are respectively connected to the first and second connection terminals of the power switch module, and its output terminal is connected to the second input terminal of the logic processing drive circuit. This circuit sends a second protection signal to the logic processing drive circuit when overcurrent or short-circuit is detected. The output terminal of the logic processing drive circuit is connected to the controlled terminal of the power switch module, and is used to turn off the power switch module upon receiving the first or second protection signal.

6. The battery protection chip as described in claim 5, characterized in that: The overcharge and over-discharge detection circuit, overcurrent and short-circuit detection circuit, and logic processing drive circuit in the basic functional module all use the potential at the negative input terminal as the internal reference ground.

7. The battery protection chip according to any one of claims 1 to 4, characterized in that: The battery voltage acquisition and processing unit includes an operational amplifier OP1, resistors R1, R2, R3, and R4. The positive power supply terminal of the operational amplifier OP1 is electrically connected to the power supply terminal VCC. The non-inverting input terminal of the operational amplifier OP1 is electrically connected to the positive detection terminal VBAT+ through resistor R3. The non-inverting input terminal of the operational amplifier OP1 is also electrically connected to its negative power supply terminal through resistor R4. The negative power supply terminal of the operational amplifier OP1 is electrically connected to the ground terminal Vneg. The inverting input terminal of the operational amplifier OP1 is electrically connected to the negative detection terminal VBAT- through resistor R1. The inverting input terminal of the operational amplifier OP1 is also electrically connected to its output terminal through resistor R2. The output terminal of the operational amplifier OP1 is electrically connected to the detection output terminal VOUT.

8. The battery protection chip as described in claim 7, characterized in that: The resistance values ​​of resistors R1 and R3 are equal, and the resistance values ​​of resistors R2 and R4 are equal.

9. The battery protection chip as described in claim 8, characterized in that: When used in a multi-cell lithium battery protection circuit, the output voltage of operational amplifier OP1 is kept within a predetermined voltage range by adjusting the ratio of the resistance of resistor R2 to that of resistor R4.

10. The battery protection chip according to any one of claims 1 to 4, characterized in that: The power switching module includes two switching MOS transistors, which are connected back-to-back in a source-to-source manner.

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