Battery protection circuit and battery protection chip

Abstract

The invention discloses a battery protection circuit and a battery protection chip, and the battery protection circuit comprises a charging and discharging switching circuit, a logic control circuit, an overcurrent detection circuit, and a reference voltage selection circuit. The charge-discharge switch circuit is connected with the battery and the charge-discharge interface; the reference voltage selection circuit is connected with the signal receiving end and the at least two voltage input ends, receives a voltage switching signal of the signal receiving end, and determines a target reference voltage from the reference voltages input by the at least two voltage input ends; the overcurrent detection circuit is connected with the charging and discharging switching circuit and the reference voltage selection circuit, and is used for acquiring a charging and discharging signal of the charging and discharging switching circuit and outputting an overcurrent detection signal according to the charging and discharging signal and the target reference voltage; and the logic control circuit is connected with the over-current detection circuit and the charging and discharging switching circuit and is used for controlling the charging and discharging switching circuit to work according to the over-current detection signal. According to the technical scheme, the target reference voltage of the overcurrent detection circuit is flexibly adjusted through the voltage switching signal.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery protection circuit and a battery protection chip. Background Art

[0002] Lithium battery protection chips are widely used to ensure the safety of lithium battery systems, providing overcharge, over-discharge, overcurrent and over-temperature protection functions. In early designs, the power tube was external and the current was detected through an external resistor, allowing the overcurrent protection level to be adjusted by replacing the resistor or the power tube. However, in order to reduce costs, the power tube and the control part are generally integrated into the same chip. However, because the on-resistance and internal reference voltage of the integrated MOS tube are fixed, this method limits the flexibility of the overcurrent protection level. Summary of the invention

[0003] The embodiments of the present invention provide a battery protection circuit and a battery protection chip to solve the problem that the overcurrent protection gear position of the existing battery protection chip cannot be flexibly adjusted.

[0004] A battery protection circuit includes a charge and discharge switch circuit, a logic control circuit, an overcurrent detection circuit and a reference voltage selection circuit; The charge and discharge switch circuit is used to connect the battery and the charge and discharge interface; The reference voltage selection circuit is used to connect the signal receiving end and at least two voltage input ends, receive the voltage switching signal of the signal receiving end, and determine the target reference voltage from the reference voltages input from at least two voltage input ends according to the voltage switching signal; The overcurrent detection circuit is connected to the charge and discharge switch circuit and the reference voltage selection circuit, and is used to collect the charge and discharge signals of the charge and discharge switch circuit, and output an overcurrent detection signal according to the charge and discharge signals and the target reference voltage; The logic control circuit is connected to the overcurrent detection circuit and the charge and discharge switch circuit, and is used to control the operation of the charge and discharge switch circuit according to the overcurrent detection signal.

[0005] Furthermore, the reference voltage selection circuit is used to determine the target reference voltage from the reference voltages input from at least two of the voltage input terminals according to the delay time corresponding to each level signal in the voltage switching signal.

[0006] Further, the reference voltage selection circuit includes a signal processing circuit and a selection switch circuit; The signal processing circuit is connected to the signal receiving end, and is used to output a switch control signal according to the delay time corresponding to each level signal in the voltage switching signal; The selection switch circuit is connected to the signal processing circuit, the overcurrent detection circuit and at least two of the voltage input terminals, and is used to select one of the voltage input terminals to be connected to the overcurrent detection circuit according to the switch control signal, so that the turned-on voltage input terminal outputs the target reference voltage to the overcurrent detection circuit.

[0007] Further, the signal processing circuit includes a charging control circuit, a capacitor circuit, a first trigger and a second trigger; The first end of the charging control circuit is connected to the first power supply end, the second end of the charging control circuit is grounded, the third end of the charging control circuit is connected to the signal receiving end, and the fourth end of the charging control circuit is connected to the capacitor circuit, and is used to charge the capacitor circuit according to the level signal in the voltage switching signal; A first end of the capacitor circuit is connected to an input end of the first trigger, and a second end of the capacitor circuit is grounded; The output end of the first trigger is connected to the input end of the second trigger, and is used to output a level delay signal according to the capacitor voltage of the capacitor circuit; The output end of the second trigger is connected to the selection switch circuit, and the control end of the second trigger is connected to the signal receiving end, and is used to output a switch control signal according to the voltage switching signal and the level delay signal.

[0008] Furthermore, the first trigger is a Schmitt trigger.

[0009] Further, the second trigger is a D trigger; the D trigger includes a first latch and a second latch; The input end of the first latch is connected to the output end of the first trigger, and the first output end of the first latch is connected to the input end of the second latch; The control end of the first latch and the control end of the second latch are connected in common and connected to the signal receiving end; The first output end of the first latch, the second output end of the first latch, the first output end of the second latch, and the second output end of the second latch are all connected to the selection switch circuit.

[0010] Further, the selection switch circuit includes a first AND gate circuit, a second AND gate circuit, a third AND gate circuit, a fourth AND gate circuit and a switch network; The input end of the switch network is connected to at least two of the voltage input ends, and the output end of the switch network is connected to the overcurrent detection circuit; The first input terminal of the first AND gate circuit is connected to the first output terminal of the first latch, the second input terminal of the first AND gate circuit is connected to the first output terminal of the second latch, and the output terminal of the first AND gate circuit is connected to the first control terminal of the switch network; The first input terminal of the second AND gate circuit is connected to the second output terminal of the first latch, the second input terminal of the second AND gate circuit is connected to the first output terminal of the second latch, and the output terminal of the second AND gate circuit is connected to the second control terminal of the switch network; The first input terminal of the third AND gate circuit is connected to the first output terminal of the first latch, the second input terminal of the third AND gate circuit is connected to the second output terminal of the second latch, and the output terminal of the third AND gate circuit is connected to the third control terminal of the switch network; The first input terminal of the fourth AND gate circuit is connected to the second output terminal of the first latch, the second input terminal of the fourth AND gate circuit is connected to the second output terminal of the second latch, and the output terminal of the fourth AND gate circuit is connected to the fourth control terminal of the switch network.

[0011] Furthermore, the switch network includes multiple switch branches in parallel; each of the switch branches includes a first switch tube; the first end of the first switch tube is connected to the voltage input end, the second end of the switch tube is connected to the overcurrent detection circuit, and the third end of the first switch tube is the control end.

[0012] Further, the overcurrent detection circuit includes a comparator; The non-inverting input terminal of the comparator is connected to the charge and discharge switch circuit, the inverting input terminal of the comparator is connected to the reference voltage selection circuit, and the input terminal of the comparator is connected to the logic control circuit.

[0013] A battery protection chip comprises the above-mentioned battery protection circuit.

[0014] The battery protection circuit and the battery protection chip are configured by connecting the charge and discharge switch circuit to the battery and the charge and discharge interface; connecting the reference voltage selection circuit to the signal receiving end and at least two voltage input ends to receive the voltage switching signal of the signal receiving end, and determining the target reference voltage from the reference voltages input from the at least two voltage input ends according to the voltage switching signal; connecting the overcurrent detection circuit to the charge and discharge switch circuit and the reference voltage selection circuit to collect the charge and discharge signals of the charge and discharge switch circuit, and outputting the overcurrent detection signal according to the charge and discharge signals and the target reference voltage; and connecting the logic control circuit to the overcurrent detection circuit and the charge and discharge switch circuit to control the operation of the charge and discharge switch circuit according to the overcurrent detection signal, so that the target reference voltage of the overcurrent detection circuit can be flexibly adjusted through the voltage switching signal, so that the battery protection circuit can adapt to different application scenarios, flexibly adjust the overcurrent thresholds in different application scenarios, and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0016] Figure 1 is a circuit diagram of a battery protection chip in one embodiment of the present invention; Figure 2 is a circuit diagram of a battery protection circuit in one embodiment of the present invention; Figure 3 1 is a schematic diagram of a level signal waveform in an embodiment of the present invention.

[0017] In the figure: 1. Battery protection chip; 11. Charge and discharge switch circuit; 12. Logic control circuit 12; 13. Overcurrent detection circuit; 14. Reference voltage selection circuit; 141. Signal processing circuit; 1411. Charge control circuit; 1412. Capacitor circuit; 1413. First trigger; 1414. Second trigger; 142. Select switch circuit; 1421. Switch network; 2. Battery; 3. Charge and discharge interface; DETAILED DESCRIPTION The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0019] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0020] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0021] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0022] In order to fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0023] This embodiment provides a battery protection circuit, which is applied to a battery protection chip 1. For example, the battery protection chip 1 is applied to a battery module. Figure 1 As shown, the battery module includes a battery 2, a battery protection chip 1 and a charge and discharge interface 3. The battery protection chip 1 is arranged between the battery 2 and the charge and discharge interface 3, and is used to perform charge and discharge protection on the battery 2. Exemplarily, the charge and discharge protection includes functions such as overcharge, over discharge, over current and over temperature protection.

[0024] This embodiment provides a battery protection circuit. Figure 1 and Figure 2 As shown, it includes a charge and discharge switch circuit 11, a logic control circuit 12, an overcurrent detection circuit 13 and a reference voltage selection circuit 14; the charge and discharge switch circuit 11 is used to connect the battery 2 and the charge and discharge interface 3 (P+, P-); the reference voltage selection circuit 14 is used to connect the signal receiving terminal CNT and at least two voltage input terminals, receive the voltage switching signal of the signal receiving terminal CNT, and determine the target reference voltage from the reference voltages input from at least two voltage input terminals according to the voltage switching signal; the overcurrent detection circuit 13 is connected to the charge and discharge switch circuit 11 and the reference voltage selection circuit 14, and is used to collect the charge and discharge signals of the charge and discharge switch circuit 11, and output the overcurrent detection signal according to the charge and discharge signals and the target reference voltage; the logic control circuit 12 is connected to the overcurrent detection circuit 13 and the charge and discharge switch circuit 11, and is used to control the charge and discharge switch circuit 11 to work according to the overcurrent detection signal.

[0025] As an example, the charge and discharge switch circuit 11 includes a charge and discharge switch tube. Exemplarily, the charge switch tube and the discharge opening tube are integrated on a battery protection chip 1 through single-chip integration technology to form a charge and discharge switch tube. Through the complementary metal oxide semiconductor process, the connection mode of the substrate is switched inside the battery protection chip 1 to achieve different working states of the power tube. For example, by switching between an N-type substrate and a P-type substrate, the functions of an N-channel and a P-channel switch tube can be achieved on the same charge and discharge switch tube. Thereby reducing the chip cost.

[0026] As an example, the reference voltage selection circuit 14 is used to connect the signal receiving terminal CNT and at least two voltage input terminals (VREF1 to VREFN), receive the voltage switching signal of the signal receiving terminal CNT, and determine the target reference voltage from the reference voltages input from the at least two voltage input terminals according to the voltage switching signal. The voltage switching signal can be customized by a signal generator. Exemplarily, when the battery protection chip 1 needs to be applied in other application scenarios, and different overcurrent protection thresholds need to be set in the application scenarios, the voltage switching signal can be configured by configuring the signal generator and input to the reference voltage selection circuit 14 in the battery protection chip 1. The reference voltage selection circuit 14 determines the target reference voltage from the reference voltages input from the at least two voltage input terminals according to the voltage switching signal of the signal receiving terminal CNT, thereby flexibly adjusting the target reference voltage, and then indirectly adjusting the overcurrent protection threshold of the battery protection chip 1. The at least two voltage input terminals can be set inside the battery protection chip 1, provided by the power module inside the battery protection chip 1, or provided by the power module outside the battery protection chip 1.

[0027] As an example, the overcurrent detection circuit 13 is connected to the charge and discharge switch circuit 11 and the reference voltage selection circuit 14, and is used to collect the charge and discharge signals of the charge and discharge switch circuit 11, and output the overcurrent detection signal according to the charge and discharge signals and the target reference voltage. Exemplarily, the charge and discharge signal includes the charge and discharge voltage. The overcurrent detection circuit 13 is connected to the charge and discharge switch circuit 11 through the detection resistor integrated in the battery protection chip 1, so that the charge and discharge voltage is fed back through the detection resistor. It should be noted that the overcurrent detection circuit 13 can also collect the charge and discharge current of the charge and discharge switch circuit 11, convert the charge and discharge current into a charge and discharge voltage, and then output an overcurrent detection signal through the charge and discharge voltage and the target reference voltage to determine whether the battery 2 has charge and discharge abnormalities.

[0028] As an example, the logic control circuit 12 is connected to the overcurrent detection circuit 13 and the charge and discharge switch circuit 11, and is used to control the charge and discharge switch circuit 11 to work according to the overcurrent detection signal. As an example, when the logic control circuit 12 analyzes the overcurrent detection signal and determines that an overcurrent or overvoltage situation occurs, the charge and discharge switch circuit 11 is controlled to be turned off, and when it is determined that no overcurrent or overvoltage situation occurs, the charge and discharge switch circuit 11 is controlled to be turned on.

[0029] In this embodiment, the charge and discharge switch circuit 11 is used to connect the battery 2 and the charge and discharge interface 3; the reference voltage selection circuit 14 is used to connect the signal receiving terminal CNT and at least two voltage input terminals to receive the voltage switching signal of the signal receiving terminal CNT, and according to the voltage switching signal, the target reference voltage is determined from the reference voltages input from the at least two voltage input terminals; the overcurrent detection circuit 13 is connected to the charge and discharge switch circuit 11 and the reference voltage selection circuit 14 to collect the charge and discharge signals of the charge and discharge switch circuit 11, and output the overcurrent detection signal according to the charge and discharge signals and the target reference voltage; and the logic control circuit 12 is connected to the overcurrent detection circuit 13 and the charge and discharge switch circuit 11 to control the operation of the charge and discharge switch circuit 11 according to the overcurrent detection signal, so that the target reference voltage of the overcurrent detection circuit 13 can be flexibly adjusted through the voltage switching signal, so that the battery protection circuit can adapt to different application scenarios, flexibly adjust the overcurrent threshold in different application scenarios, and reduce costs.

[0030] In one embodiment, the reference voltage selection circuit 14 is used to determine the target reference voltage from the reference voltages input from at least two voltage input terminals according to the delay time corresponding to each level signal in the voltage switching signal.

[0031] As an example, the voltage switching includes a high level signal and a low level signal. Exemplarily, different voltage switching signals are configured by custom configuration. That is, the delay time of the high level signal or the low level signal in the voltage switching signal is configured, so that the reference voltage selection circuit 14 determines the target reference voltage from the reference voltages input from at least two voltage input terminals according to the delay time corresponding to each level signal in the voltage switching signal, so as to indirectly realize the switching of the overcurrent threshold by switching the target reference voltage of the overcurrent detection circuit 13.

[0032] Exemplarily, the voltage switching signal includes high-level signals with different delay times. The reference voltage selection circuit 14 analyzes the voltage switching signal. When the delay time of the high-level signal in the voltage switching signal is greater than the preset time, the analysis result is read as 1. When the delay time of the high-level signal in the voltage switching signal is not greater than the preset time, the analysis result is read as 0. Thus, by combining and judging the analysis result 1 or 0 of the high-level signal in the voltage switching signal, the target reference voltage is determined from the reference voltages input from at least two voltage input terminals.

[0033] In this embodiment, by setting the delay time of the level signal in the voltage switching signal, the target reference voltage can be determined from the reference voltages input from at least two voltage input terminals by combining and judging the delay time corresponding to each level signal.

[0034] In one embodiment, the reference voltage selection circuit 14 includes a signal processing circuit 141 and a selection switch circuit 142; the signal processing circuit 141 is connected to the signal receiving terminal CNT, and is used to output a switch control signal according to the delay time corresponding to each level signal in the voltage switching signal; the selection switch circuit 142 is connected to the signal processing circuit 141, the overcurrent detection circuit 13 and at least two voltage input terminals, and is used to select a voltage input terminal to be connected to the overcurrent detection circuit 13 according to the switch control signal, so that the turned-on voltage input terminal outputs the target reference voltage to the overcurrent detection circuit 13.

[0035] As an example, the signal processing circuit 141 is connected to the signal receiving terminal CNT, and is used to output a switch control signal according to the delay time corresponding to each level signal in the voltage switching signal. In this example, the signal processing circuit 141 outputs different binary combinations, i.e., switch control signals, such as 01, 10, 00, and 11, according to the delay time corresponding to each level signal in the voltage switching signal. The selection switch circuit 142 can switch the voltage input terminal to output the target reference voltage to the overcurrent detection circuit 13 according to the switch control signal, so that the overcurrent detection circuit 13 receives the target reference voltage output by different voltage input terminals, and realizes the switching of the overcurrent threshold.

[0036] In this embodiment, the reference voltage selection circuit 14 includes a signal processing circuit 141 and a selection switch circuit 142; the signal processing circuit 141 is connected to the signal receiving terminal CNT, and is used to output a switch control signal according to the delay time corresponding to each level signal in the voltage switching signal; the selection switch circuit 142 is connected to the signal processing circuit 141, the overcurrent detection circuit 13 and at least two voltage input terminals, and is used to select a voltage input terminal to be connected to the overcurrent detection circuit 13 according to the switch control signal, so that the turned-on voltage input terminal outputs the target reference voltage to the overcurrent detection circuit 13, and forms different binary combinations through the delay time corresponding to each level signal, namely the switch control signal, through which the selection switch circuit 142 is instructed to select a voltage input terminal to be connected to the overcurrent detection circuit 13, so that the turned-on voltage input terminal outputs the target reference voltage to the overcurrent detection circuit 13, thereby flexibly switching the overcurrent threshold.

[0037] In one embodiment, the signal processing circuit 141 includes a charging control circuit 1411, a capacitor circuit 1412, a first trigger 1413 and a second trigger 1414; the first end of the charging control circuit 1411 is connected to the first power supply end, the second end of the charging control circuit 1411 is grounded, the third end of the charging control circuit 1411 is connected to the signal receiving end CNT, and the fourth end of the charging control circuit 1411 is connected to the capacitor circuit 1412, which is used to charge the capacitor circuit 1412 according to the level signal in the voltage switching signal; the first end of the capacitor circuit 1412 is connected to the input end of the first trigger 1413, and the second end of the capacitor circuit 1412 is grounded; the output end of the first trigger 1413 is connected to the input end of the second trigger 1414, which is used to output a level delay signal according to the capacitor voltage of the capacitor circuit 1412; the output end of the second trigger 1414 is connected to the selection switch circuit 142, and the control end of the second trigger 1414 is connected to the signal receiving end CNT, which is used to output a switch control signal according to the voltage switching signal and the level delay signal.

[0038] As an example, the capacitor circuit 1412 includes a first capacitor C1. It is understandable that the capacitance value of the first capacitor C1 can be set according to actual needs, such as the delay time of the high level signal in the voltage switching signal.

[0039] As an example, since the voltage switching signal includes level signals with different delay times. Assume that the charging control circuit 1411 is triggered by a high level signal. When the charging control circuit 1411 detects two consecutive high level signals, it can charge the capacitor circuit 1412. When the high level signal finishes charging the capacitor circuit 1412, the capacitor voltage of the capacitor circuit 1412 triggers the first trigger 1413. It is determined that the delay time of the high level signal is greater than the preset time. When the high level signal finishes charging the capacitor circuit 1412, the capacitor voltage of the capacitor circuit 1412 does not trigger the first trigger 1413. It is determined that the delay time of the high level signal is not greater than the preset time, so that the first trigger 1413 sends a signal to the second trigger 1413. 4 outputs different high and low level signals, and the second trigger 1414 combines the voltage switching signal and the first trigger 1413 to output different high and low level signals to form different binary combinations, so as to use the capacitor voltage of the capacitor circuit 1412 to judge the delay time of the level signal, so that the second trigger 1414 combines the voltage switching signal and the first trigger 1413 to output different high and low level signals to form different binary combinations, instructing the selection switch circuit 142 to select the corresponding voltage input terminal to be turned on with the overcurrent detection circuit 13, so that the turned-on voltage input terminal outputs the target reference voltage to the overcurrent detection circuit 13, thereby flexibly switching the overcurrent threshold.

[0040] In one embodiment, the first trigger 1413 is a Schmitt trigger. In this embodiment, the hysteresis characteristic of the Schmitt trigger can effectively suppress the noise and interference in the capacitor voltage collected by the capacitor circuit 1412, so that the signal output by the first trigger 1413 is more stable.

[0041] In one embodiment, the second trigger 1414 is a D trigger; the D trigger includes a first latch D1 and a second latch D2; the input end of the first latch D1 is connected to the output end of the first trigger 1413, and the first output end of the first latch D1 is connected to the input end of the second latch D2; the control end (CLK) of the first latch D1 and the control end (CLK) of the second latch D2 are connected in common and connected to the signal receiving end CNT; the first output end of the first latch D1, the second output end of the first latch D1, the first output end of the second latch D2, and the second output end of the second latch D2 are all connected to the selection switch circuit 142.

[0042] As an example, the Reset terminal of the first latch D1 and the Reset terminal of the second latch D2 are commonly connected to the reset signal terminal PORP for receiving the reset signal.

[0043] In this embodiment, under the premise that the first trigger 1413 and the capacitor circuit 1412 cooperate to detect the delay time of the level signal in the voltage switching signal, by setting a D trigger, the first output end of the first latch D1, the second output end of the first latch D1, the first output end of the second latch D2 and the second output end of the second latch D2 are all connected to the selection switch circuit 142, so that different binary combinations are output through the first output end of the first latch D1, the second output end of the first latch D1, the first output end of the second latch D2 and the second output end of the second latch D2, indicating that the selection switch circuit 142 selects different voltage input ends to be turned on with the overcurrent detection circuit 13, so as to output different target reference voltages to the overcurrent detection circuit 13. The circuit structure is simple, the cost is low, and it has good accuracy.

[0044] In one embodiment, the selection switch circuit 142 includes a first AND gate circuit y0, a second AND gate circuit y1, a third AND gate circuit y2, a fourth AND gate circuit y3 and a switch network 1421; the input end of the switch network 1421 is connected to at least two voltage input ends, and the output end of the switch network 1421 is connected to the overcurrent detection circuit 13; the first input end of the first AND gate circuit y0 is connected to the first output end of the first latch D1, the second input end of the first AND gate circuit y0 is connected to the first output end of the second latch D2, and the output end of the first AND gate circuit y0 is connected to the first control end of the switch network 1421; the first input end of the second AND gate circuit y1 is connected to the second output end of the first latch D1, and the second AND gate circuit y2 is connected to the first output end of the second latch D2. The second input terminal of the circuit y1 is connected to the first output terminal of the second latch D2, and the output terminal of the second AND gate circuit y1 is connected to the second control terminal of the switch network 1421; the first input terminal of the third AND gate circuit y2 is connected to the first output terminal of the first latch D1, the second input terminal of the third AND gate circuit y2 is connected to the second output terminal of the second latch D2, and the output terminal of the third AND gate circuit y2 is connected to the third control terminal of the switch network 1421; the first input terminal of the fourth AND gate circuit y3 is connected to the second output terminal of the first latch D1, the second input terminal of the fourth AND gate circuit y3 is connected to the second output terminal of the second latch D2, and the output terminal of the fourth AND gate circuit y3 is connected to the fourth control terminal of the switch network 1421.

[0045] As an example, the third terminal of the charging control circuit 1411 can be connected to the signal receiving terminal CNT through an inverter, so that the second trigger 1414 can be triggered at the falling edge of the voltage switching signal by setting the inverter. It should be noted that setting the inverter so that the second trigger 1414 can be triggered at the falling edge of the voltage switching signal is only an example and can be selected according to actual needs.

[0046] As an example, the charging control circuit 1411 includes a first transistor M1 and a second transistor M2, wherein the first transistor M1 is a PMOS transistor and the second transistor M2 is an NMOS transistor. The first transistor M1 and the second transistor M2 are arranged in series between the first power supply terminal and the ground, and the gate of the first transistor M1 is connected to the gate of the second transistor M2. The connection node between the source of the first transistor M1 and the source of the second transistor M2 is connected to the capacitor circuit 1412.

[0047] Exemplarily, when the rising edge of the voltage switching signal arrives, the third terminal of the charging control circuit 1411 is at a low level, the first transistor M1 of the charging control circuit 1411 is turned on, and the capacitor circuit 1412 is charged. When the capacitor voltage of the capacitor circuit 1412 exceeds the flip threshold of the first trigger 1413, the output terminal of the first trigger 1413 is at a high level. When the falling edge of the voltage switching signal arrives, the control terminal of the first latch D1 is at a high level, and at this time, the first output terminal q of the first latch D1 is <0> When the next falling edge of the pressure switching signal comes, the first output terminal q of the first latch D1 is <0> The value of is assigned to the first output terminal q of the second latch D2 <1> When the delay time of the high level signal of the voltage switching signal is not enough, the capacitor voltage of the capacitor circuit 1412 triggers the flip threshold of the first trigger 1413. When the falling edge of the high level signal arrives, the output end of the first trigger 1413 is low level. Thus, by reading the delay time of the high level signal of the voltage switching signal, the first output end q of the first latch D1 is given. <0> and the first output terminal q of the second latch D2 <1> Assignment, then combine the first output terminal nq of the first latch D1 <0> and the second output terminal nq of the second latch D2 <1> The value of forms different binary combinations. Since the first input terminal of the first AND gate circuit y0 is connected to the first output terminal of the first latch D1, and the second input terminal of the first AND gate circuit y0 is connected to the first output terminal of the second latch D2; the first input terminal of the second AND gate circuit y1 is connected to the second output terminal of the first latch D1, and the second input terminal of the second AND gate circuit y1 is connected to the first output terminal of the second latch D2; the first input terminal of the third AND gate circuit y2 is connected to the first output terminal of the first latch D1, and the second input terminal of the third AND gate circuit y2 is connected to the second output terminal of the second latch D2; the first input terminal of the fourth AND gate circuit y3 is connected to the second output terminal of the first latch D1, and the second input terminal of the fourth AND gate circuit y3 is connected to the second output terminal of the second latch D2, the first AND gate circuit y0, the second AND gate circuit y1, the third AND gate circuit y2, and the fourth AND gate circuit y3 can obtain the values ​​of y0, y1, y2, and y3 respectively. It can be understood that when the first input terminal and the second input terminal of the first AND gate circuit y0, the second AND gate circuit y1, the third AND gate circuit y2 or the fourth AND gate circuit y3 are all 1, the switch network 1421 can be controlled to select the corresponding voltage input terminal to be turned on with the overcurrent detection circuit 13, so that the turned-on voltage input terminal outputs the target reference voltage to the overcurrent detection circuit 13, thereby flexibly switching the overcurrent threshold.

[0048] In one embodiment, the switch network 1421 includes multiple switch branches in parallel; each switch branch includes a first switch tube; the first end of the first switch tube is connected to a voltage input end, the second end of the switch tube is connected to the overcurrent detection circuit 13, and the third end of the first switch tube is the control end.

[0049] The first switch tube includes a switch tube M3, a switch tube M4, a switch tube M5 or a switch tube M5. Exemplarily, the first switch tube is a field effect transistor.

[0050] like Figure 3 As shown, the voltage switching signal CNT includes a first high level signal and a second high level signal, the delay time of the first high level signal is greater than the delay time of the second high level signal, and the delay time of the first high level signal is greater than the preset time. At this time, the first output terminal q of the first latch D1 <0> is low level, the first output terminal q of the second latch D2 <1> is high level, so that the first input terminal and the second input terminal of the second AND gate circuit y1 are both high level, the switch tube M4 is turned on, and the target reference voltage is VREF2. It can be understood that the binary values ​​of the two input terminals of the first AND gate circuit y0, the second AND gate circuit y1, the third AND gate circuit y2, and the fourth AND gate circuit y3 can be set to set different overcurrent threshold gears by setting the delay time of different high and low level signals in the voltage switching signal. No limitation is made here.

[0051] In one embodiment, the overcurrent detection circuit 13 includes a comparator; the non-inverting input terminal of the comparator is connected to the charge and discharge switch circuit 11, the inverting input terminal of the comparator is connected to the reference voltage selection circuit 14, and the input terminal of the comparator is connected to the logic control circuit 12.

[0052] In this embodiment, the non-inverting input terminal of the comparator is connected to the charge and discharge switch circuit 11, the inverting input terminal of the comparator is connected to the reference voltage selection circuit 14, and the input terminal of the comparator is connected to the logic control circuit 12, so that according to the charge and discharge signal and the target reference voltage, the voltage comparison signal, that is, the overcurrent detection signal, is generated, so that the logic control circuit 12 controls the charge and discharge switch circuit 11 according to the overcurrent detection signal, so that the overcurrent detection circuit 13 has a simple structure and reduces costs.

[0053] This embodiment provides a battery protection chip 1, comprising the above-mentioned battery protection circuit.

[0054] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A battery protection circuit, characterized in that: It includes a charge and discharge switch circuit, a logic control circuit, an overcurrent detection circuit and a reference voltage selection circuit; The charge and discharge switch circuit is used to connect the battery and the charge and discharge interface; The reference voltage selection circuit is used to connect the signal receiving end and at least two voltage input ends, receive the voltage switching signal of the signal receiving end, and determine the target reference voltage from the reference voltages input from at least two voltage input ends according to the voltage switching signal; The overcurrent detection circuit is connected to the charge and discharge switch circuit and the reference voltage selection circuit, and is used to collect the charge and discharge signals of the charge and discharge switch circuit, and output an overcurrent detection signal according to the charge and discharge signals and the target reference voltage; The logic control circuit is connected to the overcurrent detection circuit and the charge and discharge switch circuit, and is used to control the operation of the charge and discharge switch circuit according to the overcurrent detection signal.

2. The battery protection circuit according to claim 1, characterized in that: The reference voltage selection circuit is used to determine a target reference voltage from the reference voltages input from at least two of the voltage input terminals according to a delay time corresponding to each level signal in the voltage switching signal.

3. The battery protection circuit according to claim 2, characterized in that: The reference voltage selection circuit includes a signal processing circuit and a selection switch circuit; The signal processing circuit is connected to the signal receiving end, and is used to output a switch control signal according to the delay time corresponding to each level signal in the voltage switching signal; The selection switch circuit is connected to the signal processing circuit, the overcurrent detection circuit and at least two of the voltage input terminals, and is used to select one of the voltage input terminals to be connected to the overcurrent detection circuit according to the switch control signal, so that the turned-on voltage input terminal outputs the target reference voltage to the overcurrent detection circuit.

4. The battery protection circuit as claimed in claim 3, characterized in that: The signal processing circuit includes a charging control circuit, a capacitor circuit, a first trigger and a second trigger; The first end of the charging control circuit is connected to the first power supply end, the second end of the charging control circuit is grounded, the third end of the charging control circuit is connected to the signal receiving end, and the fourth end of the charging control circuit is connected to the capacitor circuit, and is used to charge the capacitor circuit according to the level signal in the voltage switching signal; A first end of the capacitor circuit is connected to an input end of the first trigger, and a second end of the capacitor circuit is grounded; The output end of the first trigger is connected to the input end of the second trigger, and is used to output a level delay signal according to the capacitor voltage of the capacitor circuit; The output end of the second trigger is connected to the selection switch circuit, and the control end of the second trigger is connected to the signal receiving end, and is used to output a switch control signal according to the voltage switching signal and the level delay signal.

5. The battery protection circuit according to claim 4, characterized in that: The first trigger is a Schmitt trigger.

6. The battery protection circuit according to claim 4, characterized in that: The second trigger is a D trigger; the D trigger includes a first latch and a second latch; The input end of the first latch is connected to the output end of the first trigger, and the first output end of the first latch is connected to the input end of the second latch; The control end of the first latch and the control end of the second latch are connected in common and connected to the signal receiving end; The first output end of the first latch, the second output end of the first latch, the first output end of the second latch, and the second output end of the second latch are all connected to the selection switch circuit.

7. The battery protection circuit according to claim 6, characterized in that: The selection switch circuit includes a first AND gate circuit, a second AND gate circuit, a third AND gate circuit, a fourth AND gate circuit and a switch network; The input end of the switch network is connected to at least two of the voltage input ends, and the output end of the switch network is connected to the overcurrent detection circuit; The first input terminal of the first AND gate circuit is connected to the first output terminal of the first latch, the second input terminal of the first AND gate circuit is connected to the first output terminal of the second latch, and the output terminal of the first AND gate circuit is connected to the first control terminal of the switch network; The first input terminal of the second AND gate circuit is connected to the second output terminal of the first latch, the second input terminal of the second AND gate circuit is connected to the first output terminal of the second latch, and the output terminal of the second AND gate circuit is connected to the second control terminal of the switch network; The first input terminal of the third AND gate circuit is connected to the first output terminal of the first latch, the second input terminal of the third AND gate circuit is connected to the second output terminal of the second latch, and the output terminal of the third AND gate circuit is connected to the third control terminal of the switch network; The first input terminal of the fourth AND gate circuit is connected to the second output terminal of the first latch, the second input terminal of the fourth AND gate circuit is connected to the second output terminal of the second latch, and the output terminal of the fourth AND gate circuit is connected to the fourth control terminal of the switch network.

8. The battery protection circuit according to claim 7, characterized in that: The switch network includes multiple switch branches connected in parallel; each of the switch branches includes a first switch tube; the first end of the first switch tube is connected to a voltage input end, the second end of the switch tube is connected to the overcurrent detection circuit, and the third end of the first switch tube is a control end.

9. The battery protection circuit according to claim 2, characterized in that: The overcurrent detection circuit includes a comparator; The non-inverting input terminal of the comparator is connected to the charge and discharge switch circuit, the inverting input terminal of the comparator is connected to the reference voltage selection circuit, and the input terminal of the comparator is connected to the logic control circuit.

10. A battery protection chip, characterized in that: The invention comprises a battery protection circuit as claimed in any one of claims 1 to 9.

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