CN114487567A - Voltage detection module, battery protection circuit and system - Google Patents

Voltage detection module, battery protection circuit and system Download PDF

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Publication number
CN114487567A
CN114487567A CN202111654736.7A CN202111654736A CN114487567A CN 114487567 A CN114487567 A CN 114487567A CN 202111654736 A CN202111654736 A CN 202111654736A CN 114487567 A CN114487567 A CN 114487567A
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voltage
bipolar transistor
connection
detection
circuit
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王钊
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Zgmicro Corp
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Zgmicro Corp
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides a voltage detection module, a battery protection circuit and a system, wherein the voltage detection circuit comprises: a reference voltage generating circuit for generating a reference voltage, wherein a first connection terminal of the bipolar transistor Q3 is connected to the node B, a second connection terminal thereof is grounded, a control terminal thereof is connected to the first connection terminal of the bipolar transistor Q1, both the second connection terminal and the control terminal of the bipolar transistor Q1 are grounded, the first connection terminal of the bipolar transistor Q4 is connected to the node E, the second connection terminal thereof is grounded, the control terminal thereof is connected to the first connection terminal of the bipolar transistor Q2, and both the second connection terminal and the control terminal of the bipolar transistor Q2 are grounded; a voltage dividing circuit that generates a detection voltage based on a voltage of a detected input voltage terminal; the comparator is used for comparing the reference voltage with the detection voltage and outputting a corresponding detection signal through an output end of the comparator based on the comparison result. Compared with the prior art, the invention can further improve the threshold accuracy of charging overvoltage detection, thereby improving the safety of the battery.

Description

Voltage detection module, battery protection circuit and system
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of integrated circuits, in particular to a voltage detection module, a battery protection circuit and a system.
[ background of the invention ]
Please refer to fig. 1, which is a schematic circuit diagram of a voltage detection module for detecting charging overvoltage in a battery protection circuit in the prior art, wherein the voltage detection module includes a PMOS transistor MP1, an operational amplifier OP, a comparator Comp, resistors R1 to R5, a PNP transistor Q1, and a PNP transistor Q2. The operational amplifier OP adjusts so that the voltages at the positive and negative inputs of the OP are equal, so that the voltage at point A is equal to the emitter voltage of Q2, and also equal to Vbe2 (i.e., the base-emitter voltage of Q2). The voltage at point B is equal to the emitter voltage of Q1 and also equal to Vbe1 (i.e., the base-emitter voltage of Q1), and the voltage across resistor R3 is equal to the difference between the voltages at points a and B (i.e., (Vbe2-Vbe1), which is a positive temperature coefficient voltage. Since the resistor R3 and the resistor R1 have equal currents, the voltage across the resistor R1 is equal to (Vbe2-Vbe1). R1/R3, where Vbe2 is the base-emitter voltage of Q2, Vbe1 is the base-emitter voltage of Q1, R1 is the resistance of the resistor R1, and R3 is the resistance of the resistor R3. It can be seen that the voltage across resistor R1 is also a positive temperature coefficient voltage. The voltage at the point A is Vbe2 and is a negative temperature coefficient voltage, and the voltage at the point BG is equal to the voltage at the point A plus the voltage on the resistor R1, so that the voltage at the point BG is a negative temperature coefficient voltage plus a positive temperature coefficient voltage, and BG can be a zero temperature coefficient voltage through proper design. VIN voltage is battery voltage, after being divided by resistors R4 and R5, the voltage at the point C is generated and compared with the voltage at the point BG, when the voltage at the point C is greater than the voltage at the point BG, a comparator Comp outputs a signal OC to output a high level, which indicates that the charging overvoltage condition occurs; when the voltage at point C is less than the voltage at point BG, the comparator Comp outputs a low signal OC, indicating that no charging overvoltage condition has occurred. The equivalent charging overvoltage threshold is vbg. (R4+ R5)/R5, where VBG is the voltage value at BG, R4 is the resistance of R4, and R5 is the resistance of R5. Since VBG is a zero temperature coefficient voltage value, the charging overvoltage threshold is also a zero temperature coefficient voltage. Since the operational amplifier OP has an input mismatch voltage, which will cause the BG voltage to be inaccurate, the protection threshold accuracy of the charging overvoltage detection in the battery protection circuit is affected, for example, VBG ═ Vbe1+ [ (Vbe2-Vbe1) + Vos ]. R1/R3, Vos is the equivalent input offset voltage of the operational amplifier OP. Since the comparator Comp also has an input mismatch voltage, it will also directly affect the protection threshold accuracy of the charging overvoltage detection in the battery protection circuit.
In order to further improve the threshold accuracy of the charging overvoltage detection, it is necessary to improve fig. 1.
[ summary of the invention ]
The invention aims to provide a voltage detection module, a battery protection circuit and a system, which can further improve the threshold accuracy of charging overvoltage detection so as to improve the safety of a battery.
According to one aspect of the present invention, there is provided a voltage detection circuit comprising: the reference voltage generating circuit is used for generating reference voltage and comprises an operational amplifier OP, a bipolar transistor Q1, a bipolar transistor Q2, a bipolar transistor Q3 and a bipolar transistor Q4, wherein a first connecting end of the bipolar transistor Q3 is connected with the connecting node B, a second connecting end of the bipolar transistor Q3538 is grounded, a control end of the bipolar transistor Q1 is connected with the first connecting end of the bipolar transistor Q1, a second connecting end and a control end of the bipolar transistor Q1 are both grounded, the first connecting end of the bipolar transistor Q4 is connected with the connecting node E, a second connecting end of the bipolar transistor Q4 is grounded, a control end of the bipolar transistor Q2 is connected with the first connecting end of the bipolar transistor Q2, a second connecting end and a control end of the bipolar transistor Q2 are both grounded, wherein the current flowing out of the control end of the bipolar transistor Q3 is equal to the current flowing in the first connecting end of the bipolar transistor Q1, the current flowing out of the control terminal of the bipolar transistor Q4 is equal to the current flowing in the first connection terminal of the bipolar transistor Q2; a voltage dividing circuit that generates a detection voltage based on a voltage of a detected input voltage terminal; and the comparator is used for comparing the reference voltage with the detection voltage and outputting a corresponding detection signal through an output end of the comparator based on the comparison result.
According to another aspect of the present invention, the present invention provides a battery protection circuit, which includes a connection terminal VM connected to a negative electrode of a battery, a connection terminal VSS connected to a negative electrode of a battery cell, a connection terminal VIN connected to a positive electrode of the battery cell, a charging control terminal CO connected to a control terminal of a charging power switch, and a discharging control terminal DO connected to a control terminal of a discharging power switch, wherein the discharging power switch and the charging power switch are connected in series between the connection terminal VM and the connection terminal VSS, and the battery protection circuit further includes a charging overvoltage detection circuit, other detection circuits, and a logic circuit. The charging overvoltage detection circuit is as the voltage detection circuit, the connection end VIN is the input voltage end, and the other detection circuits detect a charging and discharging loop of the battery cell BAT1 based on the connection end VM or the connection end VIN to output corresponding other detection signals; the logic circuit generates a charging control signal and a discharging control signal according to the detection signal output by the charging overvoltage detection circuit and other detection signals output by other detection circuits, the charging control signal is output through the charging control terminal CO, and the discharging control signal is output through the discharging control terminal DO.
According to another aspect of the present invention, there is provided a battery protection system including: an electric core; a switching combination circuit comprising a charging power switch and a discharging power switch connected in series; such as the aforementioned battery protection circuit.
Compared with the prior art, the invention reduces the relative error introduced by the OP input offset of the operational amplifier and reduces the relative error introduced by the OP input offset of the operational amplifier by laminating the bipolar transistors in the reference voltage generating circuit, thereby improving the protection threshold precision of the charging overvoltage detection and further improving the safety of the battery.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
fig. 1 is a schematic circuit diagram of a voltage detection module for detecting charging overvoltage in a battery protection circuit in the prior art;
FIG. 2 is a schematic circuit diagram of a voltage detection module capable of detecting charging overvoltage according to an embodiment of the present invention;
FIG. 3 is a circuit schematic of a battery protection circuit in one embodiment of the present invention;
fig. 4 is a circuit diagram of a battery protection system according to an embodiment of the invention.
[ detailed description ] embodiments
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Unless otherwise specified, the terms connected, and connected as used herein mean electrically connected, directly or indirectly.
Fig. 2 is a schematic circuit diagram of a voltage detection module capable of detecting charging overvoltage according to an embodiment of the invention. The voltage detection module shown in fig. 2 includes: a reference voltage generating circuit 210, a voltage dividing circuit 220 and a comparator Comp.
The reference voltage generating circuit 210 is used for generating a reference voltage (or a bandgap reference voltage) VREF, and includes an operational amplifier OP, a bipolar transistor Q1, a bipolar transistor Q2, a bipolar transistor Q3, a bipolar transistor Q4, a PMOS transistor MP1, and resistors R1, R2, and R3.
In one embodiment, the resistor R1 is connected between the connection node D and the connection node a, the resistor R2 is connected between the connection node D and the connection node E, the first input terminal of the operational amplifier OP is connected to the connection node a, the second input terminal thereof is connected to the connection node E, the resistor R3 is connected between the connection node B and the connection node a, the connection node B is connected to the bipolar transistor Q3, and the connection node E is connected to the bipolar transistor Q4; the bipolar transistor Q1 and the bipolar transistor Q3 are stacked, and the bipolar transistor Q2 and the bipolar transistor Q4 are stacked, so that the voltage difference across the resistor R3 is equal to (Vbe2-Vbe1) + (Vbe4-Vbe3), wherein Vbe2 is the base-emitter voltage difference of the bipolar transistor Q2, Vbe1 is the base-emitter voltage difference of the bipolar transistor Q1, Vbe3 is the base-emitter voltage difference of the bipolar transistor Q3, and Vbe4 is the base-emitter voltage difference of the bipolar transistor Q4.
As shown in FIG. 2, the more specific connection relationship among the devices in the reference voltage generating circuit 210 is: the source of the PMOS transistor MP1 is connected to the input voltage terminal VIN, the gate thereof is connected to the output terminal of the operational amplifier OP, and the drain thereof is connected to the connection node D; resistor R1 is connected between connection node D and connection node a; resistor R3 is connected between connection node a and connection node B; the first connection end of the bipolar transistor Q3 is connected with the connection node B, the second connection end of the bipolar transistor Q3 is grounded, the control end of the bipolar transistor Q1 is connected with the first connection end of the bipolar transistor Q1, and the second connection end and the control end of the bipolar transistor Q1 are both grounded; resistor R2 is connected between connection node D and connection node E; the first connection end of the bipolar transistor Q4 is connected with the connection node E, the second connection end of the bipolar transistor Q4 is grounded, the control end of the bipolar transistor Q2 is connected with the first connection end of the bipolar transistor Q2, and the second connection end and the control end of the bipolar transistor Q2 are both grounded; the current flowing out of the control terminal of the bipolar transistor Q3 is equal to the current flowing in the first connection terminal of the bipolar transistor Q1, and the current flowing out of the control terminal of the bipolar transistor Q4 is equal to the current flowing in the first connection terminal of the bipolar transistor Q2. That is, no other current flows into or out of the connection node G between the control terminal of the bipolar transistor Q3 and the first connection terminal of the bipolar transistor Q1, for example, no current source is connected to the node G. Similarly, no other current flows into or out of the connection node F between the control terminal of the bipolar transistor Q4 and the first connection terminal of the bipolar transistor Q4, for example, no current source is connected to the connection node F.
The first input of the operational amplifier OP is connected to the connection node a, and the second input thereof is connected to the connection node E. Wherein, the voltage at the connection node D is a reference voltage (or a bandgap reference voltage) VREF; the voltage of the input voltage terminal VIN is a cell voltage, and may also be referred to as a detected input voltage in this embodiment.
In the specific embodiment shown in fig. 2, the bipolar transistors Q1, Q2, Q3 and Q4 may be PNP bipolar transistors parasitic in a common CMOS process, and the first connection terminal, the second connection terminal and the control terminal of the bipolar transistors Q1, Q2, Q3 and Q4 are the emitter, the collector and the base of the PNP bipolar transistor, respectively; the first input terminal and the second input terminal of the operational amplifier OP are a non-inverting input terminal and an inverting input terminal thereof, respectively. The emitter area of the bipolar transistor Q1 is typically designed to be larger than the emitter area of the bipolar transistor Q2, and the emitter area of the bipolar transistor Q3 is designed to be larger than the emitter area of the bipolar transistor Q4.
In other embodiments, the PMOS transistor MP1 may also be an NMOS transistor, and the bipolar transistors Q1, Q2, Q3, and Q4 may also be NPN bipolar transistors, and the specific connection relationship is not described again to avoid redundancy.
The operation of the reference voltage generating circuit 210 shown in fig. 2 is described in detail below.
In comparison to fig. 1, the reference voltage generation circuit 210 shown in fig. 2 reduces the relative error introduced by the offset of the OP input of the operational amplifier by stacking bipolar transistors (e.g., bipolar transistors Q3 and Q1 are stacked; bipolar transistors Q4 and Q2 are stacked). The operational amplifier OP forms negative feedback and adjusts the voltages of the positive and negative input terminals to be equal, so that the voltage at the point a (or the connection node a) is equal to Vbe2+ Vbe4, where Vbe2 is the base-emitter voltage of the bipolar transistor Q2, and Vbe4 is the base-emitter voltage of the bipolar transistor Q4. And the voltage at point B (or connecting node B) is equal to Vbe1+ Vbe3, where Vbe1 is the base-emitter voltage of bipolar transistor Q1 and Vbe3 is the base-emitter voltage of bipolar transistor Q3. The voltage difference across the resistor R3 is (Vbe2+ Vbe4) - (Vbe1+ Vbe3) — (Vbe2-Vbe1) + (Vbe4-Vbe 3). The current of the resistor R3 is equal to [ (Vbe2-Vbe1) + (Vbe4-Vbe3) ]/R3 is equal to 2(Vbe2-Vbe1)/R3, where Vbe2 is the base-emitter voltage of the bipolar transistor Q2, Vbe1 is the base-emitter voltage of the bipolar transistor Q1, Vbe3 is the base-emitter voltage of the bipolar transistor Q3, Vbe4 is the base-emitter voltage of the bipolar transistor Q4, R3 is the resistance value of the resistor R3, and Vbe2-Vbe1 is designed to be equal to Vbe4-Vbe3 is equal to Δ Vbe. Δ Vbe is a positive temperature coefficient voltage. If the resistances of the resistors R1 and R2 are equal, the currents of the bipolar transistors Q3 and Q4 can be equal, because the voltage of R1 is equal to the voltage of R2. . The voltage at point a (or connection node a) is Vbe2+ Vbe4, which is a negative temperature coefficient. The voltage VR1 across the resistor R1 is (2 Δ Vbe/R3) — R1, wherein R1 is the resistance of the resistor R1, and the resistors R1 and R3 adopt the same type of resistors, so that the temperature coefficients can be cancelled, and thus the voltage across the resistor R1 is a positive temperature coefficient. Vbe2 is a negative temperature coefficient voltage, and Vbe4 is also a negative temperature coefficient voltage. The voltage VREF connecting node D is VR1+ Vbe2+ Vbe4 is Vbe2+ Vbe4+ (2 Δ Vbe/R3) — R1, equation (1)
By means of a proper ratio of R3/R1, the temperature coefficients of the positive temperature coefficient voltage VR1 and the negative temperature coefficient voltage Vbe2 can be equal and offset, and therefore the VREF voltage value with zero temperature coefficient can be achieved.
Considering the influence of the offset voltage input to the operational amplifier OP, equation (1) is modified as:
VBG ═ Vbe2+ Vbe4) + (2 Δ Vbe + Vos) · R1/R3 equation (2)
The voltage divider circuit 220 samples based on the voltage of the input voltage terminal VIN to generate the detection voltage VC. In the embodiment shown in fig. 2, the voltage divider circuit 220 includes resistors R4 and R5 connected in series to the input voltage terminal VIN and the ground terminal in sequence, and the detection voltage VC is a voltage at a connection node C between the resistors R4 and R5.
The comparator Comp has a first input connected to node D for receiving the reference voltage VREF and a second input connected to node C for receiving the detection voltage VC. The comparator Comp is used for comparing the reference voltage VREF and the detection voltage VC, and outputting a corresponding detection signal (or charging overvoltage protection signal) OC based on the comparison result.
In the specific embodiment shown in fig. 2, the first input and the second input of the comparator Comp are its negative input and its positive input, respectively.
The input voltage end VIN is a cell voltage, a detection voltage VC is obtained through voltage division of the resistors R4 and R5, the comparator Comp compares the detection voltage VC with a reference voltage VREF, when a voltage at a point C (i.e., the detection voltage VC) exceeds the reference voltage VREF, a detection signal OC output by the comparator Comp is inverted, and the judgment of charging overvoltage can be realized by using the state change. Since the reference voltage VREF generated by the reference voltage generation circuit 210 is accurate, and the voltage division ratio of the resistor R4 and the resistor R5 is accurate, the charging overvoltage threshold Voc for OC detection (or charging overvoltage detection) is more accurate.
The equivalent charging overvoltage threshold Voc is VREF (R4+ R5)/R5, where VREF is the voltage value of the D node, which is a relatively accurate voltage value with zero temperature coefficient, R4 is the resistance value of the resistor R4, and R5 is the resistance value of the resistor R5. In fig. 2, considering the input mismatch voltage Vos of the operational amplifier OP, the relative error introduced by the input mismatch voltage Vos is proportional to 2 Δ Vbe (see the foregoing formula 3), while the relative error introduced by the input mismatch voltage Vos in fig. 1 is proportional to Δ Vbe (see the foregoing background art), and the relative error introduced by the input mismatch voltage Vos in fig. 2 is smaller (smaller) than the relative Δ Vbe, so the influence of the input mismatch voltage Vos of the operational amplifier OP on the reference voltage VREF is smaller than the influence of the input mismatch voltage Vos of the operational amplifier OP in fig. 1 on the bandgap reference voltage BG. In addition, the bandgap reference voltage BG in fig. 1 is based on Vbe + k. Δ Vbe (see the aforementioned background art), and its voltage is about 1.2V or so; the reference voltage VREF in fig. 2 is based on 2Vbe + k.2 Δ Vbe (see the aforementioned formula 3), and its voltage is about 2.4V or so, and for the comparator Comp, the relative proportion of the input mismatch voltage Vos to the reference voltage VREF is smaller than that to the bandgap reference voltage BG for the same comparator Comp, and therefore, fig. 2 has a higher accuracy of the voltage threshold (or charging overvoltage threshold Voc) than fig. 1.
Fig. 3 is a schematic circuit diagram of a battery protection circuit according to an embodiment of the invention. Fig. 4 is a schematic circuit diagram of a battery protection system according to an embodiment of the invention. The battery protection system shown in fig. 4 includes a battery cell BAT1, a battery protection circuit 410, a charging power switch 420, and a discharging power switch 430.
The charging power switch 420 and the discharging power switch 430 are sequentially connected in series between the negative electrode of the battery cell BAT1 and the negative electrode BP-of the battery, and the positive electrode of the battery cell BAT1 is directly connected with the positive electrode BP + of the battery.
The charge power switch 420 includes an NMOS (N-Metal-Oxide-Semiconductor) field effect transistor MC and a diode (not shown) parasitic in the body thereof. The discharge power switch 430 includes an NMOS field effect transistor MD and a diode (not shown) parasitic within its body. The drain electrodes of the NMOS field effect transistor MD and the NMOS field effect transistor MC are connected, the source electrode of the NMOS field effect transistor MD is connected to the negative electrode of the battery cell BAT1, and the source electrode of the NMOS field effect transistor MC is connected to the negative electrode BP-of the battery.
The battery protection circuit 410 includes three connection ends (or called detection ends) and two control ends, the three connection ends are a positive connection end VIN of the battery cell, a negative connection end VSS of the battery cell and a negative connection end VM of the battery cell, and the two control ends are a charging control end CO and a discharging control end DO. Wherein, the connection end VIN is connected with the positive electrode of the battery cell BAT 1; the connection terminal VSS is connected to the negative electrode of the battery cell BAT 1; the connecting end VM is connected with the negative electrode BP-of the battery; the charge control terminal CO is connected to the control terminal of the charge power switch 420, i.e. to the gate of the NMOS field effect transistor MC, and the discharge control terminal DO is connected to the control terminal of the discharge power switch 430, i.e. to the gate of the NMOS field effect transistor MD.
The battery protection circuit 410 may employ the battery protection circuit shown in fig. 3, which includes the charging overvoltage detection circuit 310, the other detection circuits 320, and the logic circuit 330 shown in fig. 3.
The charging overvoltage detection circuit 310 can adopt the voltage detection circuit shown in fig. 2, wherein the connection terminal VIN shown in fig. 3 and 4 is the detected input voltage terminal VIN.
The other detection circuit 320 detects the charge-discharge loop of the battery cell BAT1 based on the connection end VM or the connection end VIN to output corresponding other detection signals. For example, depending on the application, the functions of the other detection circuit 320 may include one or more of the following: overvoltage discharge detection, charging overcurrent detection, discharging overcurrent detection, short circuit detection and the like.
The logic circuit 330 generates a charging control signal CO and a discharging control signal DO according to the detection signal output by the charging overvoltage detection circuit 310 and the other detection signals output by the other detection circuits 320, wherein the charging control signal CO is output through the charging control terminal CO, and the discharging control signal DO is output through the discharging control terminal DO. The charging control signal CO controls the charging power switch 420 to connect or disconnect a charging loop of the battery cell BAT 1; the discharging control signal DO controls the discharging power switch 430 to connect or disconnect the discharging loop of the battery cell BAT 1. When the charge control signal CO is at a high level, the charge power switch 420 is controlled to allow charging (i.e., to connect the charge circuit of the battery cell BAT 1), and when the charge control signal CO is at a low level, the charge power switch 420 is controlled to prohibit charging (i.e., to disconnect the charge circuit of the battery cell BAT 1). When the discharge control signal DO is at a high level, the discharge power switch 430 is controlled to allow discharge (i.e., to connect the discharge loop of the battery cell BAT 1), and when the discharge control signal DO is at a low level, the discharge power switch 430 is controlled to prohibit discharge (i.e., to disconnect the discharge loop of the battery cell BAT 1). When the charging overvoltage is detected, the charging control signal CO is controlled to be low level, and charging is prohibited. When the discharge overvoltage is detected, the discharge control signal DO is controlled to become low level, and the discharge is prohibited. When charging overcurrent is detected, the charging control signal CO is controlled to become low level, and charging is prohibited. When the discharge overcurrent is detected, the discharge control signal DO is controlled to become low level, and the discharge is prohibited. When a short circuit is detected, the discharge control signal DO is controlled to become low, and discharge is prohibited.
In summary, the bipolar transistors are stacked in the reference voltage generating circuit, so as to reduce the relative error introduced by the OP input offset of the operational amplifier, and reduce the relative error introduced by the OP input offset of the operational amplifier, thereby improving the protection threshold precision of the charging overvoltage detection, and further improving the battery safety.
In the present invention, the terms "connected", "connecting", and the like mean electrical connections, and direct or indirect electrical connections unless otherwise specified. The direct electrical connection means a direct connection between two or more objects without any intervening objects, and the indirect electrical connection means a connection between two or more objects with one or more intervening objects (e.g., electrical elements or units such as resistors, capacitors, inductors, switches, filters, etc.).
It should be noted that those skilled in the art can make modifications to the embodiments of the present invention without departing from the scope of the appended claims. Accordingly, the scope of the appended claims is not to be limited to the specific embodiments described above.

Claims (10)

1. A voltage detection circuit, comprising:
a reference voltage generating circuit, configured to generate a reference voltage, including an operational amplifier OP, a bipolar transistor Q1, a bipolar transistor Q2, a bipolar transistor Q3, and a bipolar transistor Q4, where a first connection end of the bipolar transistor Q3 is connected to the connection node B, a second connection end of the bipolar transistor Q3 is grounded, a control end of the bipolar transistor Q1 is connected to the first connection end of the bipolar transistor Q1, a second connection end and a control end of the bipolar transistor Q1 are both grounded, a first connection end of the bipolar transistor Q4 is connected to the connection node E, a second connection end of the bipolar transistor Q4 is grounded, a control end of the bipolar transistor Q2 is connected to the first connection end of the bipolar transistor Q4, a second connection end and a control end of the bipolar transistor Q2 are both grounded, where a current flowing out of the control end of the bipolar transistor Q3 is equal to a current flowing in the first connection end of the bipolar transistor Q1, the current flowing out of the control terminal of the bipolar transistor Q4 is equal to the current flowing in the first connection terminal of the bipolar transistor Q2;
a voltage dividing circuit that generates a detection voltage based on a voltage of a detected input voltage terminal;
and the comparator is used for comparing the reference voltage with the detection voltage and outputting a corresponding detection signal through an output end of the comparator based on the comparison result.
2. The voltage detection circuit of claim 1, wherein the reference voltage generation circuit further comprises resistors R1, R2, and R3,
resistor R1 is connected between connection node D and connection node a,
resistor R2 is connected between connection node D and connection node E,
a first input terminal of said operational amplifier OP being connected to said connection node A, a second input terminal thereof being connected to said connection node E,
the resistor R3 is connected between the connection node B, which is connected to the bipolar transistor Q3,
connection node E is connected to bipolar transistor Q4;
the bipolar transistor Q1 and the bipolar transistor Q3 are stacked, and the bipolar transistor Q2 and the bipolar transistor Q4 are stacked, so that the voltage difference across the resistor R3 is equal to (Vbe2-Vbe1) + (Vbe4-Vbe3), wherein Vbe2 is the base-emitter voltage difference of the bipolar transistor Q2, Vbe1 is the base-emitter voltage difference of the bipolar transistor Q1, Vbe3 is the base-emitter voltage difference of the bipolar transistor Q3, and Vbe4 is the base-emitter voltage difference of the bipolar transistor Q4.
3. The voltage detection circuit of claim 1,
the reference voltage generating circuit further comprises a MOS transistor,
the first connecting end of the MOS transistor is connected with the input voltage end, the control end of the MOS transistor is connected with the output end of the operational amplifier OP, and the second connecting end of the MOS transistor is connected with the connecting node D;
wherein, the voltage on the connection node D is a reference voltage.
4. The voltage detection circuit of claim 3,
the voltage of the input voltage end is the cell voltage;
the voltage at the input voltage terminal is referred to as the input voltage under test,
the MOS transistor is a PMOS transistor, and the first connecting end, the second connecting end and the control end of the MOS transistor are respectively a source electrode, a drain electrode and a grid electrode of the PMOS transistor.
5. The voltage detection circuit of claim 3,
the bipolar transistors Q1, Q2, Q3 and Q4 are PNP bipolar transistors, and the first connection end, the second connection end and the control end of the bipolar transistors Q1, Q2, Q3 and Q4 are respectively an emitter, a collector and a base of the PNP bipolar transistors.
6. The voltage detection circuit of claim 3,
the emitter area of the bipolar transistor Q1 is greater than the emitter area of the bipolar transistor Q2, and the emitter area of the bipolar transistor Q3 is greater than the emitter area of the bipolar transistor Q4.
7. The voltage detection circuit of claim 5,
the first input terminal and the second input terminal of the operational amplifier OP are a non-inverting input terminal and an inverting input terminal thereof,
the voltage dividing circuit comprises resistors R4 and R5, the resistors R4 and R5 are sequentially connected in series between the input voltage end and the ground end, and the voltage of a connection node C between the resistors R3 and R4 is the detection voltage.
8. The voltage detection circuit of claim 5,
the resistances of the resistors R1 and R2 are equal;
the resistors R1 and R3 adopt the same temperature type resistor.
9. A battery protection circuit comprises a connection end VM connected with a battery cathode, a connection end VSS connected with the battery cell cathode, a connection end VIN connected with a battery cell anode, a charge control end CO connected with a control end of a charge power switch, and a discharge control end DO connected with a control end of a discharge power switch, wherein the discharge power switch and the charge power switch are connected in series between the connection end VM and the connection end VSS, and the battery protection circuit is characterized by further comprising a charge overvoltage detection circuit, other detection circuits and a logic circuit,
the charging overvoltage detection circuit according to any one of claims 1 to 8, wherein the connection terminal VIN is the input voltage terminal,
the other detection circuit detects a charge-discharge loop of the battery cell BAT1 based on the connection end VM or the connection end VIN to output corresponding other detection signals; (ii) a
The logic circuit generates a charging control signal and a discharging control signal according to the detection signal output by the charging overvoltage detection circuit and other detection signals output by other detection circuits, the charging control signal is output through the charging control terminal CO, and the discharging control signal is output through the discharging control terminal DO.
10. A battery protection system, comprising:
an electric core;
a switching combination circuit comprising a charging power switch and a discharging power switch connected in series;
the battery protection circuit of claim 9.
CN202111654736.7A 2021-12-30 2021-12-30 Voltage detection module, battery protection circuit and system Pending CN114487567A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111654736.7A CN114487567A (en) 2021-12-30 2021-12-30 Voltage detection module, battery protection circuit and system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111654736.7A CN114487567A (en) 2021-12-30 2021-12-30 Voltage detection module, battery protection circuit and system

Publications (1)

Publication Number Publication Date
CN114487567A true CN114487567A (en) 2022-05-13

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111654736.7A Pending CN114487567A (en) 2021-12-30 2021-12-30 Voltage detection module, battery protection circuit and system

Country Status (1)

Country Link
CN (1) CN114487567A (en)

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