Battery protection circuit and charging power switch control signal generating circuit thereof

Abstract

The present invention provides a battery protection circuit and a charging power switch control signal generating circuit thereof. The charging power switch control signal generating circuit includes: a controller for detecting whether battery charging is permitted; a first MOS transistor, a first connection terminal of which is connected to a first detection terminal, a second connection terminal of which is connected to a charging control terminal, and a control terminal of which is connected to an output terminal of the controller; a first resistor and a second resistor, the first resistor and the second resistor being sequentially connected in series between the charging control terminal and the second detection terminal; a second MOS transistor, a first connection terminal of which is connected to the charging control terminal, a second connection terminal of which is connected to a connection node between the first resistor and the second resistor, and a control terminal of which is connected to an output terminal of a charging overcurrent detection circuit; and a charging overcurrent detection circuit for detecting whether the battery is charging overcurrent. Compared with the prior art, the present invention can accelerate the speed of pulling down the charging power switch control signal in the event of a charging overcurrent state, thereby causing the charging power switch to be shut down in a timely manner.

Description

Technical field

[0001] The present invention relates to the field of circuit design, and in particular to a battery protection circuit and a charging power switch control signal generating circuit thereof. [Background Technology]

[0002] Battery protection circuits are typically installed inside the battery. For example, a mobile phone battery contains a small printed circuit board (PCB) on which the battery protection circuit is mounted. This circuit controls the battery's charge and discharge. Its basic functions include overvoltage protection for charging, overvoltage protection for discharging, overcurrent protection for discharging, overcurrent protection for charging, and short-circuit protection.

[0003] Please refer to Figure 1 As shown in FIG, a circuit diagram of a battery protection system in the prior art is shown. The battery protection system includes a battery protection circuit (or battery protection chip), a charging power switch (or charging power tube) MN2, a discharging power switch (or discharging power tube) MN1, a resistor R, and a capacitor C. The battery protection circuit needs to output a charging power switch control signal CO and a discharging power switch control signal DO to control the charging and discharging of the battery cell BT1.

[0004] Please refer to Figure 2 As shown, it is a generation circuit (or driving circuit) of a charging power switch control signal CO in the prior art. For details, please refer to Chinese patent application: CN201210484658.5. For processes without high-voltage isolation NMOS, use Figure 2 The circuit structure shown in the figure can well realize the driving of CO signal; for the battery protection circuit without charging overcurrent protection circuit, it is used Figure 2 The circuit structure shown can work well. However, it has the following disadvantages: First, when the battery protection circuit needs to integrate charging overcurrent protection, Figure 2 The circuit shown causes the CO signal to fall for an excessively long time, potentially causing the charging power tube (or charging power switch) to protect too slowly in the overcurrent state, thus damaging the charging power tube. Secondly, when the circuit is in a normal, unprotected state, resistor R1 consumes current, causing the normal operating current to be excessively high.

[0005] Therefore, it is necessary to propose an improved technical solution to overcome the above problems. [Summary of the invention]

[0006] One of the objectives of the present invention is to provide a battery protection circuit and a charging power switch control signal generating circuit thereof. The battery protection circuit integrates a charging overcurrent protection function. When a charging overcurrent state is detected, the charging power switch control signal generating circuit can accelerate the speed of pulling down the charging power switch control signal CO, thereby causing the charging power switch to be turned off in a timely manner, thereby improving the charging overcurrent protection speed of the battery protection circuit.

[0007] According to one aspect of the present invention, the present invention provides a battery protection circuit and a charging power switch control signal generating circuit thereof.

[0008] The charging power switch control signal generating circuit includes: a controller, which is used to detect whether charging of the battery is allowed and output a corresponding first control signal through its output end; a first MOS transistor, whose first connection end is connected to the first detection end, whose second connection end is connected to the charging control end, and whose control end is connected to the output end of the controller; a first resistor and a second resistor, the first resistor and the second resistor being connected in series between the charging control end and the second detection end; a second MOS transistor, whose first connection end is connected to the charging control end, whose second connection end is connected to the connection node between the first resistor and the second resistor, and whose control end is connected to the output end of the charging overcurrent detection circuit; and the charging overcurrent detection circuit, which is used to detect whether the battery is charging overcurrent and output a corresponding second control signal through its output end.

[0009] Furthermore, when it is detected that the battery is allowed to be charged, the controller controls the first MOS transistor to be turned on through its output end; when it is detected that the battery is prohibited from being charged, the controller controls the first MOS transistor to be turned off through its output end; when it is detected that the battery is not overcurrented during charging, the charging overcurrent detection circuit controls the second MOS transistor to be turned off through its output end; when it is detected that the battery is overcurrented during charging, the charging overcurrent detection circuit controls the second MOS transistor to be turned on through its output end.

[0010] Furthermore, the first MOS transistor and the second MOS transistor are both PMOS transistors, and the first connection end, the second connection end and the control end of the first MOS transistor and the second MOS transistor are respectively the source, the drain and the gate of the PMOS transistor; and the substrate ends of the first MOS transistor and the second MOS transistor are both connected to the first detection end.

[0011] Furthermore, the first power supply terminal of the charging overcurrent detection circuit is connected to the first detection terminal, and the second power supply terminal thereof is connected to the third detection terminal. When a battery charging overcurrent is detected, the voltage of the first control signal outputted from the output terminal of the charging overcurrent detection circuit to the control terminal of the second MOS transistor is equal to the voltage of the third detection terminal G, so that the second MOS transistor is turned on.

[0012] Furthermore, the first detection end is a connection end for connecting the battery protection circuit to the positive electrode of the battery cell; the second detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery; the third detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery cell, and the first resistance is greater than or equal to 10 6 Ohm; the second resistance is less than or equal to 500 ohms.

[0013] The battery protection circuit includes a second detection terminal connected to the negative electrode of the battery, a third detection terminal connected to the negative electrode of the battery cell, a first detection terminal connected to the positive electrode of the battery cell, a discharge control terminal connected to the control terminal of a discharge power switch, and a charge control terminal connected to the control terminal of a charge power switch, wherein the discharge power switch and the charge power switch are connected between the third detection terminal and the second detection terminal. The battery protection circuit also includes a charge power switch control signal generating circuit. The charge power switch control signal generating circuit includes: a controller for detecting whether battery charging is permitted and outputting a corresponding first control signal through its output terminal; a first MOS transistor having a first connection terminal connected to the first detection terminal, a second connection terminal connected to the charge control terminal, and a control terminal connected to the output terminal of the controller; a first resistor and a second resistor, the first resistor and the second resistor being connected in series between the charge control terminal and the second detection terminal; a second MOS transistor having a first connection terminal connected to the charge control terminal, a second connection terminal connected to the node between the first resistor and the second resistor, and a control terminal connected to the output terminal of the charge overcurrent detection circuit; and a charge overcurrent detection circuit for detecting whether the battery is overcharged and outputting a corresponding second control signal through its output terminal.

[0014] According to another aspect of the present invention, the present invention provides another battery protection circuit and a charging power switch control signal generating circuit thereof.

[0015] The charging power switch control signal generating circuit includes: a controller, configured to detect whether charging of the battery is permitted and output a corresponding first control signal through its output terminal; a first MOS transistor, having a first connection terminal connected to the first detection terminal V, a second connection terminal connected to the charging control terminal, and a control terminal connected to the output terminal of the controller; a first resistor, a second resistor, and a third resistor, wherein the first resistor, the third resistor, and the second resistor are sequentially connected in series between the charging control terminal and the second detection terminal; a second MOS transistor, having a first connection terminal connected to the charging control terminal and a second connection terminal connected to a connection node between the first resistor and the third resistor; a third MOS transistor, having a first connection terminal connected to the first detection terminal and a second connection terminal connected to the control terminal of the second MOS transistor, and a control terminal connected to the output terminal of the charging overcurrent detection circuit; and a fourth resistor, having one end connected to the second connection terminal of the third MOS transistor and the other end connected to the connection node between the third resistor and the second resistor. The charging overcurrent detection circuit is configured to detect whether the battery is overcharged and output a corresponding third control signal through its output terminal.

[0016] Furthermore, when it is detected that battery charging is allowed, the controller controls the first MOS transistor to be turned on through its output end; when it is detected that battery charging is prohibited, the controller controls the first MOS transistor to be turned off through its output end; when it is detected that the battery is not overcurrent, the charging overcurrent detection circuit controls the third MOS transistor to be turned on through its output end, and the third MOS transistor is turned on so that the second MOS transistor is turned off; when it is detected that the battery is overcurrent, the charging overcurrent detection circuit controls the third MOS transistor to be turned off through its output end, and the third MOS transistor is turned off so that the second MOS transistor is turned on.

[0017] Furthermore, the first MOS transistor, the second MOS transistor and the third MOS transistor are all PMOS transistors, and the first connection end, the second connection end and the control end of the first MOS transistor, the second MOS transistor and the third MOS transistor are respectively the source, the drain and the gate of the PMOS transistor; the substrate ends of the first MOS transistor, the second MOS transistor and the third MOS transistor are all connected to the first detection end.

[0018] Furthermore, the first power supply terminal of the charging overcurrent detection circuit is connected to the first detection terminal, and the second power supply terminal is connected to the third detection terminal. When a battery charging overcurrent is detected, the charging overcurrent detection circuit controls the third MOS tube to turn off. At this time, the voltage at the control terminal of the second MOS tube is less than the voltage at the second detection terminal.

[0019] Furthermore, the first detection end is a connection end for connecting the battery protection circuit to the positive electrode of the battery cell; the second detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery; the third detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery cell, and the first resistance is greater than or equal to 106 Ohm; the second resistance is less than or equal to 500 ohms.

[0020] The battery protection circuit includes a second detection terminal connected to the negative electrode of the battery, a third detection terminal connected to the negative electrode of the battery cell, a first detection terminal connected to the positive electrode of the battery cell, a discharge control terminal connected to the control terminal of a discharge power switch, and a charge control terminal connected to the control terminal of a charge power switch. The discharge power switch and the charge power switch are connected between the third detection terminal and the second detection terminal. The battery protection circuit also includes a charging power switch control signal generating circuit. The charging power switch control signal generating circuit includes: a controller, configured to detect whether charging of the battery is permitted and output a corresponding first control signal through its output terminal; a first MOS transistor, having a first connection terminal connected to the first detection terminal V, a second connection terminal connected to the charging control terminal, and a control terminal connected to the output terminal of the controller; a first resistor, a second resistor, and a third resistor, wherein the first resistor, the third resistor, and the second resistor are sequentially connected in series between the charging control terminal and the second detection terminal; a second MOS transistor, having a first connection terminal connected to the charging control terminal and a second connection terminal connected to a connection node between the first resistor and the third resistor; a third MOS transistor, having a first connection terminal connected to the first detection terminal and a second connection terminal connected to the control terminal of the second MOS transistor, and a control terminal connected to the output terminal of the charging overcurrent detection circuit; and a fourth resistor, having one end connected to the second connection terminal of the third MOS transistor and the other end connected to the connection node between the third resistor and the second resistor. The charging overcurrent detection circuit is configured to detect whether the battery is overcharged and output a corresponding third control signal through its output terminal.

[0021] Compared with the prior art, the present invention further includes a charging overcurrent detection circuit and a MOS transistor MP2 connected in parallel with the resistor R1. When the charging overcurrent detection circuit detects a charging overcurrent, the MOS transistor MP2 is controlled to conduct, thereby accelerating the speed of pulling down the charging power switch control signal CO, thereby causing the charging power switch MN2 to be turned off in a timely manner, thereby improving the charging overcurrent protection speed of the battery protection circuit.

Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0023] Figure 1 This is a circuit diagram of a battery protection system in the prior art;

[0024] Figure 2A circuit for generating a charging power switch control signal CO in the prior art;

[0025] Figure 3 1 is a circuit diagram of a charging power switch control signal generating circuit in a battery protection circuit of the present invention in one embodiment;

[0026] Figure 4 FIG. 4 is a circuit diagram of another embodiment of a charging power switch control signal generating circuit in a battery protection circuit of the present invention. [Specific implementation method]

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to separate or selective embodiments that are mutually exclusive of other embodiments. Unless otherwise specified, the terms "connected," "connected," and "connected" herein, indicating electrical connection, refer to direct or indirect electrical connection.

[0029] Please combine Figure 1 As shown, the battery protection system of the present invention includes a battery cell BT1, a resistor R, a capacitor C, a battery protection circuit (or battery protection chip) 110, a charging power switch 120, and a discharging power switch 130. The resistor R and the capacitor C are connected in series between the positive electrode B+ and the negative electrode B- of the battery cell BT1, the discharging power switch MN1 and the charging power switch MN2 are connected in series between the negative electrode B- of the battery cell and the negative electrode P- of the battery, and the positive electrode B+ of the battery cell BT1 is directly connected to the positive electrode P+ of the battery.

[0030] The charging power switch 120 includes a charging switch tube and a parasitic diode (not shown) within the charging switch tube. In one embodiment of the present invention, the charging switch tube is an NMOS (N-channel Metal Oxide Semiconductor) field effect transistor MN2. The discharging power switch 130 includes a discharging switch tube and a parasitic diode (not shown) within the charging switch tube. In one embodiment of the present invention, the discharging switch tube is an NMOS field effect transistor MN1. The drain of the NMOS transistor MN1 is connected to the drain of the NMOS transistor MN2, the source of the NMOS transistor MN1 is connected to the negative electrode B- of the battery cell, and the source of the NMOS transistor MN2 is connected to the negative electrode P- of the battery.

[0031] The battery protection circuit 110 includes three detection terminals (or connection terminals) and two control terminals. The three detection terminals are a detection terminal VDD for the positive electrode B+ of the battery cell, a detection terminal G for the negative electrode B- of the battery cell, and a detection terminal VM for the negative electrode P- of the battery cell. The two control terminals are a charge control terminal CO and a discharge control terminal DO. The detection terminal VDD is connected between a resistor R and a capacitor C, the detection terminal G is connected to the negative electrode B- of the battery cell, and the detection terminal VM is connected to the negative electrode P- of the battery. The charge control terminal CO is connected to the control terminal of the charging power switch 120 (i.e., the gate of the NMOS transistor MN2), and the discharge control terminal DO is connected to the control terminal of the discharging power switch 130 (i.e., the gate of the NMOS transistor MN1).

[0032] The battery protection circuit 110 can realize charging protection and discharging protection for the battery cell BT1 by controlling the conduction and shutdown of the NMOS transistors MN1 and MN2. In normal state, the battery protection circuit 110 controls the NMOS transistors MN1 and MN2 to be turned on at the same time, at which time both charging and discharging are possible. When charging is abnormal, the battery protection circuit 110 controls the NMOS transistor MN2 to be turned off, thereby cutting off the charging circuit, but discharging is still possible. When discharging is abnormal, the battery protection circuit 110 controls the NMOS transistor MN1 to be turned off, thereby cutting off the discharging circuit, but charging is still possible.

[0033] Please refer to Figure 3 , which is a circuit diagram of a charging power switch control signal generating circuit in a battery protection circuit of the present invention in one embodiment.

[0034] like Figure 3 As shown, the charging power switch control signal generating circuit in the battery protection circuit of the present invention includes a controller 310 , a first MOS transistor MP1 , a second MOS transistor MP2 , a first resistor R1 , a second resistor R2 , and a charging overcurrent detection circuit 320 .

[0035] The controller 310 is configured to detect whether battery charging is permitted and output a corresponding first control signal through its output terminal. The first connection terminal of the first MOS transistor MP1 is connected to the first detection terminal VDD, its second connection terminal is connected to the charge control terminal CO, and its control terminal is connected to the output terminal of the controller 310. The first resistor R1 and the second resistor 2 are connected in series between the charge control terminal CO and the second detection terminal VM. The first connection terminal of the second MOS transistor MP2 is connected to the charge control terminal CO, its second connection terminal is connected to the connection node O1 between the first resistor R1 and the second resistor R2, and its control terminal is connected to the output terminal of the charge overcurrent detection circuit 320. The charge overcurrent detection circuit 320 is configured to detect whether the battery is overcharged and output a corresponding second control signal ECIB through its output terminal.

[0036] exist Figure 3 In the specific embodiment shown, the first MOS transistor MP1 and the second MOS transistor MP2 are both PMOS transistors (P-channel Metal Oxide Semiconductor), and the first connection terminal, the second connection terminal, and the control terminal of the first MOS transistor MP1 and the second MOS transistor MP2 are respectively the source, the drain, and the gate of the PMOS transistor; the first power supply terminal of the charging overcurrent detection circuit 320 is connected to the first detection terminal VDD, and the second power supply terminal thereof is connected to the third detection terminal G; the substrate terminals of the first MOS transistor MP1 and the second MOS transistor MP2 are both connected to the first detection terminal VDD; the first detection terminal VDD is the connection terminal for connecting the battery protection circuit to the positive electrode of the battery cell; the second detection terminal VM is the connection terminal for connecting the battery protection circuit to the negative electrode of the battery cell; and the third detection terminal G is the connection terminal for connecting the battery protection circuit to the negative electrode of the battery cell.

[0037] The following combination Figure 1 , detailed introduction Figure 3 The working principle of the charging power switch control signal generating circuit in the battery protection circuit shown.

[0038] When it is detected that battery charging is permitted, the controller 310 outputs a first logic level of a first control signal through its output terminal to control the first MOS transistor MP1 to turn on, causing the charging control terminal CO to output a high level. The charging power switch 120 then turns on, and the battery protection circuit 110 permits battery charging. When it is detected that battery charging is prohibited, the controller 310 outputs a second logic level of the first control signal through its output terminal to control the first MOS transistor MP1 to turn off. At this time, the potential of the charging control terminal CO is pulled down by at least the first resistor R1 and the second resistor R2, causing the charging control terminal CO to output a low level. The charging power switch 120 then turns off, and the battery protection circuit 110 prohibits battery charging. Prohibiting battery charging includes battery charging overvoltage and battery charging overcurrent.

[0039] When it is detected that the battery is not over-current charged, the charging over-current detection circuit 320 outputs the second logic level of the second control signal ECIB through its output terminal to control the second MOS tube MP2 to be turned off. When it is detected that the battery is over-current charged, the charging over-current detection circuit 320 outputs the first logic level of the second control signal ECIB through its output terminal to control the second MOS tube MP2 to be turned on. When it is detected that the battery is over-current charged, the charging over-current detection circuit 320 controls the second MOS tube MP2 to be turned on. In this way, the resistance connected in series from the charging control terminal CO to the second detection terminal VM is equivalently reduced, thereby speeding up the speed of pulling down the potential of the charging control terminal CO, that is, reducing the time it takes for the potential of the charging control terminal CO to drop. Due to Figure 3 The battery protection circuit shown can speed up the discharge speed, so the total resistance (first resistor R1 + second resistor R2) can be made larger, thereby reducing the current consumption in the unprotected state. Among them, the resistor R2 mainly plays the role of electrostatic protection. The resistance value of the resistor R2 can actually be very small. Generally, the second resistor R2 is less than or equal to 500 ohms, for example, the second resistor R2 is equal to 200 ohms; while the first resistor R1 is designed to be large, for example, the first resistor R1 is greater than or equal to 10 6 ohm.

[0040] It should be noted that in Figure 3 In the illustrated embodiment, the first logic level of each of the first and second control signals ECIB is low, and the second logic level of each of the first and second control signals ECIB is high. The first and second logic levels represent two logical states of the same control signal. The low level (i.e., the first logic level) of the second control signal ECIB is equal to the voltage of the third detection terminal G (i.e., the ground node). When a charger adapter is inserted, the second detection terminal VM is at a negative voltage relative to the third detection terminal G.

[0041] Please refer to Figure 4 , which is a circuit diagram of a charging power switch control signal generating circuit in a battery protection circuit of the present invention in another embodiment. Figure 3 compared to, Figure 4 The illustrated embodiment adds a third MOS transistor MP3, a third resistor R3, and a fourth resistor R4.

[0042] like Figure 4 As shown, the charging power switch control signal generating circuit in the battery protection circuit of the present invention includes a controller 310, a first MOS transistor MP1, a second MOS transistor MP2, a third MOS transistor MP3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a charging overcurrent detection circuit 320.

[0043] The controller 310 is configured to detect whether battery charging is permitted and output a corresponding first control signal through its output terminal. The first connection terminal of the first MOS transistor MP1 is connected to the first detection terminal VDD, its second connection terminal is connected to the charge control terminal CO, and its control terminal is connected to the output terminal of the controller 310. The first resistor R1, the third resistor R3, and the second resistor 2 are sequentially connected in series between the charge control terminal CO and the second detection terminal VM. The first connection terminal of the second MOS transistor MP2 is connected to the charge control terminal CO, and its second connection terminal is connected to the connection node O2 between the first resistor R1 and the third resistor R3.

[0044] The first connection terminal of the third MOS transistor MP3 is connected to the first detection terminal VDD, and the second connection terminal is connected to the control terminal of the second MOS transistor MP2, and the control terminal is connected to the output terminal of the charging overcurrent detection circuit 320. One end of the fourth resistor R4 is connected to the second connection terminal of the third MOS transistor MP3, and the other end of the fourth resistor R4 is connected to the connection node O3 between the third resistor R3 and the second resistor R2. The charging overcurrent detection circuit 320 is used to detect whether the battery is charging overcurrent and output a corresponding third control signal ECI through its output terminal.

[0045] exist Figure 4 In the specific embodiment shown, the first MOS transistor MP1, the second MOS transistor MP2, and the third MOS transistor MP3 are all PMOS transistors, and the first connection terminal, the second connection terminal, and the control terminal of the first MOS transistor MP1, the second MOS transistor MP2, and the third MOS transistor MP3 are respectively the source, the drain, and the gate of the PMOS transistors; the first power supply terminal of the charging overcurrent detection circuit 320 is connected to the first detection terminal VDD, and the second power supply terminal thereof is connected to the third detection terminal G; the substrate terminals of the first MOS transistor MP1, the second MOS transistor MP2, and the third MOS transistor MP3 are all connected to the first detection terminal VDD; the first detection terminal VDD is the connection terminal for connecting the battery protection circuit to the positive electrode of the battery cell; the second detection terminal VM is the connection terminal for connecting the battery protection circuit to the negative electrode of the battery; and the third detection terminal G is the connection terminal for connecting the battery protection circuit to the negative electrode of the battery cell.

[0046] The following combination Figure 1 , detailed introduction Figure 4 The working principle of the charging power switch control signal generating circuit in the battery protection circuit shown.

[0047] When it is detected that battery charging is permitted, the controller 310 outputs a first logic level of a first control signal through its output terminal to control the first MOS transistor MP1 to turn on, causing the charging control terminal CO to output a high level. The charging power switch 120 then turns on, and the battery protection circuit 110 permits battery charging. When it is detected that battery charging is prohibited, the controller 310 outputs a second logic level of the first control signal through its output terminal to control the first MOS transistor MP1 to turn off. At this time, the potential of the charging control terminal CO is pulled down by at least the first resistor R1, the second resistor R2, and the third resistor R3, causing the charging control terminal CO to output a low level. The charging power switch 120 then turns off, and the battery protection circuit 110 prohibits battery charging. Prohibiting battery charging includes battery charging overvoltage and battery charging overcurrent.

[0048] When it detects that the battery is not overcurrent-charging, the charging overcurrent detection circuit 320 outputs a first logic level of the third control signal ECI through its output terminal to turn on the third MOS transistor MP3. At this time, the second connection terminal of the third MOS transistor MP3 outputs a second logic level of the second control signal ECIB to turn off the second MOS transistor MP2. When it detects that the battery is overcurrent-charging, the charging overcurrent detection circuit 320 outputs a second logic level of the third control signal ECI through its output terminal to turn off the third MOS transistor MP3. At this time, the second connection terminal of the third MOS transistor MP3 outputs a first logic level of the second control signal ECIB to turn on the second MOS transistor MP2. The second control signal ECIB and the third control signal ECI are inverted signals. When a charger adapter is inserted, the second detection terminal VM is a negative voltage relative to the third detection terminal G.

[0049] exist Figure 4 In the specific embodiment shown, the first logic levels of the first control signal, the second control signal ECIB, and the third control signal ECI are all low levels; the second logic levels of the first control signal, the second control signal ECIB, and the third control signal ECI are all high levels, wherein the first logic level and the second logic level are two logic states of the same control signal.

[0050] It should be noted that Figure 3 The circuit shown mainly speeds up the time when the voltage of the charge control terminal CO drops from the first detection terminal VDD to VG+|Vthp|, where VG is the voltage value of the third detection terminal G and Vthp is the threshold voltage of the second MOS transistor MP2. Because the second MOS transistor MP2 can only be turned on during this time. When the voltage of the charge control terminal CO is lower than VG+|Vthp|, the discharge is still determined by the first resistor R1, and therefore is also very slow. Figure 4In the circuit design shown, when a discharge overcurrent state is detected, the third control signal ECI becomes high, the third MOS transistor MP3 is turned off, and the fourth resistor R4 pulls down the gate of the second MOS transistor MP2 to a relatively low voltage VN (that is, the second control signal ECIB becomes low, and the low-level voltage is VN). The VN voltage is lower than the voltage of the third detection terminal G. Therefore, the second MOS transistor MP2 can be turned on for a longer time, further accelerating the speed of pulling down the potential of the charging control terminal CO. Therefore, Figure 4 Can achieve Figure 3 A shorter potential drop time of the charging control terminal CO.

[0051] because Figure 4 The battery protection circuit shown can speed up the discharge speed, so the total resistance (first resistor R1 + second resistor R2 + third resistor R3) can be made larger, thereby reducing the current consumption in the unprotected state. Among them, the resistor R2 mainly plays the role of electrostatic protection. The resistance value of the resistor R2 can actually be very small. Generally, the second resistor R2 is less than or equal to 500 ohms, for example, the second resistor R2 is equal to 200 ohms; while the first resistor R1 is designed to be large, for example, the first resistor R1 is greater than or equal to 10 6 ohm.

[0052] In the present invention, words such as “connect,” “connected,” “connect,” and “connected” that represent electrical connection, unless otherwise specified, represent direct or indirect electrical connection.

[0053] It should be noted that any changes made by those skilled in the art to the specific embodiments of the present invention do not depart from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the aforementioned specific embodiments.

Claims

1. A charging power switch control signal generating circuit, characterized in that: It includes: a controller configured to detect whether charging of the battery is permitted and output a corresponding first control signal via an output terminal thereof; A first MOS transistor, whose first connection end is connected to the first detection end, whose second connection end is connected to the charging control end, and whose control end is connected to the output end of the controller; a first resistor and a second resistor, wherein the first resistor and the second resistor are sequentially connected in series between the charging control terminal and the second detection terminal; a second MOS transistor, having a first connection end connected to the charging control end, a second connection end connected to the connection node between the first resistor and the second resistor, and a control end connected to the output end of the charging overcurrent detection circuit; The charging overcurrent detection circuit is used to detect whether the battery is overcharged and output a corresponding second control signal through its output terminal. When it is detected that the battery is allowed to be charged, the controller controls the first MOS transistor to be turned on through its output terminal; When it is detected that charging of the battery is prohibited, the controller controls the first MOS transistor to be turned off through its output terminal; When it is detected that the battery is not over-currented, the charging over-current detection circuit controls the second MOS tube to be turned off through its output end; when it is detected that the battery is over-currented, the charging over-current detection circuit controls the second MOS tube to be turned on through its output end.

2. The charging power switch control signal generating circuit according to claim 1, characterized in that: The first MOS transistor and the second MOS transistor are both PMOS transistors, and the first connection end, the second connection end and the control end of the first MOS transistor and the second MOS transistor are the source, the drain and the gate of the PMOS transistor respectively; The substrate ends of the first MOS transistor and the second MOS transistor are both connected to the first detection end.

3. The charging power switch control signal generating circuit according to claim 2, characterized in that: The first power supply terminal of the charging overcurrent detection circuit is connected to the first detection terminal, and the second power supply terminal is connected to the third detection terminal. When battery charging overcurrent is detected, the voltage of the first control signal outputted by the output terminal of the charging overcurrent detection circuit to the control terminal of the second MOS transistor is equal to the voltage of the third detection terminal G, so that the second MOS transistor is turned on.

4. The charging power switch control signal generating circuit according to claim 3, characterized in that: The first detection end is a connection end for connecting the battery protection circuit to the positive electrode of the battery cell; the second detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery; the third detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery cell. The first resistance is greater than or equal to 10 6 Ohm; the second resistance is less than or equal to 500 ohms.

5. A battery protection circuit, comprising a second detection terminal connected to the negative electrode of the battery, a third detection terminal connected to the negative electrode of the battery cell, a first detection terminal connected to the positive electrode of the battery cell, a discharge control terminal connected to the control terminal of a discharge power switch, and a charge control terminal connected to the control terminal of a charge power switch, wherein: The discharging power switch and the charging power switch are connected between the third detection terminal and the second detection terminal, and are characterized in that they also include the charging power switch control signal generating circuit according to any one of claims 1 to 4.

6. A charging power switch control signal generating circuit, characterized in that: It includes: a controller configured to detect whether charging of the battery is permitted and output a corresponding first control signal via an output terminal thereof; A first MOS transistor, whose first connection end is connected to the first detection end V, whose second connection end is connected to the charging control end, and whose control end is connected to the output end of the controller; a first resistor, a second resistor, and a third resistor, wherein the first resistor, the third resistor, and the second resistor are sequentially connected in series between the charging control terminal and the second detection terminal; a second MOS transistor, a first connection end of which is connected to the charging control end, and a second connection end of which is connected to a connection node between the first resistor and the third resistor; A third MOS transistor, a first connection end of which is connected to the first detection end, a second connection end of which is connected to the control end of the second MOS transistor, and a control end of which is connected to the output end of the charging overcurrent detection circuit; a fourth resistor, one end of which is connected to the second connection end of the third MOS transistor, and the other end of which is connected to the connection node between the third resistor and the second resistor, The charging overcurrent detection circuit is used to detect whether the battery is charging overcurrent and output a corresponding third control signal through its output terminal.

7. The charging power switch control signal generating circuit according to claim 6, characterized in that: When it is detected that the battery is allowed to be charged, the controller controls the first MOS transistor to be turned on through its output end; when it is detected that the battery is prohibited to be charged, the controller controls the first MOS transistor to be turned off through its output end; When it is detected that the battery is not overcurrented during charging, the charging overcurrent detection circuit controls the third MOS transistor to be turned on through its output end, and the third MOS transistor is turned on so that the second MOS transistor is turned off; when it is detected that the battery is overcurrented during charging, the charging overcurrent detection circuit controls the third MOS transistor to be turned off through its output end, and the third MOS transistor is turned off so that the second MOS transistor is turned on.

8. The charging power switch control signal generating circuit according to claim 7, characterized in that: The first MOS transistor, the second MOS transistor and the third MOS transistor are all PMOS transistors, and the first connection end, the second connection end and the control end of the first MOS transistor, the second MOS transistor and the third MOS transistor are respectively the source, the drain and the gate of the PMOS transistor; The substrate ends of the first MOS transistor, the second MOS transistor and the third MOS transistor are all connected to the first detection end.

9. The charging power switch control signal generating circuit according to claim 8, characterized in that: The first power supply terminal of the charging overcurrent detection circuit is connected to the first detection terminal, and the second power supply terminal is connected to the third detection terminal. When a battery charging overcurrent is detected, the charging overcurrent detection circuit controls the third MOS tube to turn off. At this time, the voltage at the control end of the second MOS tube is lower than the voltage at the second detection end.

10. The charging power switch control signal generating circuit according to claim 9, characterized in that: The first detection end is a connection end for connecting the battery protection circuit to the positive electrode of the battery cell; the second detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery; the third detection end is a connection end for connecting the battery protection circuit to the negative electrode of the battery cell. The first resistance is greater than or equal to 10 6 Ohm; the second resistance is less than or equal to 500 ohms.

11. A battery protection circuit, comprising a second detection terminal connected to the negative electrode of the battery, a third detection terminal connected to the negative electrode of the battery cell, a first detection terminal connected to the positive electrode of the battery cell, a discharge control terminal connected to the control terminal of a discharge power switch, and a charge control terminal connected to the control terminal of a charge power switch, wherein: The discharging power switch and the charging power switch are connected between the third detection end and the second detection end, and are characterized in that they also include the charging power switch control signal generating circuit according to any one of claims 6 to 10.

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