A battery protection circuit and a battery charging and discharging circuit

Abstract

The present invention provides a battery protection circuit, in which an enabling circuit is added to an existing battery protection circuit, wherein a first output end of the enabling circuit is connected to a first input end of a reference circuit, and a second output end is connected to a first input end of a voltage protection circuit, so as to generate an intermittent first enabling signal; under the action of the first enabling signal, the reference circuit generates a bias voltage required by the voltage protection circuit; the voltage protection circuit detects the battery voltage and outputs a voltage overcharge signal or a voltage overdischarge signal; the switch tube control circuit controls the charging tube or the discharging tube in the switch tube to be turned off according to the voltage overcharge signal and the voltage overdischarge signal, so that the reference circuit and the voltage protection circuit work intermittently; and at the same time, the switch tube control circuit also generates a second enabling signal to enable the current protection circuit, so as to avoid the current protection circuit being in a normally open state all the time, thereby effectively reducing the power consumption of the battery protection circuit.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to a battery protection circuit and a battery charging and discharging circuit. Background Art

[0002] In recent years, portable electronic devices such as wearable devices and Bluetooth devices have become increasingly popular in the market. Lithium-ion batteries have become the first choice for powering portable electronic devices because of their small size, high energy density, no memory effect, and cyclic charge and discharge. The high energy density of lithium-ion batteries corresponds to certain safety risks. Overcharging and overcurrent in charge and discharge can cause lithium-ion batteries to catch fire and rupture, and overdischarge can greatly shorten the battery life. The existing technology mainly uses battery protection circuits to control the charge and discharge of batteries. However, the various voltage detection modules and current detection modules in the existing battery protection circuits are in a normally open state, so that the power consumption of the battery protection circuit is 280nA in normal working state and 180nA in sleep state. The power consumption of the battery protection circuit is large, which greatly compresses the battery life. Summary of the invention

[0003] The present invention provides a battery protection circuit and a battery charging and discharging circuit to solve the problems of large power consumption and short battery life of the existing battery protection circuit.

[0004] The present invention is implemented in this way: a battery protection circuit comprises:

[0005] Reference circuit, enabling circuit, voltage protection circuit, current protection circuit, switch tube control circuit, switch tube;

[0006] The first output terminal of the enabling circuit is connected to the first input terminal of the reference circuit, and the second output terminal is connected to the first input terminal of the voltage protection circuit;

[0007] The second input terminal of the reference circuit is connected to the reference voltage output, the first output terminal is connected to the second input terminal of the voltage protection circuit, and the second output terminal is connected to the first input terminal of the current protection circuit;

[0008] The third input terminal of the voltage protection circuit is connected to the battery voltage sampling point, and the output terminal is connected to the first input terminal of the switch tube control circuit;

[0009] The second input end of the current protection circuit is connected to the loop current sampling point, and the output end is connected to the second input end of the switch tube control circuit;

[0010] The first output end of the switch tube control circuit is connected to the switch tube, and the switch tube is connected in series in a charge and discharge loop between a battery and a charging power source or a load;

[0011] The second output terminal of the switch tube control circuit is connected to the third input terminal of the current protection circuit;

[0012] The enabling circuit is used to generate a first enabling signal, and provide the first enabling signal to the reference circuit and the voltage protection circuit respectively, wherein the first enabling signal is an intermittent signal; the reference circuit is used to generate a bias voltage required by the voltage protection circuit under the action of the first enabling signal; the voltage protection circuit is used to detect the battery voltage under the action of the first enabling signal, and output a voltage overcharge signal when the battery voltage is overcharged, or output a voltage overdischarge signal when the battery voltage is overdischarged; the switch tube control circuit is used to control the charging tube in the switch tube to turn off according to the voltage overcharge signal, or control the discharge tube in the switch tube to turn off according to the voltage overdischarge signal, and put the battery protection circuit into a dormant state;

[0013] The switch tube control circuit is also used to generate a second enable signal when the battery protection circuit is in a non-sleep state, and provide the second enable signal to the current protection circuit; the reference circuit is also used to generate the bias current required by the current protection circuit; the current protection circuit is used to detect the charging current and the discharging current under the action of the second enable signal, and generate a detection abnormality signal when the charging current and the discharging current are abnormal; the switch tube control circuit is used to generate a control signal according to the detection abnormality signal, and send the control signal to the switch tube to control the switch tube to shut down.

[0014] Optionally, the first enabling signal generated by the enabling circuit is an intermittent pulse signal;

[0015] The reference circuit and the voltage protection circuit are started and run when the pulse signal arrives, and are shut down after the pulse signal ends.

[0016] Optionally, the voltage protection circuit includes: a voltage detection module, an overcharge comparator, an overdischarge comparator, and a register;

[0017] The voltage detection module, the overcharge comparator, the overdischarge comparator and the enable end of the register are respectively connected to the second output end of the enable circuit;

[0018] The first input end of the voltage detection module is connected to the battery voltage sampling point as the third input end of the voltage protection circuit, the second input end is connected to the negative electrode of the power supply, the first output end is connected to the positive input end of the overcharge comparator, and the second output end is connected to the positive input end of the overdischarge comparator;

[0019] The inverting input terminal of the overcharge comparator and the inverting input terminal of the overdischarge comparator are respectively connected to the first output terminal of the reference circuit;

[0020] The output end of the overcharge comparator is connected to the first input end of the register, and the output end of the overdischarge comparator is connected to the second input end of the register;

[0021] The output end of the register is connected to the first end of the switch tube control circuit as the output end of the voltage protection circuit;

[0022] The reference circuit is used to generate a first voltage threshold of the overcharge comparator and a second voltage threshold of the overdischarge comparator under the action of the first enable signal; the voltage detection module is used to obtain the battery voltage from the battery voltage sampling point under the action of the first enable signal, and send the battery voltage to the overcharge comparator and the overdischarge comparator respectively; the overcharge comparator is used to compare the battery voltage with the first voltage threshold under the action of the first enable signal, generate a voltage overcharge signal when the battery voltage is greater than the first voltage threshold, and send the voltage overcharge signal to the register; the overdischarge comparator is used to compare the battery voltage with the second voltage threshold under the action of the first enable signal, generate a voltage overdischarge signal when the battery voltage is less than the second voltage threshold, and send the voltage overdischarge signal to the register; the register is used to latch the voltage overcharge signal or the voltage overdischarge signal under the action of the first enable signal, and send the voltage overcharge signal or the voltage overdischarge signal to the switch tube control circuit.

[0023] Optionally, the current protection circuit includes: a short-circuit comparator and an overcurrent comparator;

[0024] The enabling terminals of the short-circuit comparator and the overcurrent comparator are respectively connected to the second output terminal of the switch tube control circuit;

[0025] The positive phase input terminals of the short-circuit comparator and the overcurrent comparator are respectively connected to the loop current sampling point;

[0026] The inverting input terminal of the short-circuit comparator is connected to the short-circuit bias output terminal of the second output terminal in the reference circuit, and the inverting input terminal of the overcurrent comparator is connected to the overcurrent bias output terminal of the second output terminal in the reference circuit;

[0027] The output ends of the short-circuit comparator and the overcurrent comparator are respectively connected to the switch tube control circuit;

[0028] The reference circuit is used to generate a short-circuit voltage threshold of the short-circuit comparator and a charging overcurrent threshold / discharging overcurrent threshold of the overcurrent comparator. The switch tube control circuit is used to generate a second enable signal for the short-circuit comparator and the overcurrent comparator when the battery protection circuit is in a non-sleep state; the short-circuit comparator is used to obtain the loop voltage from the loop current sampling point under the action of the second enable signal, and generate a short-circuit signal when the loop voltage is greater than the short-circuit voltage threshold, and send the short-circuit signal to the switch tube control circuit; the overcurrent comparator is used to obtain the charging current / discharging current from the loop current sampling point under the action of the second enable signal, and generate a charging overcurrent signal / discharging overcurrent signal when the charging current / discharging current is greater than the charging overcurrent threshold / discharging overcurrent threshold, and send the charging overcurrent signal / discharging overcurrent signal to the switch tube control circuit.

[0029] Optionally, the switch tube control circuit further includes:

[0030] Logic circuits, delay circuits;

[0031] The first input terminal of the logic circuit is connected to the output terminal of the register, the second input terminal is connected to the input terminal of the short-circuit comparator, and the third input terminal is connected to the output terminal of the overcurrent comparator;

[0032] The first output end of the logic circuit is connected to the switch tube, the second output end is connected to the enable end of the short-circuit comparator and the overcurrent comparator respectively, and the third output end is connected to the delay circuit;

[0033] The delay circuit is used to delay processing of the voltage over-discharge signal, voltage over-charge signal, short-circuit signal, charging over-current signal or discharging over-current signal;

[0034] The logic circuit is used to perform logic processing on the output signal of the delay circuit to generate a control signal for the switch tube, wherein, for a voltage overcharge signal or a charge overcurrent signal, the logic circuit outputs a charge tube shutdown signal to shut down the charge tube in the switch tube; for the short circuit signal or the discharge overcurrent signal, the logic circuit outputs a discharge tube shutdown signal to shut down the discharge tube in the switch tube; for the voltage overdischarge signal, the logic circuit outputs a discharge tube shutdown signal to shut down the discharge tube in the switch tube and put the battery protection circuit into a sleep state.

[0035] Optionally, the battery protection circuit further includes a charging / load detection module;

[0036] The fourth output terminal of the logic circuit is connected to the enable terminal of the charging / load detection module;

[0037] The input end of the charging / load detection module is connected to the loop current sampling point;

[0038] The logic circuit is also used to perform logic processing on the output signal of the delay circuit to generate a third enable signal, and send the third enable signal to the charging / load detection module to start or shut down the charging / load detection module.

[0039] A battery charging and discharging circuit, the battery charging and discharging circuit comprising:

[0040] A first resistor, a first capacitor, a second capacitor, and a battery protection circuit as described above;

[0041] The first end of the first resistor is connected to the positive electrode of the battery;

[0042] A common point between the second end of the first resistor and the first end of the first capacitor is connected to a battery voltage sampling point of the battery protection circuit;

[0043] A common point between the second end of the first capacitor, the second end of the second capacitor and the negative electrode of the battery is connected to the negative electrode of the power supply of the battery protection circuit;

[0044] A first end of the second capacitor is connected to a reference voltage output end of the battery protection circuit;

[0045] The first capacitor is used for filtering the battery current; the second capacitor is used for providing a reference voltage to the reference circuit.

[0046] The battery protection circuit provided by the present invention adds an enable circuit to the existing battery protection circuit, wherein the first output end of the enable circuit is connected to the first input end of the reference circuit, and the second output end is connected to the first input end of the voltage protection circuit, for generating a first enable signal and providing it to the reference circuit and the voltage protection circuit respectively, wherein the first enable signal is an intermittent signal; the reference circuit is used to generate a bias voltage required by the voltage protection circuit under the action of the first enable signal; the voltage protection circuit is used to detect the battery voltage under the action of the first enable signal, and output a voltage overcharge signal or a voltage overdischarge signal; the switch tube control circuit is used to control the charging tube in the switch tube to be turned off according to the voltage overcharge signal, or to control the discharge tube in the switch tube to be turned off according to the voltage overdischarge signal, and to make the battery protection circuit enter a dormant state, so that the reference circuit and the voltage protection circuit work intermittently; and the switch tube control circuit is also used to generate a second enable signal to enable the current protection circuit when the battery protection circuit is in a non-dormant state, and not enable the current protection circuit in the dormant state, so as to avoid the current protection circuit being in a normally open state, thereby effectively reducing the power consumption of the battery protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0048] Figure 1 is a schematic diagram of a battery protection circuit provided by an embodiment of the present invention;

[0049] Figure 2 is a schematic diagram of a battery protection circuit provided by another embodiment of the present invention;

[0050] Figure 3 is a schematic diagram of a battery protection circuit provided by another embodiment of the present invention;

[0051] Figure 4 is a schematic diagram of a battery protection circuit provided by another embodiment of the present invention;

[0052] Figure 5 It is a schematic diagram of a battery charging and discharging circuit provided by another embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0054] The battery protection circuit provided by the present invention adds an enable circuit to the existing battery protection circuit, wherein the first output end of the enable circuit is connected to the first input end of the reference circuit, and the second output end is connected to the first input end of the voltage protection circuit, for generating a first enable signal and providing it to the reference circuit and the voltage protection circuit respectively, wherein the first enable signal is an intermittent signal; the reference circuit is used to generate a bias voltage required by the voltage protection circuit under the action of the first enable signal; the voltage protection circuit is used to detect the battery voltage under the action of the first enable signal, and output a voltage overcharge signal or a voltage overdischarge signal; the switch tube control circuit is used to control the charging tube in the switch tube to be turned off according to the voltage overcharge signal, or to control the discharge tube in the switch tube to be turned off according to the voltage overdischarge signal, and to make the battery protection circuit enter a dormant state, so that the reference circuit and the voltage protection circuit work intermittently; and the switch tube control circuit is also used to generate a second enable signal to enable the current protection circuit when the battery protection circuit is in a non-dormant state, and not enable the current protection circuit in the dormant state, so as to avoid the current protection circuit being in a normally open state, thereby effectively reducing the power consumption of the battery protection circuit.

[0055] Figure 1 Schematic diagram of a battery protection circuit provided by an embodiment of the present invention. Figure 1 As shown, the battery protection circuit 1 includes: a reference circuit 10, an enabling circuit 20, a voltage protection circuit 30, a current protection circuit 40, a switch tube control circuit 50, and a switch tube 60;

[0056] The first output terminal of the enabling circuit 20 is connected to the first input terminal of the reference circuit 10 , and the second output terminal is connected to the first input terminal of the voltage protection circuit 30 ;

[0057] The second input terminal of the reference circuit 10 is connected to the reference voltage output terminal Vref, the first output terminal is connected to the second input terminal of the voltage protection circuit 30, and the second output terminal is connected to the first input terminal of the current protection circuit 40;

[0058] The third input terminal of the voltage protection circuit 30 is connected to the battery voltage sampling point VDD, and the output terminal is connected to the first input terminal of the switch tube control circuit 50;

[0059] The second input terminal of the current protection circuit 40 is connected to the loop current sampling point VM, and the output terminal is connected to the second input terminal of the switch tube control circuit 50;

[0060] The first output end of the switch tube control circuit 50 is connected to the switch tube 60, and the switch tube 60 is connected in series in the charge and discharge loop between the battery and the charging power source or the load;

[0061] The second output terminal of the switch tube control circuit 50 is connected to the third input terminal of the current protection circuit 40;

[0062] The enabling circuit 20 is used to generate a first enabling signal, and provide the first enabling signal to the reference circuit 10 and the voltage protection circuit 30 respectively, wherein the first enabling signal is an intermittent signal; the reference circuit 10 is used to generate a bias voltage required by the voltage protection circuit 30 under the action of the first enabling signal; the voltage protection circuit 30 is used to detect the battery voltage under the action of the first enabling signal, and output a voltage overcharge signal when the battery voltage is overcharged, or output a voltage overdischarge signal when the battery voltage is overdischarged; the switch tube control circuit 50 is used to control the charging tube in the switch tube 60 to turn off according to the voltage overcharge signal, or control the discharge tube in the switch tube 60 to turn off according to the voltage overdischarge signal, and put the battery protection circuit into a dormant state;

[0063] The switch tube control circuit 50 is also used to generate a second enable signal when the battery protection circuit is in a non-sleep state, and provide the second enable signal to the current protection circuit 40; the reference circuit 10 is also used to generate a bias current required by the current protection circuit 40; the current protection circuit 40 is used to detect the charging current and the discharging current under the action of the second enable signal, and generate a detection abnormality signal when the charging current and the discharging current are abnormal; the switch tube control circuit 50 is used to generate a control signal according to the detection abnormality signal, and send the control signal to the switch tube 60 to control the switch tube 60 to shut down.

[0064] Since a lithium battery can be equivalent to a huge capacitor, and its voltage change process is slow, the embodiment of the present invention adopts an intermittent working mode for the reference circuit 10 and the voltage protection circuit 30. By adding an enabling circuit 20 on the basis of the existing battery protection circuit, the enabling circuit 20 generates a first enabling signal, which is an intermittent signal, and provides the first enabling signal to the reference circuit 10 and the voltage protection circuit 30 respectively, so that the reference circuit 10 and the voltage protection circuit 30 are started and shut down at intervals under the action of the first enabling signal.

[0065] Optionally, as a preferred example of the present invention, the enabling circuit 20 can be a clock circuit. The first enabling signal generated by the enabling circuit 20 is an intermittent pulse signal. The reference circuit 10 and the voltage protection circuit 30 start and run when the pulse signal arrives, and shut down after the pulse signal ends. For example, for an intermittent pulse signal with a pulse width of 1ms and a period of 11ms, the reference circuit 10 and the voltage protection circuit 30 will operate in a manner of working for 1ms every 10ms, that is, a voltage detection is performed every 10ms, and the reference circuit 10 and the voltage protection circuit 30 are started synchronously, and the reference circuit 10 and the voltage protection circuit 30 run for 1ms in one cycle.

[0066] Among them, when the pulse of the first enable signal arrives, the reference circuit 10 generates the bias voltage required by the voltage protection circuit 30; the voltage protection circuit 30 detects the battery voltage, and outputs a voltage overcharge signal when the battery voltage is overcharged or outputs a voltage overdischarge signal when the battery voltage is overdischarged; the switch tube control circuit 50 controls the charging tube in the switch tube 60 to turn off according to the voltage overcharge signal, or controls the discharge tube in the switch tube 60 to turn off according to the voltage overdischarge signal, and puts the battery protection circuit into a dormant state, so that the reference circuit 10 and the voltage protection circuit 30 implement an intermittent working mode according to the first enable signal, avoiding the reference circuit 10 and the voltage protection circuit 30 from being in a normally open state all the time, effectively reducing the power consumption of the battery protection circuit, and helping to extend the battery life.

[0067] In this embodiment, when the battery protection circuit is in a dormant state, the current protection circuit 40 is in a closed state. When the battery protection circuit is in a non-dormant state, the switch tube control circuit 50 generates a second enable signal and provides the second enable signal to the current protection circuit 40, and the second enable signal is a continuous signal. The current protection circuit 40 starts and runs when receiving the second enable signal, and shuts down if the second enable signal is not received. The reference circuit 10 continuously generates the bias voltage required by the current protection circuit 40 regardless of whether it is in a dormant state or a non-dormant state. When enabled, the current protection circuit 40 detects the charging current and the discharging current, and generates a detection abnormality signal when the charging current and the discharging current are abnormal; the switch tube control circuit 50 generates a control signal according to the detection abnormality signal, and sends the control signal to the switch tube 60 to control the shutdown of the charging tube or the discharge tube in the switch tube 60. It can be seen that in this embodiment, the current protection circuit is not always in a normally open state, thereby effectively reducing the power consumption of the battery protection circuit, which is conducive to extending the battery life.

[0068] Optionally, as a preferred example of the present invention, Figure 2 As shown, the voltage protection circuit 30 includes: a voltage detection module 31, an overcharge comparator 32, an over-discharge comparator 33, and a register 34;

[0069] The enabling terminals of the voltage detection module 31, the overcharge comparator 32, the overdischarge comparator 33 and the register 34 are respectively connected to the second output terminal of the enabling circuit 20;

[0070] The first input terminal of the voltage detection module 31 is connected to the battery voltage sampling point VDD as the third input terminal of the voltage protection circuit 30, the second input terminal is connected to the negative power supply VSS, the first output terminal is connected to the positive input terminal of the overcharge comparator 32, and the second output terminal is connected to the positive input terminal of the over-discharge comparator 33;

[0071] The inverting input terminal of the overcharge comparator 32 and the inverting input terminal of the overdischarge comparator 33 are respectively connected to the first output terminal of the reference circuit 10;

[0072] The output end of the overcharge comparator 32 is connected to the first input end of the register 34, and the output end of the overdischarge comparator 33 is connected to the second input end of the register 34;

[0073] The output end of the register 34 is connected to the first end of the switch tube control circuit 50 as the output end of the voltage protection circuit 30;

[0074] The reference circuit 10 is used to generate a first voltage threshold of the overcharge comparator 32 and a second voltage threshold of the overdischarge comparator 33 under the action of the first enable signal; the voltage detection module 31 is used to obtain the battery voltage from the battery voltage sampling point VDD under the action of the first enable signal, and send the battery voltage to the overcharge comparator 32 and the overdischarge comparator 33 respectively; the overcharge comparator 32 is used to compare the battery voltage with the first voltage threshold under the action of the first enable signal, and generate a voltage overcharge signal when the battery voltage is greater than the first voltage threshold, and send the voltage overcharge signal to the register 34; the overdischarge comparator 33 is used to compare the battery voltage with the second voltage threshold under the action of the first enable signal, and generate a voltage overdischarge signal when the battery voltage is less than the second voltage threshold, and send the voltage overdischarge signal to the register 34; the register 34 is used to latch the voltage overcharge signal or the voltage overdischarge signal under the action of the first enable signal, and send the voltage overcharge signal or the voltage overdischarge signal to the switch tube control circuit 50.

[0075] Here, the voltage detection module 31 , the overcharge comparator 32 , the overdischarge comparator 33 and the register 34 receive the first enable signal output by the enable circuit 20 , and are started and shut down intermittently according to the first enable signal.

[0076] Among them, when the pulse of the first enable signal arrives, the reference circuit 10 generates the first voltage threshold of the overcharge comparator 32 and the second voltage threshold of the overdischarge comparator 33; the voltage detection module 31 obtains the battery voltage from the battery voltage sampling point VDD, and provides the battery voltage to the overcharge comparator 32 and the overdischarge comparator 33 respectively; the overcharge comparator 32 compares the battery voltage with the first voltage threshold, and when the battery voltage is greater than the first voltage threshold, it is considered that voltage overcharge occurs, a voltage overcharge signal is generated, and the voltage overcharge signal is sent to the register 34; the overdischarge comparator 33 compares the battery voltage with the second voltage threshold, and when the battery voltage is less than the second voltage threshold, it is considered that voltage overdischarge occurs, a voltage overdischarge signal is generated, and the voltage overdischarge signal is sent to the register 34. The embodiment of the present invention latches the voltage overcharge signal or the voltage overdischarge signal through the register 34, until the next pulse arrives, the state of the register is changed, and the voltage overcharge signal or the voltage overdischarge signal is transmitted to the switch tube control circuit 50.

[0077] It can be seen that in this embodiment, the voltage detection module 31, the overcharge comparator 32, the over-discharge comparator 33, and the register 34 all work intermittently according to the first enable signal to avoid each device being in a normally-on state all the time, thereby effectively reducing the power consumption of the battery protection circuit.

[0078] Optionally, as another preferred example of the present invention, Figure 3 As shown, the current protection circuit 40 includes: a short-circuit comparator 41 and an overcurrent comparator 42;

[0079] The enabling terminals of the short-circuit comparator 41 and the overcurrent comparator 42 are respectively connected to the second output terminal of the switch tube control circuit 50;

[0080] The positive phase input terminals of the short circuit comparator 41 and the overcurrent comparator 42 are respectively connected to the loop current sampling point VM;

[0081] The inverting input terminal of the short-circuit comparator 41 is connected to the short-circuit bias output terminal of the second output terminal in the reference circuit 10, and the inverting input terminal of the overcurrent comparator 42 is connected to the overcurrent bias output terminal of the second output terminal in the reference circuit 10;

[0082] The output ends of the short-circuit comparator 41 and the overcurrent comparator 42 are respectively connected to the switch tube control circuit 50;

[0083] The reference circuit 10 is used to generate a short-circuit voltage threshold of the short-circuit comparator 41 and a charging overcurrent threshold / discharging overcurrent threshold of the overcurrent comparator 42. The switch tube control circuit 50 is used to generate a second enable signal for the short-circuit comparator 41 and the overcurrent comparator 42 when the battery protection circuit is in a non-sleep state; the short-circuit comparator 41 is used to obtain the loop voltage from the loop current sampling point VM under the action of the second enable signal, and generate a short-circuit signal when the loop voltage is greater than the short-circuit voltage threshold, and send the short-circuit signal to the switch tube control circuit 50; the overcurrent comparator 42 is used to obtain the charging current / discharging current from the loop current sampling point VM under the action of the second enable signal, and generate a charging overcurrent signal / discharging overcurrent signal when the charging current / discharging current is greater than the charging overcurrent threshold / discharging overcurrent threshold, and send the charging overcurrent signal / discharging overcurrent signal to the switch tube control circuit 50.

[0084] In this embodiment, when the battery protection circuit is in a dormant state, the current protection circuit 40 is in a turned-off state, and the short-circuit comparator 41 and the overcurrent comparator 42 are turned off. When the battery protection circuit is in a non-dormant state, the switch tube control circuit 50 generates a second enable signal, and provides the second enable signal to the short-circuit comparator 41 and the overcurrent comparator 42. Here, the second enable signal is a continuous signal, and the short-circuit comparator 41 and the overcurrent comparator 42 will start running only when they receive the second enable signal, and will be turned off when the second enable signal is not received. When enabled, the short-circuit comparator 41 obtains the loop voltage from the loop current sampling point VM. When the loop voltage is greater than the short-circuit voltage threshold, it is considered that a short circuit has occurred, a short-circuit signal is generated, and the short-circuit signal is sent to the switch tube control circuit 50; similarly, the overcurrent comparator obtains the charging current / discharging current from the loop current sampling point VM. When the charging current / discharging current is greater than the charging overcurrent threshold / discharging overcurrent threshold, it is considered that a charging overcurrent or a discharging overcurrent has occurred, a charging overcurrent signal / discharging overcurrent signal is generated, and the charging overcurrent signal / discharging overcurrent signal is sent to the switch tube control circuit 50.

[0085] It can be seen that in this embodiment, the short-circuit comparator 41 and the overcurrent comparator 42 in the current protection circuit are turned off in the sleep state, and the current is detected only in the non-sleep state, which avoids each device being in a normally open state all the time, and effectively reduces the power consumption of the battery protection circuit.

[0086] Optionally, as another preferred example of the present invention, Figure 4 As shown, the switch tube control circuit 50 also includes:

[0087] Logic circuit 51, delay circuit 52;

[0088] The first input terminal of the logic circuit 51 is connected to the output terminal of the register 34, the second input terminal is connected to the input terminal of the short-circuit comparator 41, and the third input terminal is connected to the output terminal of the overcurrent comparator 42;

[0089] The first output end of the logic circuit 51 is connected to the switch tube 60, the second output end is connected to the enable end of the short-circuit comparator 41 and the overcurrent comparator 42 respectively, and the third output end is connected to the delay circuit 52;

[0090] The delay circuit 52 is used to delay the voltage over-discharge signal, voltage over-charge signal, short-circuit signal, charge over-current signal or discharge over-current signal;

[0091] The logic circuit 51 is used to perform logic processing on the output signal of the delay circuit 52 to generate a control signal for the switch tube 60, wherein, for a voltage overcharge signal or a charge overcurrent signal, the logic circuit 51 outputs a charge tube shutdown signal to shut down the charge tube in the switch tube 60; for the short circuit signal or the discharge overcurrent signal, the logic circuit 51 outputs a discharge tube shutdown signal to shut down the discharge tube in the switch tube 60; for the voltage overdischarge signal, the logic circuit 51 outputs a discharge tube shutdown signal to shut down the discharge tube in the switch tube 60 and put the battery protection circuit into a sleep state.

[0092] In the embodiment of the present invention, the register 34 receives the voltage overcharge signal generated by the overcharge comparator 32 and the voltage overdischarge signal generated by the overdischarge comparator 33 under the action of the first enable signal, and sends the voltage overcharge signal and the voltage overdischarge signal to the logic circuit 51; the short-circuit signal generated by the short-circuit comparator 41 or the charging overcurrent signal and the discharging overcurrent signal generated by the overcurrent comparator 42 are directly provided to the logic circuit 51. The logic circuit 51 further sends the voltage overdischarge signal, the voltage overcharge signal, the short-circuit signal, the charging overcurrent signal or the discharging overcurrent signal to the delay circuit 52 for delay processing; then the output signal of the delay circuit 52 is logically processed to generate a control signal of the switch tube 60, and the charging tube or the discharging tube in the switch tube 60 is controlled to be turned off, so as to protect the battery.

[0093] Optionally, as a preferred example of the present invention, Figure 4 As shown, the battery protection circuit also includes a charging / load detection module 70;

[0094] The fourth output terminal of the logic circuit 51 is connected to the enable terminal of the charging / load detection module 70;

[0095] The input end of the charging / load detection module 70 is connected to the loop current sampling point VM;

[0096] The logic circuit 51 is further used to perform logic processing on the output signal of the delay circuit to generate a third enable signal, and send the third enable signal to the charging / load detection module 70 to start or shut down the charging / load detection module 70.

[0097] In this embodiment, for a voltage overcharge signal or a charge overcurrent signal, after the logic circuit 51 outputs a charge tube shutdown signal to shut down the charge tube in the switch tube 60, it can further output a third enable signal to shut down the charge / load detection module 70 to reduce the power consumption of the battery protection circuit. For the short circuit signal or the discharge overcurrent signal or the voltage overdischarge signal, after the logic circuit 51 outputs a discharge tube shutdown signal to shut down the discharge tube in the switch tube 60, it can further output a third enable signal to shut down the charge / load detection module 70 to reduce the power consumption of the battery protection circuit.

[0098] In summary, the battery protection circuit provided in the embodiment of the present invention adopts an intermittent working mode for the reference circuit, the voltage detection circuit, the overcharge comparator, and the overcurrent comparator, and latches the output results of the overcharge comparator and the overcurrent comparator through a register. When and only when the first pulse signal arrives, the state of the register is allowed to follow the output results of the overcharge comparator and the overcurrent comparator, thereby greatly reducing the power consumption of the battery protection circuit. At the same time, the subthreshold characteristic is used to design the current protection circuit to avoid the current protection circuit being in a normally open state, so that the power consumption of the battery protection circuit can be reduced to 120nA in non-sleep mode and to 70nA in sleep mode.

[0099] like Figure 5 As shown in FIG. 1 , a battery charging and discharging circuit provided by an embodiment of the present invention, that is, an application example of the battery protection circuit. Figure 5 As shown, the battery charging and discharging circuit includes a first resistor R1, a first capacitor C1, a second capacitor C2 and the battery protection circuit 1 as described above;

[0100] The first end of the first resistor R1 is connected to the positive electrode of the battery;

[0101] A common point between the second end of the first resistor R1 and the first end of the first capacitor C1 is connected to a battery voltage sampling point VDD of the battery protection circuit 1;

[0102] A common point between the second end of the first capacitor C1, the second end of the second capacitor C2 and the negative electrode of the battery is connected to the negative power supply electrode VSS of the battery protection circuit 1;

[0103] A first end of the second capacitor C2 is connected to a reference voltage output end Vref of the battery protection circuit 1;

[0104] The first capacitor C1 is used for filtering the battery current; the second capacitor C2 is used for providing a reference voltage Vref to the reference circuit 10 .

[0105] like Figure 5 As shown, P+ represents the positive electrode of the battery charging and discharging circuit, and P- represents the negative electrode of the battery charging and discharging circuit. The charger or load is connected to the battery charging and discharging circuit through the positive electrode P+ and the negative electrode P-. In the battery charging and discharging circuit, the positive electrode of the battery is connected to the battery voltage sampling point VDD of the battery protection circuit 1 through the first resistor R1, and the negative electrode of the battery is connected to the negative power supply VSS of the battery protection circuit 1, and a first capacitor C1 is connected between the battery voltage sampling point VDD and the negative power supply VSS. The first capacitor C1 is a filter capacitor for filtering the battery current. A second capacitor C2 is connected between the reference voltage Vref of the battery protection circuit 1 and the negative power supply VSS. The second capacitor C2 is a maintenance capacitor for providing the reference voltage Vref of the battery protection circuit 1 and maintaining the reference voltage Vref at a preset value. Of course, in other embodiments, the second capacitor C2 can also be used as a built-in capacitor of the battery protection circuit, which is not limited here.

[0106] 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: include: Reference circuit, enabling circuit, voltage protection circuit, current protection circuit, switch tube control circuit, switch tube; The first output terminal of the enabling circuit is connected to the first input terminal of the reference circuit, and the second output terminal is connected to the first input terminal of the voltage protection circuit; The second input terminal of the reference circuit is connected to the reference voltage output terminal, the first output terminal is connected to the second input terminal of the voltage protection circuit, and the second output terminal is connected to the first input terminal of the current protection circuit; The third input terminal of the voltage protection circuit is connected to the battery voltage sampling point, and the output terminal is connected to the first input terminal of the switch tube control circuit; The second input end of the current protection circuit is connected to the loop current sampling point, and the output end is connected to the second input end of the switch tube control circuit; The first output end of the switch tube control circuit is connected to the switch tube, and the switch tube is connected in series in a charge and discharge loop between a battery and a charging power source or a load; The second output terminal of the switch tube control circuit is connected to the third input terminal of the current protection circuit; The enabling circuit is used to generate a first enabling signal, and provide the first enabling signal to the reference circuit and the voltage protection circuit respectively, wherein the first enabling signal is an intermittent signal; The reference circuit is used to generate a bias voltage required by the voltage protection circuit under the action of the first enable signal; The voltage protection circuit is used to detect the battery voltage under the action of the first enable signal, and output a voltage overcharge signal when the battery voltage is overcharged or output a voltage overdischarge signal when the battery voltage is overdischarged; the switch tube control circuit is used to control the charging tube in the switch tube to turn off according to the voltage overcharge signal, or control the discharge tube in the switch tube to turn off according to the voltage overdischarge signal, and put the battery protection circuit into a dormant state; The switch tube control circuit is also used to generate a second enable signal when the battery protection circuit is in a non-sleep state, and provide the second enable signal to the current protection circuit; the reference circuit is also used to generate a bias voltage required by the current protection circuit; The current protection circuit is used to detect the charging current and the discharging current under the action of the second enable signal, and generate a detection abnormality signal when the charging current and the discharging current are abnormal; The switch tube control circuit is used to generate a control signal according to the abnormal detection signal, and send the control signal to the switch tube to control the switch tube to turn off; The voltage protection circuit includes: a voltage detection module, an overcharge comparator, an overdischarge comparator, and a register; The voltage detection module, the overcharge comparator, the overdischarge comparator and the enable end of the register are respectively connected to the second output end of the enable circuit; The first input end of the voltage detection module is connected to the battery voltage sampling point as the third input end of the voltage protection circuit, the second input end is connected to the negative electrode of the power supply, the first output end is connected to the positive input end of the overcharge comparator, and the second output end is connected to the positive input end of the overdischarge comparator; The inverting input terminal of the overcharge comparator and the inverting input terminal of the overdischarge comparator are respectively connected to the first output terminal of the reference circuit; The output end of the overcharge comparator is connected to the first input end of the register, and the output end of the overdischarge comparator is connected to the second input end of the register; The output end of the register is connected to the first end of the switch tube control circuit as the output end of the voltage protection circuit; The reference circuit is used to generate a first voltage threshold of the overcharge comparator and a second voltage threshold of the overdischarge comparator under the action of the first enable signal; the voltage detection module is used to obtain the battery voltage from the battery voltage sampling point under the action of the first enable signal, and send the battery voltage to the overcharge comparator and the overdischarge comparator respectively; the overcharge comparator is used to compare the battery voltage with the first voltage threshold under the action of the first enable signal, and generate a voltage overcharge signal when the battery voltage is greater than the first voltage threshold, and send the voltage overcharge signal to the register; the overdischarge comparator is used to compare the battery voltage with the second voltage threshold under the action of the first enable signal, and generate a voltage overdischarge signal when the battery voltage is less than the second voltage threshold, and send the voltage overdischarge signal to the register; the register is used to latch the voltage overcharge signal or the voltage overdischarge signal under the action of the first enable signal, and send the voltage overcharge signal or the voltage overdischarge signal to the switch tube control circuit; The current protection circuit includes: a short-circuit comparator and an overcurrent comparator; The enabling terminals of the short-circuit comparator and the overcurrent comparator are respectively connected to the second output terminal of the switch tube control circuit; The positive phase input terminals of the short-circuit comparator and the overcurrent comparator are respectively connected to the loop current sampling point; The inverting input terminal of the short-circuit comparator is connected to the short-circuit bias output terminal of the second output terminal in the reference circuit, and the inverting input terminal of the overcurrent comparator is connected to the overcurrent bias output terminal of the second output terminal in the reference circuit; The output ends of the short-circuit comparator and the overcurrent comparator are respectively connected to the switch tube control circuit; The reference circuit is used to generate a short-circuit voltage threshold of the short-circuit comparator and a charging overcurrent threshold / discharging overcurrent threshold of the overcurrent comparator. The switch tube control circuit is used to generate a second enable signal for the short-circuit comparator and the overcurrent comparator when the battery protection circuit is in a non-sleep state; the short-circuit comparator is used to obtain the loop voltage from the loop current sampling point under the action of the second enable signal, and generate a short-circuit signal when the loop voltage is greater than the short-circuit voltage threshold, and send the short-circuit signal to the switch tube control circuit; the overcurrent comparator is used to obtain the charging current / discharging current from the loop current sampling point under the action of the second enable signal, and generate a charging overcurrent signal / discharging overcurrent signal when the charging current / discharging current is greater than the charging overcurrent threshold / discharging overcurrent threshold, and send the charging overcurrent signal / discharging overcurrent signal to the switch tube control circuit.

2. The battery protection circuit according to claim 1, characterized in that: The first enabling signal generated by the enabling circuit is an intermittent pulse signal; The reference circuit and the voltage protection circuit are started and run when the pulse signal arrives, and are shut down after the pulse signal ends.

3. The battery protection circuit according to claim 1, characterized in that: The switch tube control circuit also includes: Logic circuits, delay circuits; The first input terminal of the logic circuit is connected to the output terminal of the register, the second input terminal is connected to the input terminal of the short-circuit comparator, and the third input terminal is connected to the output terminal of the overcurrent comparator; The first output end of the logic circuit is connected to the switch tube, the second output end is connected to the enable end of the short-circuit comparator and the overcurrent comparator respectively, and the third output end is connected to the delay circuit; The delay circuit is used to delay processing of the voltage over-discharge signal, voltage over-charge signal, short-circuit signal, charging over-current signal or discharging over-current signal; The logic circuit is used to perform logic processing on the output signal of the delay circuit to generate a control signal for the switch tube, wherein, for a voltage overcharge signal or a charge overcurrent signal, the logic circuit outputs a charge tube shutdown signal to shut down the charge tube in the switch tube; for the short circuit signal or the discharge overcurrent signal, the logic circuit outputs a discharge tube shutdown signal to shut down the discharge tube in the switch tube; for the voltage overdischarge signal, the logic circuit outputs a discharge tube shutdown signal to shut down the discharge tube in the switch tube and put the battery protection circuit into a sleep state.

4. The battery protection circuit according to claim 3, characterized in that: The battery protection circuit also includes a charging / load detection module; The fourth output terminal of the logic circuit is connected to the enable terminal of the charging / load detection module; The input end of the charging / load detection module is connected to the loop current sampling point; The logic circuit is also used to perform logic processing on the output signal of the delay circuit to generate a third enable signal, and send the third enable signal to the charging / load detection module to start or shut down the charging / load detection module.

5. A battery charging and discharging circuit, characterized in that: The battery charging and discharging circuit comprises: A first resistor, a first capacitor, a second capacitor, and a battery protection circuit as claimed in any one of claims 1 to 4; The first end of the first resistor is connected to the positive electrode of the battery; A common point between the second end of the first resistor and the first end of the first capacitor is connected to a battery voltage sampling point of the battery protection circuit; A common point between the second end of the first capacitor, the second end of the second capacitor and the negative electrode of the battery is connected to the negative electrode of the power supply of the battery protection circuit; A first end of the second capacitor is connected to a reference voltage output end of the battery protection circuit; The first capacitor is used for filtering the battery current; the second capacitor is used for providing a reference voltage to the reference circuit.

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