KR20160043544A

KR20160043544A - Protection circuit for battery

Info

Publication number: KR20160043544A
Application number: KR1020140137242A
Authority: KR
Inventors: 송윤귀; 정용재; 손상우; 이승형; 이주완; 이용섭
Original assignee: (주)샌버드
Priority date: 2014-10-13
Filing date: 2014-10-13
Publication date: 2016-04-22
Also published as: WO2016060356A1

Abstract

Disclosed is a protection circuit for a battery which can actively cope with a temperature change in the battery. The protection circuit for a battery which controls the charge and discharge of the battery, includes a reference voltage circuit which generates a reference voltage, a partial pressure circuit which divides the input voltage of the battery or the reference voltage of the reference voltage circuit, a change unit which changes the partial pressure ratio of the partial pressure circuit, and a selection part which controls the change unit according to the temperature of the battery and selects the partial pressure.

Description

[0001] The present invention relates to a protection circuit for a battery,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery protection circuit, and more particularly, to a battery protection circuit capable of varying a detection voltage and a release voltage according to a battery temperature change.

2. Description of the Related Art Portable electronic devices such as mobile phones, digital cameras, notebooks, and the like are widely used. Accordingly, batteries for supplying power for operating these portable electronic devices have been developed.

The battery may be provided in the form of a battery pack including a battery cell and a protection circuit for controlling charging and discharging of the battery cell. The battery can be classified into any one of a lithium ion (Li-ion) battery, a nickel cadmium (Ni-Cd) battery, and the like depending on the type of the battery cell. Such a battery cell can be recharged as a rechargeable secondary battery.

However, as the secondary battery has high energy density and high capacity, the characteristics of the battery become very sensitive and it is necessary to maximize the safety and reliability of the battery. That is, a secondary battery such as a lithium ion battery has a drawback in that its performance can not be exhibited unless a precise voltage current is managed, because there is a danger of ignition by overcharging and deterioration of characteristics due to overdischarge.

Therefore, in general, the battery is equipped with a protection circuit for preventing overcharging, overdischarging and overcurrent, and the protection circuit is attached to the rechargeable battery.

As described above, the protection circuit of the battery pack is provided with an overcharge protection function, an over discharge protection function, an over current protection function, and a normal charge / discharge function.

8 is a graph showing the operating voltage characteristics with respect to a temperature change of a general protection circuit.

Referring to FIG. 8, a general protection circuit is designed to have a maximum constant detection value for a temperature change. However, lithium ion batteries and lithium polymer batteries have different characteristics depending on the temperature. Especially, at a high temperature, since the battery is more unstable and the battery may explode, many circuits for protecting the battery have been reported. However, the protection circuit against this temperature generally has a structure that stops charging when a certain temperature is exceeded.

Therefore, this instability is not a phenomenon occurring at a specific temperature for a moment, so it is required to develop a protection circuit that actively responds to a change in temperature.

Japanese Patent Application Laid-Open No. 2009-152129

The present invention relates to a protection circuit capable of actively coping with temperature changes. That is, it is an object of the present invention to provide a battery protection circuit capable of varying a detection voltage, a release voltage, a detection delay time, or a release delay time according to a battery temperature change.

According to an aspect of the present invention, there is provided a battery protection circuit for controlling charging and discharging of a battery, comprising: a reference voltage circuit for generating a reference voltage; A voltage divider circuit for dividing an input voltage of the battery or a reference voltage of the reference voltage circuit; Changing means for changing a partial pressure ratio of the voltage dividing circuit; And a selection unit for selecting the partial pressure ratio by controlling the changing unit according to the temperature of the battery.

According to the present invention, it is possible to change the detection and release voltage of the battery protection circuit in accordance with the battery temperature change, thereby making it possible to use the battery as efficiently as possible in response to the temperature change of the battery.

1 is a block diagram illustrating a battery protection circuit according to an embodiment of the present invention.
2 is a circuit diagram for explaining a detection circuit according to the first embodiment of the present invention by using an overcharge detection circuit.
3 is a circuit diagram illustrating a detection circuit according to a second embodiment of the present invention by using an overcharge detection circuit.
4 is a circuit diagram for explaining a detection circuit according to the third embodiment of the present invention by using an overcharge detection circuit.
5 is a circuit diagram for explaining a detection circuit according to the fourth embodiment of the present invention by using an overcharge detection circuit.
6 is a circuit diagram illustrating the voltage discharge function according to the temperature change of the present invention.
7 is a circuit diagram for explaining a detection circuit according to the fifth embodiment of the present invention by using an overcharge detection circuit.
8 is a graph showing the operating voltage characteristics with respect to a temperature change of a general protection circuit.
9 is a graph showing the operating voltage characteristics with respect to the temperature change of the protection circuit according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Referring to the accompanying drawings, the same or corresponding components are denoted by the same reference numerals, .

1 is a block diagram illustrating a battery protection circuit according to an embodiment of the present invention.

Referring to FIG. 1, a battery 101 supplies power stored in an electronic device in which a battery pack 100 is mounted. Also, when the charger is connected to the battery pack 100, the battery 101 can be charged with external power. The battery 101 cell may be a rechargeable secondary battery such as a nickel-cadmium battery, a lead acid battery, a nickel-hydrogen battery, a lithium ion battery, and a lithium polymer battery.

The battery 101 is connected in parallel with a resistor R11 and a capacitor C11 connected in series and the positive electrode is connected to the external positive electrode terminal 102 by wiring and the negative electrode is connected to a charge control And is connected to the external negative electrode terminal 103 using a switch and a discharge control switch.

The charge control switch includes a first field effect transistor M11 and a first parasitic diode D11 and supplies a current flow from the external positive terminal 102 to the battery 101 or from the battery 101 to the external negative terminal 103 Respectively. That is, the first field effect transistor M11 is used to block the charging current from flowing. At this time, a first field effect transistor M11 is formed so that a discharge current can flow through the first parasitic diode D11.

The discharge control switch includes a second field effect transistor M12 and a second parasitic diode D12 and supplies a current flow from the external negative electrode terminal 103 to the external positive electrode terminal 102 from the battery 101 or the battery 101. [ Respectively. That is, the second field effect transistor M12 is used to block the discharge current from flowing. At this time, the second field effect transistor M12 is formed so that the charging current can flow through the second parasitic diode D12.

The first field effect transistor M11 and the second field effect transistor M12 are connected in common to the drain electrode and the source terminal of the first field effect transistor M11 is connected to the external negative electrode terminal 103, The source terminal of the second field effect transistor M12 is connected to the cathode of the battery 101. [

The protection circuit 104 includes an overcharge detection circuit 110, an over discharge detection circuit 111, a discharge over current detection circuit 112, a charge over current detection circuit 113 and a short detection circuit 114.

Overcharge detection of the battery 101 is detected by the overcharge detection circuit 110. [ The voltage of the battery 101 is input through the VDD terminal 105, and when the overcharge detection voltage is higher than the preset overcharge detection voltage, the overcharge is detected. The detected overcharge signal is transferred to the logic circuit 118 and the oscillator 116 and the frequency divider 117 are operated to change the output of the COUT terminal 108 from a high level to a low level after a constant delay time, The effect transistor M11 is turned off to shut off the charging of the battery 101. [

The discharge current continues to flow through the first parasitic diode D11 of the first field effect transistor M11 even when overcharging is detected and charging is interrupted.

When the voltage of the VDD terminal 105 becomes lower than the overcharge release voltage, the output of the COUT terminal 108 is changed from the low level to the high level and the first field effect transistor M11 is turned on to charge the battery 101 .

The overdischarge detection of the battery 101 is detected by the overdischarge detection circuit 111. [ The voltage of the battery 101 is input through the VDD terminal 105, and when the overdischarge detection voltage is lower than a predetermined overdischarge detection voltage, overdischarge is detected. The detected overdrive signal is transmitted to the logic circuit 118 and the oscillator 116 and the frequency divider 117 are operated to change the output of the DOUT terminal 107 from a high level to a low level after a predetermined delay time, The field effect transistor M12 is turned off to shut off the discharge of the battery 101. [

The charging current flows through the second parasitic diode D12 of the second field effect transistor M12 even when over discharge is detected and the discharge is blocked.

When the voltage of the VDD terminal 105 is higher than the overdischarge detection voltage, the output of the DOUT terminal 107 is changed to the high level and the second field effect transistor M12 is turned on to discharge the battery 101. [

The discharge overcurrent detection detects the discharge overcurrent when the discharge overcurrent detection circuit 112 detects the voltage of the V- terminal 109 and becomes higher than a preset discharge overcurrent detection voltage. The detected discharge overcurrent signal is transferred to the logic circuit 118, and the output of the DOUT terminal 107 is changed from a high level to a low level to turn off the second field effect transistor M12 to shut off the discharge.

The discharging overcurrent cancellation resistance R12 maintains the off state by the second field effect transistor M12 when the battery 101 operates in the steady state and when the discharge overcurrent or short circuit current is detected, the second field effect transistor M12 Is turned on and the VSS terminal 106 and the V- terminal 109 are connected through the resistor R12. At this time, if the load is not connected, the voltage of the V- terminal 109 is lowered and the discharging overcurrent state or the short-circuit current state is automatically canceled.

The charging over-current detection detects the charging over-current when the charging over-current detection circuit 113 detects the voltage of the V- terminal 109 and becomes lower than a preset discharge over-current detection voltage. The detected charge overcurrent signal is transferred to the logic circuit 118 and changes the output of the COUT terminal 108 from high level to low level to turn off the first field effect transistor M11 to shut off charging.

The short-circuit current detection detects the voltage of the V- terminal 109 when the battery 101 is charged or discharged in the short-circuit current circuit. When a large current flows instantaneously due to the short-circuit of the external load, the voltage of the V- terminal 109 becomes higher than the short-circuit detection voltage, and the short-circuit detection signal is transmitted to the logic circuit 118. At this time, the output of the DOUT terminal 107 is changed from the high level to the low level to turn off the second field effect transistor M12 to block the short-circuit current from flowing.

Although the discharge overcurrent detection, charge overcurrent detection and shortcurrent detection both have a delay time due to the signal transmitted from the distributor 117 to the logic circuit 118, the shortcircuit current is much shorter than the discharge overcurrent, And has a delay time.

The operation of the general protection circuit 104 described above is designed so as to have a maximum constant detection value with respect to a change in temperature. That is, the charging is stopped when the temperature exceeds a certain temperature. However, lithium ion or lithium polymer batteries have different characteristics depending on the temperature, and explosion may occur due to unstable characteristics particularly at high temperatures.

9 is a graph showing the operating voltage characteristics with respect to the temperature change of the protection circuit according to the present invention.

Referring to FIG. 9, the protection circuit according to the present invention is characterized in that a detection voltage, a detection voltage, and a release delay time vary with an increase or decrease in temperature, not an operating voltage having a predetermined detection value according to a conventional temperature change, .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a battery protection circuit using an overcharge detection circuit according to an embodiment of the present invention will be described with reference to the accompanying drawings.

First Embodiment

Fig. 2 is a circuit diagram for explaining a detection circuit according to the first embodiment of the present invention by using an overcharge detection circuit, and Fig. 6 is a circuit diagram for explaining a voltage discharge function according to the temperature change of the present invention.

2 and 6, the overcharge detecting circuit 110A according to the present invention includes a voltage dividing circuit 201, a changing means 202, a selecting unit 203, a temperature sensor 204, a comparing circuit 205, And a reference voltage circuit (206).

The voltage dividing circuit 201 is constituted by connecting resistors R21, R22, R23, R24, R25 and R26 in series to divide the voltage between the power source VDD and the power source VSS. One end of the resistor R21 is connected to the VDD terminal VDD and the resistor R26 is connected to the VSS terminal VSS.

The changing means 202 is constituted by field effect transistors M21, M22, M23 and M24. The field effect transistors M21, M22, M23 and M24 are means for changing the partial pressure ratio of the voltage dividing circuit 201. [ The gates of the field effect transistors M21, M22, M23 and M24 are connected to the resistors R22, R23, R24 and R25 connected in series, M22, M23, and M24 are turned on / off by the signal of the selector 203 to change the resistance value. The positions of the resistors R22, R23, R24 and R25 and the field effect transistors M21, M22, M23 and M24 of the changing means 202 may be located below the node A.

The selector 203 receives the output of the temperature sensor 204 and is connected to the gates of the field effect transistors M21, M22, M23 and M24 of the changing means 202, (M21, M22, M23, M24).

The temperature sensor 204 detects the temperature of the battery 101 and outputs the detected temperature to the selection unit 203. The temperature sensor 204 may be an internal temperature sensor or an external temperature sensor, and the external temperature sensor may be a thermistor, a thermocouple, or an IC temperature sensor.

The non-inverting input terminal of the comparing circuit 205 is connected to the node A, and the inverting input terminal of the comparing circuit 205 is connected to the reference voltage circuit 206. [ The output signal of the comparison circuit 205 is supplied to the logic circuit 118.

When the temperature sensor 204 detects a change in the temperature of the battery 101, the temperature sensor 204 outputs the temperature signal detected by the selection unit 203. [ The selector 203 receives the output of the temperature sensor and selectively outputs each of the field effect transistors M21, M22, M23 and M24 of the changing means 202 to the high level or low level signal On / off control. The field effect transistors M21, M22, M23, and M24 to which the high level signal is applied are turned on and short-circuited.

If the selection unit 203 selectively controls ON / OFF of the field effect transistors M21, M22, M23 and M24 of the changing means 202 in accordance with the temperature characteristic in accordance with the temperature change, And the reference voltage 206 are compared with each other. The voltage of the node A is set such that the resistances R21, R22, R23, R24, R25 and R26 of the voltage dividing circuit 201 are divided by the resistances except for the resistance short-circuited by the changing means 202, Voltage.

The comparison circuit 205 determines overcharge when the voltage of the node A exceeds the reference voltage and outputs a high level signal indicating overcharge. The overcharge detection signal is supplied to the logic circuit 118 and the logic circuit 118 outputs the output signal of the COUT terminal 108 to the low level to shut off the first field effect transistor M11 to stop charging.

6, the discharge control unit M61 and the discharge selection unit R61 are provided between the VDD terminal VDD and the VSS terminal VSS, as shown in FIG. 6 601 to turn on / off the discharge selection transistor M61 in accordance with the discharge control signal of the logic circuit 118, thereby discharging the discharge selection transistor M61 until the voltage exceeds the overcharge voltage, thereby ensuring maximum safety.

According to the first embodiment, since the ratio of the input to be compared with the reference voltage can be adjusted according to the temperature characteristic according to the temperature of the battery 101, the detection voltage, the release voltage, and the detection and release delay time can be varied . Further, it is possible to individually control the overcurrent, overcurrent, discharge overcurrent and charge overcurrent detection circuits so as to have different characteristics.

Second Embodiment

3 is a circuit diagram illustrating a detection circuit according to a second embodiment of the present invention by using an overcharge detection circuit.

3, the overcharge detecting circuit 110B according to the present invention includes a first voltage dividing circuit 301, a second voltage dividing circuit 302, a changing means 303, a selecting unit 304, a temperature sensor 305, And a comparison circuit 306. [

The first voltage dividing circuit 301 is constituted by connecting resistors R31, R32 and R33 in series to divide the voltage between the power source VDD and the power source VSS. One end of the resistor R31 is connected to the VDD terminal VDD, and the resistor R33 is connected to the VSS terminal VSS.

The second voltage divider circuit 302 is constituted by connecting resistors R34, R35, R36 and R37 in series, and changes the resistance value to change the output of the reference voltage.

The changing means 303 is constituted by field effect transistors M31, M32 and M33. The field effect transistors M31, M32 and M33 are means for changing the partial pressure ratio of the second voltage dividing circuit 302. [ The gates of the field effect transistors M31, M32, and M33 are connected to the selectors 304, respectively, and the field effect transistors M31, M32, and M33 are connected to the resistors R35, R36, And the resistance value is changed by on / off control of the field effect transistors M31, M32, and M33 by the selection unit 304 signal.

The selection unit 304 receives the output of the temperature sensor 305 and is connected to the gates of the respective field effect transistors M31, M32 and M33 of the changing means 303 and controls the respective field effect transistors M31 , M32, and M33.

The temperature sensor 305 detects the temperature of the battery 101 and outputs the detected temperature to the selection unit 304. The temperature sensor 305 may be an internal temperature sensor or an external temperature sensor, and a thermistor, a thermocouple, or an IC temperature sensor may be used as the external temperature sensor.

The non-inverting input terminal of the comparing circuit 306 is connected to the first node B, and the inverting input terminal of the comparing circuit 306 is connected to the second node C. The output signal of the comparison circuit 306 is supplied to the logic circuit 118.

When the temperature sensor 305 detects the temperature change of the battery 101, the temperature sensor 305 outputs the temperature signal detected by the selection unit 304. [ The selector 304 receives the output of the temperature sensor 305 and selectively outputs each of the field effect transistors M31, M32 and M33 of the changing means 303 to a high level or a low level On / off control by applying a signal. The field effect transistors M31, M32, and M33 to which the high level signal is applied are turned on and short-circuited.

If the selection unit 304 selectively controls ON / OFF of the field effect transistors M31, M32 and M33 of the changing means 303 in accordance with the temperature characteristic in accordance with the temperature change, the comparing circuit 306 compares the first field B ) And the reference voltage of the second node (C). The voltage of the first node B is a divided voltage obtained by dividing the resistances R31, R32 and R33 of the first voltage dividing circuit 301 and the voltage of the second node C is divided by the second voltage dividing circuit 302 (R34, R35, R36, R37) are divided voltages divided by resistances except for the resistance short-circuited by the changing means 303. [

The comparison circuit 306 determines overcharge when the voltage of the first node B exceeds the reference voltage of the second node C and outputs a high level signal indicating overcharge. The overcharge detection signal is supplied to the logic circuit 118 and the logic circuit 118 outputs the output signal of the COUT terminal 108 to the low level to shut off the first field effect transistor M11 to stop charging.

According to the second embodiment, the ratio of the input voltage to the reference voltage to be compared can be adjusted differently according to the temperature of the battery 101, so that the detection voltage and the release voltage can be varied. Also, since all the battery protection circuits such as overcharge, over discharge, discharge overcurrent and charge overcurrent use the reference voltage, it is possible to collectively reflect the change of the reference voltage according to the temperature.

Third Embodiment

4 is a circuit diagram for explaining a detection circuit according to the third embodiment of the present invention by using an overcharge detection circuit.

4, the overcharge detecting circuit 110C according to the present invention includes a voltage dividing circuit 401, a changing unit 402, a selecting unit 403, a temperature sensor 404, a comparing circuit 405, (406).

The voltage dividing circuit 401 comprises resistors R41, R42, R43, R44, R45 and R46 connected in series to divide the voltage between the power source VDD and the power source VSS. One end of the resistor R41 is connected to the VDD terminal VDD, and the resistor R46 is connected to the VSS terminal VSS.

The changing means 402 is constituted by connecting the set resistors R42, R43, R44 and R45 in series, and the changing means 402 may be located below the node D. [

The selector 403 receives the output of the temperature sensor 404 and is connected to each node of the changing means 402 to select the nodes of the resistors R42, R43, R44 and R45 according to the temperature change.

The temperature sensor 404 detects the temperature of the battery 101 and outputs the detected temperature to the selection unit 403. The temperature sensor 404 may be an internal temperature sensor or an external temperature sensor, and a thermistor, a thermocouple, or an IC temperature sensor may be used as the external temperature sensor.

The non-inverting input terminal of the comparing circuit 405 is connected to the selecting section 403, and the reference voltage circuit 406 is connected to the inverting input terminal. The output signal of the comparison circuit 405 is supplied to the logic circuit 118.

When the temperature sensor 404 detects the temperature change of the battery 101, the temperature sensor 404 outputs the temperature signal detected by the selection unit 403 and the output of the temperature sensor 404 403 select one node of each of the resistors R42, R43, R44, R45 of the changing means 402 according to the detected temperature according to the temperature characteristic and transmit it to the input of the comparing circuit 405 do.

The comparator circuit 405 judges overcharge when the output voltage output from the selector 403 exceeds the reference voltage and outputs a high level signal indicating overcharging. The overcharge detection signal is supplied to the logic circuit 118 and the logic circuit 118 outputs the output signal of the COUT terminal 108 to the low level to shut off the first field effect transistor M11 to stop charging.

According to the above-described third embodiment, the nodes of the respective resistors, which have been set in advance, are selected according to the temperature characteristics without changing the resistances, and different voltages are output, and these output voltages can be selected as the input values of the comparator according to the temperature. In addition, since the ratio of the input to be compared with the reference voltage can be adjusted differently according to the temperature of the battery 101, the detection voltage, the release voltage, and the detection and release delay time can be varied.

Fourth Embodiment

5 is a circuit diagram for explaining a detection circuit according to the fourth embodiment of the present invention by using an overcharge detection circuit.

5, the overcharge detecting circuit 110D according to the present invention includes a first voltage dividing circuit 501, a second voltage dividing circuit 502, a changing means 503, a selecting unit 504, a temperature sensor 505, , And a comparison circuit 506.

The first voltage dividing circuit 501 is constituted by resistors R51, R52 and R53 connected in series to divide the voltage between the power source VDD and the power source VSS. One end of the resistor R51 is connected to the VDD terminal VDD and the resistor R53 is connected to the VSS terminal VSS.

The changing means 503 is constituted by connecting the set resistors R54, R55 and R56 in series and the changing means 503 may be located below the second node F. [

The second voltage dividing circuit 502 is constituted by connecting resistors R54, R55, R56 and R57 in series, and according to the nodes of the resistors R54, R55 and R56 selected by the selector 504, .

The selection unit 504 receives the output of the temperature sensor 505 and is connected to the respective nodes of the change unit 503 to select the nodes of the resistors R54, R55, and R56 according to the temperature change.

The temperature sensor 505 detects the temperature of the battery 101 and outputs it to the selection unit 504. [ The temperature sensor 505 may be an internal temperature sensor or an external temperature sensor, and a thermistor, a thermocouple, or an IC temperature sensor may be used as the external temperature sensor.

The non-inverting input terminal of the comparing circuit 506 is connected to the first node E, and the selecting section 504 is connected to the inverting input terminal. The output signal of the comparison circuit 506 is supplied to the logic circuit 118.

The temperature sensor 505 detects the temperature change of the battery 101 by the temperature sensor 505. The temperature sensor 505 outputs the temperature signal detected by the selection unit 504 and the output of the temperature sensor 505, 504 change one of the nodes of the resistors R54, R55, R56 of the changing means 503 according to the detected temperature according to the temperature characteristic to change the reference voltage.

The comparing circuit 506 compares the voltage of the first node E with the reference voltage changed by the selecting unit 504 and determines whether the overdrive is over when the voltage of the first node E exceeds the changed reference voltage, And outputs a high level signal as shown in FIG. The overcharge detection signal is supplied to the logic circuit 118 and the logic circuit 118 outputs the output signal of the COUT terminal 108 to the low level to shut off the first field effect transistor M11 to stop charging.

According to the above-described fourth embodiment, since it is possible to select the node of each resistor previously set without changing the resistance, and to adjust the ratio of the reference voltage to be compared with the input voltage to different values, can do. Also, since all the battery protection circuits such as overcharge, over discharge, discharge overcurrent and charge overcurrent use the reference voltage, it is possible to collectively reflect the change of the reference voltage according to the temperature.

Fifth Embodiment

7 is a circuit diagram for explaining a detection circuit according to the fifth embodiment of the present invention by using an overcharge detection circuit.

7, the overcharge detecting circuit 110E according to the present invention has a voltage dividing circuit 701, a comparing circuit 702, and a reference voltage circuit 703. [

The voltage dividing circuit 701 is constituted by connecting resistors R71, R72, R73 and R74 in series, and divides the voltage between the power source VDD and the power source VSS. One end of the resistor R71 is connected to the VDD terminal VDD, and the resistor R74 is composed of a variable resistor capable of fusing the resistor and is connected to the VSS terminal.

The non-inverting input terminal of the comparing circuit 702 is connected to the node F, and the inverting input terminal of the comparing circuit 702 is connected to the reference voltage circuit 703. [ The output signal of the comparison circuit 702 is supplied to the logic circuit 118.

The reference voltage circuit 703 has an output characteristic in which the output characteristic is variable in accordance with the temperature of the battery 101 itself. Therefore, the reference voltage can be varied by itself to the temperature of the battery 101 without additional circuit or block such as a control circuit controlled according to the temperature sensor or the temperature sensor, thereby changing the detection and release voltage of the battery protection circuit.

According to the above-described fifth embodiment, the reference voltage circuit 703 is designed so as to have a slope in accordance with the temperature characteristic of the battery 101 without providing a temperature sensor and a special block or a control circuit, The detection and release voltage of the circuit can be varied. In addition, the battery 101 can be protected in accordance with the chemical characteristics of the battery 101, and the battery 101 can be used as efficiently as possible.

The battery protection circuit according to the present invention may include a voltage changing unit for changing the voltage by the sensing information of the temperature sensor according to the temperature of the battery and a selecting unit for controlling the voltage changing unit, A reference voltage circuit having a characteristic that varies according to temperature can be provided so that the detection and release voltage of the battery protection circuit can be changed according to the temperature of the battery to actively cope with the temperature change of the battery, And provides a battery protection circuit that can be used.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

201: voltage dividing circuit 202: changing means
203: selection unit 204: temperature sensor
205: comparison circuit 206: reference voltage
R21, R22, R23, R24, R25: resistance
M21, M22, M23, M24: Field effect transistor

Claims

A battery protection circuit for controlling charging and discharging of a battery,
A reference voltage circuit for generating a reference voltage;
A voltage divider circuit for dividing an input voltage of the battery or a reference voltage of the reference voltage circuit;
Changing means for changing a partial pressure ratio of the voltage dividing circuit; And
And a selection unit for selecting the partial pressure ratio by controlling the changing unit according to the temperature of the battery.

The method according to claim 1,
Further comprising a temperature sensor for sensing the temperature of the battery and forming sensing information,
Wherein the sensing information is input to the selection unit to change the voltage division ratio of the input voltage or the voltage division ratio of the reference voltage.

3. The method of claim 2,
Wherein the voltage divider circuit includes a plurality of resistors connected in series to divide an input voltage,
Wherein said changing means has a field effect transistor whose source or drain is connected to both terminals of at least one of said resistors.

4. The battery protection circuit as claimed in claim 3, wherein an output of the selection unit is connected to a gate terminal of the field effect transistor, and selectively turns on / off the field effect transistor.

3. The method of claim 2,
The voltage-
A first voltage dividing circuit having a plurality of resistors connected in series to divide the input voltage;
And a second voltage dividing circuit having a plurality of resistors connected in series to divide the reference voltage,
Wherein the changing means comprises a field effect transistor having a source or a drain connected to both terminals of at least one resistor constituting the second voltage dividing circuit.

6. The battery protection circuit as claimed in claim 5, wherein an output of the selection unit is connected to a gate terminal of the field effect transistor, and selectively turns on / off the field effect transistor.

3. The method of claim 2,
Wherein the voltage divider circuit comprises a plurality of resistors connected in series to divide an input voltage and a node between the resistors is connected to the selector.

The battery protection circuit according to claim 7, wherein the selection unit selects any one of voltages input from nodes between the resistors according to the sensing information.

3. The method of claim 2,
The voltage-
A first voltage dividing circuit having a plurality of resistors connected in series to divide the input voltage;
And a second voltage dividing circuit having a plurality of resistors connected in series to separate the reference voltage,
And the nodes between the plurality of resistors constituting the second voltage division circuit are connected to the selection unit.

The battery protection circuit according to claim 9, wherein the selection unit selects any one of voltages inputted from nodes between the resistors according to the sensing information.

The method according to claim 1,
Wherein the reference voltage circuit has an output whose output characteristic is self-varying according to the temperature of the battery.

The method according to claim 1,
A discharge control unit is further included between the VDD terminal and the VSS terminal,
Wherein the discharge control unit performs discharge by a discharge control signal until the input voltage has a value equal to or higher than the overcharge when the input voltage has a value equal to or higher than the overcharge voltage.

The plasma display apparatus according to claim 12,
A discharge selection transistor for receiving the input voltage and performing an on / off operation in accordance with the discharge control signal; And
And a discharge selection resistor connected between the discharge selection transistor and the VSS terminal.