KR20070105219A - Protection circuit of battery pack - Google Patents

Abstract

A protection circuit of a battery pack is provided to secure the margin when planning the pattern of a protection circuit module by securing a space which is for a secondary protection circuit IC. A protection circuit of a battery pack includes a self control protecting apparatus(115), a micro computer(117) and a controlling pin(123). The self control protecting apparatus consists of a fuse(115a), a heater(115c), and a controlling switch(115b). The self control projecting apparatus is connected to the path of the large current between a battery cell(111) and an outer terminal. The micro computer is parallel connected between the battery cell and the outer terminal, and provides the cell information which is transmitted from the battery cell to an outer system(200) through an SMBUS terminal(124), and is connected to a gate terminal of the controlling switch, and controls the self control protecting apparatus. The controlling pin transmits the controlling signal to the controlling terminal to turn off the fuse of the self control protecting apparatus using the controlling switch when the outer system which monitors the cell information detects the charge and the discharge unusual phenomenon of the battery cell by connecting the gate terminal of the controlling switch and a controlling terminal(112a) of the outer terminal.

Description

Protection circuit of battery pack

1 is a block diagram illustrating a configuration in which a protection circuit of a battery pack is connected between a battery cell and an external system according to an embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating a protection circuit of a battery pack connected between a battery cell and an external system in FIG. 1.

FIG. 3 is a flowchart illustrating a process of melting a fuse under the control of the external system of FIG. 2.

FIG. 4 is a flowchart illustrating another process of fusing the fuse under the control of the external system of FIG. 2.

* Explanation of symbols for the main parts of the drawings

100: battery pack 111: battery cell

112: external terminal 112a: control terminal

113: charging element 114: discharge element

115: self-control protective device (SCP) 115a: fuse

115b: control switch 115c: heater

116: analog front end (AFE) IC 117: microcomputer

118: sensor resistance 121: reverse current prevention diode

123: control pin 124: SMBUS terminal

124a: clock line 124b: data line

200: external system 221: adapter

222: load 223: control unit

224: gate driver

The present invention relates to a battery pack, and more particularly, by eliminating an integrated circuit (IC) for controlling a self control protector from a protection circuit module, thereby reducing the total number of components, thereby The present invention relates to a battery pack protection circuit that can reduce component costs and provide margin in terms of the pattern design of the protection circuit module.

In general, rechargeable batteries are being actively researched by the development of portable electronic devices such as cellular phones, notebook computers, camcorders, personal digital assistants (PDAs), and the like. In particular, the secondary battery may be a nickel-caddimium battery, a lead acid battery, a nickel metal hydride battery (NiMH), a lithium ion battery, or a lithium polymer battery. ), Metal lithium batteries, air zinc accumulators, etc. are being developed. The secondary battery is combined with a circuit to form a battery pack, and charging and discharging are performed through external terminals of the battery pack.

A conventional battery pack includes a battery cell and a peripheral circuit including a charge and discharge circuit, which is made of a printed circuit board and then coupled with the battery cell.

When external power is connected through the external terminal of the battery pack, the battery cell is charged by the external power supplied through the external terminal and the charge / discharge circuit, and when a load is connected through the external terminal, the power of the battery cell The operation supplied to the load through this charge / discharge circuit and an external terminal occurs. At this time, the charge / discharge circuit controls the charge / discharge of the battery cell between the external terminal and the battery cell.

BACKGROUND Battery packs comprising lithium ion battery cells or a plurality of battery cells (secondary battery cells) connected in series are used in various types of systems, for example portable notebook computers. Since such a battery cell has a small structure but has a high output, charge and discharge abnormalities can easily occur. Various types of charging and discharging abnormalities exist such as an increase in voltage due to overcharging of a battery cell, a decrease in voltage due to overdischarge, an overcharge current flowing from an external path to the battery cells, and an overdischarge current flowing from the battery cells to the outside. It is desired to protect the battery cells and the external system from the case where such abnormality occurs.

Accordingly, the conventional battery pack has charge and discharge elements (FETs) that are turned on / off to block overcharging and overdischarging of the battery cells when the battery cells are abnormally charged or discharged. These charge and discharge devices (FETs) are switching devices, and are controlled by an analog front end (AFE) IC.

In recent years, the performance of a battery pack has been improved by including various functions such as a residual charge display function. As a result, battery packs having a microcomputer (μC) for controlling a plurality of integrated circuits (ICs), for example, analog front end ICs, have been implemented in many different ways.

Such a microcomputer (μC) is in an overcharge state or an overdischarge state when the voltage detected from the battery cell is at the primary protection level, for example, at or above the primary overcharge voltage level of 4.35V or below the primary overdischarge voltage level of 2.30V. By judging, the charge / discharge device (FET) is turned on / off through the analog front end IC to block overcharging or overdischarging of the battery cell. In addition, the microcomputer (μC) functions to communicate with other controllers of the external system via an SMBUS having a clock signal line (CLK) and a data signal line (data).

As described above, in the case of a lithium ion battery pack, since charge and discharge abnormalities easily occur, there is a high risk of ignition, combustion or explosion.

In order to reduce this risk and improve the stability of the lithium ion battery pack, the lithium ion battery pack is turned on / off during overcharging or overdischarging of a battery cell to prevent overcharge and overdischarge. In addition, it further includes a Self Control Protector (SCP) composed of a heater, a fuse, and a control switch. This is to prevent overcharge and overdischarge of the battery cell using a self-control protection device in case the analog front end IC controlling the charge and discharge elements (FET) fails due to a failure or the like. That is, the fuse of the self-controlled protection device (SCP) is blown to cut off the flow of current to block overcharge and overdischarge of the battery cell.

However, in the conventional lithium ion battery pack, when the fuse is blown to block the overcharging and overdischarging of the battery cell, the fuse itself does not operate so a separate secondary protection circuit IC is required. Done. The addition of such a separate IC is a factor of the increase in price, and the number of parts is thereby increased, resulting in a small component mounting space in the printed circuit board. Therefore, the manufacturing cost of the protection circuit module due to the secondary protection circuit IC increases, there is a disadvantage that the margin is low in terms of the pattern design of the protection circuit module.

The present invention is to solve the above problems of the prior art, by removing the secondary protection circuit IC (Integrated Circuit) for controlling the self control protector (Self control protector) in the protection circuit module to reduce the total number of parts, It is an object of the present invention to provide a battery pack capable of reducing component cost and securing margin in terms of pattern design.

According to the present invention for achieving the above object, a rechargeable battery cell, connected in parallel via a high current path with the battery cell and connected to an external system to operate as a terminal during charging or discharging by the battery cell The protection circuit of the battery pack including an external terminal is composed of a fuse, a heater and a control switch, the self-controlling protection device connected to the large current path between the battery cell and the external terminal; Connected in parallel between the battery cell and the external terminal to provide cell information received from the battery cell to the external system through the SMBUS terminal of the external terminal, and connected to the gate terminal of the control switch to protect the self control Microcomputer to control the device; And connecting the gate terminal of the control switch and the control terminal of the external terminal to protect the self-control by using the control switch when the external system that monitors the cell information detects an abnormal charge and discharge of the battery cell. And a control pin which transmits a control signal to the control terminal to output a control signal to turn off (block) the fuse of the device.

The fuse is connected in series to a high current path between the battery cell and the external terminal, the control switch has a gate terminal connected to the control pin and the microcomputer, and the heater is connected to one end of the fuse and the control switch. It may be connected to the drain terminal.

Charging elements and discharging elements may be further included in a large current path between the battery cell and the self-control protection device.

Connected in parallel between the battery cell and the charging and discharging elements and in series between the battery cell and the microcomputer, detecting the voltage of the battery cell and transferring the detected cell voltage to the microcomputer; It may further include an analog front end (AFE) for operating the charging element and the discharge element under the control of the microcomputer.

The microcomputer turns off the charging device or the discharge device through the analog front end AFE when the voltage value of the battery cell is equal to or greater than the overcharge level voltage set therein or below the overdischarge voltage. The fuse may be blown by turning on the control switch.

The analog front end and the microcomputer can be an integrated circuit.

When the voltage of the battery cell received through the microcomputer to the external system is above the overcharge level voltage or below the overdischarge level voltage set in the external system, the system supplies a control signal through the control pin to The fuse may be blown by turning on a control switch.

The overcharge level voltage set in the external system may be greater than the overcharge level voltage set in the microcomputer.

The overdischarge level voltage set in the external system may be smaller than the overdischarge level voltage set in the microcomputer.

When the voltage of the battery cell is not received from the microcomputer by the controller of the external system more than a specific number of times, the controller transmits a control signal corresponding to the gate driver of the external system and outputs the high signal outputted from the gate driver. A fuse may be blown by transmitting a high signal to the gate terminal of the control switch through the control pin to turn on the control switch.

The control switch may be an NMOS field effect transistor.

The microcomputer can connect a clock line and a data line between the SMBUS terminal of the external terminal to communicate with the external system.

The external system may be a portable electronic device including a charger.

The sensor resistor may further include a sensor resistor connected in series to a large current path between the battery cell and the external terminal to sense current of the battery cell.

When the overcurrent is detected from the sensor resistor, the microcomputer connected to the sensor resistor may transmit overcurrent information to the external system through the SMBUS terminal of the external terminal and supply a control signal according to the overcurrent detection to the analog front end. .

A reverse current preventing diode may be further formed on the control pin.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram illustrating a configuration in which a protection circuit of a battery pack is connected between a battery cell and an external system according to an embodiment of the present invention, and FIG. 2 is a protection diagram of a battery pack connected between the battery cell and an external system in FIG. 1. A circuit diagram showing a circuit.

1 and 2, a battery pack 100 according to an embodiment of the present invention includes a rechargeable battery cell 111 and a protection circuit, and includes an external system such as a portable notebook computer (PC). Mounted in the cell 200, the battery cell 111 is charged and discharged by the battery cell 111.

The battery pack 100 is connected in series to a battery cell 111, an external terminal 112 connected in parallel with the battery cell 111, and a high current path (HCP) between the battery cell 111 and the external terminal 112. Self control protector (SCP) 115 connected in series to the high current path (HCP) between the charging element 113 and the discharge element 114, the discharge element 114 and the external terminal 112, Analog Front End (hereinafter referred to as AFE) IC 116 connected in parallel with the battery cell 111, the charging element 113 and the discharge element 114, one end is the AFE IC 116 and the other end is SCP ( And a protection circuit comprising a microcomputer 117 connected to 115. The protection circuit of the battery pack 100 further includes a sensor resistor 118 connected in series with the high current path HCP between the battery cell 111 and the external terminal 112 and also connected to the microcomputer 117.

The battery pack 100 configured as described above is connected to the external system 200 through the external terminal 112 to perform charging or discharging. The large current path HCP of the path between the external terminal 112 and the battery cell 111 is used as a charge / discharge path, and a relatively large current flows through the large current path HCP. The battery pack 100 includes an SMBUS 124, a self-controlled protective device 115, and an external terminal between the microcomputer 117 of the protection circuit and the external terminal 112 for communication with the external system 200. It further includes a control pin 123 connected in parallel between the 112 to supply a control signal from the external system 200 to the self-control protection device 115.

The external system 200 is a portable electronic device, such as a portable notebook computer, and may include an adapter 221 for power supply separately. Thus, when the external system 200 is connected to the adapter 221, the external system 200 can be operated by the adapter 221, the power of the adapter 221 is a large current path (through the external terminal 112) ( The battery cells 111 may be supplied to the battery cells 111 through the HCP to charge the battery cells 111. When the external system 200 is separated from the adapter 221, a discharge may be performed from the battery cell 111 to the load 222 of the external system 200 through the external terminal 112.

That is, when the external system 200 to which the adapter 221 is connected to the external terminal 112 is connected, a charging operation occurs, and the charging path at this time is from the adapter 221 to the external terminal 112, the SCP 115, It leads to the battery cell 111 via the discharge element 114, the charging element 113. When the adapter 221 is disconnected from the external system 200 and a load 222 of the external system 200 is connected to the external terminal 112, a discharge operation occurs, and the discharge path at this time is a battery cell ( 111 from the charging device 113, the discharge device 114, the SCP 115, the discharge device 114, and the external terminal 112 to the load 221 of the external system 200.

Components of the battery pack 100 and the protection circuit operation of the battery pack 100 connected to the external system 200 will be described in detail with reference to FIG. 2.

Referring to FIG. 2, first, a battery cell 111 is a secondary battery cell capable of charging and discharging. In the drawing, B + and B- indicate high current stages, and power supply units at both ends of the battery cells 111 connected in series. Indicates. The battery cell 111 outputs various information therein, that is, cell related information such as the temperature of the cell, the charging voltage of the cell, and the amount of current flowing through the cell, to the AFE IC 116 to be described below.

The external terminal 112 is connected in parallel with the battery cell 111, is connected to the adapter 221 or the load 222 of the external system 200 to charge to the battery cell 111 or by the battery cell 111 Acts as a terminal during discharge. In the drawing, P + denotes a positive terminal connected to the positive electrode power supply unit B + of the battery cell 111, and P− denotes a negative terminal connected to the negative electrode power supply unit B− of the battery cell 111. The battery pack 100 is connected to the adapter 211 or the load 222 through the external terminal 112. That is, when the external system 200 to which the adapter 221 is connected to the external terminal 112 is connected, charging is performed from the adapter 221 to the battery cell 111, and the adapter 221 is connected to the external terminal 112. When disconnected from the external system 200 and the load 222 is connected, discharge from the battery cell 111 to the load 222 is performed.

 The charging device 113 and the discharge device 114 are connected in series on the high current path HCP between the external terminal 112 and the battery cell 111 to perform charging or discharging of the battery pack. Each of the charging device 113 and the discharge device 114 is composed of a field effect transistor (hereinafter referred to as FET) and a parasitic diode (hereinafter referred to as D), that is, the charging device 113 is referred to as FET1 and D1. The discharge element 114 is composed of FET2 and D2. The connection direction between the source and the drain of the field effect transistor FET1 of the charging element 113 is set in the opposite direction to the field effect transistor FET2 of the discharge element 114. With this configuration, the field effect transistor FET1 of the charging element 113 is connected to limit the current flow from the external terminal 112 to the battery cell 111, while the field effect transistor FET2 of the discharge element is connected to the battery cell ( Connected to limit current flow from 111 to external terminal 112. Here, the electric field effect transistors FET1 and FET2 of the charge and discharge devices 113 and 114 are switching devices, and the technical scope of the present invention is not limited thereto, and an electric device that performs other types of switching functions may be used. In addition, the parasitic diodes D1 and D2 included in the charging and discharging elements 113 and 114 are configured such that the current flows in a direction opposite to the direction in which the current is restricted.

The AFE IC 116 is connected in parallel between the battery cell 111, the charging device 113, and the discharge device 114, and is connected in series between the battery cell 111 and the microcomputer 117 to be described below. The AFE IC 116 detects a voltage of the battery cell 111 and transfers the detected voltage to the microcomputer 117, and controls the charging device 113 and the discharge device 114 under the control of the microcomputer 117. To control the operation.

In detail, when the external system 221 having the adapter 221 connected to the battery cell 111 is connected, the AFE IC 116 turns on the field effect transistor FET1 of the charging device 113. The field effect transistor FET2 of the discharge element 114 is set to an on state so that the battery cell 111 can be charged. Similarly, when the load 222 of the external system 200 is connected to the battery cell 111, the AFE IC 116 turns on the field effect transistor FET1 of the charging element 113, the discharge element The field effect transistor FET2 of 114 is turned on to allow the battery cell 111 to be discharged.

The microcomputer 117 is an integrated circuit (IC) connected in series between the AFE IC 116 and the external system 200, and the charging device 113 and the discharge device 114 through the AFE IC 116. ) To block overcharge, overdischarge, and overcurrent of the battery cell 111. That is, the voltage of the battery cell 11 received from the battery cell 111 through the AFE IC 116 is compared with the voltage level value set therein, and the control signal according to the comparison result is output to the AFE IC 116. By turning on / off the charging element 13 and the discharging element 14, the overcharge, overdischarge and overcurrent of the battery cell 111 are blocked.

In detail, when the voltage of the battery cell 111 received by the microcomputer 117 is overcharge level voltage value set therein, for example, 4.35V or more, the microcomputer 117 determines that it is in an overcharge state and correspondingly. The control signal is output to the AFE IC 116 to turn off the field effect transistor FET1 of the charging element 13. Then, charging from the adapter 221 of the external system 200 to the battery cell 111 is cut off. In this case, the parasitic diode D1 of the charging device 113 may serve to discharge the battery pack even when the field effect transistor FET1 of the charging device 113 is turned off. On the contrary, when the voltage of the battery cell 111 received by the microcomputer 117 is set to an overdischarge level voltage value, for example, 2.30V or less, the microcomputer 117 determines that the overdischarge state is corresponding to the overdischarge state. The control signal is output to the AFE IC 116 to turn off the field effect transistor FET2 of the discharge element 114. Then, the discharge from the battery cell 111 to the load 222 of the external system 200 is interrupted. At this time, the parasitic diode D2 of the discharge element 114 serves to perform a charging function of the battery pack even when the field effect transistor FET2 of the discharge element 14 is turned off.

In addition, the microcomputer 117 has a function of communicating with the external system 200 through the SMBUS (124). That is, the microcomputer 117 receives information such as the voltage of the battery cell 111 from the AFE IC 116 and transmits the information to the external system 200. At this time, the information of the battery cell 111 is transferred to the external system 200 through the data line 124b in synchronization with the clock signal of the clock line 124a of the SMBUS 124.

SCP 115 consists of a fuse 115a, a heater 115c and a control switch 115b and is connected to the high current path (HCP) between the battery cell 111 and the positive terminal P + of the external terminal 112. . Looking closely at the configuration of SCP 115, fuse 115a is connected between the drain terminal of FET2 of discharge element 114 and the anode terminal P + of external terminal 112, and control switch 115b has a micro gate terminal. The heater 115c is connected between one end of the fuse 115a and the drain terminal of the control switch 115b. With this structure, when the microcomputer 117 determines that the battery cells 111 are in the overcharged and overdischarged states, the microcomputer 117 turns off the charging element 13 and the discharge element 14 as described above, The fuse 115a of the SCP 115 is blown to block overcharge and overdischarge of the battery cell 111. That is, when the microcomputer 17 determines that the battery cell 111 is in the overcharged and overdischarged state, the microcomputer 17 outputs a control signal corresponding thereto to turn on the control switch 115b so that the large current of the high current path (HCP) fuses. It is led to the heater 115c through the 115a. The heater 115c heated due to the induced large current causes the fuse 15 to melt. Therefore, the current flow of the high current path (HCP) is cut off, the overcharge and overdischarge of the battery cell 111 can be blocked. Here, the source terminal of the control switch 115b is configured to be grounded.

On the other hand, the battery pack 100 according to an embodiment of the present invention further includes a sensor resistor 118 connected in series between the battery cell 111 and the negative terminal P- of the external terminal 112.

The sensor resistor 118 is a means for sensing the current of the battery pack 100. Current information sensed by the sensor resistor 118 is input to the microcomputer 117. If an overcurrent flows in the battery pack 100, the microcomputer 117 outputs a control signal that blocks the flow of current to turn off the charging device 113, the discharge device 114, or the fuse 115a. The overcurrent state of the battery pack 100 is blocked.

As described above, in the case of overcharging, overdischarging, and overcurrent of the battery cell 111, the protection circuit of the battery pack 100 is controlled by the charging element 113 and the discharging element through the AFE IC 116 under the control of the microcomputer 117. By turning off the 114 or by melting the fuse 115a using the control switch 115b, the overcharge, overdischarge, and overcurrent states of the battery cell 111 can be blocked.

However, there may be a case where the line connecting the microcomputer 117 and the control switch 115b is disconnected, or the AFE IC 116 or the microcomputer 117 is inoperable due to a failure or the like. In consideration of this point, a process of protecting the battery cell during overcharging, overdischarging, and overcurrent of the battery cell 111 will be described with reference to FIGS. 3 and 4.

FIG. 3 is a flowchart illustrating a process of melting a fuse under the control of the external system of FIG. 2.

As shown in FIG. 2, the protection circuit of the battery pack 100 further includes a control pin 123 connecting the gate terminal of the control switch 115b of the SCP 115 to the external system 200.

The control pin 123 transmits a control signal generated from the external system 200 to the control switch 115b through the control terminal 112a of the external terminal. In detail, the external system 200 receives and monitors information about the battery cell 111 from the microcomputer 117, for example, the voltage of the battery cell 111, thereby overcharging the battery cell 111. When overdischarge and overcurrent are detected, the control switch 115b is turned on to generate a control signal corresponding to the fuse 115a. The generated control signal is transmitted to the control switch 115b through the control pin 123. As a result, the control switch 115b is turned on and the fuse is blown to cut off the flow of current, thereby preventing the battery cell 111 from being charged and discharged by the battery cell 111. Therefore, overcharge, overdischarge, and overcurrent states of the battery cell 111 may be blocked. Here, the control switch 115b is an NMOS transistor, which is a switch that is turned on only when a high signal is input. Accordingly, the external system 200 outputs a high signal when detecting abnormalities such as overcharge, overdischarge, and overcurrent of the battery cell 111.

The reverse current prevention diode 121 may be further formed on the control pin 123 connecting the gate terminal of the control switch 115b to the external system 200.

When the reverse current prevention diode 121 blows the fuse 115a primarily to block overcharge, overdischarge, and overcurrent, the current for the control signal supplied from the microcomputer 117 is controlled by the control switch ( It does not flow in the opposite direction of the gate terminal of 115b).

2 and 3, the line connecting the AFE IC 16, the charging device 113, and the discharge device 114 or the line connecting the microcomputer 117 and the control switch 115 are disconnected. In this case, when the battery cell 111 is hard to be protected from overcharge, overdischarge, and overdischarge, the operation of the protection circuit that can protect the battery cell 111 second will be described.

First, the battery pack 100 is mounted in the external system 200 to perform a charging operation and a discharging operation.

Information about the battery cell, for example, the voltage of the battery cell 111 from the battery cell 111 via the AFE IC 116 and the microcomputer 117, is synchronized with the clock of the clock line 124a of the SMBUS 124. And is transferred to the controller 223 of the external system 200 along the data line 124b.

The controller 223 of the external system 200 monitors the voltage of the battery cell 111 received in step S11 of the protection circuit operation of FIG. 3.

In operation S12, when the voltage of the battery cell 111 is greater than or equal to the overcharge level voltage set in the controller 223, for example, 4.5 V, the control signal corresponding to the control signal is transmitted to the gate driver 224 in operation S13. Will output Then, the gate driver 224 outputs a high signal high to turn on the control switch 115b. Accordingly, the high signal high output from the gate driver 224 is input to the gate terminal of the control switch 115b through the control pin 123, thereby turning on the control switch 115b to provide a high current path. The large current is led in the direction of the heater 115c. The heater 115c heated by the induced large current causes the fuse 115a located in the large current path HCP to be blown. As a result, the current flow on the high current (HCP) is interrupted, and charging from the external system 200 to the battery cell 111 is interrupted.

In addition, the controller 223 of the external system 200 monitors the voltage of the battery cell 111 received in step S11 of the protection circuit operation of FIG. 3. In operation S12, when the voltage of the battery cell 111 is less than the over-discharge level voltage set in the controller 223, for example, 2.1 V, the control signal corresponding to the control signal is transmitted to the gate driver 224. ) Then, the gate driver 224 causes the fuse 115a to blow, as the control unit 223 determines the overcharge state of the battery cell 111, and cuts off the current flow on the high current HCP, thereby discharging the battery cell 111. To discharge the discharge.

In addition, when the voltage of the battery cell 111 transferred to the controller 223 of the external system 200 is lower than the overcharge level voltage or higher than the overdischarge level voltage in step S12, the controller 223 may operate the battery cell 111. In operation S11, the controller 110 continuously monitors the voltage of the battery cell 111 based on the determination of the normal state.

Here, since melting the fuse under the control of the controller 223 of the external system 200 protects the battery cell 111 secondaryly, the overcharge level voltage set in the controller 223 is applied to the microcomputer 117. It is preferable to set higher than the set overcharge level voltage, and it is preferable to set the overdischarge level voltage set in the controller 223 to be lower than the overdischarge level voltage set in the microcomputer 117.

Although not shown in the drawing, when the controller 223 of the external system 200 determines the battery cell 111 as an overcurrent state based on the received information of the battery cell 111, the controller 223 determines that the battery cell 111 is in an overcurrent state. As in the case of overcharge and overdischarge, the control switch 115b is turned on to blow the fuse 115a to cut off the overcurrent state of the battery cell 111.

Next, referring to FIGS. 2 and 4, when the AFE IC 116 or the microcomputer 117 is inoperable due to a failure, the battery cell 111 may be hard to be protected from overcharge, overdischarge, and overdischarge. At this time, the operation of the protection circuit that can protect the battery cell 111 secondary will be described.

First, the battery pack 100 is mounted in the external system 200 to perform a charging operation and a discharging operation.

Information about the battery cell, for example, the voltage of the battery cell 111 from the battery cell 111 via the AFE IC 116 and the microcomputer 117, is synchronized with the clock of the clock line 124a of the SMBUS 124. And is transferred to the controller 223 of the external system 200 along the data line 124b.

Accordingly, the controller 223 of the external system 200 monitors the voltage of the battery cell 111 in step S21 during the protection circuit operation of FIG. 4.

However, when the AFE IC 116 or the microcomputer 117 fails due to a failure, the controller 223 of the external system 200 receives the information of the battery cell 111 such as the voltage of the battery cell 111. Since the voltage of the battery cell 111 cannot be monitored. Accordingly, the controller of the external system 200 in step S22, if the voltage of the battery cell 111 is not received more than a certain number of times in the range that does not give stability to the battery pack 100, the safety of the battery pack 100 It is determined that there is a problem, and in step S23 outputs a control signal corresponding to the gate driver 224. Then, the gate driver 224 outputs a high signal high to turn on the control switch 115b. Accordingly, the high signal high output from the gate driver 224 is input to the gate terminal of the control switch 115b through the control pin 123, thereby turning on the control switch 115b to provide a high current path. The large current is led in the direction of the heater 115c. The heater 115c heated by the induced large current causes the fuse 115a located in the large current path HCP to be blown. Therefore, when an abnormal phenomenon such as overcharging, overdischarging, and overcurrent of the battery cell 111 cannot be detected immediately after a failure of a microcomputer or the like, the flow of current to the battery cell 111 is blocked, thereby reducing the safety of the battery pack. It can be secured.

When the voltage of the battery cell 111 is received by the controller 223 of the external system 200, the controller 223 repeats the operation of FIG. 3 again.

As described above, the protection circuit of the battery pack according to the present invention includes a control pin for connecting the self-control protection device (SCP) and the external system by melting the fuse of the self-protection device (SCP) under the control of the external system, If the AFE IC or microcomputer inside the battery pack fails due to a malfunction, the battery cells can shut off overcharge, overdischarge and overcurrent conditions. Therefore, it is possible to reduce safety problems that may occur due to an abnormal phenomenon such as overcharging, overdischarging, and overcurrent of the battery pack.

In addition, the protection circuit of the battery pack according to the present invention, since the self-control protection device (SCP) is controlled by an external system, a separate secondary protection circuit for controlling the self-protection device (SCP) in the protection circuit of the conventional battery pack. No IC is required.

Accordingly, the manufacturing cost of the protection circuit module can be lowered by the part cost occupied by the secondary protection circuit IC deleted when the protection circuit module including the protection circuit is manufactured. In addition, by securing a space occupied by the secondary protection circuit IC, it is possible to secure a margin when designing the pattern of the protection circuit module.

As described above, the present invention is not limited to the specific preferred embodiments described above, and any person having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Various modifications are possible, of course, and such changes are within the scope of the claims.

Claims (16)

A battery pack comprising a rechargeable battery cell and an external terminal connected in parallel with the battery cell through a high current path and connected to an external system to operate as a terminal during charging or discharging by the battery cell. A self-control protective device comprising a fuse, a heater and a control switch and connected to a high current path between the battery cell and the external terminal; Connected in parallel between the battery cell and the external terminal to provide cell information received from the battery cell to the external system through the SMBUS terminal of the external terminal, and connected to the gate terminal of the control switch to protect the self control Microcomputer to control the device; And The self-control protection device using the control switch when the external system monitoring the cell information by connecting the gate terminal of the control switch and the control terminal of the external terminal detects an abnormality in charging and discharging of the battery cell. And a control pin configured to transmit a control signal output to the control terminal so as to turn off (block) the fuse of the battery pack. The method of claim 1, The fuse is connected in series to a high current path between the battery cell and the external terminal, the control switch has a gate terminal connected to the control pin and the microcomputer, and the heater is connected to one end of the fuse and the control switch. The protection circuit of the battery pack, characterized in that connected to the drain terminal. The method of claim 1, And a charge element and a discharge element are further included in a large current path between the battery cell and the self-control protection device. The method of claim 3, wherein Connected in parallel between the battery cell and the charging and discharging elements and in series between the battery cell and the microcomputer, detecting the voltage of the battery cell and transferring the detected cell voltage to the microcomputer; And an analog front end (AFE) for operating the charging and discharging elements under control of the microcomputer. The method of claim 4, wherein The microcomputer turns off the charging device or the discharge device through the analog front end AFE when the voltage value of the battery cell is equal to or greater than the overcharge level voltage set therein or below the overdischarge voltage. And the fuse is blown by turning on the control switch. The method of claim 3, wherein The analog front end and the microcomputer are integrated circuits. The method of claim 5, When the voltage of the battery cell received through the microcomputer to the external system is above the overcharge level voltage or below the overdischarge level voltage set in the external system, the system supplies a control signal through the control pin to A protection circuit for a battery pack, characterized in that the fuse is blown by turning on a control switch. The method of claim 7, wherein The overcharge level voltage set in the external system is greater than the overcharge level voltage set in the microcomputer. The method of claim 7, wherein The overdischarge level voltage set in the external system is smaller than the overdischarge level voltage set in the microcomputer. The method of claim 4, wherein When the voltage of the battery cell is not received from the microcomputer by the controller of the external system more than a specific number of times, the controller transmits a control signal corresponding to the gate driver of the external system and outputs the high signal outputted from the gate driver. high) signal is transmitted to the gate terminal of the control switch through the control pin, and the fuse is blown by turning on the control switch. The method of claim 10, And the control switch is an NMOS field effect transistor. The method of claim 1, And the microcomputer connects a clock line and a data line between the SMBUS terminal of the external terminal to communicate with the external system. The method of claim 1, The external system is a protection circuit of a battery pack, characterized in that the portable electronic device including a charger. The method of claim 1, And a sensor resistor connected in series to a large current path between the battery cell and the external terminal to sense current of the battery cell. The method of claim 13, When the overcurrent is detected from the sensor resistor, the microcomputer connected to the sensor resistor transfers overcurrent information to the external system through the SMBUS terminal of the external terminal and supplies a control signal according to the overcurrent detection to the analog front end. A battery pack protection circuit. The method of claim 1, The protection circuit of the battery pack, characterized in that the reverse current prevention diode is further formed on the control pin.

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