KR20050057693A - Charge-discharge protect circuit - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge / discharge protection circuit, and implements charging and discharging control of a secondary battery as a single switching element to reduce switching loss and manufacturing cost. An overvoltage detection circuit, a discharge overvoltage detection circuit connected in parallel to the battery to detect discharge overvoltage, a charge overcurrent detection circuit connected in parallel to the battery to detect charge overcurrent, and a discharge overcurrent connected in parallel to the battery A discharge over-current detection circuit for detecting a control circuit, a control circuit for outputting a predetermined control signal for protecting the battery when detecting a charge, discharge over-voltage or over-current from the detection circuits, and a control circuit of the control circuit A switch element that is turned off by a signal so that the charging and discharging operation of the battery is stopped Also characterized in that consisting of W.

Description

Charge-discharge protect circuit

The present invention relates to a charge and discharge protection circuit, and more specifically, to a charge and discharge protection circuit that can reduce the switching loss and manufacturing cost by implementing the charge and discharge protection function of the secondary battery as a single switch element. .

In general, since a secondary battery (hereinafter, abbreviated as a battery) has a very high energy density, a protection circuit is built in to protect a user from overcharge or overdischarge. Referring to FIG. 1, a conventional charge / discharge protection circuit 100 ′ is shown, which is connected in parallel with the battery 101 ′ to detect charge and discharge voltages and currents during charge and discharge operations. .

That is, the conventional charge / discharge protection circuit 100 'is connected to the battery 101' in parallel to the charge overvoltage detection circuit 110 'for detecting the charge overvoltage and the discharge overvoltage detection circuit 120' for detecting the discharge overvoltage. A charge overcurrent detection circuit 130 'connected in parallel to the charger 102' (or load 103 ') for detecting charge overcurrent and a discharge overcurrent detection circuit 140' for detecting discharge overcurrent, and the detection circuit A control circuit 150 'which opens a circuit by outputting a predetermined control signal when a signal having a predetermined voltage or a predetermined current or more is detected from the control circuit, and opens the circuit at the time of charge overvoltage or charge overcurrent by the control signal of the control circuit 150'. And a discharge switch 162 'which opens the circuit at the time of discharge overvoltage or discharge overcurrent by the control signal of the control circuit 150'.

Here, the charge switch 161 ′ and the discharge switch 162 ′ are N-channel field effect transistors in which ordinary forward parasitic diodes 161 a ′ and 162 a ′ are formed.

The conventional charge / discharge protection circuit 100 'protects the battery 101' by the following operation.

First, the protection operation of the battery 101 'during charging will be described with the terminal Vout + and the terminal Vout- of the battery 101' connected to the charger 102 '.

The charge overvoltage detection circuit 110 ′ or the charge overcurrent detection circuit 130 ′ detects an overvoltage or an overcurrent of the battery 101 ′ and outputs it to the control circuit 150 ′. Then, the control circuit 150 'outputs a predetermined control signal to the charging switch 161' so that the charging switch 161 'is turned off. Then, the current flowing through the charger 102 ', the terminal Vout +, the battery 101', the discharge switch 162 ', the charging switch 161' and the terminal Vout- is cut off to stop the charging operation.

In this state, when the battery 101 'is connected to the load 103', the forward diode of the battery 101 ', the terminal Vout +, the load 103', the terminal Vout- and the charge switch 161 '(off state) ( 161a '), a current flows through the discharge switch 162' (on state), and thus normal discharge is performed.

Next, the battery 101 'protection operation during discharge will be described in the state where the battery 101' is connected to the load 103 '.

The discharge overvoltage detection circuit 120 'or the discharge overcurrent detection circuit 140' detects the overvoltage and overcurrent of the battery 101 'and outputs it to the control circuit 150'. Then, the control circuit 150 'outputs a predetermined control signal to the discharge switch 162' so that the discharge switch 162 'is turned off. Then, the current flowing to the load 103 ', the terminal Vout-, the charge switch 161', the discharge switch 162 ', the battery 101', and the terminal Vout + is cut off, and the discharge operation is stopped.

In this state, when the battery 101 'is connected to the charger 102', the forward diode 162a 'of the charger 102', the terminal Vout +, the battery 101 ', and the discharge switch 162' (off state) The current flows through the charge switch 161 '(on state) and the terminal Vout-, whereby normal charging is performed.

Of course, during normal charging and discharging, the control circuit 150 'turns on both the charging switch 161' and the discharge switch 162 ', so that current flows through the charging switch 161' and the discharge switch ( 162 ').

However, the conventional charge / discharge protection circuit has a problem in that the power consumption ratio is high and the usable time of the battery is shortened because the switches for controlling the charging operation and the discharge operation are respectively formed.

In addition, the volume of the entire circuit is increased due to the two switches, thereby increasing the volume occupied by the battery, thereby reducing the capacity of the battery.

In addition, due to the two switches, the manufacturing process is complicated, and the manufacturing cost of the battery also increases.

The present invention is to overcome the above-mentioned conventional problems, an object of the present invention is to provide a charge and discharge protection circuit that can reduce the switching loss and manufacturing cost by implementing the charge, discharge protection function of the battery as a single switch element It is.

In order to achieve the above object, the charge-discharge protection circuit according to the present invention includes a charge overvoltage detection circuit connected to the battery in parallel to detect the charge overvoltage, and a discharge overvoltage detection circuit connected to the battery in parallel to detect the discharge overvoltage; A charge overcurrent detection circuit connected in parallel to the battery to detect charge overcurrent, a discharge overcurrent detection circuit connected in parallel to the battery to detect discharge overcurrent, and a charge, discharge overvoltage or overcurrent detection from the detection circuits; A control circuit for outputting a predetermined control signal for protecting the battery, and one switch element connected in series with the battery and turned off so that charging and discharging operations of the battery are stopped by a control signal of the control circuit. Characterized in that the made up.

The switch element is an N-channel field effect transistor having a gate, a source, and a drain terminal, and the N-channel field effect transistor has a first parasitic diode and a second parasitic diode connected in a reverse direction between a source and a drain terminal. The common output terminal may be further formed between the first parasitic diode and the second parasitic diode.

A bypass line is further formed in parallel with the switch element, and a first switch and a second switch are connected in series with the bypass line, and between the first switch and the second switch of the N-channel field effect transistor. The common output terminal is connected, and the first and second switches may be turned on or off by a control signal of the control circuit.

When the control circuit detects charging overvoltage or overcurrent, the switching device is turned off to stop the charging operation. At the same time, the control circuit turns on the first switch so that when the load is connected to the outside of the battery, the discharge current is caused by the positive electrode, the load, and the first switch of the battery. In this case, the first parasitic diode is transferred to the negative electrode of the battery.

After the discharge current starts to flow, the control circuit turns off the first switch and applies a predetermined voltage to the gate terminal of the switch element when it is determined to be normal discharge by the overvoltage detection circuit and the overcurrent detection circuit. By being turned on, a discharge current is allowed to pass through the switch element.

The control circuit turns off the switch element when the discharge overvoltage or overcurrent is detected to stop the discharge operation, and simultaneously turns on the second switch so that when the charger is connected to the outside of the battery, the charging current is generated from the charger, the positive electrode of the battery, and the negative electrode of the battery. The second switch and the second parasitic diode are delivered to the charger.

After the charging current starts to flow, the control circuit turns off the second switch and applies a predetermined voltage to the gate terminal of the switch element when it is determined that the charging is normal by the overvoltage detection circuit and the overcurrent detection circuit. By turning on, charge current passes through the switch element.

The charge overvoltage detection circuit, the discharge overvoltage detection circuit, the charge overcurrent detection circuit, the discharge overcurrent detection circuit, the control circuit, the bypass line, the first switch and the second switch are integrally formed in one integrated circuit. It can be wired outside the integrated circuit.

In addition, the charge and discharge protection circuit according to another embodiment of the present invention to achieve the above object may be a P-channel field effect transistor having the switch element having a gate, a source and a drain terminal, the P-channel field effect The transistor may further be connected with a reverse Schottky diode between the source and the gate terminal.

A first bypass line and a second bypass line are formed in parallel with the switch element, a first switch controlled by the control circuit and a first diode in a forward direction are connected in series with the first bypass line; A second switch controlled by the control circuit and a second diode in the forward direction may be connected to the second bypass line in series.

When the control circuit detects charging overvoltage or overcurrent, the control circuit is switched off to stop the charging operation, and the first switch is turned on, so that when the load is connected to the outside of the battery, the discharge current is caused by the positive electrode, the first switch, and the first switch of the battery. Through the diode and the load to be delivered to the negative electrode of the battery.

After the discharge current starts to flow, the control circuit turns off the first switch and applies a predetermined voltage to the gate terminal of the switch element when it is determined to be normal discharge by the overvoltage detection circuit and the overcurrent detection circuit. By being turned on, a discharge current is allowed to pass through the switch element.

When the control circuit detects a discharge overvoltage or an overcurrent, the control circuit is turned off to stop the discharge operation and at the same time, the second switch is turned on so that when the charger is connected to the outside of the battery, the charging current is stored in the charger, the second switch, the second diode, It is to be delivered to the charger through the battery positive electrode and the battery negative electrode.

After the charging current starts to flow, the control circuit turns off the second switch and applies a predetermined voltage to the gate terminal of the switch element when it is determined that the charging is normal by the overvoltage detection circuit and the overcurrent detection circuit. By turning on, charge current passes through the switch element.

The charge overvoltage detection circuit, the discharge overvoltage detection circuit, the charge overcurrent detection circuit, the discharge overcurrent detection circuit, the control circuit, the first bypass line, the second bypass line, the first switch, the first diode, the second switch, and the second The diode may be integrated in one integrated circuit, and the switch element may be connected to the outside of the integrated circuit.

As described above, the charge / discharge protection circuit according to the present invention can minimize power consumption by using only one N-channel type or P-channel type field effect transistor as the charge / discharge control switch element.

In addition, it is possible to extend the usable time of the battery due to the power consumption rate decrease as described above.

In addition, one switch element results in a smaller overall circuit volume.

Finally, one switch element can simplify the manufacturing process and reduce the manufacturing cost of the battery.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that those skilled in the art may easily implement the present invention.

2, a charge and discharge protection circuit according to an embodiment of the present invention is shown.

As shown, the charge / discharge protection circuit 100 according to the present invention includes a charge overvoltage detection circuit 110, a discharge overvoltage detection circuit 120, a charge overcurrent detection circuit 130, a discharge overcurrent detection circuit 140, and a control circuit. 150 and one switch element 160.

Here, the charge overvoltage detection circuit 110 is connected to the battery 101 in parallel to detect the charge overvoltage, the discharge overvoltage detection circuit 120 is connected in parallel to the battery 101 to detect the discharge overvoltage . In addition, the charging overcurrent detection circuit 130 is connected to the battery 101 in parallel to detect the charging overcurrent, the discharge overcurrent detection circuit 140 is connected in parallel to the battery 101 to detect the discharge overcurrent do. In addition, the control circuit 150 outputs a predetermined control signal to protect the battery 101 when the charge, discharge, overvoltage or overcurrent is detected from the detection circuits, and the configuration and operation thereof are the same as before.

On the other hand, the charge and discharge protection circuit 100 according to the present invention is connected in series to the battery 101, when the battery 101 is abnormally charged, discharged by the control signal of the control circuit 150 It includes one switch element 160 that is turned off. Of course, the switch element 160 maintains an on state during normal charging and discharging.

The switch element 160 may be an N-channel field effect transistor having a gate, a source, and a drain terminal. In addition, in the switch element 160, a first parasitic diode 161 and a second parasitic diode 162 which are opposite to each other between a source and a drain terminal are connected in series. In addition, the switch device 160 has a common output terminal 163 formed between the first parasitic diode 161 and the second parasitic diode 162. For example, when the high voltage is applied to the gate, the switch device 160 flows from the drain to the source or from the source to the drain. Of course, the switch element 160 may not flow when a low voltage is applied to the gate, and may also be sourced at the drain through the first parasitic diode 161 and the second parasitic diode 162 connected in series. No charge or discharge current can flow from the furnace or source to drain.

Meanwhile, in the charge / discharge protection circuit 100 according to the present invention, a bypass line 170 is further formed in parallel with the switch element 160. That is, the bypass line 170 is further formed in the terminal VSS and the terminal V- in the figure. The bypass line 170 is a passage through which charge and discharge current flows for a while when the switch element 160 is turned off. Detailed description thereof will be described later.

In addition, the bypass line 170 is connected to the first switch 171 and the second switch 172 in series with each other. The first switch 171 and the second switch 172 is determined on or off by the control signal of the control circuit 150. For example, the first and second switches 171 and 172 may be field effect transistors whose on and off are determined according to a voltage applied to a gate, but the present invention is not limited thereto.

In addition, the common output terminal 163 of the switch element 160 may be connected between the first switch 171 and the second switch 172. That is, as shown in the drawing, the common output terminal 163 of the switch element 160 may be connected to the terminal Vbody, and the terminal Vbody is connected between the first switch 171 and the second switch 172.

Lastly, the charge / discharge protection circuit 100 according to the present invention includes the charge overvoltage detection circuit 110, the discharge overvoltage detection circuit 120, the charge overcurrent detection circuit 130, the discharge overcurrent detection circuit 140, and the control circuit. The 150, the bypass line 170, the first switch 171, and the second switch 172 are formed by being integrated in one integrated circuit (IC), and the one switch element 160 is formed in the integrated circuit. (IC) can be wired outside. Of course, the one switch element 160 may also be integrated in an integrated circuit (IC), but the present invention is not limited thereto.

Referring to FIG. 3A, the flow of the discharge current by the connection of the load 103 when the charge is stopped in FIG. 2 is illustrated. Referring to FIG. 3B, the flow of the charge current by the connection of the charger 102 is shown when the discharge is stopped. It is.

First, referring to FIG. 3A, after the switch element 160 is turned off due to the charging overvoltage or the charging overcurrent, the discharge current flow of the battery 101 by connecting the load 103 will be described.

Of course, when the charging overvoltage detection circuit 110 or the charging overcurrent detection circuit 130 detects the overvoltage or the overcurrent during the charging of the battery 101 as in the prior art, it outputs a predetermined electrical signal to the control circuit 150, For example, the control circuit 150 applies a low voltage to the gate of the switch element 160 to turn off the switch element 160. That is, the current flow from the source to the drain is interrupted to stop charging.

In this case, the control circuit 150 outputs a predetermined signal to the first switch 171 formed on the bypass line 170 so that the first switch 171 is turned on. Of course, in the normal charging and discharging operation, the first and second switches are all turned off. In addition, even if the first switch 171 is turned on as described above, since the second switch 172 and the switch element 160 are both in an off state, charging current does not flow from the terminal Vss to the terminal V-.

In this state, when the load 103 is connected to the terminal Vout + and the terminal Vout- of the charge / discharge protection circuit 100, a discharge current flows from the battery 101. That is, the discharge current reaches the cathode of the battery 101 through the anode of the battery 101, the load 103, the first switch 171, and the first parasitic diode 161. Of course, discharge current flows from terminal V- to terminal VSS.

When the discharge current starts to flow in this way, the discharge voltage and the current are detected by the overvoltage detection circuits 110 and 120 and the overcurrent detection circuits 130 and 140, and the detected result is transferred to the control circuit 150 as it is. Subsequently, when both the voltage and the current are normal, the control circuit 150 turns on the switch element 160 by applying a high voltage to the gate of the switch element 160, for example. For example, the first switch 171 is turned off by applying a low voltage. Then, the discharge current flows directly from the load 103 to the cathode of the battery 101 via the drain and the source of the switch element 160, thereby continuing the normal discharge operation.

Next, referring to FIG. 3B, after the switch element 160 is turned off due to the discharge overvoltage or the discharge overcurrent, the charging current flow of the battery 101 by connecting the charger 102 will be described.

Of course, when the discharge overvoltage detection circuit 120 or the discharge overcurrent detection circuit 140 detects an overvoltage or an overcurrent during discharge, it outputs a predetermined electrical signal to the control circuit 150, and thus the control circuit 150. For example, the low voltage is applied to the gate of the switch element 160 to cause the switch element 160 to be turned off. That is, the discharge current is stopped by blocking the flow of discharge current from the drain to the source.

In this case, the control circuit 150 outputs a predetermined signal to the second switch 172 formed on the bypass line 170 so that the second switch 172 is turned on. Of course, in the normal charging and discharging operation, the first and second switches 171 and 172 are all turned off. In addition, even when the second switch 172 is turned on as described above, since the first switch 171 and the switch element 160 are both in an off state, a discharge current does not flow from the terminal V- to the terminal Vss.

In this state, when the charger 102 is connected to the terminal Vout + and the terminal Vout- of the charge / discharge protection circuit 100, a charging current flows from the charger 102. That is, the charging current reaches the charger 102 through the charger 102, the positive electrode of the battery 101, the negative electrode of the battery 101, the second switch 172, and the second parasitic diode 162. Of course, charging current flows from terminal VSS to terminal V-.

When the charging current starts to flow in this way, the voltage and current are detected by the overvoltage detection circuits 110 and 120 and the overcurrent detection circuits 130 and 140, and the detected result is transferred to the control circuit 150 as it is.

 Subsequently, when both of the charging voltage and the charging current are normal, the control circuit 150 turns on the switch element 160 by applying a high voltage, for example, to the gate of the switch element 160, and the second switch 172. ), The second switch 172 is turned off by applying a low voltage, for example. Then, the charging current flows directly from the cathode of the battery 101 to the charger 102 via the source and the drain of the switch element 160, thereby continuing the normal charging operation.

Referring to FIG. 4, a charge / discharge protection circuit 200 according to another embodiment of the present invention is shown.

As illustrated, the charge / discharge protection circuit 200 according to the present invention includes a charge overvoltage detection circuit 210, a discharge overvoltage detection circuit 220, a charge overcurrent detection circuit 230, a discharge overcurrent detection circuit 240, and a control circuit. 250 and one switch element 260.

Here, the charging overvoltage detection circuit 210 is connected to the battery 201 in parallel to detect the charging overvoltage, and the discharge overvoltage detection circuit 220 is connected to the battery 201 in parallel to detect the discharge overvoltage. . In addition, the charging overcurrent detection circuit 230 is connected to the battery 201 in parallel to detect the charging overcurrent, the discharge overcurrent detection circuit 240 is connected in parallel to the battery 201 to detect the discharge overcurrent do. In addition, the control circuit 250 outputs a predetermined control signal to protect the battery 201 when detecting the charge, discharge, overvoltage or overcurrent from the detection circuits, the configuration and operation of the control circuit 250 and one embodiment of the present invention same.

On the other hand, the charge and discharge protection circuit 200 of another embodiment of the present invention is connected in series to the battery 201, when the battery 201 is abnormally charged, discharged, the control signal of the control circuit 250 One switch element 260 is turned off by. Of course, the switch element 260 maintains an on state during normal charging and discharging.

The switch element 260 may be a P-channel field effect transistor having a gate, a source, and a drain terminal. In addition, the switch element 260 has a Schottky diode 261 reversely connected between a source and a gate terminal.

Here, the reason for using the Schottky diode 261 will be briefly described. Field effect transistors, especially MOSFETs, have a PN junction between the source and the body, and the drain and the body, so that parasitic diodes are formed naturally. When using a MOSFET, the source and the body are connected together, so there is no parasitic diode between the source and the body, but there is a parasitic diode between the drain and the body (source). P-channel MOSFETs do not have parasitic diodes between the source and the body. However, parasitic diodes are formed between the drain and the body, that is, between the drain and the source, and current flows even when the MOSFET is turned off. Therefore, in the present invention, in order to suppress this phenomenon, the Schottky diode 261 is connected to the source and the body die to prevent the flow of current by the parasitic diode.

Subsequently, when the high voltage is applied to the gate, such a switch element 260 may flow from a drain to a source or from a source to a drain. Of course, when the low voltage is applied to the gate, the switch element 260 cannot flow current.

Meanwhile, in the charge / discharge protection circuit according to the present invention, the first bypass line 270 and the second bypass line 280 are further formed in parallel with the switch element 260. That is, first and second bypass lines 270 and 280 are further formed in the terminal VDD and the terminal VM in the figure. The first and second bypass lines 270 and 280 become passages for charging and discharging currents for a while when the switch element 260 is turned off. Detailed description thereof will be described later.

In addition, a first switch 271 and a first diode 272 forward in this direction are connected to the first bypass line 270 in series. The first switch 271 is determined on and off by a control signal of the control circuit 250. For example, the first switch 271 may be a field effect transistor whose on and off are determined according to a voltage applied to the gate, but the present invention is not limited thereto.

In addition, a second switch 281 and a second diode 282 forward to the second bypass line 280 are connected in series. The second switch 281 is turned on or off by a control signal of the control circuit 250. Similarly, the second switch 281 may also be a field effect transistor whose on and off are determined according to the voltage applied to the gate, but the present invention is not limited thereto.

Finally, the charge / discharge protection circuit 200 according to the present invention includes the charge overvoltage detection circuit 210, the discharge overvoltage detection circuit 220, the charge overcurrent detection circuit 230, the discharge overcurrent detection circuit 240, and the control circuit. The first and second bypass lines 270 and 280, the first and second switches 271 and 281, and the first and second diodes 272 and 282 are integrally formed in one integrated circuit (IC). The device 260 may be connected outside the integrated circuit IC. Of course, the one switch element 260 may also be integrated in an integrated circuit (IC), but the present invention is not limited thereto.

Referring to FIG. 5A, in FIG. 4, the flow of the discharge current by the connection of the load 203 when the charging is stopped is illustrated. Referring to FIG. 5B, the flow of the charge current by the connection of the charger 202 when the discharge is stopped is illustrated. It is.

First, referring to FIG. 5A, after the switch element 260 is turned off due to the charging overvoltage or the charging overcurrent, the discharge current flow of the battery 201 by connecting the load 203 will be described.

Of course, when the charging overvoltage detection circuit 210 or the charging overcurrent detection circuit 230 detects an overvoltage or an overcurrent during charging, a predetermined electrical signal is output to the control circuit 250, and thus the control circuit 250. For example, the low voltage is applied to the gate of the switch element 260 to cause the switch element 260 to be turned off. That is, the charging current is interrupted from the drain to the source to stop charging.

In this case, the control circuit 250 outputs a predetermined signal to the first switch 271 formed in the first bypass line 270 so that the first switch 271 is turned on. Of course, in the normal charging and discharging operation, the first and second switches 271 and 281 of the first and second bypass lines 270 and 280 are all turned off. In addition, even when the first switch 271 is turned on as described above, since the second switch 281 and the switch element 260 are both turned off, charging current does not flow from the terminal VM to the terminal VDD.

In this state, when the load 203 is connected to the terminal Vout + and the terminal Vout- of the charge / discharge protection circuit 200, a discharge current flows from the battery 201. That is, the discharge current reaches the cathode of the battery 201 through the positive electrode of the battery 201, the first switch 271 of the first bypass line 270, the first diode 272, and the load 203.

When the discharge current starts to flow in this way, the voltage and current are detected by the overvoltage detection circuits 210 and 220 and the overcurrent detection circuits 230 and 240, and the detected result is transferred to the control circuit 250 as it is. Subsequently, when both the voltage and the current are normal, the control circuit 250 turns on the switch element 260 by applying a high voltage, for example, to the gate of the switch element 260, and applies the first switch 271 to the first switch 271. For example, the first switch 271 is turned off by applying a low voltage. Then, the discharge current flows directly to the cathode of the battery 201 via the anode of the battery 201, the switch element 260, and the load 203, thereby continuing the normal discharge operation.

Next, referring to FIG. 5B, after the switch element 260 is turned off due to the discharge overvoltage or the discharge overcurrent, the charging current flow of the battery 201 by connecting the charger 202 will be described.

Of course, when the discharge overvoltage detection circuit 220 or the discharge overcurrent detection circuit 240 detects an overvoltage or an overcurrent during discharge, it outputs a predetermined electrical signal to the control circuit 250, and thus the control circuit 250. For example, the low voltage is applied to the gate of the switch element 260 to cause the switch element 260 to be turned off. That is, the current flow from the source to the drain is interrupted to stop the discharge.

In this case, the control circuit 250 outputs a predetermined signal to the second switch 281 formed in the second bypass line 280 so that the second switch 281 is turned on. Of course, in the normal charging and discharging operation, the first and second switches 271 and 281 are all turned off. In addition, even when the second switch 281 is turned on as described above, since the first switch 271 and the switch element 260 are both in an off state, a discharge current does not flow from the terminal VDD to the terminal VM.

In this state, when the charger 202 is connected to the terminal Vout + and the terminal Vout- of the charge / discharge protection circuit, the charging current flows from the charger 202. That is, the charging current is transmitted through the charger 202, the second switch 281 of the second bypass line 280, the second diode 282, the positive electrode of the battery 201, and the negative electrode of the battery 201. 202).

When the charging current starts to flow in this way, the voltage and current are detected by the overvoltage detection circuits 210 and 220 and the overcurrent detection circuits 230 and 240, and the detected result is transferred to the control circuit 250 as it is.

 Subsequently, when both the voltage and the current are normal, the control circuit 250 turns on the switch element 260 by applying a high voltage, for example, to the gate of the switch element 260, and applies the second switch 281 to the second switch 281. For example, the second switch 281 is turned off by applying a low voltage. Then, the charging current flows directly from the charger 202 to the positive electrode of the battery 201 via the drain and the source of the switch element 260, thereby continuing the normal charging operation.

As described above, the charge / discharge protection circuit according to the present invention has the effect of minimizing the power consumption rate by using only one N-channel type or P-channel type field effect transistor as the charge / discharge control switch element.

In addition, there is an effect that can extend the usable time of the battery due to the power consumption rate as described above.

In addition, there is an effect that the total circuit volume is also reduced by one switch element.

Finally, the single switch element can simplify the manufacturing process and reduce the manufacturing cost of the battery.

What has been described above is only one embodiment for implementing the charge / discharge protection circuit according to the present invention, and the present invention is not limited to the above-described embodiment, and as claimed in the following claims, the gist of the present invention Without departing from the technical spirit of the present invention to the extent that any person of ordinary skill in the art to which the present invention pertains various modifications can be made.

1 is a circuit block diagram showing a conventional charge and discharge protection circuit.

2 is a circuit block diagram illustrating a charge / discharge protection circuit according to an embodiment of the present invention.

FIG. 3A illustrates the flow of discharge current by the load connection when stopping the charge in FIG. 2, and FIG. 3B illustrates the flow of charge current by the charger connection when the discharge stops.

4 is a circuit block diagram illustrating a charge and discharge protection circuit according to another embodiment of the present invention.

FIG. 5A illustrates the flow of the discharge current by the load connection when stopping the charge in FIG. 4, and FIG. 5B illustrates the flow of the charge current by the charger connection when the discharge stops.

<Description of Symbols for Main Parts of Drawings>

101; Battery 102; charger

103; Load 110; Charge overvoltage detection circuit

120; Discharge overvoltage detection circuit 130; Charge overcurrent detection circuit

140; A discharge overcurrent detection circuit 150; Control circuit

160; Switch element 161; First parasitic diode

162; Second parasitic diode 170; Bypass line

171; First switch 172; Second switch

261; Schottky Diode 270; 1 bypass line

271; First switch 272; First diode

280; Second bypass line 281; Second switch

282; Second diode

Claims (15)

A charge overvoltage detection circuit connected to the battery in parallel and detecting a charge overvoltage; A discharge overvoltage detection circuit connected to the battery in parallel to detect a discharge overvoltage; A charge overcurrent detection circuit connected to the battery in parallel to detect a charge overcurrent; A discharge overcurrent detection circuit connected to the battery in parallel to detect a discharge overcurrent; A control circuit for outputting a predetermined control signal for protecting the battery when detecting a charge, discharge overvoltage or overcurrent from the detection circuits; And, And a switch element connected to the battery in series and turned off by a control signal of the control circuit so that the charging and discharging operation of the battery is stopped. The first parasitic diode and the second parasitic field effect transistor of claim 1, wherein the switch element is an N-channel field effect transistor having a gate, a source, and a drain terminal. A parasitic diode is connected in series, and a charge / discharge protection circuit further comprises a common output terminal formed between the first parasitic diode and the second parasitic diode. The method of claim 2, wherein a bypass line is further formed in parallel with the switch element, and a first switch and a second switch are connected to the bypass line in series, and between the first switch and the second switch. Charge and discharge protection circuit, characterized in that the common output terminal of the N-channel field effect transistor is connected, the first and second switches are turned on, off by the control signal of the control circuit. The method of claim 3, wherein the control circuit turns off the switch element when the charging overvoltage or overcurrent is detected to stop the charging operation, and at the same time by turning on the first switch, when the load is connected to the outside of the battery discharge current is positive Charge and discharge protection circuit characterized in that the transfer through the load, the first switch, the first parasitic diode to the cathode of the battery. 5. The control circuit according to claim 4, wherein the control circuit turns off the first switch and at the same time a predetermined voltage at the gate terminal of the switch element when it is determined that the normal voltage is discharged by the overvoltage detection circuit and the overcurrent detection circuit after the discharge current starts to flow. Charging and discharging protection circuitry, characterized in that the switch element is turned on so that a discharge current passes through the switch element. 4. The control circuit of claim 3, wherein the control circuit turns off the switch element when the discharge overvoltage or overcurrent is detected to stop the discharge operation, and turns on the second switch so that the charging current is generated when the charger is connected to the outside of the battery. Charge and discharge protection circuit, characterized in that to be delivered to the charger through the positive electrode, the negative electrode of the battery, the second switch and the second parasitic diode. 7. The control circuit of claim 6, wherein the control circuit turns off the second switch and at a predetermined voltage at the gate terminal of the switch element when it is determined that the charging is normal by the overvoltage detecting circuit and the overcurrent detecting circuit after the charging current starts to flow. Charging and discharging protection circuitry, characterized in that by applying a so that the switch element is turned on, the charging current passes through the switch element. The method of claim 3, wherein the charge overvoltage detection circuit, the discharge overvoltage detection circuit, the charge overcurrent detection circuit, the discharge overcurrent detection circuit, the control circuit, the bypass line, the first switch, and the second switch are integrally formed in one integrated circuit. And the switch element is connected to the outside of the integrated circuit. 2. The switch element of claim 1, wherein the switch element is a P-channel field effect transistor having a gate, a source, and a drain terminal, and the P-channel field effect transistor is further connected with a Schottky diode in a reverse direction between a source and a gate terminal. Charge and discharge protection circuit. The method of claim 9, wherein the first bypass line and the second bypass line is formed in parallel with the switch element, A first switch controlled by the control circuit and a first diode in a forward direction are connected to the first bypass line in series. A charge / discharge protection circuit according to claim 2, wherein a second switch controlled by the control circuit and a second forward diode are connected in series to the second bypass line. The method of claim 10, wherein the control circuit is switched off when the charge overvoltage or overcurrent is detected to stop the charging operation, and at the same time by turning on the first switch, when the load is connected to the outside of the battery discharge current is the positive electrode of the battery, Charge and discharge protection circuit, characterized in that to be delivered to the negative electrode of the battery through the first switch, the first diode and the load. 12. The control circuit of claim 11, wherein the control circuit turns off the first switch and a predetermined voltage at the gate terminal of the switch element when it is determined that the discharge is normal by the overvoltage detection circuit and the overcurrent detection circuit after the discharge current starts to flow. Charging and discharging protection circuitry, characterized in that the switch element is turned on so that a discharge current passes through the switch element. The method of claim 8, wherein the control circuit is switched off when the discharge overvoltage or overcurrent is detected to stop the discharge operation, and at the same time by turning on the second switch, when the charger is connected to the outside of the battery charge current, Charge and discharge protection circuit characterized in that the transfer to the charger through the switch, the second diode, the positive electrode of the battery and the negative electrode of the battery. 14. The control circuit of claim 13, wherein the control circuit turns off the second switch and at a predetermined voltage at the gate terminal of the switch element when it is determined that the charging is normal by the overvoltage detecting circuit and the overcurrent detecting circuit after the charging current starts to flow. Charging and discharging protection circuitry, characterized in that by applying a so that the switch element is turned on, the charging current passes through the switch element. The method of claim 8, wherein the charge overvoltage detection circuit, the discharge overvoltage detection circuit, the charge overcurrent detection circuit, the discharge overcurrent detection circuit, the control circuit, the first bypass line, the second bypass line, the first switch, the first diode, The second switch and the second diode are integrally formed in one integrated circuit, and the switch element is connected to the outside of the integrated circuit, the charge and discharge protection circuit.