KR100352399B1 - Charge/discharge control circuit and chargeable electric power source apparatus - Google Patents

Abstract

According to the present invention, a charging / discharging control circuit of a power supply device having an extended life is provided. A voltage dividing circuit, an overcharge voltage detecting circuit, and a control circuit are connected in parallel to the secondary battery which is a power source. The control circuit detects the state of the secondary battery in the overcharge / over-discharge voltage detecting circuit, and outputs a signal Vs for controlling the charging of the external equipment and the charging by the external power source, and controls the switching element serially installed in the voltage dividing circuit, Thereby reducing the current flowing through the dividing circuit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging / discharging control circuit and a chargeable electric power source apparatus,

The present invention relates to a charge / discharge control circuit capable of controlling charge / discharge of a secondary battery and a chargeable power supply device using the charge / discharge control circuit.

A conventional power supply apparatus having a secondary battery or a battery is shown in Fig. Such a device is described in Japanese Patent Application Laid-Open No. 4-75430 (name: rechargeable power supply device). More specifically, the secondary battery 101 is connected to the external terminal -V _o or + V _o through the switching circuit 103 and is connected in parallel with the secondary battery 101 to the charge / discharge control circuit 102 are connected. The charge / discharge control circuit 102 has a function of detecting the voltage of the secondary battery 101. [ When the voltage of the secondary battery 101 becomes an overcharged state (when the voltage becomes higher than the predetermined value) or when the overdischarged state (when the voltage becomes lower than the predetermined value), a signal for turning off the switching circuit 103 is turned off / Discharge control circuit 102 as shown in Fig. Therefore, in the overcharged state, the switching operation of the secondary battery 101 is stopped by the primary power source connected to the external terminals -V _o and + V _o by turning off the switching circuit 103. In the overcharged state, since the switching circuit 103 is turned off, supply of energy to the load (for example, a mobile phone using a secondary battery) is interrupted. That is, since the charging / discharging control circuit 102 controls the switching circuit 103 constituted between the secondary battery 101 and the external terminal, a voltage higher than necessary is charged to the booty secondary battery 101 with the external terminal And at the same time, the energy of the secondary battery 101 is supplied to the load connected to the external terminal, thereby preventing the overcharging capacity of the secondary battery from deteriorating.

30 is a block diagram of a conventional rechargeable power supply device. 30, the secondary battery 101 is connected to the external terminal -V _o or + V _o through the switching circuit 103 and the current sensing resistor 104. Further, charge / discharge control circuit 102 is connected in parallel to secondary battery 101 and overcurrent detection circuit 105. The charge / discharge control circuit 102 has a function of detecting the voltage of the secondary battery 101. [ When the voltage of the secondary battery 101 is in the overcharge or overdischarge state, a signal for turning off the switching circuit 103 from the charge / discharge control circuit 102 is outputted. The comparator 21 compares the voltage of the current sensing resistor 104 with the voltage of the reference voltage circuit 106 in case an abnormality occurs in the load due to the overcurrent.

It is assumed that V _REF [V] is the voltage value of the reference voltage circuit 106, R [OMEGA] is the resistance value of the current sense resistor 104 (in this case, the ON resistance of the switching circuit 103 is much larger than R ), And I [A] is a current, the current I [A] can be expressed by the following equation (1).

In this case, when the output of the comparator is changed from "high" to "low", the transistor 107 is turned off, the capacitor 109 is charged by the constant current source 108, Quot; low " to " high " and the switching circuit 103 is turned off. That is, the constant current source 108, the capacitor 109, and the transistor 107 constitute a time delay circuit for delaying the output of the comparator 302. The delayed signal in this time delay circuit is input to the comparator 302 together with the signal of the reference voltage circuit 106. [ Thus, in the comparator 302, the two signals are compared and the comparison output turns off the switching circuit 103.

FIG. 37 shows a conventional power supply device equipped with a secondary battery and a charging / discharging control circuit. Such a device is known from JP-A-4-75430 (name: rechargeable power supply device). More specifically, the secondary battery 24 and the charge / discharge control IC 374 are connected to the external terminals + V and -V through the switching transistors 372 and 373, respectively.

For example, when the voltage of the secondary battery 24 exceeds the overcharge voltage by the charging power source connected to the external terminals (+ V, -V), the switching transistor 372 changes from the "on" state to the " The charging operation performed on the secondary battery 24 from the external terminals is stopped. On the other hand, when a portable device such as a video camera is connected to an external terminal and a charging voltage is supplied from the secondary battery to the portable equipment, if the voltage of the secondary battery falls below the over-discharge voltage, the switching transistor 373 becomes " Quot; off " state to the " off " state. One of the transistors 372 and 373 functions as a transistor and the other functions as a diode. The functions of the transistor and the diode are alternately performed in accordance with charging or discharging conditions. The substrate of each transistor is connected to a source so as to perform a function as a diode.

2 is a conventional charge / discharge control circuit diagram, which has a drawback of shortening the lifetime of the secondary battery, which is an energy supply source, because of high power consumption. As a result, the period of use of the equipment driven by the secondary battery is shortened. Further, even when the supply of energy from the secondary battery to the external equipment is interrupted by the switching circuit in a state where the overcharge state is caused to occur and the charge capacity of the secondary battery is lowered, the power consumption of the charge / discharge control circuit The deterioration is accelerated and the service life is shortened.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a chargeable power supply device capable of reducing the power consumption of the charge / discharge control circuit, thereby extending the service life of the secondary battery.

The conventional charge / discharge control circuit as shown in Fig. 30 has the following drawbacks. The switching circuit 103 is turned off when the secondary battery is charged in a state where the terminals (-V _o , + V _o ) are connected to the charger and the secondary battery is charged, but the potential between both ends of the secondary battery 101 And the charging state, that is, the switching circuit 103 is turned on to the system. Accordingly, it is judged unstably whether charging is completed or not.

As described above, in the conventional system, when the overcharge state occurs during the charging operation for the secondary battery, the charge / discharge control circuit turns off the switching circuit to control the charging operation for the secondary battery. However, since the charge / discharge control circuit is connected in parallel to the secondary battery, the current consumed during operation is supplied from the secondary battery. As the current is supplied in this way, the voltage in the secondary battery drops and the supply voltage drops to the overcharge detection voltage or lower, whereby the switching circuit is turned on. As a result, the voltage of the secondary battery rises due to the charging operation, the overcharge voltage rises, the voltage of the secondary battery rises according to the operation of the charge / discharge control circuit, and the voltage of the secondary battery rises . Repeating this operation does not lead to an overcharged state. In addition, even when the overdischarged state is released while the overdischarged battery is being charged, the above-described drawbacks exist.

In addition, when the charge / discharge control circuit is initially connected to the secondary battery, if the logic circuit of the switching circuit is not configured, the initial state will become unstable, and even if the voltage value of the secondary battery is normal, State.

The output of the voltage detection circuit or the control circuit becomes unstable when the voltage value becomes lower than the minimum voltage at which the voltage detection circuit in the charge / discharge control circuit or the control circuit is operated due to the over discharge state of the secondary battery. That is, since the voltage of the secondary battery further decreases in the overdischarged state, even if the charging / discharging control circuit attempts to charge the secondary battery using the primary power source, the charging / discharging control circuit can not normally operate the switching circuit. As a result, the charging operation becomes impossible. That is, once the voltage of the secondary battery is lower than the minimum voltage of the charge / discharge control circuit, the charging operation becomes impossible, so that it is impossible to reuse the secondary battery even if it is the secondary battery.

Another problem of the conventional system will be described. When the secondary battery is charged while the charger is connected to both ends of the secondary battery, if the polarities of the charger are connected to the charge / discharge control circuit in reverse to the polarities of the secondary battery (that is, ), The CMOS IC forming the charge / discharge control circuit is latched up, thereby causing an abnormality in the function of the charge / discharge control circuit. As a result, a large current flows through the secondary battery to lower the quality of the battery.

Another problem of the conventional system will be described. When the amount of current flowing from the secondary battery significantly increases due to an abnormality in the load connected to both ends of the secondary battery, the overcurrent detecting circuit turns off the switching circuit 103 or turns off the switching circuit to turn off the secondary The reference voltage value of the charge / discharge control circuit is increased by rapidly increasing the voltage of the battery. As a result, the switching circuit 103 oscillates.

In order to overcome such drawbacks of the conventional system, the object of the present invention is to provide a charge / discharge control circuit that never malfunctions.

In addition, when two secondary batteries are connected in series, the following drawbacks exist. That is, as the lifetime of the two secondary batteries differ from one another, the consumption levels also differ. However, if the voltage total value of the two secondary batteries is maintained at a constant level, there is no problem in use. In the conventional system, it is impossible to monitor the voltage total because each secondary battery voltage is monitored. Although in some cases it is possible to use more batteries, they are designed to no longer use the batteries. As a result, the period of use of the equipment is shortened. Further, if the partially consumed battery is charged in the same manner as the charging method for other normal batteries, this partial consumption is further accelerated and the life of the battery is significantly shortened.

Further, the rechargeable power supply device shown in Fig. 37 has the following drawbacks. In this system, two switching transistors are configured between an external terminal and a secondary battery, and the potential of each substrate is maintained at the potential of the source electrode of the transistor on the external terminal side and the potential of the source electrode of the secondary battery side transistor. Therefore, these transistors are assembled separately from the assembly of the charge / discharge control IC. As a result, it is difficult to make the battery compact and the assembly cost is increased.

It is still another object of the present invention to provide a device having a small size, low manufacturing cost, and high reliability by having a rechargeable battery device and a charge / discharge control circuit for a rechargeable power supply device.

1 is a block diagram of a charge-discharge control circuit according to a first embodiment of the present invention;

2 is a circuit block diagram of a conventional chargeable power supply;

3 is a circuit diagram of a voltage detector;

4 is a block diagram of a charge / discharge control circuit according to another embodiment of the present invention;

5 is a block diagram of a charge / discharge control circuit according to still another embodiment of the present invention.

6 is a circuit diagram of a battery charge / discharge control circuit according to a second embodiment of the present invention.

7 is an error amplifier circuit diagram having a power on / off function.

8 is a circuit diagram of a battery charge / discharge control circuit according to another embodiment of the present invention.

9 is a circuit diagram of a battery charge / discharge control circuit according to another embodiment of the present invention.

10 is a view showing a battery charge / discharge control circuit (voltage detector) according to still another embodiment of the present invention.

11 is a block diagram of a charge-discharge control circuit according to a third embodiment of the present invention;

12 is a buffer circuit diagram.

13 is a block diagram of a charge / discharge control circuit according to a fourth embodiment of the present invention;

14 is a reference voltage circuit diagram;

15 is a block diagram of a charge / discharge control circuit using two secondary batteries.

16 is a reference voltage output circuit for outputting two reference voltages.

17 is a block diagram of a charge / discharge control circuit according to the first embodiment of the second aspect of the present invention.

18 is a signal timing chart of the charge / discharge control circuit according to the first embodiment of the second aspect of the present invention.

FIG. 19 is a block diagram of a charge / discharge control circuit according to a second embodiment of the second aspect of the present invention; FIG.

20 is a delay circuit diagram according to a second embodiment of the second aspect of the present invention;

21 is another delay circuit diagram according to a second embodiment of the second aspect of the present invention;

22 is another delay circuit diagram according to the second embodiment of the second aspect of the present invention;

23 is another delay circuit diagram according to the second embodiment of the second aspect of the present invention;

Figure 24 is a circuit block diagram of a rechargeable power supply device according to a third embodiment of the second aspect of the present invention;

25 is a block diagram of a charge / discharge control circuit according to a third embodiment of the second aspect of the present invention.

26 shows an output of a control circuit according to the invention;

FIG. 27 is a block diagram of a charge / discharge control circuit according to a fourth embodiment of the second aspect of the present invention; FIG.

28 is a reference voltage circuit diagram according to a fourth embodiment of the second aspect of the present invention;

29 is a circuit diagram of a rechargeable power supply device according to a fourth embodiment of the second aspect of the present invention;

30 is a conventional rechargeable circuit diagram;

31 is a circuit diagram of a comparator having a latch function according to the present invention.

32 is a block diagram of a charge / discharge control circuit according to the first embodiment of the third aspect of the present invention;

33 is a block diagram of a charge-discharge control circuit according to a second embodiment of the third aspect of the present invention;

34 is a voltage detector circuit diagram;

35 is a block diagram of a charge-discharge control circuit according to a second embodiment of the third aspect of the present invention;

36 is a block diagram of a charge-discharge control circuit and a chargeable power supply circuit according to a third embodiment of the third aspect of the present invention;

Figure 37 is a block diagram of a conventional chargeable power supply circuit;

38 is a switching circuit diagram of the charge / discharge control circuit according to the third aspect of the present invention.

39 is a sectional view of a transistor using a charge / discharge control circuit according to a third aspect of the present invention.

40 is a plan view of a transistor using the charge / discharge control circuit according to the third aspect of the present invention.

41 is a cross-sectional view of the transistor taken along the line A-A 'in FIG. 35;

42 is a switching circuit diagram of the charge / discharge control circuit according to the third aspect of the present invention.

In order to overcome the problems of the prior art as shown in FIG. 2, in the charging / discharging control circuit according to the present invention, the switching means for limiting current consumption is constituted in the power supply voltage detecting circuit for monitoring the voltage of the secondary battery. Particularly, the switching means for limiting current consumption is constituted in a voltage division circuit constituting a part of the power supply voltage detection circuit.

Further, according to the present invention, the current consumption is suppressed by the current limiting means configured to limit the total current consumption flowing through the error amplifier. For example, since the error amplifier of the overcharge detection circuit, which is the current limiting means, is provided with the power turn on / off function, the error amplifier is turned on or off so as to suppress the battery consumption current under the overdischarge state in accordance with the signal of the overdischarge detection circuit.

Further, in the charging / discharging control circuit according to the present invention, a switching circuit for current consumption control is configured in a buffer circuit for outputting a potential at a connection point of each battery constituting the secondary battery to the outside. This switching means is controlled by a control circuit configured in the charge / discharge control circuit. In particular, under an overdischarging state in which the capacity of the secondary battery is lowered, the control circuit controls the switching means so that the switching means is turned on.

Further, in the charge / discharge control circuit according to the present invention, a single reference voltage source is commonly used for the overcharge voltage detection circuit and the over discharge voltage detection circuit for detecting the voltage of the secondary battery.

In addition, when a plurality of cells connected in series to each other constitute a secondary battery, the overcharge detection circuit and the overdischarge detection circuit detect each battery voltage. In the voltage detecting circuit, different voltages are formed by a single reference voltage generating circuit for detecting the voltage of each battery.

In the charge / discharge control circuit according to the present invention, in order to detect the overcharge state of the secondary battery, a function of the overcharge detection voltage divider circuit for obtaining a partial voltage and a partial voltage The functions of the over-discharge detection voltage dividing circuit to be obtained are all formed by the single over-discharge / over-charge detection voltage division circuit.

In order to overcome the problems of the prior art as shown in FIG. 30, in the charge / discharge control circuit according to the present invention, after the voltage detection circuit detects the overdischarge / overcharge state of the secondary battery, The overcharge / over-discharge voltage is reset so as to be easily detected and the timing of the signal for turning off the switching circuit after reset is set.

Further, in the charge / discharge control circuit according to the present invention, a delay circuit is constituted between the voltage detection comparator and the control circuit. When the delay circuit is connected to the secondary battery, the switching circuit is turned on by securing the logic for a predetermined period of time. Therefore, the rechargeable power supply apparatus can be used from the initial state.

Also, a voltage across the external terminal of the power supply is applied to the charge / discharge control circuit according to the present invention. Even if the voltage of the secondary battery exceeds the minimum allowable voltage of the charge / discharge control circuit, the switching circuit is controlled by a specific circuit when the charger is connected to the power supply.

In the charge / discharge control circuit according to the present invention, when the positive and negative polarities of the secondary battery are reversely connected, an output signal for turning off the switching circuit is always applied from the control circuit. Specifically, the output of the voltage detection circuit for output determination of the control circuit always turns off the switching circuit. More specifically, the output of the constant voltage circuit related to the output of the voltage detection circuit is turned off by the switching circuit.

In the charge / discharge control circuit according to the present invention, the overcurrent detection circuit is provided with a latch function. Once the overcurrent is removed, the latch state is not released unless the load is removed.

In the charge / discharge control circuit of the present invention for solving the determination of the conventional system as shown in FIG. 37, the respective voltages of the two secondary batteries are detected, and in response to the detected one voltage value, Is switched over.

According to the present invention, a resistor is constituted between the terminals for applying the sum of the voltages to the voltage detection circuit so as to detect the sum of the two battery voltages.

According to the present invention, one transistor is connected in series between the external terminal and the secondary battery. In order to reduce the number of transistors to one, a transistor substrate is interposed between the source electrode and the drain electrode of the switching transistor.

Also, as the semiconductor integrated circuit device for charge / discharge control, a semiconductor substrate (hereinafter referred to as an SOI substrate) (silicon on an insulator) having a semiconductor film formed on an insulating film capable of controlling the transistor container plate is preferably used.

In the charge / discharge control circuit according to the first aspect of the present invention, the current consumption is reduced by the current-consumption limiting switching means configured in the voltage detection circuit.

In the charge / discharge control circuit configured as described above, since the consumption current through the overcharge detection circuit is particularly reduced in the overdischarge state, it is possible not only to suppress the battery power consumption in the overcharge state but also to prevent the battery quality from being lowered have.

In addition, since a single multi-input error amplifier is used as a plurality of error amplifiers, the chip area can be significantly reduced.

According to this structure, it is possible to provide a charge / discharge control circuit with a small consumption current by reducing the consumption current of the buffer circuit to a minimum level and a power supply device with a long life.

In the charge / discharge control circuit having such a structure, since the reference voltage source can be formed to a half or less of the number of the main constituent components, the consumption current and the number of constituent components (chip size in the case of IC) can be reduced .

In the charging / discharging control circuit having such a structure, since the voltage dividing circuit for voltage detection is theoretically formed at half the number of constituent components, the current is halved compared with the current of the charging / discharging control circuit in which the voltage dividing circuits are individually formed .

Since the voltage dividing circuit is commonly used for the overcharge voltage detecting circuit and the overdischarge voltage detecting circuit, the number of constituent components can be reduced. When a circuit is composed of an IC, the number of constituent components thereof is reduced, and the chip size is also reduced.

In the charge / discharge control circuit according to the second aspect of the present invention, when overcharge / overdischarge is detected, the overcharge / overdischarge detection voltage is reset to a level at which overcharge / overdischarge can be easily detected. Further, a reverse function is generated in the voltage detection circuit due to the secondary battery voltage which is later turned off by the switching circuit being turned off and turned by the turn-off of the switching circuit.

In addition, since the control circuit is operated after a predetermined time elapses after the voltage detecting comparator is operated, a large amount of penetrating current does not flow at a time, so that the voltage drop of the secondary battery can be prevented. Further, in the charging operation, the voltage of the secondary battery also rises during the delay period, so that the detection operation is performed more reliably. In addition, the delay circuit allows the logic circuit to perform the logic operation reliably for a certain period of time in the state where the secondary battery is initially connected, so that the control circuit can turn on the switching circuit and use the chargeable power supply device from the initial connection state .

In addition, the switching circuit can be controlled even if the secondary battery voltage exceeds the allowable minimum voltage of the charge / discharge control circuit. Even if the secondary battery voltage is extremely reduced, the charging operation is performed satisfactorily.

Also, when the battery is connected in reverse, the switching circuit is always turned off, so that the charger and the secondary battery are electrically disconnected. Therefore, the secondary battery is released from the reverse connection state which is in a state of influencing the charger.

Further, since the latch function is added to the overcurrent detection circuit, oscillation during the overcurrent detection operation can be prevented.

In the charge / discharge control circuit according to the third aspect of the present invention, the voltage detection operation becomes possible as a resistance is formed between the terminals to which the sum of the voltages is applied.

Also, in response to the voltage value of any one of the batteries, when the overcharge detection voltage of the other battery is switched over, the charge / discharge control operation with a small voltage difference can be performed.

Further, the substrate potentials may be set separately from each other. In addition, the size of the transistor can be reduced.

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

1 is a block diagram of a charge / discharge control circuit according to a first embodiment of the first aspect of the present invention. When the charge / discharge control circuit is supplied with power, the secondary battery is operated as the power source. That is, in this case, the secondary battery is connected to the power supply terminals -V _B and + V _B.

Voltage detecting circuits (2, 3) for detecting two output voltages of the power-supply voltage dividing means, voltage detecting circuits (2, 3) for detecting the two output voltages of the power-supply voltage dividing means, A control circuit 4 for outputting a final control signal V _s in response to output signals of the control circuit 4 is connected in parallel to the power source.

3, each of the voltage detecting circuits 2 and 3 includes a reference voltage source 42 for the power supply terminal -V _B and a comparator circuit 41 for receiving and comparing the output of the voltage dividing resistor ). The voltage detection circuit 2 is used for detecting an overcharge, and the voltage detection circuit 3 is used for detecting an over discharge. An overcharged voltage detecting circuit for detecting an overcharged state of a secondary battery that acts as a power source is constituted by a voltage divider circuit (1) and a voltage detecting circuit (2). The overdischarge voltage detecting circuit for detecting the overdischarge of the secondary battery acting as the power supply is constituted by the voltage divider circuit 1 and the voltage detecting circuit 3. [ In the present invention, it is possible to configure the voltage dividing circuits individually for the inputs of the voltage detecting circuits. Fig. 1 shows an example of a charge / discharge control circuit configured so that a voltage dividing circuit can commonly operate for each voltage detecting circuit. The control circuit 4 receives signals for overcharge / over-discharge of the secondary battery from the respective voltage detecting circuits 2 and 3 and outputs a signal V _s for turning on and off the switching circuit of the power supply unit .

The control circuit 4 also controls the switching element 5 configured to control the current flowing through the voltage dividing circuit 1. [ The configuration of the voltage division resistors constituting the power supply voltage divider circuit is so simplified as to be connected in series. Therefore, when the voltage divider circuit 1 is directly connected to the power supply lines (-V _B , + V _B ) without any means intervening, a considerably large DC current flows through the voltage divider circuit. A switching element 5 is interposed between the power supply line (-V _B ) and the voltage divider circuit 1 and the switching element 5 is controlled by a signal from the control circuit 4 or a signal generated by another circuit do.

The smaller the resistance value of the switching element 5 connected in series to the voltage divider circuit 1 becomes, the better. This is because if the resistance value of the switching element 5 is set to a value much smaller than the resistance value of the voltage dividing circuit 1, the output of the voltage dividing circuit 1 will be adversely affected by the resistance value of the switching element 5. [ Therefore, rather than interposing the switching element between the voltage division resistors, it is preferable to directly configure the switching element as a power supply line at one end of the voltage division circuit 1, as shown in Fig.

When the switching element is an insulated gate FET (field effect transistor), the "on" resistance of the transistor is suppressed because the source and gate electrode voltages of the transistor are set at the power supply voltage level, as shown in FIG. In order to reduce the current flowing through the voltage dividing circuit 1, a plurality of high-resistance crystal line films having a sheet resistance of about 10 K? /? Are used as voltage dividing resistors. The resistance value of the voltage divider circuit 1 is designed to be approximately 10 M OMEGA, which is a relatively high level. The " on " resistance of the switching element 5 is designed so as to have a low resistance value of approximately several K [Omega], which is approximately 1/1000 of the resistance value of the voltage division circuit 1. [ That is, it is to suppress the " on " resistance so as to prevent the displacement of the voltage detection circuit. It is possible to reduce the power consumption during the " off " mode because the " off " resistance of the transistor 5 is much larger than the resistance value of the voltage divider circuit 1. [

FIG. 4 is a block diagram of a charge / discharge control circuit according to the present invention, in which a P-type insulated gate FET is connected in series between a voltage divider circuit 21 and a power supply terminal (+ V _B ). The overcharge voltage detection circuit 22, the over discharge voltage detection circuit 23 and the control circuit 24 are designed in the same manner as in the first embodiment as shown in Fig. However, since the switching element 25 is a P-type insulated gate type transistor, + V _B is applied to the terminal 26 when the switching element 25 is turned off. When the " on " state is desired, -V _B is applied to terminal 26. -V _B is applied to the gate voltage of the transistor 25, the " on " resistance is insufficiently lowered.

5 is a block diagram of the charge / discharge control circuit according to the present invention in which the switching elements are inserted on both sides of the voltage division resistors. An N-type insulated gate FET 35 and a P-type transistor 36 are formed on both sides of the voltage dividing circuit 31. The overcharge voltage detection circuit 32, the over discharge voltage detection circuit 33 and the control circuit 34 are designed in the same manner as in the embodiment shown in Figs. As shown in Fig. 5, since the switching elements 35 and 36 are inserted on both sides of the power source, the power source voltage divider circuit can operate quickly. Further, since the switching elements are equally inserted, the " on " resistance of the switching element hardly affects the output of the voltage division circuit.

The charge / discharge control circuit according to the present invention can be applied to an IC configured in the same semiconductor substrate in which the divided voltage in the voltage divider circuit 1 is kept constant without being changed.

A second embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 6, when the battery voltage is not greater than the overdischarge detection voltage V _KAH of the following equation (2) (where V _ref is the voltage value of the reference voltage circuit 11), this state indicates that the battery is in a discharged state . When the battery voltage is not smaller than the overcharge detection voltage V _KAJ of the following equation (3), the voltage of the terminal 17 is at the "high" level, which indicates that the battery is in an overcharged state.

That is, it is possible to select V _KAH and V _KAJ values to arbitrary values by selecting the values of R ₁ to R ₃ and V _ref to match the battery characteristics. The error amplifier 13 of the overcharge detection circuit has a power on / off function. When the output of the error amplifier 12 is " LOW ", the power is turned OFF, whereas when the output of the error amplifier 12 is " HIGH " When the power is turned off, the error amplifier 13 is not operated to such an extent that consumption current can be saved, and the output terminal 17 is fixed at the " low " level. That is, the operation of the error amplifier 13 is controlled by the output of the error amplifier 12.

The following relationship is established between the over-discharge detection voltage V _KAH and the overcharge detection voltage V _{KAJ from the} equations (2) and (3).

That is, in the state where the over-discharge is detected, it is not always possible to say that the over-charged state is present, so that it is not necessary to operate the error amplifier 13 of the overcharge detection circuit. Accordingly, the present invention can be applied thereto. 7 is a circuit example of an error amplifier having a power-on / off function. A divided voltage and a reference voltage are input to the input terminals 61 and 62, respectively. An error amplifying operation is performed during a period in which a " high " level voltage is input to the operation control terminal 63. [ As a result of the overdischarging state, the voltage of the terminal 16 maintains a low level, the transistors M ₁ and M ₂ are turned off to reduce the current consumption, and the transistors M ₃ and M ₄ turn And the output terminal 17 is fixed to the " low " level.

Another embodiment of the present invention will be described with reference to Fig. The system includes the reference voltage circuit 11, the first error amplifiers M11, M12, M13 and M14, the second error amplifiers M16, M17, M18 and M19, (M15). The output of the reference voltage circuit 11 is applied to M14 of the first error amplifier and M18 of the second error amplifier, respectively. Although not shown in FIG. 8, the divided voltage obtained by the voltage dividing means is applied to the transistors M13 and M19 as inputs b and d in a synchronous manner. A signal indicating the discharge state of the battery is outputted from the outputs (a, c) of the error amplifier.

In Fig. 8, a current limiting transistor M15 is connected in series to each of the amplifiers that function as current limiting means in order to limit the consumption current of both the first and second error amplifiers. With the current limiting transistor M15, the consumption current sum of the first and second error amplifiers can be reduced to the same value as the consumption current of the single error amplifier.

An embodiment in which a plurality of error amplifiers are integrated in a single multi-input error amplifier will be described with reference to FIG. 10 is a circuit diagram of a battery charge controller in which two batteries are connected in series with each other. The circuit as shown in Fig. 6 is a structure arranged for each of the batteries 18 or 19. Fig. The pair of transistors M12 and M14 that form the error amplifier are the same in configuration as the pair of transistors M16 and M18 that form the next error amplifier. If any one of these two pairs is removed, the error amplifier circuit It is possible to obtain a circuit as shown in Fig. 9 showing a circuit for a two-input type reference voltage circuit as error amplification means.

N1, N2, N3, N4 and N5 in Fig. 9, N5 is a constant current source, N1 and N2 are active loads, and N3 and N4 are pairs in which a source is coupled. The output (a) can be obtained by comparing (or amplifying) the N3 gate input voltage (b) and the gate input voltage (reference voltage) of N4.

Since the gate-source voltages of N1 and N2 are equal to each other, the currents flowing through N3 and N4 are always the same. Therefore, if the gate input voltage b of N3 is higher than the gate input voltage of N4 (i.e., the reference voltage), the resistance component and the output a are reduced to "low" because N3 is more likely to turn on than N4. On the other hand, if the gate input voltage b of N3 is lower than the gate input voltage of N4 (i.e., the reference voltage), the resistance component increases because N3 is more likely to turn off than N4. The output a is increased to " high ".

Similarly, with respect to N2, N6, N4, N7 and N5, N5 can constitute a constant current source, N2 and N6 are active loads, and N4 and N7 can constitute a conventional error amplifier with the sources coupled together. It is possible to obtain the output c by comparing (or amplifying) the N7 gate input voltage d and the N4 gate input voltage (reference voltage).

Since the gate-source voltages of N2 and N6 are the same, the currents flowing in N2 and N6, that is, the currents flowing in N4 and N7, are always kept the same. Therefore, if the gate input voltage d of N7 is greater than the gate input voltage of N4 (i.e., the reference voltage), then N4 is more likely to turn on than N7, so the resistance component decreases and the output c goes low . On the other hand, if the gate input voltage d of N7 is less than the gate input voltage of N4 (i.e., the reference voltage), the resistance component is increased and the output c is higher &Quot;

Therefore, when the different voltages are compared with the same reference voltage, the reference voltages are input to the gate of N4 and the other voltages are input to the gates of N3 and N7 to compare the outputs (a, c) Can be obtained.

Further, since the transistor N5 serving as a current limiting transistor for determining the consumption current of the error amplifier is commonly used in the two-input system, the current consumption of the single amplifier is used to perform the function of the two error amplifiers The error amplifying means can be driven.

As described above, it is apparent that the present invention applies equally to a P-channel transistor input type error amplifier as well as to an N-channel transistor input type error amplifier.

A third embodiment of the present invention will be described in detail with reference to the drawings.

11 is a block diagram of charge / discharge control circuit according to the present invention.

As the secondary battery, two batteries 111 and 112 are connected in series between the power supply terminals + V _B and -V _B of the charge / discharge control circuit. The voltage of the battery 111 is divided by the voltage divider circuit 113. [ This divided voltage is detected by the overcharge / overdischarge voltage detecting circuit 115. The output of the voltage detection circuit 115 is input to the control circuit 117. When each of the battery is under the overcharge or over-discharge state, the control circuit 117 outputs a signal (V _s) for interrupting the secondary battery and the power connection between the external terminal of the. Therefore, the control circuit 117 is composed of only a logic circuit. The overcharge and overdischarge states of the battery 112 are also detected by the voltage dividing circuit 114 and the voltage detecting circuit 116 in the same manner. The detection result is input to the control circuit 117 in the form of a digital signal. Therefore, if any one of the two cells 111 and 112 is in the overcharge or overdischarge state, the connection between the battery and the external power supply is interrupted so that the overcharge or overdischarge does not proceed further. Since the charging characteristics and the discharging characteristics of these two batteries are not always the same, it is necessary to detect and overcharge and overdischarge individually.

The buffer 118 is a circuit for outputting the voltage V _I as a signal B to the outside while each battery is connected to each other. The charging / discharging equilibrium condition between the respective batteries is detected by the signal (B). The buffer circuit 118 is provided to prevent current consumption from the potential V _I of the connection point to the outside. 12 is a detailed view of the buffer circuit. Power from both sides of + V _B and -V _B of the secondary battery is supplied to the buffer circuit. The potential V _{I at the} connection point is input to the transistors 92 and 93 of the arithmetic amplifier, which is one of the constituent components of the buffer circuit. The potential V _I at the connection point is about the middle of the entire secondary battery power source potential. Therefore, a large current flows through the transistors 92 and 93. Therefore, a switching transistor 91 for interrupting the current flow is connected in series with the transistors 92 and 93. The current interrupt transistor 91 is controlled from the control circuit through the gate electrode 95 so as to be turned off. A constant current circuit 94 is inserted in order to stably operate the buffer circuit.

As described above, when the battery is in the over-discharge state, the operation of the buffer circuit into which the intermediate potential is input is stopped, so that the current consumption of the charge / discharge control circuit is reduced.

By inserting the current interrupt transistor 91, an independent signal can be output from the terminal B even when the buffer circuit does not operate. For example, it is possible to output a signal indicating the overcharge state, the steady state, or the overdischarge state from the terminal B. [ In the steady state, the potential at the connection point of the two batteries is output. In the overcharge or overdischarge state, the condition according to the digital signal level corresponding to + V _B and -V _B can be outputted as the terminal B is maintained or disconnected. That is, the current interrupt transistor configured in the buffer circuit not only interrupts the current of the buffy circuit, but also outputs signals of different kinds through the terminal B.

A fourth embodiment of the present invention will be described with reference to the drawings.

13 is a block diagram of the charge / discharge control circuit according to the present invention. The secondary battery to be charged is connected between the power terminals -V _B and + V _B. The power supply terminal includes a voltage divider circuit 1 for dividing the voltage of the secondary battery, comparators 52 and 53 for forming a voltage detection circuit for detecting the voltage divided by the voltage divider circuit 1, 52, and 53 and a control circuit 4 that outputs the final control signal V _S.

The voltage detection circuit is composed of two voltage detection circuits which are an overcharge voltage detection circuit and an over discharge voltage detection circuit. The overcharge voltage detecting circuit is composed of a reference voltage source (V _R ) and a comparator circuit (52) receiving a voltage divided by the resistors (R ₁ , R ₂ ). The over-discharge voltage detection circuit is composed of a reference voltage source (V _R ) and a comparator circuit (53) receiving a voltage divided by the resistors (R ₂ , R ₃ ). Since the resistance values of the resistors R ₁ , R ₂ and R ₃ constituted in the voltage divider circuit 1 are designed in relation to the reference voltage source V _R , the output of the comparators 52 and 53 . When the voltage of the secondary battery is within the overcharge region and the overdischarge region, the output of the inverted comparators is input to the control circuit 4. [ The control circuit 4 receives signals from the comparators 52 and 53 and outputs a signal for turning off the switching circuit of the power supply device to the switching circuit so that the overcharge or overdischarge does not proceed further. As shown in FIG. 13, the reference voltage V _R is used for the overcharge and overdischarge comparator circuits.

14 is a circuit diagram of a reference voltage source. For example, the increase type N type insulated gate type FET 61 and the depletion type N type insulated gate type FET 62 are directly connected by using a secondary battery whose voltage is variable, as a power source. Each gate electrode is connected to a connection terminal. The constant voltage V _ref is outputted from the connection terminal with respect to -V _B irrespective of the secondary cell voltage fluctuation corresponding to the threshold potential difference of each transistor. Although not limited to the example shown in Fig. 14, the reference voltage source consumes energy of the secondary battery. Therefore, as shown in FIG. 13, since the reference voltage source is commonly used for the voltage detection circuits, not only can the consumption current be reduced as compared with the circuit in which the reference voltage sources are individually configured for the respective detection circuits, The number can be reduced. The current consumption of the charge / discharge control circuit is one of the important factors in determining the lifetime of the secondary battery. Particularly, when the voltage of the secondary battery is reduced under the overdischarge state, the voltage of the secondary battery is rapidly reduced due to the increase of the consumption current, so that the service life is shortened. Therefore, a rechargeable power supply having a long lifetime is required to operate the charge / discharge control circuit with the minimum possible current.

15 is a charge / discharge control circuit diagram when two secondary batteries 71 and 72 are connected in series with each other. As shown in Fig. 15, when the secondary battery is constituted by a plurality of cells, it is necessary to separately detect each battery voltage and form a charge / discharge control circuit. Generally, the battery voltage is determined depending on the battery material. Therefore, when a high voltage is required for the equipment driven by the battery power source, as shown in Fig. 15, the required high voltage can be obtained by connecting the batteries in series. As shown in Fig. 15, the charge / discharge control circuit as shown in Fig. 13 is connected to each of the batteries 71 and 72. As shown in Fig. A control circuit which is commonly used in all of the battery 79 and outputs a switching circuit control signal (V _S) receives input signals from the comparator (75, 76, 77,78).

In the circuit shown in Fig. 15, each battery 71, 72 has a positive voltage side (+ V _B ) and a negative voltage side (-V _B ) with respect to the ground voltage level G. Therefore, as shown in Figure 15, it is preferable to detect the battery voltage by means of two cells if the (71, 72) is connected in series with each other, + V _B and -V _B voltage. The reference voltage source V _R1 based on + V _B is input to the comparators 75 and 76 forming the voltage detection circuit for the battery 71. On the other hand, the reference voltage source V _R2 based on -V _B is input to the comparators 77 and 78 forming the voltage detection circuit for the battery 72. The reference voltages (V _R1 , V _R1 ) are different from each other (+ V _B , -V _B ). In general, the overcharge and overdischarge-dedicated voltages are kept the same for the purpose of controlling the charging / discharging of the battery. Therefore, a reference voltage source is required in which the same value is obtained for each reference even if the reference is different.

Fig. 16 shows an example of a reference voltage circuit for outputting a constant voltage from + V _B and -V _B. In this example, one or more incremental isolation gate FETs are connected in series to the reference voltage circuit. That is, the connection lines of the transistors 82 and 83 are the same as the connection lines of the reference voltage circuit of Fig. 14, and the flanger 81 is additionally connected. In this circuit, V _R1 and V _R2 are output from the junction of each transistor. V _R1 outputs a constant voltage (V _ref ) to + V _B. Further, V _R2 outputs the constant voltage V _ref for -V _B. Therefore, the constant voltage can be outputted by using the reference voltage circuit of Fig. 16 without additionally consuming current. When V _R1 and V _{R2 shown} in FIG. 15 are formed by the single reference circuit of FIG. 16 (one current path between + V _B and -V _B ), even if the secondary battery is composed of a plurality of batteries, It is possible to configure the charge / discharge control circuit without increasing the charge / discharge control circuit.

As described above, according to the present invention, a reference voltage source including a plurality of reference voltage sources corresponding to the number of voltage detecting comparator circuits can be commonly constituted by a single circuit. The charge / discharge control circuit according to the present invention requires a plurality of comparator circuits due to its inherent arrangement, and in order to extend the lifetime of the secondary battery, it is one of the most important factors to reduce the consumption current. Therefore, the present invention is based on a simplified charge / discharge control circuit, and by doing so, a substantial gain can be obtained.

The current consumption can be further reduced if the current is interrupted as the current limiting transistor is connected in series to the common constant voltage circuit used in the present invention and the transistor is controlled by the control circuit. In this case, since the single constant current circuit is constituted, there is an advantage that the circuit is not complicated.

17 is a block diagram of the charge / discharge control circuit according to the first embodiment of the second aspect of the present invention. When the charging / discharging control circuit is applied to the power source device, the secondary battery is used as the power source. That is, the secondary battery is connected to -V _B and + V _B so as to supply power.

(2, 3) for detecting two output voltages of the power supply voltage dividing means, and a voltage dividing circuit (1) for dividing the power supply voltage dividing means in response to the output signals of the respective voltage detecting circuits And a control circuit 4 for outputting a final control signal V _S are connected in parallel to the power source.

3, each of the voltage detecting circuits 2 and 3 includes a reference voltage source 42 for the power supply terminal -V _B and a comparator circuit 41 for receiving the output of the voltage dividing circuit Consists of. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is for overdischarge detection. A voltage detection circuit for overcharge detection of a secondary battery that performs a function as a power supply comprises a power supply voltage divider circuit (1) and a voltage detection circuit (2). The voltage detection circuit for overdischarge detection of the secondary battery which functions as a power source is constituted by a voltage divider circuit 1 and a voltage detection circuit 3. In the present invention, the voltage dividing circuit for input of the voltage detecting circuit can be separately configured. 17 shows an example of the charge / discharge control circuit in which the voltage dividing circuit is commonly configured for each voltage detecting circuit. The control circuit 4 receives a signal before an overcharge / over-discharge of the secondary battery from the voltage detection circuit (2, 3) and outputs a signal (V _S) for turning on and turning off the switching circuit of the power supply.

For example, when the charging power source is connected to the secondary battery connected between the terminals -V _B and + V _B through the switching circuit, the voltages (-V _B , + V _B ) Is gradually increased. When the secondary battery becomes overcharged, the output signal of the overcharge voltage detecting circuit is inverted. The voltage indicating the overcharged state varies depending on the type of the secondary battery. For example, for a lithium ion battery, the voltage is 4.3V. In other words, the output of the charge / discharge control circuit 102 is designed to be inverted when the secondary battery is charged using the voltage of the secondary battery of 4.3V from the voltage divider circuit 1. [ The inverse signal output from the voltage detection circuit 2 is fed back to the voltage divider circuit 1. [ That is, the signal of the voltage detecting circuit 2 is inputted to the gate electrode of the divided voltage control transistor 175 so as to control the partial voltage of the voltage dividing circuit 1. [ The transistor is immediately turned on in accordance with the output signal inverted from the voltage detection circuit 2 so that the divided voltage is further increased and stabilized so that the voltage detection circuit 2 outputs the inverted signal. Thus, since the transistor 175 is turned on, even if the voltage of the secondary battery changes to, for example, 4.0 V or less, the voltage at the resistor R ₁ becomes a level at which the voltage detection circuit 2 can be sufficiently inverted Lt; / RTI >

By constituting the charge / discharge control circuit with the voltage divider circuit 1 and the overdischarge voltage detection circuit as described above, after overcharge detection, the overcharge detection signal is set again to a lower value having its detection signal, The overcharge detection operation can be performed. When the lower value is set again, a signal V _S for turning off the switching circuit is output from the control circuit 4. [ As the switching circuit is turned off, the voltage of the secondary battery is reduced by a voltage corresponding to the product of the internal resistance of the battery and the charging current, resulting in a voltage generated by the inherent chemical potential in the lithium ion battery. That is, the voltage is decreased by a value corresponding to the voltage drop due to the internal resistance. However, the overcharge detection voltage is set to a value reduced from 4.3V to 4.0V, and the output of the voltage detection circuit is maintained to detect overcharge. Therefore, it is necessary that the voltage reduced to 0.3V (4.3V - 4.0V) during the overcharge resetting is determined to be larger than the voltage drop due to the internal resistance of the secondary battery during charging. In general, the voltage difference between the initial set amount and the reset voltage is within the range of 0.2V to 0.5V. If it is set to 0.5V or more, the overcharge range becomes too large. As a result, the use range of the steady state is narrowed. That is, the life span is shortened.

18 is a timing chart of each circuit. The detection voltage (a) for overcharging is set by charging the secondary battery with an overcharge voltage of 4.3V and decreasing again to 4.2V. The divided voltage control transistor 175 is provided for the purpose of reducing the voltage from 4.3V to 4.2V. The output of the voltage detection circuit 2 is fed back to the gate voltage of the transistor 175. That is, when the voltage of the secondary battery is 4.3 V, the output of the voltage detection circuit 2 is inverted from + V _B to -V _B. When the voltage of -V _B is input to the transistor 175, the split ratio of the breeder resistor is changed so that the transistor 175 is turned on and the voltage at the overcharge detection point is reset to 4.2V at 4.3V. The output signal (V _S ) of the control circuit is changed from + V _B to OV for the time Δt after resetting. As a result, the switching circuit switching signal is changed from " on " to " off " The output of the voltage detection circuit 2 is delayed by the delay circuit in order to set the time Δt.

The over-discharge detection has already been described. In the case of overdischarge, the system can be operated stably using a similar configuration. When the over-discharge state is detected, the reset level is increased as opposed to the overcharge state.

A second embodiment of the second aspect of the present invention will be described with reference to the drawings.

19 is a charge / discharge control circuit diagram according to the second embodiment of the second aspect of the present invention. This charge / discharge control circuit is operated by the secondary battery. That is, the secondary battery is connected to the power terminals (-V _B and + V _B ) so as to supply electric power. A voltage dividing circuit 1 as a power supply voltage dividing means, voltage detecting circuits 2 and 3 for detecting two output voltages of the power source, delay circuits 191 and 192 for delaying the output signal of the power source voltage dividing means for a predetermined time, And a control circuit 4 for outputting the final control signal V _S in accordance with the output signals of the delay circuits 191 and 192 are connected in parallel to the power source.

3, each of the voltage detecting circuits 2 and 3 includes a comparator circuit 41 in which the reference voltage source 42 for the power source terminal -V _B receives the output of the voltage dividing circuit 1 . The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is for overdischarge detection. An overcharged voltage detection circuit for detecting overcharging of a secondary battery that performs a function as a power supply comprises a voltage divider circuit (1) and a voltage detection circuit (2). The overdischarge detection circuit for detecting the overdischarge of the secondary battery that performs the function as the power supply is composed of the voltage divider circuit 1 and the voltage detection circuit 3. [ In the present invention, it is possible to separately configure the voltage division resistors for the input of the voltage detection circuit.

19 shows an example of charge / discharge control circuit in which the voltage divider circuit 1 is commonly configured for each of the voltage detection circuits. When the overcharge / over-discharge is detected by the voltage detection circuits 2 and 3, the delay circuits 191 and 192 generate a time delay and the output signal is inverted. The control circuit 4 receives signals for overcharge / overdischarge of the secondary battery from the respective delay circuits 191 and 192, and outputs a signal V _S for turning on and off the switching circuit of the power supply. For this operation, the control circuit 4 is composed of a logic circuit. Even if the switching circuit of the power supply signal (V _S) is turned on or off by, even if the capacitance or the resistance component exists in the input terminal of the switching circuit, so it is necessary to change the signal (V _S) for a predetermined period the control circuit ( It is necessary to keep the impedance of the output terminal (V _S ) of the output terminal (4) at a low level. For example, when the control circuit 4 is made of a MOSFET (metal oxide semiconductor field effect transistor), the number of transistor elements forming the logic circuit is increased. At the same time, in order to maintain the output terminal V _S at a low impedance, it is necessary to increase the size of the final output stage. Therefore, the penetration current is consumed when the control circuit 4 turns on or off the signal V _S. This penetration current is also generated not only in the control circuit 4 but also in the voltage detection circuits 2 and 3 at the timing when the output is reversed by these penetration currents, so that the voltage of the secondary battery connected in parallel drops.

Further, the control circuit 4 performs a logic operation on the signal V _{S as it} receives a signal from the delay circuits 191 and 192. However, if the logic state of the delay circuits 191 and 192 becomes unstable during the initial connection of the battery, the signal V _S output from the control circuit 4 is logic low enough to accurately detect the voltage of the secondary battery. . Therefore, the switching circuit 103 is erroneously operated. When such a phenomenon occurs, charging / discharging is strongly controlled even if a secondary battery having a normal voltage value is connected to the charge / discharge control circuit.

In order to solve such an erroneous operation, delay circuits 191 and 192 are configured. Particularly, after the signal of the voltage detection circuit 2 or 3 is reversed, a time delay is generated and a signal is inputted to the control circuit 4. [ Therefore, it is prevented that the penetration current is simultaneously generated in the voltage detection circuit (2 or 3) and the control circuit (4) at the point where the voltage is detected. Further, due to the time lag, for example, during charging, the charging of the secondary battery is continued until the secondary battery is maintained at the overcharge voltage and the signal (V _S ) of the control circuit 4 is reversed, 3) operate correctly. Therefore, the detection operation is reliably performed.

Further, the delay circuit is configured so that the logic at the initial power supply timing is maintained for a certain period of time. Specifically, as shown in Fig. 20, a capacitance 205 is connected between the output terminal V _out and the power supply terminal -V _B by an inverter constituted by CMOSFETs between power supply terminals + V _B and -V _B. In this case, when a signal changed from + V _B to -V _B is applied to the input terminal V _in by the capacitance 205, the CR delay circuit generates a delay time, and the inverted signal changes from -V _B to + V _B The impedance of the P-channel transistor is output at the terminal V _out until the voltage Vout changes to Vout. Also, as long as the secondary battery is connected in the state where the initial power is supplied, the potential of the output terminal V _out is delayed by the capacitance 205 until it is held at + V _B. That is, the voltage -V _B in the initial stage is maintained for a certain period.

20, the delay time is realized when the voltage at the input terminal V _in is changed from + V _B to -V _B. However, when the delay is required when the potential at the input terminal V _in is changed from -V _B to + V _B , the output terminal V _out and the power supply terminal + V _B is connected to the capacitance 205.

To form the delay circuit, a constant current circuit 226, a P-channel transistor 203 and a capacitance 205 may be formed to have the same effect as the circuit shown in FIG. 20, as shown in FIG.

Fig. 22 shows a circuit for providing a time delay when the output terminal V _out changes from + V _B to -V _B. The initial power supply step -V _B is maintained for a certain period of time.

Using a circuit as shown in Fig. 23 can cause a time delay when the output terminal V _out changes from -V _B to + V _B. By using the delay circuit as described above, it is possible to set the logic and the time delay for the initial power supply timing as desired. In the present embodiment, the delay circuit has been described as a MOSFET, but any other electronic component or element can be used to achieve the same effect. These delay circuits are merely exemplary and may be configured in lieu of other circuits.

The charge / discharge control circuit according to the present invention is suitable for an IC configured on a single substrate in which the divided voltages of the voltage division resistor can be stably maintained.

A third embodiment of the second aspect of the present invention will be described with reference to the drawings.

24 is a block diagram of charge / discharge control circuit according to the present invention. Is different from the conventional power supply circuit in that the voltage of the terminal (-V _O ) is applied to the charge / discharge control conference 102.

25 is a block diagram of the charge / discharge control circuit according to the third embodiment of the second aspect of the present invention. When the charge / discharge control circuit is connected to the power supply, this charge / discharge control circuit operates with the secondary battery as the power source. That is, the secondary battery is connected to the power supply terminals (-V _B and + V _B ) so as to supply electric power. Further, the additional terminal V _e according to the present invention is connected to the external terminal -V _O of the power source device. A voltage dividing circuit 1 as a power supply voltage dividing means, voltage detecting circuits 2 and 3 for detecting the voltages of two outputs of the power source, and a final control signal V (1) according to the output signals of the voltage detecting circuits 2 and 3, _S and the like are connected in parallel to the power source.

According to the present invention, the voltage divider circuit (1) can be separately configured to generate the divided voltage applied to the voltage detecting circuit.

25 is an exemplary diagram of a charge / discharge control circuit in which the voltage divider circuit 1 is commonly configured for each voltage detection circuit. The control circuit 4 receives a signal indicating overcharge / overdischarge of the secondary battery from each of the voltage detecting circuits 2 and 3 and a signal indicating the voltage of the terminal V _e to the terminal (-V _O ) And outputs a signal V _S for turning on or off the switching circuit of the power supply device in accordance with each of these signals.

That is, the control circuit 4 is constituted by a logic circuit and the power source is a secondary battery. Therefore, when the voltage of the secondary battery is further lowered in the overdischarge state, the signal V _S of the control circuit 4 becomes unstable. For example, if the output of the control circuit 4 is comprised of a C-MOS (complementary metal oxide semiconductor) inverter, a sufficient voltage to operate the circuit is given in the range of + V _B to -V _B , If the same voltage as V _B is applied to the input terminal (V _in ), the voltage of -V _{B is} applied to the output terminal (V _S ). When the voltage between + V _B and -V _B falls below the allowable minimum voltage, the -V _B voltage is not applied to the output terminal (V _S ). Since the output terminal V _S of the control circuit is connected to the switching circuit of the power supply device, it is difficult to control charge / discharge of the power supply under the minimum allowable operating voltage of the control circuit. In this case, the following problems arise.

In other words, in the power supply device as shown in Fig. 2, the secondary battery 101 maintains charge / discharge state, and the switching circuit 103 is turned off so that the supply of energy to the external load is interrupted. However, since the secondary battery 101 is connected to the charge / discharge control circuit 102, energy corresponding to the consumption current through the charge / discharge control circuit 102 is consumed. Therefore, after a relatively long time from the change to the over-discharge state, the secondary battery is lowered to the allowable minimum voltage of the control circuit 4, and the control signal V _S becomes unstable as shown in Fig. 25 . As long as the power source device remains in this state, the switching circuit operates unstably even when charging is performed by the main power source. In the worst case, even charging the battery becomes impossible. Therefore, according to the present invention, in order to overcome such a problem, the output section of the control circuit 4 as shown in Fig. 25 is configured as shown in Fig. The power source for the C-MOS inverter is the voltage between + V _B and V _e . The voltage of the output terminal V _S is also controlled by the voltage of the terminal -V _B.

24, the terminal + V _B is connected to the positive terminal of the secondary battery, the terminal -V _B is connected to the negative terminal of the secondary battery, and the terminal V _e is connected to the external terminal -V _O ).

When the charging operation is performed by the power supply device, the switching circuit 103 of FIG. 24 is turned on, so that the voltage at the terminal A becomes equal to -V _O. When the power supply circuit is discharged, the switching circuit 103 of Fig. 24 is turned off, so that the potential at the terminal A becomes equal to the potential at the terminal -V _o . In the circuit of Fig. 26, the voltage of the secondary battery is applied between the terminals + V _B and V _e . A potential substantially equal to the potential of V _e is supplied to the terminal (-V _B ) and the N-channel transistor 269 is turned off. As a result, since the output of the output terminal V _S is controlled by the voltage of the terminal V _IN , it performs the same operation as a normal CMOS inverter. The voltage of the secondary battery is reduced below the allowable minimum voltage of the circuit of Fig. 26 and the signal at the output terminal V _S becomes unstable, but when the charging is performed by the main power supply, the circuit performs stable operation. A voltage higher than the voltage of the secondary battery is supplied between the terminals -V _O and + V _O configured in the circuit of FIG. 24 during charging. At this time, since a common voltage is applied to the positive terminal B of the secondary battery and the external terminal + V _{O to} which the positive voltage of the charger is applied, the potential at the negative terminal A of the secondary battery is the potential at the external terminal -V _O ). 26, the voltage from the charger is supplied between the terminals (+ V _B ) and (V _O ). In this case, since the entire position between the terminals (+ V _B ) and (-V _B ) is small, the N-channel transistor 269 is turned on so that the potential of C is maintained at the same level as the potential of the terminal V _e . Therefore, when the charger is connected to the secondary battery, the potential at the output terminal (V _S ) of the control circuit keeps the same value as the potential at the terminal (+ V _B ) even if the voltage of the secondary battery is low The switching circuit control is reliably performed.

26, when the voltage (between + V _B and -V _B ) of the secondary battery is smaller than the voltage of the charger (between + V _B and V _e ), the inverter circuit 266 turns the N-channel transistor 269 Turn on. The threshold voltage (reverse voltage) of the inverter circuit 266 changes according to the size of the P-channel or N-channel transistor. When the threshold voltage is set higher than the minimum operable voltage of the control circuit 4, the above-described operation is surely performed.

Although the output section of the control circuit has been described above based on CMOS for convenience of explanation, it is obvious that other elements are also possible. Other suitable circuitry may also be used for the output to address the problems inherent in conventional systems.

A fourth embodiment of the second aspect of the present invention will be described with reference to the accompanying drawings.

27 is a block diagram of charge / discharge control circuit according to the fourth embodiment of the present invention. When the charge / discharge control circuit is constituted in the power supply device, this charge / discharge control circuit is operated by the secondary battery. That is, the secondary battery is connected to the power supply terminals (-V _B and + V _B ) so as to form a power source.

A voltage detection circuit (2, 3) for detecting two output voltages of the power supply voltage dividing means, and a voltage detection circuit (2, 3) A control circuit 4 for outputting a control signal V _S is connected in parallel to the power source.

The voltage detection circuit 2 is for overcharge state detection, and the voltage detection circuit 3 is for overdischarge state detection. The overcharge voltage detecting circuit for detecting the overcharged state of the secondary battery that functions as a power supply comprises a voltage divider circuit (1) and a voltage detecting circuit (2). The overdischarge voltage detection circuit for detecting the overdischarge state of the secondary battery that functions as a power supply is composed of the voltage divider circuit 1 and the voltage detection circuit 3. [ In the present invention, the voltage dividing circuit for the input of the voltage detecting circuit can be separately configured. 27 is an exemplary diagram of a charge / discharge control circuit in which a voltage dividing circuit is commonly provided for each voltage detecting circuit. The control circuit 4 receives a signal for overcharge / overdischarge of the secondary battery from each of the voltage detecting circuits 2 and 3 and outputs a signal V _S for turning on and off the switching circuit of the power supply device do.

28 is a circuit diagram showing a reference voltage circuit for generating a reference voltage input to the comparator circuit of the voltage detection circuits 2 and 3. Fig. The voltage of the secondary battery is applied to both terminals of the reference voltage. The reference voltage circuit is a circuit that outputs a reference voltage (V _R ) that does not depend on the voltage fluctuation of the secondary battery at the connection point between the transistor 201 and the transistor 202. The transistor 201 is a depletion type MOS-FET, and the transistor 202 is an increasing type MOS-FET. The transistors 201 and 202 are both N-type transistors. The gate electrodes of the two transistors are connected to the reference voltage output terminal.

When the semiconductor IC forming the charge / discharge control circuit is constituted by a CMOS circuit, the charge / discharge control circuit latches up when positive / negative reverse connection is made to the power source. In the case of latch-up, the intermediate potential setting means is provided at the reference voltage output terminal (V _R ) to realize the output of the reference voltage circuit at the intermediate potential. In the embodiment shown in FIG. 28, the intermediate divided voltage output IN ₂ of the voltage divider circuit is applied to the reference voltage circuit via the diode 283. The intermediate divided voltage output (IN ₂ ) is set at the midpoint between the voltages + V _B and -V _B of the secondary battery. Thus, in the case of the latch-up of the charge / discharge control circuit, the reference voltage output is reduced by approximately 0.6 V, which is the forward voltage drop of the diode at the intermediate split voltage output (IN ₂ ). Since this value is an intermediate voltage of the secondary battery voltage, the voltage detection circuit outputs a signal for turning off the switching circuit through the control circuit 4. [

In the case of the embodiment shown in Fig. 28, the means for setting the output of the reference voltage circuit of the voltage detection circuit is provided to prevent the malfunction of the switching circuit by latch-up. When the switching circuit is turned off by latch-up, it is possible to prevent an uncontrollable state. Therefore, it is possible to modify the circuit so that the switching circuit is turned off when the output of the control circuit 4 itself latches up.

The present invention is inevitable for CMOS ICs that malfunction due to latch-up when the power supply is in the reverse polarity connection state.

A fifth embodiment of the second aspect of the invention will be described with reference to the drawings.

29 is a circuit block diagram showing a charge / discharge control circuit according to a fifth embodiment of the second aspect of the invention. 29, external terminals (-V _O , + V _O ), a switching circuit 103, a current sensing resistor 104, a secondary battery 101, a reference voltage circuit 106, a transistor 107 A constant current source 108, a capacitor 109, and a pull down high resistance 110 are formed.

29, when the current exceeds the level given by Equation (1), the output of the comparator 301 changes from "high" to "low" to turn off the transistor 107 The capacitor 109 is charged by the constant current source 108. When the voltage of the capacitor 109 exceeds the voltage value V _REF of the reference voltage circuit 106, the output of the comparator 292 is changed from "high" to "low" so that the switching circuit 103 is cut off. At this time, the comparator has a latch function. So that the output of comparator 292 remains " low " such that this state is maintained.

The latch function is released by the output of the comparator 301.

31 is a circuit diagram showing a comparator 292 having a latch function. When the voltage at the negative input terminal 314 exceeds the voltage at the positive input terminal 313, the output of the output terminal 315 is held at a low level. At this time, the output of the inverter 317 remains in the " high " state as long as the negative input remains in the " high " state. Therefore, the output of the comparator 292 having the latch function is latched to " low " even if the voltage of the plus input terminal changes to some extent.

The input terminal of the comparator 301 is pulled up to + V _O due to the load, so that the overcurrent state is maintained (i.e., the overcurrent state is maintained) when the load of the electronic equipment such as the video tape recorder is turned off. do.

Thereafter, the negative input voltage of the comparator is reduced to " low " by the pull down resistor 110 when the load is removed, so that the output of the comparator 301 remains " high ". Since the latch release terminal 316 of the comparator 301 having the latch function is " high ", the output of the comparator 292 having the latch function becomes " high "

29, the overcurrent detecting circuit includes a voltage detector for detecting a voltage between both terminals of the overcurrent detecting resistor 104 provided between the external terminal (-V _O ) and the switching circuit 103, a delay for delaying the output of the voltage detector And a voltage detecting circuit provided with a latch up function for detecting an output voltage of the delay circuit. The voltage detection circuit is composed of a reference voltage generation circuit 106 and a comparator circuit 301. The delay circuit is composed of a constant current source 108, a capacitor 109, and a transistor 107. In the above description, the charge / discharge control circuit 102 and the overcurrent detection circuit 105 will be described separately by way of example.

However, the charge / discharge control circuit may include both the charge / discharge circuit 102 and the overcurrent detection circuit 105 described in the above embodiment.

32 is a circuit block diagram showing the charge / discharge control circuit according to the first embodiment of the third aspect of the present invention. When the charge / discharge control circuit is applied to the power source, the charge / discharge control circuit operates with the secondary battery as the power source. That is, in this case, two secondary cells are connected in series to the power terminals (-V _B , + V _B ) as a power source. A voltage dividing circuit 1 as a power supply voltage dividing means for dividing a power supply voltage and a voltage detecting circuit 2 for detecting an output voltage of the power supply voltage dividing means are connected to a power source.

The voltage detection circuit 2 includes a reference voltage source 43 for the power supply terminal -V _B and a comparator 44 which receives the output of the voltage divider circuit 1 as input . The circuit for detecting the sum of the voltages of the secondary cells used as the power source is composed of the voltage divider circuit 1 and the voltage detecting circuit 2. [ The voltage detection circuit 2 outputs a signal V _S for turning on and off the switching circuit of the power supply device.

The charge / discharge control circuit according to the present invention is suitable for an IC provided in a single semiconductor substrate whose divided voltage of the voltage divider circuit 1 is variable within a narrow range. It is natural that the present invention can be applied to a case where three or more secondary batteries are connected to each other in series.

As described above, by detecting the sum of the voltages of the cells formed by the secondary cells, it becomes possible to perform appropriate charge / discharge control even under the condition that each of the cells is locally consumed. As a result, it is possible to extend the service life of the secondary battery.

A second embodiment of the third aspect of the present invention will be described with reference to the drawings. 33, the voltage detection circuit 3 detects the overcharge voltage V ₁ of the secondary battery 6 and the voltage detection circuit 332 detects the overcharge voltage V (V ₁ ) of the secondary battery 7, ₂ ), and the control circuit outputs the output signal V _S. At the same time, the voltage of the secondary battery 6 is detected by the voltage detection circuit 2, and it is assumed that the detection voltage V ₃ is smaller than the overcharge voltage V ₁ . In addition, the same 2 and the voltage of the battery (7) detected by the voltage detection circuit 333, the detection voltage (V ₄₎ is assumed to be smaller than the overcharge voltage (V _2). The output signals of the voltage detection circuits 2 and 333 are input to the voltage detection circuits 332 and 3 to change the voltage values of the overcharge detection voltages V ₂ and V ₁ of the voltage detection circuits 332 and 3.

Specifically, when the charger is connected to the terminals (+ V _B , -V _B ) from the outside and when the secondary batteries 6, 7 are charged, the overcharge detection voltage V ₁ , V ₂₎ it is 4.2V. However, for example, when the charging performance of the secondary battery is remarkably deteriorated due to the failure of the secondary battery 6, only the secondary battery 7 is charged so that the voltage difference between the two batteries 6 and 7 is increased. If the voltage of the secondary battery 6 does not exceed 3.2 V when the detection voltage V ₃ of the voltage detection circuit 2 is set to about 3.2 V in order to avoid this, (V ₂₎ is a detection voltage (V ₂₎ of the voltage detection circuit 332, if the setting is, the secondary battery voltage exceeds 3.2V exhausted to a value of 4.2V or less is set to a detected voltage value of 4.2V. The setting is performed in accordance with the output signal of the voltage detection circuit 2. [

Likewise, the performance degradation of the secondary battery 7 is monitored in accordance with the output signal of the voltage detection circuit 333. When the voltage of the secondary battery 7 does not exceed 3.2 V due to the deterioration of the performance of the battery, the detection voltage V ₁ of the voltage detection circuit 3 is set to a value of 4.2 V or less, 7) exceeds 3.2 V, the detection voltage (V ₁ ) is set to 4.2V. The voltage detection circuit 333 performs the setting in accordance with the output signal.

In the above description, voltage values of 3.2 V and 4.2 V were used as examples. However, it is apparent that these values depend on the battery characteristics and are not limited to the values used herein.

Specific circuits for realizing the block diagrams shown in Figs. 35 and 33 will be described. The output of the voltage detection circuit 333 is input to the gate of the transistor 9 connected in parallel to the resistor R ₃ . The overcharge detection voltage value V ₁ of the voltage detection circuit 3 is changed by turning the transistor 9 on and off.

Similarly, the output of the voltage detection circuit 2 turns on and off the transistor 10 connected in parallel to the resistor connected in parallel to the secondary battery 7 to detect the overcharge detection voltage ( V ₂ ).

36 is a block diagram showing the charge / discharge control circuit and the chargeable type power supply device according to the present invention. The voltage detection circuit 2 for detecting the voltage of the secondary battery 101 and the secondary battery 101 and the control circuit 4 for controlling the impedance of the switching circuit 5 are connected to the external terminals + Respectively. The switching circuit 5 is connected in series between the secondary battery 101 and the external terminal -V so that the secondary battery 101 and the external terminal are electrically connected according to the electrical control. The control circuit 4 receives the output of the voltage detection circuit, logically processes it, and outputs a signal for turning the switching circuit 5 on and off.

When the voltage of the secondary battery 101 exceeds the overcharge voltage level of the secondary battery 101 when the power is connected to the external terminal for charging the secondary battery 101, The signal of the voltage detection circuit 2 is inverted. The control circuit 4 sends out a signal to turn off the switching circuit 5 to stop charging. Conversely, when an electric device such as a video camera consuming power is connected to external terminals (+ V, -V) and power is supplied from the secondary battery 101 to the electric equipment, When the voltage is lower than the over-discharge voltage level, the signal of the voltage detection circuit 2 is inverted to a signal opposite to the normal voltage range. Then, the control circuit 4 outputs a signal to turn off the switching circuit 5 to stop discharging. &Quot; Regular voltage range " means an intermediate state between an overcharged state and an overdischarged state.

In the above charge / discharge control circuit, the voltage detection circuit 2, the control circuit 4 and the switching circuit 5 may be formed of a semiconductor IC disposed on a single substrate.

38 is a circuit diagram showing a switching circuit used in the charge / discharge control circuit according to the embodiment of the present invention. The switching circuit is formed between the external terminal (-V) and the negative terminal 384 of the secondary battery. An N-type insulated gate field effect transistor (hereinafter referred to as an N-type MISFET) is provided between the external terminal (-V) and the negative terminal 384 of the switching circuit. An N-type MISFET 382 and an N-type MISFET 383 are provided between the external terminal -V / minus terminal 384 of the secondary battery and the substrate of the N-type MISFET 381. The gate electrodes 381G, 382G, and 383G of the three N-type MISFETs are controlled by a control circuit.

For example, when the power source is connected to an external terminal to charge a secondary battery, transistors 381 and 382 are turned on and transistor 383 is turned off. The output of the voltage detection circuit is inverted so that a signal for turning off the switching circuit is outputted by the control circuit under an overcharge state. That is, the transistors 381 and 383 are turned off, and the transistor 382 is kept turned on.

When a portable device such as a video camera is connected to an external terminal to supply power to the portable device from the secondary battery, the switching circuit shown in Fig. 38 is controlled to turn on. Transistors 381 and 383 are turned on, but transistor 382 is turned off. Under the over-discharge condition, the output signal of the voltage detection circuit is inverted and a signal for turning off the switching circuit is supplied from the control circuit. That is, the transistors 381 and 382 are turned off, but the transistor 383 remains turned on.

Under normal conditions, the voltage of the external terminal -V and the negative terminal 384 of the secondary battery are compared with each other to detect whether the system is in a charged state or a discharged state. The charging state and the discharging state are detected, and the impedance of the transistors 382 and 383 is controlled by the control circuit. That is, the control circuit has a function of detecting discharging / charging.

In the switching circuit described in connection with Fig. 38, the number of transistors through which current flows is one (transistor 381 only). Thus, in general, a transistor with high current driving capability is composed of half of the conventional components to reduce the voltage drop through the switching circuit. Each of the transistors 382 and 383 of the switching circuit of the IC for controlling discharging / charging according to the present invention selectively connects the substrate of the current driving transistor 381 to one of the negative terminal of the secondary battery and the external terminal Switching transistors. Therefore, the small current driving capability of the trenches 382 and 383 for switching the substrate potential is sufficient. Typically, the current drive capability of transistor 381 requires several amperes, while the current drive capability of transistors 382 and 383 is one thousandth of that of transistor 381. When the circuit is formed of an IC, the area of the transistors 382 and 383 is negligibly small.

As described above, with the switching circuit shown in Fig. 38, it is possible to increase the current driving capability of the current driving transistor up to about twice the conventional system. Therefore, it is possible to reduce the area of the transistor for driving the small current by about half of the conventional system. This facilitates circuit compacting, and the substrate potential of each transistor is electrically isolated by an N well. Therefore, it is easy to provide a transistor on the same semiconductor substrate. However, the transistors 381, 382, and 383 operate identically, although the transistors are composed of discrete transistors.

39 is a sectional view showing a transistor for charge / discharge control circuit according to the present invention. The transistor is formed of the single crystal silicon films 393, 394, and 395 placed on the insulating film 392 of the silicon substrate 391. In general, a substrate having a monocrystalline silicon film formed on an insulating film is referred to as an SOI substrate. An SIP substrate is used to form a transistor having a cross section as shown in Fig. An N type source region 393 and an N type drain region 395 are disposed on both sides of the channel forming region 394 and the gate electrode 397 is formed on the channel forming region 394 through the gate insulating film 396. [ . 39, the potential of the channel forming region 394, which is a part of the substrate of the transistor, is formed to be electrically independent of the transistor formed on the same substrate. That is, the substrate potentials of the transistors are electrically separated from each other so that ICs for charge / discharge control circuits having switching circuits can be easily manufactured.

40 is a plan view showing a transistor in which the potential of the channel forming region which is the substrate is the same as the potential of the source region. The N-type source region 403, the drain region 402 and the channel forming region between these regions 402 and 403 are formed in the single crystal semiconductor film 401 formed on the insulating film, An electrode 407 is disposed. The P-type source region 404 is formed in a part of the source region 403 so that the potential of the source region 403 is maintained at the same potential as the channel forming region by the source electrode 405. [

41 is a cross-sectional view taken along the line A-A 'in FIG. The single crystal semiconductor film 401 is provided on the silicon substrate 411 through the insulating film 418. [ A P-type source region 414, a P-type channel formation region 419, and an N-type drain region 412 are formed in the single crystal silicon semiconductor film 401. The gate electrode 417 is provided over the channel forming region 419 through the gate insulating film 413. [ The P-type source region 414 and the N-type source region are connected to the source electrode 415. The N-type drain region 412 is connected to the drain electrode 416.

FIG. 42 is a circuit diagram showing a switching circuit of the charge / discharge control circuit according to the present invention. This switching circuit is composed of a transistor-type MISFET as shown in FIG. The N type MISFETs 421 and 422 using the SOI substrate are connected in series between the external terminal -V and the negative terminal 420 of the secondary battery. The substrates of the transistors 421 and 422 are connected to maintain the same potential as the external terminal and the terminal of the secondary battery, respectively. By using an SOI substrate it is possible to set the respective potentials of the substrates to different levels.

As described above, the charge / discharge control circuit in which the switching circuit is disposed on the same substrate is realized by the present invention.

In the charge / discharge control circuit according to the present invention, it is possible to reduce the current consumption by the structure in which the current consumption reduction switching element is provided in the voltage division resistors for the overcharge / over discharge detection circuit incorporated in the charge / discharge control circuit. It is also possible to provide a power supply device by a charge / discharge control circuit, a secondary battery, and a switching circuit.

The consumption current flowing to the error amplifier of the overcharge detection circuit is cut off in the overdischarge state, so that it is possible to prevent the power consumption of the battery in the discharge state and the deterioration of the performance of the battery.

In addition, since the consumption current flowing in the error amplifier of the overcharge detection circuit is cut off, it is possible to suppress the power consumption of the battery in the discharge state and to prevent the deterioration of the performance of the battery.

Since a large number of comparator circuits are integrated, it is possible to reduce the size and current consumption of the IC chip, and to produce a high performance battery charge / discharge control circuit with a low manufacturing cost.

Further, a current blocking transistor is connected in series with the buffy circuit so as to detect the voltage between the cells of the built-in secondary battery so that current consumption can be suppressed. Particularly, it is possible to save the consumption current in a discharge state in which the capacity of the secondary battery is rapidly lowered. Furthermore, by inserting the current blocking transistor, it is possible to output a signal indicating overcharge / overdischarge and steady states to the connected battery voltage detecting terminal which is the output terminal of the buffer circuit.

In addition, since the reference voltage source for detecting overdischarge is commonly used for overcharge detection of a built-in secondary battery, it is necessary to reduce the number of components of the charge / discharge control circuit to manufacture a system with a low manufacturing cost, It is possible to increase the lifetime of the rechargeable power supply device by reducing the current consumption through the charge / discharge control circuit.

Further, since the voltage division resistors for detecting the voltage of the secondary battery are commonly used for the over discharge voltage detection and the overcharge detection, the number of circuits connected in parallel to the secondary battery is reduced and the current consumption is thereby suppressed. Also, the current consumption flowing through the charge / discharge control circuit is reduced, thereby increasing the service life of the secondary battery. Furthermore, since the voltage division resistors are commonly used for overcharge and overdrive, it is possible to manufacture the chip compactly with a low manufacturing terminal when the charge / discharge control circuit is integrated.

As described above, in the charge / discharge control circuit, immediately after the voltage detection circuit detects the overcharge or overdischarge, the detection signal is reset to be feed-packed and the overcharge or over-discharge level can detect overcharge or over discharge. This function can be eliminated. Further, since the switching circuit is switched between the secondary battery and the charging power source after the resetting, unstable oscillation of the voltage detecting circuit due to the voltage change of the secondary battery due to the impedance change of the switching circuit is avoided.

By having a structure in which a delay circuit is interposed between the built-in overcharge / over-discharge circuit and the control circuit, the malfunction can be avoided during the detection operation. Further, it is possible to prevent the malfunction during the initial connection step of the secondary battery. A charge / discharge control circuit, a secondary battery, and a switching circuit realize a power supply device with stable operation.

The external terminal voltage of the power supply is supplied to the charge / discharge control circuit. It is possible to control the switching circuit when the charger is connected even if the voltage of the secondary battery that is the power source of the charge / discharge control circuit is equal to or less than the minimum operable voltage of the charge / discharge control circuit. Therefore, it is possible to provide a power supply device capable of positively charging regardless of the voltage of the secondary battery.

As described above, in the charge / discharge control circuit composed of the CMOS IC according to the present invention, when a reverse voltage opposite to the normal connection is applied to the charge / discharge control circuit, the output of the control circuit is not limited The switching circuit is turned off so as to prevent unauthorized operation.

Further, the overcurrent detection circuit of the charge / discharge control circuit according to the present invention is provided with a latch function. Therefore, the oscillation phenomenon between the overcurrent detection can be avoided.

In the charging / discharging control circuit according to the present invention, the voltage dividing resistor and the voltage detecting circuit are installed between the terminals to which a sum of two or more secondary batteries connected in series is applied. It is therefore possible to provide a power supply having a long service life.

When the secondary battery is connected in series and charging is performed, only the normal battery is charged even if there is a defect or accident that one of the secondary batteries significantly degrades the charging characteristic, thereby suppressing the voltage difference between the two cells.

Further, the charge / discharge control circuit and the chargeable power supply device according to the present invention have the following advantages by being constituted by an integrated component including a switching circuit.

(1) Reduction of assembly manufacturing cost

(2) Compact size

(3) Increasing reliability as a system

Various modifications and alterations of the present invention can be made without departing from the spirit and scope of the present invention. Furthermore, the above-described embodiments according to the present invention are provided for illustrative purposes and do not control the invention defined in the appended claims.

Claims (4)

In the charge / discharge control circuit, Voltage dividing means for dividing the power supply voltage; Over-discharge voltage detecting means and over-discharge voltage detecting means for detecting a voltage output level divided from the voltage dividing means; Control means for receiving and processing signals from the overcharge voltage detecting means and the overdischarge voltage detecting means and outputting a signal for controlling charging / discharging of the power supply; And And activating means for activating said voltage dividing means connected in series. And a charge / discharge control circuit connected in parallel to the secondary battery for controlling the switching-on means, the charge / discharge control circuit comprising: a charge / The discharge control circuit includes: Voltage dividing means for dividing the power supply voltage; Over-discharge voltage detecting means and over-discharge voltage detecting means for detecting a voltage output divided from the voltage dividing means; Control means for receiving and processing signals from the overcharge voltage detecting means and the overdischarge voltage detecting means and outputting a signal for controlling charging / discharging of the power supply, And activating means for activating said voltage dividing means connected in series. In the charge / discharge control circuit, Voltage dividing means for dividing the power supply voltage; Over-discharge voltage detecting means and over-discharge voltage detecting means for detecting a voltage output level divided from the voltage dividing means; And And control means for receiving and processing signals from said overcharge voltage detection means and said over discharge voltage detection means and outputting a signal for controlling charge / discharge of power supply. A secondary battery connected to an external power supply terminal through a switching on means and a charge / discharge control circuit connected in parallel to the secondary battery for controlling the switching on means, The discharge control circuit includes: Voltage dividing means for dividing the voltage of the secondary battery; Over-discharge voltage detecting means and over-discharge voltage detecting means for detecting a voltage output level divided from the voltage dividing means; And control means for receiving and processing a signal from the overcharge voltage detecting means and the overdischarge voltage detecting means and controlling the switch-on means.