JP2003061252A - Charge/discharge control circuit and rechargeable power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lengthen the life of a rechargeable power supply unit and reduce the current consumption of the charge/discharge control circuit of the power supply unit for this purpose. SOLUTION: A voltage dividing circuit 1, a voltage detection circuit 2 against overcharge, a voltage detection circuit 3 against overdischarge, and a control circuit 4 are respectively connected in parallel with a secondary battery as a power supply. The control circuit 4 detects the state of the secondary battery from the voltage detection circuits against overcharge and overdischarge, and outputs a signal Vs for controlling power supply to external equipment or charging by an external power supply. Further, the control circuit controls a switch element 5 placed in series with the voltage dividing circuit 1, and reduces current passed through the voltage dividing circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge / discharge control circuit capable of controlling charge / discharge of a secondary battery and a rechargeable power supply device using the circuit.

[0002]

2. Description of the Related Art As a conventional rechargeable power supply device including a secondary battery, a power supply device as shown in a circuit block diagram of FIG. 2 has been known. For example, it is disclosed in Japanese Patent Application Laid-Open No. 4-75430 "Rechargeable power supply device". That is, the secondary battery 101 is connected to the external terminal -V0 or + V0 via the switch circuit 103. Furthermore, the secondary battery 101
A charging / discharging control circuit 102 is provided in parallel with. The charge / discharge control circuit 102 has a function of detecting the voltage of the secondary battery 101. Then, when the voltage of the secondary battery 101 is in either the overcharged state (the voltage is higher than a predetermined high voltage value) or the overdischarged state (the voltage is lower than the predetermined low voltage value), the switch circuit A signal is output from the charge / discharge control circuit 102 to turn off 103. Therefore, in the overcharged state, the switch circuit 103
Is turned off to stop the charging of the secondary battery 101 from the primary power source connected to the external terminals −V0 and + V0. In the case of the over-discharged state, the switch circuit 103 is similarly turned off to stop the energy supply to the load (for example, a secondary battery operated mobile phone or the like) connected to the external terminals −V0 and + V0. That is, the charging / discharging control circuit 102 controls the switching circuit 103 between the secondary battery 101 and the external terminal to prevent the secondary battery 101 from being charged more than necessary from the external terminal, and Battery 101
This prevents a transient decrease in the storage capacity of the secondary battery 101 due to the energy supply to the load connected to the external terminal.

As another embodiment, a rechargeable power supply device as shown in the circuit block diagram of FIG. 30 is known. In FIG. 30, the secondary battery 101 is connected to the external terminal -V0 or + V0 via the switch circuit 103 and the current sensing resistor 104. Furthermore, the secondary battery 101
A charge / discharge control circuit 102 and an overcurrent detection circuit 105 are provided in parallel with each other. Charge / discharge control circuit 10
2 has a function of detecting the voltage of the secondary battery 101, and 1
When the voltage 01 is in the overcharged state or the overdischarged state, a signal is output from the charge / discharge control circuit 102 to turn off the switch circuit 103. In addition, when an abnormality occurs in the load and an overcurrent state occurs, the current sensing resistor 10
The voltage of 4 is monitored by the comparator 21 and compared with the voltage of the reference voltage circuit 106.

Assuming that the voltage value of the reference voltage circuit 106 is V
REF [V], the resistance value of the current sensing resistor 104 is set to R
[Ω] (At this time, the ON resistance of the switch circuit 103 is R
The current flowing therethrough is I
Assuming that [A], when I ≧ VREF / R [A] (1), the output of the comparator circuit 21 becomes “H” → “L”, the transistor 107 is turned off, and the constant current source 108 is turned on.
The capacitor 109 is charged by this, and after a certain delay time, the output of the comparator circuit 302 becomes “H” →
It becomes “L” and the switch circuit 103 is turned off. That is, the constant current source 108, the capacitor 109, and the transistor 107 form a delay circuit for delaying the output of the comparator circuit 302. The delayed signal is input to the comparator circuit 302 together with the signal of the reference voltage circuit 106. The comparator circuit 302 performs comparison processing, and its output operates so as to turn off the switch circuit 103.

Further, as a conventional rechargeable power supply device using a secondary battery and a charge / discharge control circuit, a power supply device as shown in the circuit block diagram of FIG. 37 is known. For example, Japanese Patent Application Laid-Open No. 4-75430, "Rechargeable power supply device"
Is disclosed in. That is, the secondary battery 2 is connected to the external terminals + V and −V via the switch transistors 372 and 373.
4 and the charge / discharge control IC 21 are provided in parallel. The charge / discharge control IC 21 has a function of detecting the voltage of the secondary battery 24 and controlling the impedance of the switch transistors 372 and 373 according to the detected voltage level.

For example, the voltage of the secondary battery 24 is the external terminal +
When the charging power source connected to V and -V exceeds the overcharge voltage, the switch transistor 372 is turned off.
By switching to, the charging of the secondary battery 24 from the external terminal is stopped. On the contrary, when a portable device such as a video camera is connected to the external terminal and electricity is supplied from the secondary battery 24 to the portable device, the voltage of the secondary battery drops and falls below the over-discharge voltage, The switch transistor 373 is turned off to prevent discharge. One of the transistors 372 and 373 functions as a transistor and the other functions as a diode. The substrate of each transistor is connected to each source so that it can function as a transistor during charging and discharging.

[0007]

However, the conventional charge / discharge control circuit shown in FIG. 2 consumes a large amount of current by itself, which shortens the life of the secondary battery serving as the energy supply source. Had a problem. As a result, there is a problem that the usage time of the device driven by the secondary battery is shortened. Furthermore, when the secondary battery is in an over-discharged state in which the storage capacity of the secondary battery is reduced, it is provided in the power supply unit even though the switch circuit stops the energy supply from the secondary battery to external equipment. The current consumption of the charging / discharging control circuit itself promotes further overdischarging,
There was a problem of accelerating the deterioration and shortening of the life of the battery.

Therefore, in order to solve such a conventional problem, an object of the present invention is to obtain a rechargeable power supply device composed of a secondary battery having a long life by reducing the current consumption of a charge / discharge control circuit. Is intended. Also, FIG.
The conventional example shown in (1) has the following various drawbacks. That is, connect a charger to the terminals -V0, + V0 from the outside,
When the secondary battery 101 is being charged, the switch circuit 103 is turned off when the secondary battery is fully charged.
To do. When it is turned off, the potentials at both ends of the secondary battery 101 decrease, and the state of charge again, that is, the switch circuit 10
Turns ON 3. At such voltages before and after the completion of charging, the detection of full charge may oscillate in an unstable manner.

As described in the prior art, when the secondary battery is overcharged during charging, the charge / discharge control circuit operates to turn off the switch circuit for controlling the charging of the secondary battery. However, since the charge / discharge control circuit is connected in parallel with the secondary battery, the current consumed during operation is supplied from the secondary battery. When the secondary battery supplies a current, a voltage drop occurs, the voltage drops below the overcharge detection voltage, and the switch circuit is turned on. For this reason, (the voltage of the secondary battery rises by charging → rises to the overcharge voltage → the voltage of the secondary battery decreases by the operation of the charge / discharge control circuit → the voltage of the secondary battery rises again by charging). There was a problem that could not move to. The same problem also occurs when the over-discharged state is released during charging of the over-discharged battery.

If the logic of the switch circuit is not fixed when the charge control circuit is connected to the secondary battery for the first time, the initial state becomes unstable and the voltage value of the secondary battery is normal. Also, there is a problem that the battery becomes overcharged or overdischarged. When the over-discharge of the secondary battery progresses and its voltage value falls below the minimum voltage at which the voltage detection circuit or control circuit in the charge / discharge control circuit operates, the output of the voltage detection circuit or control circuit is undefined. It becomes a state. That is, since the voltage of the secondary battery has dropped further from the over-discharged state, the charging / discharging control circuit cannot operate the switch circuit normally even if an attempt is made to charge it from the primary power source, so charging is not possible. It will be possible. That is, once the voltage of the secondary battery becomes equal to or lower than the minimum voltage of the charge / discharge control circuit, charging cannot be performed, and thus the secondary battery cannot be used again.

Another problem of the conventional example is that when a charger is connected to both ends of the secondary battery and the secondary battery is charged, the polarity of the charger and the polarity of the secondary battery are made different. When the so-called reverse connection is made to the charging / discharging control circuit, the CMOSIC forming the charging / discharging control circuit latches up, causing the charging / discharging control circuit to malfunction and causing a large current to flow in the secondary battery to cause deterioration. There was a problem.

As another problem, if an excessive current flows from the secondary battery when an abnormality occurs in the load connected across the secondary battery, the overcurrent detection circuit turns off the switch circuit 103. Or turn off this switch circuit
By doing so, there is a problem that the voltage of the secondary battery sharply rises, and thereby the reference voltage value of the overcurrent detection circuit rises, the switch circuit 103 is closed again, and oscillation occurs.

Therefore, an object of the present invention is to provide a charging / discharging control circuit which does not malfunction in order to solve such a conventional problem. Furthermore, when two secondary batteries are connected in series, the conventional example has the following drawbacks.
That is, the two secondary batteries have a one-sided crack depending on their life. However, even in that case, if the sum of the two voltages is a certain voltage or more, there is no problem in using. In the conventional example, since the voltage of each battery is monitored, the sum voltage cannot be monitored, and despite being a usable battery,
Since the use has to be stopped, the usage time of the device is significantly shortened. Further, if one-sided charging occurs and the battery is charged in the same manner as the other normal battery, the one-sided charging is further promoted and the life of the battery is significantly shortened.

Further, in the conventional rechargeable power source device, as shown in FIG. 37, two switch transistors provided between the external terminal and the secondary battery are provided, and each substrate is externally connected. Since the source electrode of the transistor on the terminal side and the transistor on the secondary battery side are set to the potential, they are assembled separately from the charge / discharge control IC, and as a result, it is difficult to miniaturize the battery. There was a problem that the cost was high.

Therefore, the object of the present invention is to reduce the size and the cost.
Another object is to obtain a highly reliable charge / discharge control circuit for a rechargeable battery device and a rechargeable power supply device.

[0016]

Means for Solving the Problems (Means 1) In order to solve the above-mentioned problems of the prior art shown in FIG. 2, the present invention provides a power supply voltage for monitoring the voltage of a secondary battery in a charge / discharge control circuit. The detection circuit is provided with a switch means for limiting current consumption. More specifically, the voltage division circuit, which is a part of the power supply voltage detection circuit, is provided with a switch means for limiting current consumption.

Further, according to the present invention, the current consumption is suppressed by the current limiting means for limiting the overall current consumption flowing through the error amplifier. For example, the present invention adds a power ON / OFF function as a current limiting means to the error amplifier of the overcharge detection circuit, and turns on / off the error amplifier with the signal of the overdischarge detection circuit.
The FF is controlled so that the current consumption of the battery at the time of over discharge is suppressed.

Further, according to the present invention, in the charge / discharge control circuit, a buffer circuit for externally outputting the potential at the connection point of each battery constituting the secondary battery is provided with a switch means for controlling the consumed current. And The switch means is configured to be controlled by a control circuit provided in the charge / discharge control circuit. In particular, the control circuit controls so that the switch means of the buffer circuit is turned on only in the over-discharged state where the capacity of the secondary battery is lowered.

Further, according to the present invention, in the charge / discharge control circuit, each of the overcharge voltage detecting circuits for monitoring the voltage of the secondary battery and the reference voltage source of the overdischarge voltage detecting circuit are combined. Further, when a plurality of secondary batteries are connected in series, an overcharge voltage detection circuit and an overdischarge voltage detection circuit configured to monitor the voltage of each battery are configured. Different reference voltages of the voltage detection circuit for monitoring the voltage of each battery are supplied by one reference voltage generation circuit.

Further, according to the present invention, in a charge / discharge control circuit, an overcharge detection voltage dividing circuit for obtaining a divided voltage for overcharge detection of a secondary battery and an overdischarge for obtaining a divided voltage for overdischarge detection are provided. Both functions of the detection voltage division circuit are configured by one overdischarge / overcharge detection voltage division circuit.

(Means 2) In order to solve the above-mentioned problems of the prior art shown in FIG. 30, in the present invention, in the charge / discharge control circuit, the voltage detection circuit detects overcharge or overdischarge set in the secondary battery. After that, the voltage was reset to a voltage at which it was easier to detect overcharge / overdischarge than the set voltage, and the signal timing was set so that the switch circuit was turned off after the reset.

Further, according to the present invention, in a charge / discharge control circuit,
A delay circuit is provided between the voltage detecting comparator and the control circuit. Further, the delay circuit is configured such that the switch circuit is turned on by fixing the logic for a certain period when the secondary battery is connected, and the rechargeable power supply device can be used even from the initial stage.

Further, according to the present invention, the voltage of the external terminal of the power supply device is input to the charge / discharge control circuit, and the charger operates as the power supply device even when the voltage of the secondary battery becomes equal to or lower than the minimum operating voltage of the charge / discharge control circuit. The circuit configuration is such that the switch circuit can be controlled when connected. Further, according to the present invention, in the charge / discharge control circuit, when the secondary battery is reversely connected, the output signal of the control circuit always outputs a signal for turning off the switch circuit. More specifically, the output of the voltage detection circuit that determines the output of the control circuit is always the OF circuit.
It is configured so as to perform F. More specifically, the switch circuit turns off the output of the constant voltage circuit related to the output of the voltage detection circuit.

Further, according to the present invention, a latch function is provided in the overcurrent detection circuit in the charge / discharge control circuit, and once the overcurrent is detected, the latch is not released unless the load is removed. (Means 3) In order to solve the above-described conventional problem shown in FIG. 37, the present invention monitors the respective voltages of two secondary batteries in a charge / discharge control circuit, and according to the monitored voltage value, the other The voltage detection value is switched.

Further, according to the present invention, in order to monitor the sum voltage of the two batteries, a resistor is provided between the terminals where the sum voltage is output, and the voltage detection circuit is constructed. Further, the present invention has a configuration in which one transistor is connected in series between the external terminal and the secondary battery. In order to form one transistor, the substrate of the transistor is provided between the source electrode and the drain electrode of the switching transistor.

Further, according to the present invention, a semiconductor substrate having a semiconductor film provided on an insulating film capable of freely controlling a substrate of a transistor (hereinafter referred to as an SOI substrate. SOI is Silico).
n On Insulator) is used for the configuration of the semiconductor integrated circuit device for charge / discharge control.

[0027]

In the charge / discharge control circuit configured as in the means 1, the consumption current is reduced by the consumption current limiting switch means provided in the voltage detection circuit. In the battery charge / discharge control circuit configured as described above, the current consumption of the overcharge detection circuit is cut especially when the battery is in the overdischarge state, so the power consumption in the battery overdischarge state should be kept small. This will prevent deterioration of the battery.

Further, since the plurality of error amplifiers are one multi-input type error amplifier, the chip area can be remarkably reduced. With such a configuration, by reducing the current consumption of the buffer circuit to the necessary minimum,
It is possible to obtain a charge / discharge control circuit that consumes less current and a rechargeable power supply device that has a longer life.

In the charge / discharge control circuit configured as described above, the number of reference voltage sources can be reduced to less than half. Can be reduced. In the charge / discharge control circuit configured as described above, the voltage dividing circuit for voltage detection is theoretically configured in half. Therefore, the current flowing therethrough is reduced to half the value of the charge / discharge control circuit in which the voltage division circuit is separately configured.

Further, since the voltage dividing circuit for detecting the overcharge voltage and the voltage dividing circuit for detecting the overdischarge voltage are combined, the number of parts can be reduced. When formed as an integrated circuit, the chip size can be reduced by reducing the number of parts. In the charge / discharge control circuit configured as the means 2, after detecting overcharge or overdischarge, the detection voltage in the overcharge or overdischarge state is reset to a level at which it is detected as more overcharge or overdischarge. Further, thereafter, the switch circuit is turned off so that the voltage detection circuit does not malfunction due to the voltage fluctuation of the secondary battery due to the switch circuit being turned off.

Further, since the control circuit operates after a delay period of a certain time from the operation of the voltage detecting comparator, an excessive shoot-through current does not flow at a time, and the voltage drop of the secondary battery is prevented. You can Further, for example, at the time of charging, the detection operation becomes more reliable because the voltage of the secondary battery rises even during the delay period. Furthermore, since the delay circuit determines the logic for a certain period of time when the secondary battery is initially connected, the control circuit turns on the switch circuit, and the rechargeable power supply device can be used from the initial connection of the secondary battery.

Further, even if the voltage value of the secondary battery becomes equal to or lower than the minimum operating voltage of the charge / discharge control circuit, the switch circuit can be reliably controlled, and the charging is surely performed even if the voltage of the secondary battery becomes extremely low. To be done. Further, since the switch circuit is always turned off in the case of reverse connection, the charger and the secondary battery are electrically separated. Therefore, the secondary battery is completely unaffected by the reverse connection state of the charger.

Further, the latch function provided in the overcurrent detection circuit has an effect such that oscillation at the time of overcurrent detection can be avoided. In the charge / discharge control circuit configured as in the above means 3, a resistor is provided between the terminals that output the sum voltage, so that voltage detection can be performed.

By switching the overcharge detection voltage of the other battery according to the voltage value of one battery, charge / discharge control with a small difference between the voltage values of the two can be performed. Furthermore, the substrate potential can be set independently for each transistor. Further, the area of the transistor can be reduced.

[0035]

EXAMPLE 1 Example 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram of a first embodiment of a charge / discharge control circuit in the means 1 of the present invention.
This charge / discharge control circuit, when applied to the power supply device,
It operates using the secondary battery as a power source. That is, the secondary battery is connected to the power supply terminals -VB and + VB to supply power.

For the power supply, the resistor 1 of the power supply voltage dividing means for dividing the power supply voltage, the voltage detection circuits 2 and 3 for respectively detecting the two output voltages of the power supply voltage dividing means, and the respective voltage detection circuits 2 and A control circuit 4 for outputting a final control signal VS according to the output signal 3 is connected in parallel with each other.

The voltage detection circuits 2 and 3 are specifically shown in FIG.
Reference voltage source 42 for power supply terminal -VB as shown in FIG.
And a comparator circuit 41 to which the output of the voltage dividing resistor is input. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit.
The power supply voltage division circuit 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery that is a power supply. Further, the power supply voltage division circuit 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit for detecting overdischarge of the secondary battery as a power supply. In the case of the present invention, the power supply division circuit input to each voltage detection circuit may be provided separately. In the case of FIG. 1, the voltage division circuit 1 is an example of a charge / discharge control circuit that is provided commonly to the voltage detection circuits of each other. The control circuit 4 inputs signals regarding overcharge and overdischarge of the secondary battery from the respective voltage detection circuits 2 and 3, and outputs a signal VS for turning on or off the switch circuit of the power supply device.

The control circuit 4 also controls the switch element 5 provided to limit the current flowing through the voltage dividing resistor 1. The voltage dividing resistor, which is a power supply voltage dividing circuit, is a circuit in which a plurality of resistors are simply connected in series. Therefore, if the power supply lines -VB and + VB are directly connected to the voltage dividing resistor, a large direct current will flow. The switch element 5 is inserted between the power supply line -VB and the voltage dividing resistor 1 and controlled by a signal from the control circuit 4 or a signal generated by another circuit.

The smaller the resistance of the switch element 5 connected in series with the voltage dividing resistor 1, the better. This is because the output of the voltage dividing resistor 1 is affected by the resistance value of the switch element unless the value is set sufficiently smaller than the resistance value of the voltage dividing resistor 1. Therefore, rather than being provided in the middle of the voltage dividing resistor 1 as shown in FIG. .

When the switch element is an insulated gate field effect transistor as shown in FIG. 1, the ON resistance of the transistor is reduced by setting the voltage between the source and gate electrode of the transistor to the power supply voltage level. be able to. The voltage dividing resistor 1 uses a high resistance polycrystalline film having a sheet resistance of about 10 kΩ / □ in order to reduce the current flowing therethrough. The resistance value of the voltage dividing resistor 1 is designed to have a high resistance value of about 10 MΩ. The ON resistance of the switch element 5 is designed to have a low resistance value of several kΩ at most, and is set to about 1/1000 or less as compared with the resistance value of the voltage dividing resistor 1. The ON resistance is reduced to prevent the voltage detection circuit from shifting. Since the OFF resistance of the transistor 5 is sufficiently larger than the resistance value of the voltage dividing resistor 1, it is possible to prevent most of the current consumption when it is OFF.

FIG. 4 is a circuit block diagram in which a P-type insulated gate field effect transistor is inserted in series with the voltage dividing resistor 21 between the power supply terminal + VB in the charge / discharge control circuit of the present invention. The overcharge detection voltage detector 22, the overdischarge detection voltage detector 23, and the control circuit 24 are designed in the same manner as in the embodiment of FIG. However, since the switch element 25 is a P-type insulated gate transistor, + VB is applied to the terminal 2 when it is desired to turn off the switch element 25.
6 is input to the gate of the switch element, and when it is desired to turn it on, -VB is input to the terminal 26. The ON resistance becomes sufficiently low because -VB is applied to the gate voltage of the transistor 25.

FIG. 5 is a circuit block diagram of the charge / discharge control circuit of the present invention when the switch element is inserted on both sides of the voltage dividing resistor. An N-type insulated gate field effect transistor 35 and a P-type transistor 36 are provided on both ends of the voltage dividing resistor 31.
And are formed. The overcharge voltage detection circuit 32, the overdischarge voltage detection circuit 33, and the control circuit 34 are formed in the same manner as in the embodiments of FIGS. 1 and 4. By inserting both switching elements 35 and 36 on the power supply side as shown in FIG. 5, the power supply voltage dividing circuit can be operated quickly. Further, since they are inserted almost equally in the division circuit, there is an effect that the ON resistance of the switch element hardly affects the output of the voltage division circuit.

The charge / discharge control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate in which the division voltage of the voltage division resistor 1 has a small variation. (Embodiment 2) Embodiment 2 of the present invention will be described below with reference to the drawings.

In FIG. 6, assuming that the voltage value of the reference voltage circuit 11 is Vref, when the voltage of the battery becomes equal to or lower than the overdischarge detection voltage VKAH of the equation (2), the voltage of the terminal 16 becomes
When it becomes “Low” level, indicating that the battery is in the over-discharged state, and when it becomes the overcharge detection voltage VKAJ or more of the formula (3), the voltage of the terminal 17 becomes “High” level,
Indicates that the battery is overcharged.

VKAH = (R1 + R2 + R3) × Vref / (R2 + R3) ・ ・ ・ (2) VKAJ = (R1 + R2 + R3) × Vref / (R3) ・ ・ ・ (3) That is, to match the battery characteristics. And the values of R1 to R3,
By setting the values of Vref and Vref, VKAH and VKAJ can be set arbitrarily. The error amplifier 13 of the overcharge detection circuit has a power ON / OFF function, and when the output of the error amplifier 12 of the overdischarge detection circuit is at "Low" level, the power is OFF, and when it is at "High" level,
Power is turned on. Error amplifier 13 when power is off
Cuts the current consumption without operating, and fixes the output terminal 17 to the “Low” level. That is, the error amplifier 1
3 has its operation controlled by the output of the error amplifier 12.

Overdischarge detection voltage VKAH and overcharge detection voltage V
KAJ has the relationship of Expression (4) from Expressions (2) and (3). VKAH <VKAJ
(4) That is, in a state where over-discharge is detected, it is not necessarily an over-charge state, and it is not necessary to operate the error amplifier 13 of the over-charge detection circuit. Therefore, the present invention is possible.

FIG. 7 shows a circuit example of an error amplifier having a power ON / OFF function. Input terminals 61 and 62,
The division voltage and the reference voltage are input. The configuration is such that the error amplification operation is executed during the period in which the "High" level voltage is input to the operation control terminal 63. With the over-discharged state, the voltage of the terminal 16 becomes "Low" level,
The transistors M1 and M2 are turned off to cut the current consumption, and the transistors M3 and M4 are turned on to fix the output terminal 17 to the "Low" level.

Next, another embodiment of the present invention will be described with reference to FIG. The reference voltage generating circuit 11 and the first error amplifier (M11, M1) are connected to the battery connecting terminals 14, 15.
2, M13 and M14) and a second error amplifier (M1
6, M17, M18 and M19) and transistor M15
It consists of The outputs from the reference voltage generating circuit 11 are input to the transistors M14 and M18, respectively, as inputs to the first and second error amplifiers. Although not shown in FIG. 8, the divided voltage of the battery obtained by the divided voltage means is similarly input to the transistors M13 and M19 b, d.
It is included as. A signal indicating the battery charge / discharge state is output from the outputs a and c of each error amplifier.

In FIG. 8, in order to limit the current consumption of both the first and second error amplifiers, a current limiting transistor M15 is connected in series to each error amplifier as a current limiting means. This current limiting transistor M
The effect of 15 is that the total current consumption of the first and second error amplifiers can be reduced as much as the current consumption of one error amplifier.

Next, an embodiment in which a plurality of error amplifiers are integrated into one multi-input type error amplifier will be described with reference to FIG. FIG. 10 shows a battery charge control circuit diagram when two batteries are connected in series. Battery 18,
The circuits shown in FIG. Transistor M1 forming the error amplifier shown in FIG.
The pair of transistors M16 and M18 forming the error amplifier of the second stage and M14 and the next stage is an amplifying circuit having the same configuration, so if one transistor pair is omitted, the circuit shown in FIG. 9 is obtained.
FIG. 9 is a diagram of a two-input type error amplifier circuit and a reference voltage circuit as the error amplifying means.

In FIG. 9, N1, N2, N3, N4
, N5 is an error amplifier in which N5 is a constant current source N1 and N2 is active broad, and N3 and N4 are source coupled pair. N3 gate input voltage (b) and N4 gate input voltage (reference voltage) ) Can be compared (or amplified) to obtain the output at a.

Since the gate-source voltages of N1 and N2 are the same, the currents flowing through N1 and N2, that is, N3 and N
The current flowing in 4 is always considered to be the same. Therefore, from the gate input voltage (reference voltage) of N4,
If the gate input voltage (b) of N3 is high, N3 turns on more than N4, the resistance component of N3 decreases, and the output a becomes Low.
Go down to the side. If the gate input voltage (b) of N3 is lower than the gate input voltage (reference voltage) of N4, N3 will be
OFF, the resistance component of N3 increases, and the output a rises to the High side.

Similarly, N2, N6, N4, N7, N
Focusing on 5, it is a conventional error amplifier in which N5 is a constant current source, N2 and N6 are active loads, and N4 and N7 are source-coupled pairs, and N7 gate input voltage (d) and N4 gate input voltage (d) The reference voltage can be compared (or amplified) to obtain the output at c.

Since the gate and source voltages of N2 and N6 are the same, the current flowing through N2 and N6, that is, N4 and N6.
It is considered that the current flowing through 7 is always the same. Therefore, from the gate input voltage (reference voltage) of N4 to N7
If the gate input voltage (d) of N7 is high, N7 is turned on more than N4, the resistance component of N7 is decreased, and the output c is Low.
Go down to the side. If the gate input voltage (d) of N7 is lower than the gate input voltage (reference voltage) of N4, N7 is
OFF, the resistance component of N7 increases, and output c
Goes up to the High side.

Therefore, when comparing (or amplifying) different voltages with respect to the same reference voltage, the reference voltages are compared (or amplified) by inputting the reference voltage to the gate of N4 and the other voltage to the gates of N3 and N7, respectively. The amplified outputs can be obtained as a and c, respectively.

Further, since the current limiting transistor N5, which determines the current consumption of the error amplifier, is commonly used, the error amplifying means having the function of two error amplifiers has one error. It can be driven by the current consumption of the amplifier. Although the present invention has been described with respect to the Nch transistor input type error amplifier, it can also be applied to the Pch transistor input type error amplifier.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to the drawings. FIG. 11 is a circuit block diagram of the charge / discharge control circuit of the present invention. As the secondary battery, two batteries 111 and 112 are the power terminal + VB of the charge / discharge control circuit.
And -VB are inserted in series. The voltage of the battery 111 is divided by the voltage dividing circuit 113, and the divided voltage is detected by the overcharge and overdischarge voltage detection circuit 115. The output of the voltage detection circuit 115 is input to the control circuit 117. The control circuit 117 outputs a signal VS for turning off between the secondary battery and the external terminal of the power source when each battery is in the overcharged state or the overdischarged state. Therefore,
The control circuit 117 is composed of only logic circuits. Similarly, the battery 112 is also configured to detect the overcharged state and the overdischarged state by the voltage division circuit 114 and the voltage detection circuit 116. The detection result is similarly input to the control circuit 117 as a digital signal. Therefore, the control circuit 117 functions to stop the progress of overcharge and overdischarge by disconnecting the electrical connection between the battery and an external power source when one of the batteries 111 and 112 is overcharged or overdischarged. Since the charging and discharging characteristics of the two batteries are not exactly the same, it is necessary to detect and control overcharging and overdischarging separately.

The buffer 118, during connection of each battery,
This is a circuit for outputting the potential VI as a signal B to the outside. The balance state of charge and discharge between the batteries can be detected by the signal B. The buffer circuit 118 is provided so that no current is consumed from the potential VI at the connection point to the outside. A more specific circuit diagram of the buffer circuit is shown in FIG. The buffer circuit is supplied with power from both the secondary batteries + VB and -VB. In the buffer circuit, the connection point potential VI is input to the transistors 92 and 93 in the operational amplifier which is a component thereof. This connection point potential VI is almost the middle potential of the entire secondary battery power supply. Therefore, transistors 92 and 93
A large current flows through. Therefore, the switch transistor 9 for current cut is connected in series with the transistors 92 and 93.
1 is connected. This current cut transistor 91
Are controlled by the control circuit via the gate electrode 95 so as to be turned off in the overdischarge state. The constant current circuit 94 is inserted for stable operation of the buffer circuit.

As described above, the current consumption of the charging / discharging control circuit can be reduced by stopping the operation of the buffer circuit which receives the intermediate potential as an input in the overdischarge state. Also,
By inserting the current cutting transistor 91, an independent signal can be output from the terminal B when the buffer circuit is not operating. For example, it is possible to output a signal indicating the over-discharged state, the normal state or the over-charged state from the B terminal. In the normal state, the connection potential of the two batteries is output. In the over-discharged or over-charged state, by pulling up or pulling down the B terminal, the state can be output at a digital signal level of + VB or -VB. That is, the current cutting transistor inserted in the buffer circuit not only cuts the current of the buffer circuit, but also has the function of outputting different kinds of signals from the terminal B.

(Fourth Embodiment) A fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 13 is a circuit block diagram of the charge / discharge control circuit of the present invention. The secondary battery to be charged is connected to the power supply terminals -VB and + VB. Power supply terminal -VB,
+ VB includes a voltage dividing resistor 1 that is a voltage dividing circuit that divides the voltage of the secondary battery, and comparators 52 and 53 that are voltage detecting circuits that detect the divided voltage of the voltage dividing resistor 1.
The control circuit 4 that receives the output signals of the comparators 52 and 53 and outputs the final control signal VS is connected in parallel.

The voltage detection circuit is composed of two voltage detection circuits, an overcharge voltage detection circuit and an overdischarge voltage detection circuit. The overcharge voltage detection circuit is composed of a comparator circuit 52 which receives the reference voltage source VR and the divided voltage between the resistors R1 and R2 as inputs. The overdischarge voltage detection circuit is composed of a comparator circuit 53 which receives the reference voltage source VR and the divided voltage between the resistors R2 and R3 as inputs. The resistance values of R1, R2, and R3 of the voltage dividing resistor 1 are designed in relation to the reference voltage source VR such that the output of the comparator 52 is inverted at the time of overcharge and the output of the comparator circuit 53 is inverted at the time of overdischarge. Has been done. When the voltage of the secondary battery reaches the overcharge region or the overdischarge region, the output of each comparator circuit is inverted and input to the control circuit 4. The control circuit 4 receives the signals from the comparator circuits 52 and 53, and outputs V to turn off the switch circuit of the power supply device so that overcharge or overdischarge does not proceed further.
Output S to the switch circuit. As shown in FIG. 13, the reference voltage VR is used for both overcharge and overdischarge comparator circuits.

FIG. 14 is a circuit diagram of the reference voltage source. Using a secondary battery whose voltage fluctuates as a power source, for example, an enhanced N-type insulated gate field effect transistor 61 is used.
And a depletion type N-type insulated gate field effect transistor 62 are connected in series. The respective gate electrodes are connected to the respective connection terminals. The connection terminal outputs a constant voltage Vref that does not depend on the fluctuation of the secondary battery voltage corresponding to the threshold voltage difference of each transistor with reference to -VB. The reference voltage source is not limited to the example of FIG. 14, but consumes the energy of the secondary battery. Therefore, by using the reference voltage source for both the voltage detection circuits as shown in FIG. 13, it is possible to reduce not only the number of parts but also the consumption current in the circuit in which the reference voltage source is provided separately.
The current consumption of the charge / discharge control circuit is an important parameter that determines the life of the secondary battery. In particular, in the case of an over-discharged state in which the voltage of the secondary battery has dropped, the voltage of the secondary battery suddenly shortens its life with energy consumption. Therefore, it has been a point to make the charge / discharge control circuit function with a minimum current in order to make a rechargeable power supply device having a long life.

In FIG. 15, the secondary batteries are two batteries 71 and 7.
2 shows a circuit block of a charge / discharge control circuit when 2 and 2 are used in series connection. When the secondary battery is composed of a plurality of batteries as in the embodiment shown in FIG.
It is necessary to have a circuit for independently detecting the voltage of each battery and controlling the charging / discharging voltage. Generally, the voltage of a battery is determined by the substances that make up the battery. Therefore, when a device functioning as a power source requires a high voltage, batteries are often connected in series to increase the voltage as shown in FIG.
As shown in FIG. 15, the charging / discharging control circuit shown in FIG. 13 is connected to each of the batteries 71 and 72. The control circuit 79, which is a common circuit, includes comparators 75, 76,
Upon receiving the signals from 77 and 78, it outputs a signal VS for controlling the switch circuit.

In the circuit of FIG. 15, each of the batteries 71 and 72 has a positive voltage side + VB with respect to the ground voltage level G.
And the voltage on the negative voltage side -VB. Therefore, FIG.
When the two batteries 71 and 72 are connected in series as shown in FIG. 3, it is preferable to detect each voltage by the voltage from + VB and -VB. A reference voltage source VR1 with + VB as a reference is input to comparators 75 and 76 which are voltage detection circuits of the battery 71. On the other hand, the reference voltage source VR2 with -VB as a reference is input to the comparators 77 and 78 which are the voltage detection circuits of the battery 72. The reference voltage sources VR1 and VR2 have different references from + VB and -VB. Generally, for the purpose of battery charge / discharge control, the overcharge and overdischarge voltages are the same. Therefore, although the references are different, each requires a reference voltage source that obtains the same value.

FIG. 16 shows an example of a reference voltage circuit which outputs equal constant voltages from + VB and -VB. It is a circuit in which another enhance type insulated gate field effect transistor is connected in series to the reference voltage circuit shown in FIG. That is, the connection between the transistors 82 and 83 in FIG. 16 is the same as that in the reference voltage circuit in FIG. 14, and the transistor 81 is additionally connected. In this circuit, VR1 and VR2 are output from the connection points of the respective transistors. VR1 outputs a constant voltage Vref with respect to + VB. Also, VR2 is the same constant voltage Vre as -VB.
Output f. Therefore, the reference voltage circuit of FIG. 16 can output two constant voltages without increasing current consumption. One reference voltage circuit (current path is +
There is only one way between VB and -VB)
By forming R1 and VR2, even if the secondary battery is composed of a plurality of batteries, it can be formed without increasing the current consumption of the charge / discharge control circuit.

As described above, according to the present invention, one circuit also serves as the reference voltage source, which has required the number of comparator circuits for voltage detection up to now. The charge / discharge control circuit of the present invention requires a plurality of comparator circuits due to its configuration, and further, reduction of current consumption is the most important parameter for improving the life of the secondary battery. Therefore, the present invention is invented from a simplified charge / discharge control circuit, and its effect is great.

Further, if a current cutting 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 to cut the current, further reduction in current consumption can be achieved. Also in this case, since there is only one constant current circuit, it can be achieved without complicating the circuit.

(Embodiment 5) FIG. 17 is a circuit block diagram of Embodiment 1 in the means 2 of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, the secondary battery supplies power by connecting to the power supply terminals -VB and + VB.

For the power supply, the voltage dividing resistor 1 of the power supply voltage dividing means for dividing the power supply voltage, and the voltage detection circuits 2 and 3 for respectively detecting the two output voltages of the power supply voltage dividing means,
A control circuit 4 which outputs a final control signal VS according to the output signals of the voltage detection circuits 2 and 3 is connected in parallel with each other.

The voltage detection circuits 2 and 3 are specifically shown in FIG.
Reference voltage source 42 for power supply terminal -VB as shown in FIG.
And a comparator circuit 41 to which the output of the voltage dividing resistor is input. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit.
The power supply voltage division circuit 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery that is a power supply. Further, the power supply voltage division circuit 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit for detecting overdischarge of the secondary battery as a power supply. In the case of the present invention, the power supply division circuit 1 input to each voltage detection circuit may be provided separately. In the case of FIG. 17, the power supply division circuit 1 is
It is an example of a charging / discharging control circuit provided in common to the mutual voltage detection circuits. The control circuit 4 controls each voltage detection circuit 2
Input the signals related to overcharge and overdischarge of the secondary battery from 3 and 3, and turn on or off the switch circuit of the power supply device.
And outputs a signal VS for doing so.

For example, a case where the secondary battery connected between the terminals -VB and + VB is connected to the charging power source via the switch circuit and the secondary battery is charged will be described. In the charged state, the voltage across the secondary battery −
VB and + VB increase little by little. When the secondary battery is overcharged, the output signal of the overcharge voltage detection circuit 2 is inverted. The voltage for recognizing this overcharged state varies depending on the secondary battery. For example, in the case of a lithium-ion battery, 4.3
It is set to V. That is, the output of the overcharge voltage detection circuit 2 is designed to be inverted when the voltage of the secondary battery is charged to 4.3 V from the voltage dividing circuit 1 and the voltage dividing circuit 1. The inverted signal output from the voltage detection circuit 2 is
It is fed back to the voltage dividing circuit 1. That is, the signal of the voltage detection circuit 2 is input to the gate electrode of the voltage division control transistor 175 that controls the divided voltage of the voltage division circuit 1. The voltage output control transistor 175 is immediately turned on by the inverted output signal of the voltage detection circuit 2 to further increase the division voltage, and the voltage detection circuit 2 operates in a stable manner to output the inverted signal. When the voltage dividing control transistor 175 is turned on, the voltage of the resistor R1 is at a level at which the voltage detection circuit 2 is sufficiently inverted even if the voltage of the secondary battery fluctuates as low as 4.0V.

As described above, in the overcharge detection circuit composed of the voltage division circuit 1 and the overcharge voltage detection circuit, after detecting the overcharge, the overcharge detection voltage is set to a low value by the detection signal. It is configured to perform stable overcharge detection by resetting. After resetting to a low value, the signal VS that turns off the switch circuit from the control circuit 4
Is output. By turning off the switch circuit, the voltage of the secondary battery is reduced by the voltage corresponding to the product of the charging current and the internal resistance of the battery, and becomes only the voltage generated by the chemical potential specific to the lithium ion battery. That is, the voltage drop due to the internal resistance is reduced. However, before that, the overcharge detection voltage is reset to decrease from 4.3 V to 4.0 V, so the output of the voltage detection circuit 2 remains detecting the overcharge. Therefore, the decrease voltage of 0.3V (4.3V-4.0V) for resetting overcharge needs to be set larger than the voltage drop due to the internal resistance of the secondary battery during charging. Generally, the voltage difference between the initial set voltage and the reset voltage is between 0.2V and 0.5V. 0.5V
If the above setting is made, the overcharge range becomes wider and the use range in the normal state becomes narrower. That is, the life is shortened.

FIG. 18 is a diagram showing the signal timing of each circuit. The overcharge detection voltage a is 4.
As the secondary battery is charged to 3V, it is reset to 4.2V and reset. A division voltage control transistor 175 is provided to reduce 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 divided voltage control transistor 175. That is, when the voltage of the secondary battery becomes 4.3V, the output of the voltage detection circuit 2 is inverted from + VB to -VB. The voltage of -VB is input to the voltage dividing control transistor 175. The voltage dividing control transistor 175 is turned on, the division ratio of the bleeder resistance is changed, and the voltage at the overcharge detection point is 4.3 V.
Is reset to a low value from 4.2V to 4.2V. The output signal Vs of the control circuit 4 changes from + VB to 0V after a time period Δt after resetting, and the switch circuit is switched from ON to O.
A signal for changing to FF is output. To form Δt, the output of the voltage detection circuit 2 can be delayed by a delay circuit to delay the signal.

The above is the description of the overcharge detection. Even in the case of over-discharging, stable operation can be achieved by using the same configuration. In the case of over-discharging, the reset level is set to increase in the opposite direction to over-charging. (Example 6) Hereinafter, Example 2 in the means 2 of the present invention will be described.
Will be described with reference to the drawings.

FIG. 19 is a circuit block diagram of the second embodiment in the means 2 of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, the secondary battery supplies power by connecting to the power supply terminals -VB and + VB. The power supply includes a resistor 1 of a power supply voltage dividing means for dividing the power supply voltage, voltage detection circuits 2 and 3 for detecting two output voltages of the power supply voltage dividing means, and output signals of the respective voltage detection circuits 2 and 3. Delay circuits 191 and 19 for delaying
2 and the control circuit 4 which outputs the final control signal VS by the output signals of the delay circuits 191 and 192 are connected in parallel with each other.

The voltage detection circuits 2 and 3 are specifically shown in FIG.
Reference voltage source 42 for power supply terminal -VB as shown in FIG.
And a comparator circuit 41 to which the output of the voltage dividing resistor 1 is input. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit.
The voltage dividing resistor 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of the secondary battery that is the power supply. Further, the voltage division resistor 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit for detecting overdischarge of the secondary battery as a power source. In the case of the present invention, the voltage dividing resistors input to each voltage detection circuit may be separately provided.

In the case of FIG. 19, the voltage dividing resistor 1 is an example of a charge / discharge control circuit provided in common to each voltage detection circuit. The delay circuits 191 and 192 are circuits for generating a time delay when the voltage detection circuits 2 and 3 detect overcharge or overdischarge and the output signal is inverted. The control circuit 4 includes the delay circuits 191 and 1
Signals related to overcharge and overdischarge of the secondary battery are input from 92, and the switch circuit of the power supply device is turned on or off.
And outputs a signal VS for doing so. Therefore, the control circuit 4
Is composed of a logic circuit. Further, the switch circuit of the power supply device is turned on or off by the signal VS. However, even if the input terminal of the switch circuit has a capacitance or a resistance component, it is necessary to change the signal VS within a fixed time. The output terminal VS of 4 must have low impedance. The control circuit 4 is, for example, a MOSFET
(Metal-Oxide-Semiconductor-Field-Eftect-Transisto
When it is realized by r), the number of transistor elements is increased to form a logic circuit, and the final output stage must be increased in size in order to make the output terminal VS have a low impedance. Therefore, a through current is consumed when the control circuit 4 turns on or off the signal VS.
Not only the control signal 4 but also the voltage detection circuits 2 and 3 generate a through current when the output is inverted. Due to these shoot-through currents,
The voltage of the secondary batteries connected in parallel may be dropped.

Further, the control circuit 4 receives the signals of the delay circuits 191 and 192 and determines the logic of the signal VS.
However, the delay circuits 191 and 192 are connected at the initial battery connection.
If the logic of is uncertain, the signal VS output from the control circuit 4 will not be the logic that the voltage of the secondary battery is correctly detected, and the switch circuit 103 will malfunction. When these phenomena occur, charging or discharging is forcibly controlled even if a secondary battery showing a normal voltage value is connected to the charge / discharge control circuit.

Delay circuits 191 and 192 are provided to prevent these malfunctions. In other words, since a signal is input to the control circuit 4 by making a time delay after the signal of the voltage detection circuit 2 or 3 is inverted, the through current of the voltage detection circuit 2 or 3 and the control circuit 4 is detected at the time of voltage detection. It prevents them from happening at the same time. Further, since there is a time delay, for example, at the time of charging, the secondary battery has an overcharge voltage, and even after the voltage detection circuit 3 operates, the secondary battery is continuously charged until the signal VS of the control circuit 4 is inverted. Therefore, the detection operation becomes more reliable.

Further, the delay circuit is configured to secure the logic when the initial power is turned on for a certain period. Specifically, as shown in FIG. 20, CMOSFE is connected between the power supply terminals + VB and -VB.
An inverter is formed by T and a capacitor 205 is connected between the output terminal VOUT and the power supply terminal-VB. In this case, when a signal that changes from + VB to -VB is input to the input terminal VIN by the capacitor 205, a capacitance 2 is output before an inverted signal that changes from -VB to + VB is output to the output terminal VOUT.
05 and the impedance of the Pch transistor 203 establish a CR circuit and cause a delay. Also, when the power is initially turned on (when the secondary battery is connected), the voltage of the output terminal VOUT is delayed by the capacitance 205 until it becomes + VB voltage. That is, the -VB voltage is initially maintained for a certain period.

In FIG. 20, the input terminal VIN is changed from + VB to-.
Delay is realized when changing to VB, but input terminal V
If a delay is required when IN changes from -VB to + VB, a capacitor 205 may be connected between the output terminal VOUT and the power supply terminal + VB as shown in FIG. In order to realize the delay circuit, even if the constant current circuit 226, the Pch transistor 203 and the capacitor 205 are used as shown in FIG. 22, the same effect as the circuit of FIG. 20 can be obtained.

In FIG. 22, the output terminal VOUT changes from + VB to-.
This circuit creates a delay when changing to VB, and keeps -VB for a certain period when the initial power is turned on. With the configuration shown in FIG. 23, it is possible to generate a delay when the output terminal VOUT changes from -VB to + VB. As described above, depending on the circuit configuration of the delay circuit, the delay timing and the logic at the time of initial input can be freely set. Also,
Although the delay circuit is described as a MOSFET for convenience, it is obvious that it can be realized by other elements. Further, these delay circuits are examples, and the problem can be solved by using other circuits.

The charging / discharging control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate in which the division voltage of the voltage dividing resistors has little variation. (Embodiment 7) Embodiment 3 of means 2 of the present invention will be described below with reference to the drawings.

FIG. 24 is a circuit block diagram of the rechargeable power supply device of the present invention. The difference from the circuit of the conventional power supply device is that the voltage at the terminal -VO is applied to the charge / discharge control circuit 102. FIG. 25 is a circuit block diagram of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, the secondary battery supplies power by connecting to the power supply terminals -VB and + VB. In addition, the terminal V newly prepared in the present invention
e is connected to the external terminal -VO of the power supply. For the power supply, a voltage dividing resistor 1 of a power supply voltage dividing means for dividing the power supply voltage, voltage detection circuits 2 and 3 for respectively detecting two output voltages of the power supply voltage dividing means, and voltage detection circuits 2 and 3
Is connected in parallel with the control circuit 4 which outputs the final control signal VS according to the output signal.

In the case of the present invention, the voltage dividing resistors for generating the divided voltages input to the respective voltage detecting circuits may be separately provided. In the case of FIG. 25, the voltage division circuit 1 is
It is an example of a charging / discharging control circuit provided in common to each voltage detection circuit. The control circuit 4 controls each voltage detection circuit 2
From 3 and 3, signals relating to overcharge and overdischarge of the secondary battery and the signal of the terminal -V0 of the power supply device are input from Ve. Output. That is,
Since the control circuit 4 is composed of a logic circuit and the power source is a secondary battery, if the voltage of the secondary battery further decreases from the overdischarged state, the signal VS of the control circuit 4 becomes unstable. Become. For example, if the output of the control circuit 4 is a C-MOS (C
omplementary-Metal-Oxide-Semiconductor) When configured with an inverter, a voltage sufficient to operate the circuit is applied between + VB and -VB, and the input terminal VIN-
If the same potential as VB is applied, the output terminal VS
A voltage of -VB is output. When the voltage between + VB and -VB falls below the minimum operating voltage of the inverter, the output terminal VS
Does not output the voltage of -VB. Since the output terminal VS of the control circuit is connected to the switch circuit of the power supply device, it is impossible to control the charging / discharging of the power supply device below the minimum operating voltage of the control circuit. In this case, the following inconvenience occurs.

That is, with the power supply device as shown in FIG. 2, the secondary battery 101 is charged and discharged, and the switch circuit 103 is turned off.
F to stop the energy supply to the external load.
However, since the secondary battery 101 is connected to the charging / discharging control circuit 102, only the current consumption of the charging / discharging control circuit 102 is consumed, and a considerable amount of time elapses after shifting to the overdischarge state. After that, the secondary battery falls below the minimum operating voltage of the control circuit 4, and the control signal VS shown in FIG. 25 becomes unstable. Once the power supply unit is in this state, even if an attempt is made to charge from the primary power supply, the switch circuit operates in an unstable manner, and in the worst case, charging becomes impossible. Therefore, in order to solve this, in the present invention, the output portion of the control circuit 4 of FIG. 25 is configured as shown in FIG. C-MOS
The power source of the inverter is a voltage between + VB and Ve, and the voltage of the output terminal VS is controlled by the potential of the terminal -VB.

As shown in FIG. 24, the terminal + VB is the + terminal of the secondary battery, the terminal −VB is the −terminal of the secondary battery, and the terminal V
e is connected to the external terminal -V0 of the power supply unit.
When the power supply device is discharging, the switch circuit 103 is ON in FIG.
The potential of 0 becomes almost equal. In the output circuit of FIG. 26, the voltage of the secondary battery is applied between + VB and Ve, the terminal -VB is applied with substantially the same potential as the terminal Ve, and the Nch transistor 269 or cutoff is performed. Therefore, the output of the output terminal VS is controlled by the voltage of the terminal VIN, and the same operation as the conventional CMOS inverter is performed. When the voltage of the secondary battery drops and falls below the minimum operating voltage of the circuit of FIG. 26, the signal at the output terminal VS becomes unstable, but when charging from the primary power source, stable operation is shown. When charging, a voltage larger than the voltage of the secondary battery is applied between the terminals + V0 to -V0 of FIG. At this time, since the + terminal B of the secondary battery and the external terminal + V0 of the charger to which the + voltage is applied are common, the external terminal −V0 becomes lower than the − terminal A of the secondary battery. In this state, a voltage is applied from the charger between + VB and Ve in FIG.
Since the voltage difference between VB and -VB is small, the Nch transistor 269 is turned on, the C potential becomes the same as the potential at the terminal Ve, and the signal at the output terminal VS becomes equal to + VB. This means that even when the voltage of the secondary battery is low when the charger is connected, the output terminal VS of the control circuit becomes the same as the + VB potential, and the control of the switch circuit is performed reliably.

In FIG. 26, the inverter circuit 20 compares the voltage (+ VB to Ve) of the charger with the voltage of the secondary battery (+).
When the voltage between VB and -VB is small, Nch transistor 2
It works to turn 69 on. Inverter circuit 266
The threshold voltage (reversal voltage) can be changed by the size of the Pch transistor or the Nch transistor, etc. By setting this to a voltage equal to or higher than the minimum operating voltage of the control circuit 4, the operation described so far can be surely performed. Done.

For convenience, the output section of the control circuit of the present invention is a CMO.
Although described with S, it is obvious that other elements can also be used. The problem can be solved even if another circuit is used as the output circuit. The charge / discharge control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate in which the division voltages of the voltage division resistors have little variation.

(Embodiment 8) Embodiment 4 of the invention means 2 will be described below with reference to the drawings. FIG. 27 is a circuit block diagram of a fourth embodiment of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is,
The secondary battery supplies power by connecting to the power supply terminals -VB and + VB.

For the power supply, the voltage dividing resistor 1 of the power supply voltage dividing means for dividing the power supply voltage, and the voltage detection circuits 2 and 3 for respectively detecting the two output voltages of the power supply voltage dividing means,
A control circuit 4 which outputs a final control signal VS according to the output signals of the voltage detection circuits 2 and 3 is connected in parallel with each other.

The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit. Voltage dividing resistor 1
The voltage detection circuit 2 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of the secondary battery that is the power supply. Further, the voltage division resistor 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit for detecting overdischarge of the secondary battery as a power source. In the case of the present invention, the voltage dividing resistors 1 input to the respective voltage detecting circuits may be provided separately. Figure 2
In the case of No. 7, the voltage dividing resistor 1 is an example of the charge / discharge control circuit commonly provided in the voltage detection circuits. The control circuit 4 inputs signals regarding overcharge and overdischarge of the secondary battery from the respective voltage detection circuits 2 and 3, and outputs a signal VS for turning on or off the switch circuit of the power supply device.

FIG. 28 is a circuit diagram of a reference voltage circuit for generating a reference voltage input to the comparator circuit of the voltage detection circuit 2 or 3. The voltage of the secondary battery is applied across the reference voltage circuit. The reference voltage circuit is transistor 2
This circuit outputs a reference voltage VR that does not depend on the voltage fluctuation of the secondary battery from the connection point between 01 and the transistor 202. The transistor 201 is a depletion type MOS
The transistor 202 is a field effect transistor, and the transistor 202 is an enhancement-type MOS field effect transistor.
Both the transistors 201 and 202 are N-type transistors of the same conductivity type. Both gate electrodes are connected to the reference voltage output terminal.

Further, when the semiconductor integrated circuit forming the charge / discharge control circuit is formed of a CMOS circuit, the charge / discharge control circuit latches up when the power supply is connected in plus / minus reverse direction. An intermediate potential setting means is provided at the reference voltage output terminal VR as means for setting the output of the reference voltage circuit to the intermediate potential of the secondary battery when latched up. In the embodiment shown in FIG. 28, the intermediate voltage-divided output IN2 of the voltage dividing resistor is connected via the diode 283. The intermediate divided output IN2 is set to an approximately intermediate value between the secondary batteries + VB and -VB. Therefore, when the charge / discharge control circuit has latched up, the reference voltage output has a value that is reduced by about 0.6 V, which is the forward voltage of the diode 283, from the intermediate divided voltage output IN2. Since this value is approximately the intermediate voltage of the voltage of the secondary battery, the voltage detection circuit outputs a signal via the control circuit 4 so that the switch circuit is turned off.

The embodiment shown in FIG. 28 is an example in which malfunction of the switch circuit due to latch-up is prevented by providing means for setting the output of the reference voltage circuit of the voltage detection circuit to the intermediate potential. If the switch circuit is turned off by latch-up, runaway can be prevented. Therefore, the switch circuit may be turned off when the output itself of the control circuit 4 latches up.

The present invention is indispensable for a CMOS IC that malfunctions due to latch-up when the power supply is reversely connected. (Embodiment 9) Embodiment 5 of the means 2 of the present invention will be described below with reference to the drawings.

FIG. 29 is a circuit block diagram of the charging / discharging control circuit according to the fifth embodiment of the present invention. In FIG. 29, external terminals -V0, + V0, switch circuit 103,
The current sense resistor 104, the secondary battery 101, the reference voltage circuit 106, the transistor 107, the constant current source 108, the capacitor 109, and the pull-down high resistor 111 are the same as those in FIG.

As in the case of FIG. 30, the comparator 21 outputs “H” when the current expressed by the equation (1) is exceeded.
The voltage becomes “L”, the transistor 107 is turned off, and the capacitor 109 is charged by the constant current source 108. When the voltage of the capacitor 109 becomes higher than the voltage value VREF of the reference voltage 106, the output of the comparator 22 becomes “H” →
It becomes “L” and the switch circuit 103 is turned off. At this time, the comparator 22 has a latch function, and the output of the comparator 22 becomes "L", and this state is held.

Further, this latch function is performed by the comparator 21.
It is canceled by the output of. FIG. 31 shows a circuit diagram of the latch function comparator. When the voltage of the negative input terminal 314 becomes higher than that of the positive input terminal 313,
The voltage of the output terminal 315 becomes "L". At this time, the output of the inverter 317 becomes "H", and the input on the minus side is made "H". As a result, the output of the comparator 22 with a latch function is latched at "L" even if the voltage of the positive input terminal fluctuates to some extent.

Since the switch circuit 103 is turned off while the load is connected, the minus side input terminal of the comparator 21 is pulled up to + V0 by the load connected to the electronic device such as the video and the overcurrent is caused. State is retained. After that, when the load is removed, the negative input voltage of the comparator 21 is lowered to "L" by the pull-down high resistance 111, so that the output of the comparator 21 becomes "H". Since the latch release terminal 316 of the latch function comparator 22 is set to "H" by this "H" output, the output of the latch function comparator 22 becomes "H" and the latch is released.

In FIG. 29, the overcurrent detection circuit includes a voltage detector for detecting the voltage across the overcurrent detection resistor 104 provided between the external terminal -V0 and the switch circuit 103. It is composed of a delay circuit for delaying the output of the voltage detector in time and a voltage detection circuit with a latch-up function for detecting the output of the delay circuit.
The voltage detection circuit includes a reference voltage generation circuit 106 and a comparator circuit 21. 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 are separately configured.

However, the charge / discharge control circuit includes the charge / discharge control circuit 102 and the overcurrent detection circuit 1 described in the embodiments of the present invention.
It can also be said that the configuration includes both 05 and. (Embodiment 10) FIG. 32 is a circuit block diagram showing Embodiment 1 in the means 3 of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, two secondary batteries are connected in series to the power supply terminals -VB and + VB and supplied as a power supply. To the power source, a voltage dividing resistor 1 of a power source voltage dividing means for dividing the power source voltage and a voltage detection circuit 2 for detecting the output voltage of the power source voltage dividing means are connected.

The voltage detection circuit 2 is specifically a comparator circuit 4 which receives the reference voltage source 43 for the power supply terminal -VB and the output of the voltage dividing resistor 1 as shown in FIG.
4 and 4. The voltage dividing resistor 1 and the voltage detection circuit 2 constitute a circuit that detects the sum voltage of the secondary battery that is the power supply. The voltage detection circuit 2 outputs a signal VS for turning on or off the switch circuit of the power supply device.

The charge / discharge control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate in which the division voltage of the voltage dividing resistor 1 has a small variation. Further, it is obvious that the present invention can be applied to the case where three or more secondary batteries are connected in series. As described above, by detecting the sum voltage of each battery configured by the secondary battery, it is possible to perform optimum charge / discharge control even in the state where the voltage of each battery is partially biased. Therefore, the life of the secondary battery can be improved.

(Embodiment 11) The means 3 of the present invention will be described below.
A second embodiment in will be described with reference to the drawings. FIG. 33
[Fig. 8] is a circuit block diagram of a charge / discharge control circuit of a second embodiment in the third means of the present invention. The voltage detection circuit 3 is a secondary battery 6
Of the overcharge detection voltage V1 of the secondary battery 7
The respective overcharge detection voltages V2 are detected and output as an output signal VS by the control circuit 8. At the same time, the voltage detection circuit 2 detects the voltage of the secondary battery 6, and the detection voltage V3 is set to a voltage lower than the overcharge detection voltage V1. Similarly, the voltage detection circuit 4 detects the voltage of the secondary battery 7, and the detection voltage V4 is set to a voltage lower than the overcharge detection voltage V2. The output signals of these voltage detection circuits 2 and 4 are input to the voltage detection circuits 5 and 3, respectively, and change the voltage values of the overcharge detection voltages V2 and V1 of the voltage detection circuits 5 and 3.

Specifically, when a charger is externally connected to the terminals + VB and -VB to charge the secondary batteries 6 and 7, the original overcharge detection voltage V of the voltage detection circuits 3 and 5 is detected.
1 and V2 are set to 4.2V. However, if the secondary battery 6
When an abnormality occurs in the battery and the charging performance is significantly deteriorated, only the secondary battery 7 is charged, and the difference between the two voltage values becomes large. In order to prevent this, the detection voltage V3 of the voltage detection circuit 2 is set to about 3.2V. When the voltage of the secondary battery 6 does not exceed 3.2V due to deterioration, the voltage detection circuit 5 detects the voltage. The voltage V2 is set to a value lower than 4.2 V, and when it exceeds, the original detection voltage value 4.2 V is set. This setting is performed by the output signal of the voltage detection circuit 2.

Similarly, the output signal of the voltage detection circuit 4 monitors the deterioration of the secondary battery 7, and when the voltage of the secondary battery 7 does not exceed 3.2 V due to the deterioration, the voltage detection circuit 3 detects the voltage. The voltage V1 is set to a value lower than 4.2 V, and when it exceeds, the original detection voltage value 4.2 V is set. This setting is performed by the output signal of the voltage detection circuit 4.

In the description, 3.2V and 4.2V
Was used as an example, but these values are not limited to these values as a matter of course, depending on the battery characteristics. FIG. 35 shows a specific circuit for realizing the block diagram of FIG. The output of the voltage detection circuit 4 is input to the gate of a transistor 9 connected in parallel to a part of the resistor R3, and the voltage detection circuit 3 is turned on or off by turning on or off the transistor 9.
The overcharge detection voltage value V1 can be changed.

Similarly, the output of the voltage detection circuit 2 is turned on or off by turning on or off the transistor 10 connected in parallel to a part of the resistor connected in parallel to the secondary battery 7. The overcharge detection voltage V2 can be changed. (Embodiment 12) Embodiment 3 of the means 3 of the present invention will be described below with reference to the drawings.

FIG. 36 is a block diagram of a rechargeable power supply device of the present invention and a charge / discharge control circuit therefor. External terminal +
A secondary battery 101, a voltage detection circuit 2 for detecting the voltage of the secondary battery, and a control circuit 3 for controlling the impedance of the switch circuit 5 are connected in parallel to V and -V, respectively. The switch circuit 5 is connected in series between the secondary battery 101 and the external terminal -V, and the electrical connection between the external terminal and the secondary battery 101 is performed by electrical control. The control circuit 3 performs an input logic process on the output of the voltage detection circuit 2 and outputs a signal for turning on or off the switching circuit 5.

For example, when a power source for charging the external terminal is connected and the secondary battery 101 is charged from the power source, when the voltage of the secondary battery 101 becomes higher than the overcharge voltage level, the voltage detection circuit The signal of 2 is inverted and the control circuit 3
Entered in. Switch circuit 5 is turned off from control circuit 3
Signal is output to stop charging. Conversely, when an electronic device that consumes power, such as a video camera, is connected to the external terminals + V and −V and power is supplied from the secondary battery 101 to the electronic device, the voltage of the secondary battery 101 is over-discharged. When the voltage drops below the voltage level, the signal of the voltage detection circuit 2 is inverted into a signal opposite to the normal voltage range. Then, the control circuit 3
As a result, a signal that turns off the switch circuit 5 is output to stop the discharge. The normal voltage range is an intermediate state between the overcharge level and the overdischarge level.

In the rechargeable power supply device described above, the voltage detection circuit 2, the control circuit 3 and the switch circuit 5 can be formed by semiconductor integrated circuits arranged on the same substrate. Figure 38
FIG. 4 is a circuit diagram of an embodiment of a switch circuit used in the charge / discharge control circuit of the present invention. A switch circuit is provided between the external terminal -V and the negative terminal 34 of the secondary battery. The switch circuit is provided with an N-type insulated gate field effect transistor (hereinafter referred to as N-type MISFET) 31 between the external terminal −V and the negative terminal 34 of the secondary battery, the substrate of the N-type MISFET and the external terminal −. An N-type MISFET 32 and an N-type MISFET 33 are provided between the V and the negative terminal 34 of the secondary battery, respectively. Three N-type MI
The gate electrodes 31G, 32G and 33G of the SFET are controlled by the control circuit.

For example, when the power supply for charging the external terminal is connected to charge the secondary battery, the transistors 31 and 32 are turned on and the transistor 33 is turned off.
is doing. When the charging is overcharged, the output of the voltage detection circuit is inverted and the control circuit outputs a signal to turn off the switch circuit. That is, the transistors 31 and 33 are turned off and only the transistor 32 is kept on.

When a portable device such as a video camera is connected to the external terminal and power is supplied from the secondary battery to the portable device, the switch circuit in FIG. 38 is controlled to be turned on. That is, the transistors 31 and 33 are ON
However, the transistor 32 is off. When the electric power is supplied to cause the over-discharge state, the output signal of the voltage detection circuit is inverted, and the control circuit outputs a signal for turning off the switch circuit. That is, the transistors 31 and 32
Is turned off, and only the transistor 33 is turned on.

In the normal state, it is possible to detect whether it is operating in the charge state or the discharge state by comparing the voltage between the external terminal -V and the negative terminal 34 of the secondary battery. . The control circuit controls the impedances of the transistors 32 and 33 by detecting the charge state and the discharge state. That is, the control circuit has a function of detecting charge or discharge.

In the switch circuit of FIG. 38 described above, only one transistor 31 is the battery. Therefore, in general, a transistor having a large current driving capability can be formed with half the conventional size in order to reduce the voltage drop in the switch circuit. Transistors 32 and 33 of the switch circuit of the charge / discharge control IC of the present invention are switching transistors for selectively connecting the substrate of the current driving transistor 31 to either the external terminal or the negative terminal of the secondary battery. . Therefore, the current driving capability of the substrate potential switching transistors 32 and 33 may be small. The current driving capability of the transistor 31 is generally several A, while the transistor 3
The current drivability of 2 and 33 is as small as 1/1000 or less, and when integrated, the transistors 32 and 33 are
Area is so small that it can be ignored.

As described above, by using the switching circuit as shown in FIG. 38, the current driving capability of the current driving transistor can be almost doubled as compared with the conventional one, so that the same current driving capability can be obtained. On the other hand, the transistor area can be reduced to about half, and miniaturization can be facilitated. The potential of the substrate of each transistor can be electrically separated by the N well. Therefore, they can be easily provided on the same semiconductor substrate.
However, even if the transistors 31, 32, and 33 are composed of individual transistors, their operations are the same.

FIG. 39 is a sectional view of a transistor of the charge / discharge control IC of the present invention. The transistor is formed using single crystal silicon films 53, 54 and 55 formed on an insulating film 52 formed on a silicon substrate 51. A substrate having a single crystal silicon film provided over an insulating film is generally referred to as an SOI substrate. S
A transistor having a sectional view as shown in FIG. 39 is formed using the OI substrate. That is, the N-type source region 53 and the N-type drain region 55 are provided on both sides of the channel forming region 54, and the gate electrode 57 is provided on the channel forming region 54 via the gate insulating film 56. By using the transistor having the structure as shown in FIG. 39, the potential of the channel formation region 54 which is also the substrate of the transistor can be formed electrically independently of the transistor provided over the same substrate. That is, since the substrate potentials of the transistors can be electrically separated from each other, it is possible to easily realize a charge / discharge control IC having a switch circuit.

FIG. 40 shows a plan view of a transistor in which the potential of a channel forming region which is a substrate is set to the same potential as that of a source region. An N-type source region 73, a drain region 72, and a channel forming region therebetween are formed in the single crystal silicon semiconductor film 71 provided over the insulating film, and a gate electrode 77 is formed over the channel forming region with a gate insulating film interposed therebetween. It is provided. A P-type source region 74 is provided in a part of the source region 73, and the source electrode 75 sets the potentials of the source region 73 and the channel forming region to the same potential.

FIG. 41 is a sectional view taken along the line AA 'in FIG. A single crystal silicon semiconductor film 71 is provided on the silicon substrate 61 with an insulating film 68 interposed therebetween. In the single crystal silicon semiconductor film 71, a P-type source region 64, a P-type channel forming region 69 and an N-type drain region 62 are formed. A gate electrode 67 is provided on the channel formation region 69 via a gate insulating film 63. The P-type source region 64 and the N-type source region are connected to the source electrode 65. The N-type drain region 62 is the drain electrode 6
Connected to 6.

FIG. 42 is a circuit diagram of a switch circuit of the charge / discharge control IC of the present invention constructed by using the transistor structure MISFET as shown in FIG. External terminal −
N-type MISFETs 81 and 82 using an SOI substrate are connected in series between V and the negative terminal 80 of the secondary battery. The substrates of the transistors 81 and 82 are connected so as to have the same potential as the external terminal and the terminal of the secondary battery, respectively. By using the SOI substrate, the potentials of the substrate can be set to different potentials.

As described above, the charge / discharge control circuit in which the switch circuits are arranged on the same substrate can be realized.

[0123]

The charge / discharge control circuit of the present invention has a structure in which the voltage dividing resistors of the overcharge and overdischarge detection circuits provided therein have switch elements for reducing current consumption, thereby reducing current consumption. Has the effect of promoting Further, the charge / discharge control circuit, the secondary battery, and the switch circuit can supply a power supply device having a long life.

Further, since the current consumption of the error amplifier of the overcharge detection circuit is cut off in the overdischarge state, the power consumption of the battery in the overdischarge state can be suppressed to be small and the deterioration of the battery can be prevented. There is an effect.
Further, since the current consumption of the error amplifier of the overcharge detection circuit is cut off, the power consumption of the battery in the overdischarged state can be suppressed to be small, and the deterioration of the battery can be prevented.

Since a plurality of comparator circuits can be integrated, the IC chip size can be reduced and the current consumption can be reduced, and an inexpensive and high-performance battery charge / discharge control circuit can be realized. In addition, the current cut transistor is connected in series to the inter-battery voltage detection buffer circuit of the secondary battery provided inside, which has the effect of reducing the current consumption. In particular,
This has the effect of reducing current consumption in an over-discharged state in which the capacity of the secondary battery sharply decreases. Further, by inserting the current cutting transistor, it is possible to output a signal indicating overcharge / overdischarge and a normal state to the connected battery voltage detection terminal which is an output terminal of the buffer circuit, which is effective.

Further, by adopting a structure which also serves as a reference voltage source for detecting overcharge and detecting overdischarge of the secondary battery provided inside, the charge / discharge control circuit can be constructed at a low number of parts and can be manufactured at low cost. Moreover, there is an effect that it is possible to reduce functionally important current consumption. By reducing the current consumption of the charge / discharge control circuit, the life of the rechargeable power supply device can be improved. Further, according to the present invention, even when the secondary battery is formed of a plurality of batteries, since the reference voltage source for detecting the voltage of each battery is configured by one circuit, the charge / discharge control circuit is similarly formed. This has the effect of reducing the current consumption and improving the life of the rechargeable power supply device.

Further, the internal voltage dividing resistor for detecting the secondary battery voltage is used for detecting the overcharge pressure and for detecting the overdischarge voltage, so that a circuit connected in parallel to the secondary battery is formed. Has the effect of reducing current consumption. Further, by reducing the current consumption of the charge / discharge control circuit, the life of the secondary battery can be improved. Further, since the voltage dividing resistor has a configuration that serves both for overcharging and for overdischarging, when the charge / discharge control circuit is integrated, the chip size can be reduced,
There is an effect that it can be offered cheaply.

As described above, according to the present invention, as soon as the voltage detection circuit detects overcharge or overdischarge in the charge / discharge control circuit, the detection signal is fed back to make the overcharge or overdischarge detection level higher. Alternatively, resetting to detect over-discharging has an effect of eliminating malfunction. In addition, after the resetting, by switching the switch circuit between the secondary battery and the charging power source, there is an effect of preventing the unstable oscillation of the voltage detection circuit due to the voltage fluctuation of the secondary battery due to the impedance change of the switch circuit.

Further, since the delay circuit is provided between the control circuit and the overcharge / overdischarge detection circuit provided inside the control circuit, there is an effect of preventing malfunction at the time of detection. Further, it also has an effect of preventing malfunction of the secondary battery at the initial connection. The charge / discharge control circuit, the secondary battery, and the switch circuit can supply a power supply device with stable operation.

Further, the voltage of the external terminal of the power supply unit is input to the charge / discharge control circuit of the present invention so that the voltage of the secondary battery serving as the power source of the charge / discharge control circuit is the lowest. When the charger is connected even when the voltage is below the operating voltage, the switch circuit can be controlled, and a power supply device that can perform reliable charging regardless of the voltage of the secondary battery can be supplied.

Further, as described above, the present invention provides C
In the charge / discharge control circuit composed of MOSIC, the output of the control circuit is configured to turn off the switch circuit when a voltage reverse to the normal voltage is applied to the charge / discharge control circuit. It has the effect of preventing current runaway.

Further, the charge / discharge control circuit of the present invention has the effect of reliably preventing the oscillation phenomenon at the time of detecting the overcurrent by providing the overcurrent detection circuit with the latch function. The charge / discharge control circuit of the present invention can supply a power supply device having a long life by providing a voltage dividing resistor and a voltage detection circuit between the terminals that output the sum voltage of two or more secondary batteries connected in series.

When two rechargeable batteries are connected in series and charged, even if one battery becomes abnormal and the charging performance is significantly deteriorated, only the normal battery is charged and the difference between the voltage values of both batteries is charged. Can be prevented from increasing. Further, since the rechargeable power supply device and charge / discharge control circuit of the present invention are configured as an integrated circuit including a switch circuit, the following effects (1) assembling cost can be reduced. (2) The size can be reduced. (3) Improvement of reliability as a device.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a first embodiment of a charge / discharge control circuit of the present invention.

FIG. 2 is a circuit block diagram of a conventional rechargeable power supply device.

FIG. 3 is a circuit diagram of a voltage detector.

FIG. 4 is a circuit block diagram of another embodiment of the charge / discharge control circuit of the present invention.

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

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

FIG. 7 is a circuit example of an error amplifier having a power ON / OFF function.

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

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

FIG. 10 is a battery charge / discharge control circuit diagram showing another embodiment of the present invention. It is a circuit diagram of a voltage detector.

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

FIG. 12 is a circuit diagram showing a buffer circuit.

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

FIG. 14 is a circuit diagram of a reference voltage circuit.

FIG. 15 is a circuit block diagram of a charge / discharge control circuit when the number of secondary batteries is two.

FIG. 16

FIG. 17 is a circuit block diagram of a charge / discharge control circuit according to a first embodiment of means 2 of the present invention.

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

FIG. 19 is a circuit block diagram of a charge / discharge control circuit according to a second embodiment of the means 2 of the present invention.

FIG. 20 is a circuit diagram of a delay circuit according to a second embodiment of means 2 of the present invention.

FIG. 21 is a circuit diagram of a delay circuit according to a second embodiment of means 2 of the present invention.

FIG. 22 is a circuit diagram of a delay circuit according to a second embodiment of means 2 of the present invention.

FIG. 23 is a circuit diagram of a delay circuit according to a second embodiment of the means 2 of the present invention.

FIG. 24 is a circuit block diagram of a rechargeable power supply device according to a third embodiment of means 2 of the present invention.

FIG. 25 is a circuit block diagram of a charge / discharge control circuit according to a third embodiment of the means 2 of the present invention.

FIG. 26 is an example of a control circuit output section of the present invention.

FIG. 27 is a circuit block diagram of a charge / discharge control circuit according to a fourth embodiment of the means 2 of the present invention.

FIG. 28 is a circuit diagram of a reference voltage circuit according to a fourth embodiment of the means 2 of the present invention.

FIG. 29 is a rechargeable control circuit diagram according to the fifth embodiment of the means 2 of the present invention.

FIG. 30 is a conventional rechargeable control circuit diagram.

FIG. 31 is a circuit diagram of a comparator with a latch function of the present invention.

FIG. 32 is a circuit block diagram of a charge / discharge control circuit according to a first embodiment of means 3 of the present invention.

FIG. 33 is a circuit block diagram of a charge / discharge control circuit according to a second embodiment of means 3 of the present invention.

FIG. 34 is a circuit diagram of a voltage detector.

FIG. 35 is a circuit block diagram of another embodiment of the charge / discharge control circuit of the second embodiment in the third means of the present invention.

FIG. 36 is a circuit block diagram of a third embodiment in the means 3 of the rechargeable power supply device and the charge / discharge control circuit according to the present invention.

FIG. 37 is a circuit block diagram of a conventional rechargeable power supply device.

FIG. 38 is a circuit diagram of a switch circuit of the charge / discharge control circuit in the means 3 of the present invention.

FIG. 39 is a cross-sectional view of a transistor used in the charge / discharge control circuit in the means 3 of the present invention.

FIG. 40 is a plan view of a transistor used in the charge / discharge control circuit in the means 3 of the present invention.

41 is a cross-sectional view of the transistor of FIG. 35 taken along the line AA ′.

FIG. 42 is a circuit diagram of a switch circuit of the charge / discharge control circuit in the means 3 of the present invention.

[Explanation of symbols]

1 voltage division circuit 2, 3 voltage detection circuit 4 control circuit 5 switch element 11 reference voltage circuit 12 2'error amplifier of overdischarge detection circuit 13 3'error amplifier of overcharge detection circuit 14 battery connection terminal 15 battery connection terminal 16 excess Discharge detection circuit output terminal 17 Overcharge detection circuit output terminals 18, 19 Battery 52, 53 Comparator circuit 21 Comparator 22 Latch function comparator 23 Latch function comparator positive input terminal 24 Latch function comparator negative input terminal 25 Latch function Comparator output terminal 26 Latch function comparator latch release signal input terminal 101 Secondary battery 102 Charge / discharge control circuit 103 Switch circuit 104 Current sense resistor 106 Reference voltage circuit 111, 112 Battery 113, 114 Voltage division circuit 115, 1 16 voltage detection circuit 117 control circuit 118 buffer circuit 175 voltage division value control transistors 191, 192 delay circuit 203 Pch transistor 204 Nch transistor 205 capacitance 226 constant current circuit 266 inverter circuit 267 final output stage Pch transistor 268 final output stage Nch transistor 269 output Nch transistor for control

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[Procedure amendment]

[Submission date] June 11, 2002 (2002.6.1)
1)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Continued front page    (31) Priority claim number Japanese Patent Application No. 5-57563 (32) Priority date March 17, 1993 (March 17, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-67132 (32) Priority date March 25, 1993 (March 25, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-62259 (32) Priority date March 22, 1993 (March 22, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-52476 (32) Priority date March 12, 1993 (March 12, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-56208 (32) Priority date March 16, 1993 (March 16, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-57564 (32) Priority date March 17, 1993 (March 17, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-62260 (32) Priority date March 22, 1993 (March 22, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-65758 (32) Priority date March 24, 1993 (March 24, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-94677 (32) Priority date April 21, 1993 (April 21, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-120198 (32) Priority date May 21, 1993 (May 21, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-126238 (32) Priority date May 27, 1993 (May 27, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-220279 (32) Priority date September 3, 1993 (1993.9.3) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-223647 (32) Priority date September 8, 1993 (September 9, 1993) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-224186 (32) Priority date September 9, 1993 (September 9, 1993) (33) Priority claiming country Japan (JP) (72) Inventor Minoru Sudo             1-8 Nakase, Nakase, Mihama-ku, Chiba City, Chiba Prefecture             Ico Instruments Co., Ltd. F-term (reference) 5G003 AA01 BA01 CA14 CC02 DA07                       DA13 FA04 GA01 GC06                 5H030 AA01 FF43 FF44

Claims (6)

[Claims] 1. A voltage dividing circuit for dividing a voltage of a power source which is a secondary battery, an overdischarge voltage detecting circuit for detecting a divided voltage which is an output of the voltage dividing circuit, and a series connected to the voltage dividing circuit. A switching element connected to the voltage dividing circuit and the switching element in parallel with the switching element.
A control circuit that is connected to a secondary battery and that outputs a signal that processes signals input from the overcharge detection circuit and the overdischarge detection circuit to control charging / discharging. And a value of ON resistance of the switch element is smaller than a value of resistance of the resistor, and the control circuit is configured to prevent the secondary battery from being over-discharged. When the overdischarge voltage detection circuit detects that there is a signal output,
A charge / discharge control circuit, characterized in that the switch element is turned off. 2. A secondary battery connected to an external power supply terminal via a switch circuit, a charge / discharge control circuit connected in parallel with the secondary battery for controlling the switch circuit, and the charge / discharge control circuit. A voltage dividing circuit for dividing the voltage of the secondary battery; a switch element connected in series to the voltage dividing circuit; an overcharge voltage detecting circuit for detecting the output of the voltage dividing circuit; An over-discharge voltage detection circuit for detecting the output of the division circuit; and the voltage division circuit and the switch element in parallel
A control circuit that is connected to a secondary battery and that processes a signal from the overcharge voltage detection circuit and the overdischarge voltage detection circuit and outputs a signal that controls the switch circuit; Is composed of a plurality of resistance elements connected in series, the value of the ON resistance of the switch element is a value smaller than the value of the resistance of the resistor, the control circuit, the secondary battery A rechargeable power supply device, characterized in that the switch element is turned off upon receiving a signal output by an overdischarge voltage detection circuit detecting that it is in an overdischarge state. 3. The charge / discharge control circuit has an external terminal, and ON / OFF of the switch element is controlled by a signal input to the external terminal. Charge / discharge control circuit. 4. The rechargeable power supply device according to claim 2, wherein the rechargeable power supply device has an external terminal, and ON / OFF of the switch element is controlled by a signal input to the external terminal. 5. The charge / discharge circuit according to claim 1, wherein the switch element is connected between the voltage division circuit and one electrode of the power supply and between the voltage division circuit and the other electrode of the power supply. Control circuit. 6. The rechargeable device according to claim 2, wherein the switch element is connected between the voltage division circuit and one electrode of the power supply and between the voltage division circuit and the other electrode of the power supply. Power supply.