JP2004113000A - Charging/discharging control circuit and rechargeable type power supply apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the lifetime of a rechargeable type power supply apparatus, and to reduce the current consumption of a charging/discharging control circuit of the power supply apparatus for the same. <P>SOLUTION: A voltage-dividing circuit 1, an overcharging voltage detector circuit 2, an overdischarging voltage detector circuit 3 and a control circuit 4 are connected in parallel with a secondary cell of a power supply. The circuit 4 detects the state of the secondary cell from the overcharging and overdischarging voltage detector circuits and outputs a signal VS for controlling supplying of a power to an external unit or charging by an external power supply. Further, the control circuit controls a switching element 5, provided in series with the dividing circuit 1, to reduce current flowing to the dividing circuit. <P>COPYRIGHT: (C)2004,JPO

Description

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.

(2) 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 Unexamined Patent Publication No. Hei 4-75430, "Rechargeable power supply device". That is, the secondary battery 101 is connected to the external terminal -VO or + VO via the switch circuit 103. Further, a charge / discharge control circuit 102 is provided in parallel with the secondary battery 101. The charge / discharge control circuit 102 has a function of detecting the voltage of the secondary battery 101. When the voltage of the secondary battery 101 is either in an overcharged state (state in which the voltage is higher than a predetermined high voltage value) or in an overdischarged state (state in which the voltage is lower than a predetermined low voltage value), the switch circuit A signal is output from the charge / discharge control circuit 102 so that 103 is turned off. Therefore, in the case of an overcharged state, the switch circuit 103 is turned off, and charging of the secondary battery 101 from the primary power supply connected to the external terminals -VO and + VO is stopped. In the case of an overdischarge state, the switch circuit 103 is similarly turned off to stop supplying energy to a load (for example, a mobile phone operated by a secondary battery) connected to the external terminals -VO and + VO. That is, the charge / discharge control circuit 102 controls the switch circuit 103 between the secondary battery 101 and the external terminal, thereby preventing unnecessary charging of the secondary battery 101 from the external terminal, This prevents a transient decrease in the storage capacity of the secondary battery 101 due to energy supply from the battery 101 to a load connected to an external terminal.

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

Suppose that the voltage value of the reference voltage circuit 106 is VREF [V], the resistance value of the current sensing resistor 104 is R [Ω] (at this time, the ON resistance of the switch circuit 103 is sufficiently smaller than R), If the current flowing there is I [A],
I ≧ VREF / R [A] (1)
At this time, the output of the comparator circuit 21 changes from “H” to “L”, the transistor 107 is turned off, the capacitor 109 is charged by the constant current source 108, and after a certain delay time, the output of the comparator circuit 302 becomes “H”. "→", 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 output of the comparator circuit 302 is compared so that the switch circuit 103 is turned off.

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 a circuit block diagram of FIG. 37 is known. For example, it is disclosed in Japanese Unexamined Patent Application Publication No. 4-75430 "Rechargeable power supply device". That is, the secondary battery 24 and the charge / discharge control IC 21 are provided in parallel with the external terminals + V and −V via the switch transistors 372 and 373, respectively. 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, when the voltage of the secondary battery 24 becomes equal to or higher than the overcharge voltage by the charging power supply connected to the external terminals + V and -V, the switch terminal 372 is switched from ON to OFF to charge the external battery 24 from the external terminal. To stop. Conversely, when a portable device such as a video camera is connected to the external terminal, and electricity is supplied to the portable device from the secondary battery 24, the voltage of the secondary battery drops and drops below the overdischarge voltage. The switch transistor 373 is turned off from on 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.

However, the conventional charge / discharge control circuit shown in FIG. 2 has a problem that the life of a secondary battery as an energy supply source is shortened because the current consumption by itself is large. As a result, there is a problem that the use time of the device driven by the secondary battery is shortened. Furthermore, when the storage capacity of the secondary battery is reduced and the battery is overdischarged, the power supply is provided in the power supply device despite the fact that the energy supply from the secondary battery to the external device is stopped by the switch circuit. Due to the current consumption of the charge / discharge control circuit itself, there is a problem that further overdischarge is promoted, and deterioration of the battery and shortening of the life are accelerated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rechargeable power supply device including a long-life secondary battery by reducing the current consumption of a charge / discharge control circuit in order to solve such a conventional problem. And Further, the conventional example shown in FIG. 30 has the following various disadvantages. That is, a charger is externally connected to the terminals -VO and + VO, and when the secondary battery 101 is being charged, the switch circuit 103 is turned off when the secondary battery is fully charged. By turning OFF, the potential at both ends of the secondary battery 101 decreases, and the charging state, that is, the switch circuit 103 is turned ON again. At such a voltage before and after the completion of charging, detection of full charge may oscillate unstable.

(4) As described in the related art, when the secondary battery is overcharged during charging, the charge / discharge control circuit operates to turn off the switch circuit that controls the charging of the secondary battery. However, since the charge / discharge control circuit is connected in parallel with the secondary battery, current consumed during operation is supplied from the secondary battery. When a current is supplied to the secondary battery, a voltage drop occurs, the voltage drops below the overcharge detection voltage, and the switch circuit turns on. For this reason, (the voltage of the secondary battery rises due to charging → rises to the overcharge voltage → the voltage of the secondary battery falls due to the operation of the charge / discharge control circuit → the voltage of the secondary battery rises again due to charging) There was a problem that could not be transferred to. The same problem also occurs when the overdischarge state is released while the battery in the overdischarge state is being charged.

Also, if the logic of the switch circuit is not determined when the charge control circuit is connected to the secondary battery for the first time, the initial state will be unstable, and even if the voltage value of the secondary battery is normal, overcharging will occur. Alternatively, there is a problem that an over-discharge state occurs. When the overdischarge of the secondary battery progresses and the 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. State. In other words, since the voltage of the secondary battery has dropped further from the overdischarged state, charging cannot be performed because the charge / discharge control circuit cannot operate the switch circuit normally even if charging is performed from the primary power supply. It becomes possible. That is, if the voltage of the secondary battery drops below the minimum voltage of the charge / discharge control circuit even once, charging becomes impossible, so that the secondary battery cannot be used again.

Another problem of the conventional example is that when a charger is connected to both ends of a secondary battery and the secondary battery is charged, charge / discharge control is performed by making the polarity of the charger different from that of the secondary battery. When the circuit is connected in reverse, so-called reverse connection, the charge / discharge control circuit malfunctions due to the latch-up of the CMOS IC that constitutes the charge / discharge control circuit, causing a large current to flow through the secondary battery to deteriorate it. was there.

Further, as another problem, when an abnormality occurs in the load connected to both ends of the secondary battery and an excessive current flows from the secondary battery, the overcurrent detection circuit turns off the switch circuit 103, When the switch circuit is turned off, the voltage of the secondary battery rapidly increases, thereby increasing the reference voltage value of the overcurrent detection circuit, closing the switch circuit 103 again, and causing a problem of oscillation. .

Therefore, an object of the present invention is to provide a charge / discharge control circuit that does not malfunction so as to solve such a conventional problem. Further, when two secondary batteries are used in series, the conventional example has the following disadvantages. That is, the two rechargeable batteries are subject to one-sided burrs due to their life. However, even in this case, if the sum of the two voltages is equal to or higher than a certain voltage, there is no problem in using the voltage. In the conventional example, the sum voltage cannot be monitored because each battery voltage is monitored, and the use of the device has to be discontinued even though the battery is usable. It will be shorter. In addition, when the battery is charged in the same manner as the other normal battery due to the occurrence of the one-sided swelling, the one-sided swelling is further promoted, and the life of the battery is significantly shortened.

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

Accordingly, an object of the present invention is to provide a small, inexpensive, and highly reliable charge / discharge control circuit for a rechargeable battery device and a rechargeable power supply device.

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

In addition, according to the present invention, the current consumption is suppressed by current limiting means for limiting the entire current consumption flowing through the error amplifier. For example, the present invention adds a power ON / OFF function as current limiting means to an error amplifier of an overcharge detection circuit, controls ON / OFF of the error amplifier with a signal of the overdischarge detection circuit, To reduce current consumption.

Further, in the present invention, in the charge / discharge control circuit, a switch circuit for controlling current consumption is provided in a buffer circuit for externally outputting a potential of a connection point of each battery constituting the secondary battery. The switch means is controlled by a control circuit provided in the charge / discharge control circuit. In particular, the configuration is such that the control circuit controls the switch means of the buffer circuit to be ON only in an overdischarge state in which the capacity of the secondary battery has been reduced.

Also, the present invention is configured such that the charge / discharge control circuit serves as one reference voltage source for each of the overcharge voltage detection circuits and the overdischarge voltage detection circuit for monitoring the voltage of the secondary battery. Further, when a plurality of secondary batteries are connected in series, an overcharge voltage detection circuit and an overdischarge voltage detection circuit that monitor the voltage of each battery are configured. A different reference voltage of a voltage detection circuit for monitoring the voltage of each battery is supplied by one reference voltage generation circuit.

The present invention also provides a charge / discharge control circuit, comprising: an overcharge detection voltage division circuit for obtaining a divided voltage for overcharge detection of a secondary battery; and an overdischarge detection voltage for obtaining an overdischarge detection divided voltage. Both functions of the divider circuit are constituted by one overdischarge / overcharge detection voltage divider circuit.

(Means 2)
In order to solve the above-mentioned problem of the prior art shown in FIG. 30, the present invention relates to a charge / discharge control circuit, which detects an overcharge or an overdischarge set in a secondary battery by a voltage detection circuit, and then sets the set voltage. The voltage is reset to a voltage that can be easily detected as overcharge / overdischarge, and the signal timing is set so that the switch circuit is turned off after the reset.

In addition, the present invention has a configuration in which a delay circuit is provided between the voltage detection comparator and the control circuit in the charge / discharge control circuit. In addition, the delay circuit is configured such that the logic circuit is fixed for a certain period of time when the secondary battery is connected, the switch circuit is turned on, and the rechargeable power supply can be used from the beginning.

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 is connected to the power supply device even when the voltage of the secondary battery is lower than the minimum operating voltage of the charge / discharge control circuit. Sometimes, the circuit configuration was such that the switch circuit could be controlled. Further, the present invention has a configuration in which the output signal of the control circuit always outputs a signal for turning off the switch circuit when the secondary battery is reversely connected in the charge / discharge control circuit. More specifically, the configuration is such that the output of the voltage detection circuit that determines the output of the control circuit always turns off the switch circuit. More specifically, the switch circuit turns off the output of the constant voltage circuit related to the output of the voltage detection circuit.

Further, in 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-mentioned conventional problem shown in FIG. 37, the present invention monitors a voltage of each of two secondary batteries in a charge / discharge control circuit, and according to the monitored voltage value, detects the other voltage detection value. Is switched.

Also, in the present invention, a resistor is provided between terminals from which the sum voltage is output so that the sum voltage of the two batteries can be monitored, and a voltage detection circuit is configured. 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 a single transistor, a structure is provided in which the substrate of the transistor is provided between the source electrode and the drain electrode of the switching transistor.

Further, the present invention relates to a charge / discharge control method using a semiconductor substrate having a semiconductor film provided on an insulating film capable of freely controlling a transistor substrate (hereinafter referred to as an SOI substrate; SOI is an abbreviation for Silicon On Insulator). The configuration of the semiconductor integrated circuit device was adopted.

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

(4) Since a plurality of error amplifiers are replaced by one multi-input type error amplifier, the chip area can be significantly reduced. With such a configuration, the current consumption of the buffer circuit is reduced to a necessary minimum, so that a charge / discharge control circuit with low current consumption and a long-life rechargeable power supply device can be obtained.

In the charge / discharge control circuit configured as described above, the number of reference voltage sources can be less than half, so that the current consumption and the number of components (chip size in the case of an integrated circuit) can be reduced. . In the charge / discharge control circuit configured as described above, the voltage dividing circuit for detecting the voltage is configured by half in principle. Therefore, the current flowing therethrough is also reduced to half the value in comparison with the charge / discharge control circuit in which the voltage dividing circuit is separately formed.

Further, the number of components can be reduced because the voltage dividing circuit is also configured for overcharge voltage detection and overdischarge voltage detection. When formed as an integrated circuit, the chip size can be reduced by reducing the number of components. 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 overcharge or overdischarge is detected. Further, after that, by turning off the switch circuit, the voltage detection circuit is prevented from malfunctioning due to voltage fluctuation of the secondary battery due to the switch circuit being turned off.

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

In addition, 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 charging is reliably performed even when the voltage of the secondary battery becomes extremely low. . Further, when the connection is reversed, the switch circuit is always turned off, so that the charger and the secondary battery are electrically separated. Therefore, the secondary battery is not affected at all by the reverse connection state of the charger.

(4) The latch function provided in the overcurrent detection circuit has an effect that oscillation at the time of overcurrent detection can be avoided. In the charge / discharge control circuit configured as in the above-described means 3, a resistor is provided between the terminals from which the sum voltage is output, and thereby voltage detection can be performed.

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

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit block diagram of Embodiment 1 of the charge / discharge control circuit in the means 1 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 is connected to the power terminals -VB and + VB to supply power.

The power supply includes a resistor 1 of 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 division means, and outputs of the voltage detection circuits 2 and 3 respectively. A control circuit 4 that outputs a final control signal VS by a signal is connected in parallel with each other.

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

{Circle around (4)} The control circuit 4 also controls the switch element 5 provided for limiting the current flowing through the voltage dividing resistor 1. A 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 simply connected directly to the voltage dividing resistor, a large direct current flows. The switch element 5 is inserted between the power supply line -VB and the voltage dividing resistor 1, and is controlled by a signal from the control circuit 4 or a signal generated from another circuit.

ス イ ッ チ The resistance of the switch element 5 connected in series to the voltage dividing resistor 1 is preferably as small as possible. If the resistance value of the voltage dividing resistor 1 is not set to a value sufficiently smaller than the resistance value, the output of the voltage dividing resistor 1 is affected by the resistance value of the switch element. Therefore, it is preferable to provide the voltage dividing resistor 1 directly at the end of the voltage dividing resistor 1 by directly connecting to the power supply line, rather than providing the voltage dividing resistor 1 in the middle as shown in FIG. .

As shown in FIG. 1, when the switching element is an insulated gate field effect transistor, the ON resistance of the transistor can be reduced by setting the voltage between the source and the gate electrode of the transistor to the power supply voltage level. . As the voltage dividing resistor 1, a high-resistance polycrystalline film having a sheet resistance of about 10 kΩ / □ is used in order to reduce the current flowing therethrough. The resistance value of the voltage dividing resistor 1 is designed to be a high resistance value of about 10 MΩ. O of switch element 5
The N resistor is designed to have a low resistance value of at most several kΩ, and is set to about 1/1000 or less of 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, almost no current can be consumed when the transistor 5 is OFF.

FIG. 4 is a circuit block diagram in which a P-type insulated gate field effect transistor is inserted between the voltage dividing resistor 21 and 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 input from the terminal 26 to the gate of the switch element when the switch element 25 is to be turned off, and -VB is input to the terminal 26 when the switch element 25 is to be turned on. You. The ON resistance is 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 formed at both ends of the voltage dividing resistor 31. 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 embodiment of FIGS. By inserting both switch elements 35 and 36 on the power supply side as shown in FIG. 5, the power supply voltage dividing circuit can be operated quickly. Also, since the switching elements are almost equally inserted into the dividing circuit, there is an effect that the ON resistance of the switch element hardly affects the output of the voltage dividing circuit.

The charge / discharge control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate where the division voltage of the voltage division resistor 1 has little variation.

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

In FIG. 6, when 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 Expression (2), the voltage of the terminal 16 becomes the “Low” level, This indicates that the battery is in an overdischarge state. When the voltage exceeds the overcharge detection voltage VKAJ in Expression (3), the voltage of the terminal 17 becomes a “High” level, indicating that the battery is in an overcharge state.

VKAH = (R1 + R2 + R3) × Vref / (R2 + R3) (2)
VKAJ = (R1 + R2 + R3) × Vref / (R3) (3)
That is, VKAH and VKAJ can be arbitrarily set by setting the values of R1 to R3 and the value of Vref so as to match the characteristics of the battery. The error amplifier 13 of the overcharge detection circuit has a power ON / OFF function. When the output of the error amplifier 12 of the overdischarge detection circuit is at a “Low” level, the power is turned off. When the output is at a “High” level, the power is turned on. It becomes. When the power is off, the error amplifier 13 does not operate and cuts the current consumption, and the output terminal 17 is fixed at the “Low” level. That is, the operation of the error amplifier 13 is controlled by the output of the error amplifier 12.

(4) The overdischarge detection voltage VKAH and the overcharge detection voltage VKAJ have a relationship of Expression (4) from Expressions (2) and (3).

VKAH <VKAJ (4)
That is, in a state where overdischarge is detected, the error amplifier 13 of the overcharge detection circuit does not need to be operated, not necessarily in an overcharge state. Therefore, the present invention becomes possible.

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

(4) The divided voltage and the reference voltage are input to the input terminals 61 and 62, respectively. The error amplification operation is performed during a period when the “High” level voltage is input to the operation control terminal 63. As a result of the overdischarge state, the voltage of the terminal 16 becomes “Low” level, the transistors M1 and M2 are turned off, the current consumption is cut off, and the transistors M3 and M4 are turned on and the output terminal 17 is turned “Low”. "Fix to level.

Next, another embodiment of the present invention will be described with reference to FIG. For the battery connection terminals 14 and 15, a reference voltage generation circuit 11, a first error amplifier (configured from M11, M12, M13 and M14), and a second error amplifier (configured from M16, M17, M18 and M19) ) And the transistor M15. 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 transistors M13 and M19 as inputs b and d. Signals indicating the battery charge / discharge state are output from 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 current limiting means. The current limiting transistor M15 has the effect that the total current consumption of the first and second error amplifiers can be reduced to the same level as the current consumption of one error amplifier.

Next, an embodiment of integrating a plurality of error amplifiers 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. The circuit of FIG. 6 is arranged for the batteries 18 and 19, respectively. The pair of the transistors M12 and M14 constituting the error amplifier shown in FIG. 8 and the transistors M16 and M18 constituting the error amplifier of the next stage have the same configuration. The circuit shown in FIG. FIG. 9 is a diagram of a circuit of a two-input type error amplifier and a reference voltage circuit as an error amplifier.

In FIG. 9, focusing on N1, N2, N3, N4, and N5, N5 is an error amplifier in which constant current sources N1 and N2 are active broad, N3 and N4 are source-coupled pairs, and N3 gate input. The output can be obtained by comparing (or amplifying) the voltage (b) with the N4 gate input voltage (reference voltage).

Since the voltages between the gate and the source of N1 and N2 are the same, it is considered that the current flowing in N1 and N2, that is, the current flowing in N3 and N4 is always the same. Therefore, if the gate input voltage (b) of N3 is higher than the gate input voltage (reference voltage) of N4, N3 turns on more than N4, the resistance component of N3 decreases, and the output a drops to the low side. If the gate input voltage (b) of N3 is lower than the gate input voltage (reference voltage) of N4, N3 turns OFF more than N4, the resistance component of N3 increases, and the output a rises to the High side.

Similarly, focusing on N2, N6, N4, N7, and N5, N5 is a conventional error amplifier in which a constant current source, N2 and N6 are active loads, and N4 and N7 are source-coupled pairs. The output can be obtained as c by comparing (or amplifying) the gate input voltage (d) and the N4 gate input voltage (reference voltage).

Since the voltages between the gate and the source of N2 and N6 are the same, it is considered that the current flowing in N2 and N6, that is, the current flowing in N4 and N7 is always the same. Therefore, if the gate input voltage (d) of N7 is higher than the gate input voltage (reference voltage) of N4, N4 turns on more than N4, the resistance component of N7 decreases, and the output c drops to the low side. If the gate input voltage (d) of N7 is lower than the gate input voltage (reference voltage) of N4, N7 turns OFF more than N4, the resistance component of N7 increases, and the output c rises to the High side.

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

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

Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 11 is a circuit block diagram of the charge / discharge control circuit of the present invention. Two batteries 111 and 112 are inserted in series between power supply terminals + VB and -VB of the charge / discharge control circuit as secondary batteries. The voltage of the battery 111 is divided by a voltage dividing circuit 113, and the divided voltage is detected by an 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 supply when each battery is in an overcharged state or an overdischarged state. Therefore, the control circuit 117 is composed of only a logic circuit. Similarly, the battery 112 is configured to detect an overcharged state and an overdischarged state by the voltage dividing circuit 114 and the voltage detecting circuit 116. The detection result is similarly input to the control circuit 117 as a digital signal. Therefore, when one of the batteries 111 and 112 is overcharged or overdischarged, the control circuit 117 cuts off the electrical connection between the battery and the external power supply and stops the progress of overcharge and overdischarge. Since the charging characteristics and the discharging characteristics of the two batteries are not exactly the same, it is necessary to separately control overcharge and overdischarge.

The buffer 118 is a circuit for outputting the potential VI to the outside as the signal B during connection of each battery. The charge / discharge balance state between the batteries can be detected by the signal B. The buffer circuit 118 is provided so that no current is consumed to the outside from the potential VI at the connection point. FIG. 12 shows a more specific circuit diagram of the buffer circuit. The buffer circuit is supplied with power from both the secondary batteries + VB and -VB. In the buffer circuit, the node VI is inputted to the transistors 92 and 93 to the operational amplifier which is a component thereof. This connection point potential VI is substantially an intermediate potential of the entire secondary battery power supply. Therefore, a large current flows through the transistors 92 and 93. Therefore, a switch transistor 91 for cutting current is connected in series with the transistors 92 and 93. The current cut transistor 91 is 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 charge / discharge control circuit can be reduced by stopping the operation of the buffer circuit to which the intermediate potential is input when in the overdischarge state. Further, 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, a signal indicating an overdischarge state, a normal state, or an overcharge state can be output from the B terminal. In the normal state, the connection potential of the two batteries is output. In the overdischarge or overcharge state, the state can be output at a digital signal level of + VB or -VB by pulling up or pulling down the B terminal. That is, the current cutting transistor inserted into the buffer circuit has a function of not only cutting the current of the buffer circuit but also outputting a different type of signal from the terminal B.

Hereinafter, a fourth embodiment of the present invention will be described 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 terminals -VB and + VB. The power supply terminals -VB and + VB have a voltage dividing resistor 1 as a voltage dividing circuit for dividing the voltage of the secondary battery, comparators 52 and 53 as voltage detecting circuits for detecting a divided voltage of the voltage dividing resistor 1, and a comparator. A control circuit 4 receiving the output signals of 52 and 53 and outputting a final control signal VS is connected in parallel.

The voltage detection circuit includes 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 as input a reference voltage source VR and a divided voltage between the resistors R1 and R2. The over-discharge voltage detection circuit includes a comparator circuit 53 that receives as input a reference voltage source VR and a divided voltage between the resistors R2 and R3. The resistance values of R1, R2, and R3 of the voltage dividing resistor 1 are designed in relation to the reference voltage source VR so that the output of the comparator 52 is inverted when overcharged and the output of the comparator circuit 53 is inverted when overdischarged. Have been. 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 an output VS to the switch circuit so as to turn off the switch circuit of the power supply device so that overcharge or overdischarge does not proceed further. 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 a reference voltage source. For example, an enhanced N-type insulated gate field effect transistor 61 and a depletion type N-type insulated gate field effect transistor 62 are connected in series using a secondary battery whose voltage fluctuates as a power supply. The respective gate electrodes are connected to the respective connection terminals. From the connection terminal, a constant voltage Vref is output which does not depend on the secondary battery voltage fluctuation 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 and consumes energy of the secondary battery. Therefore, by using a reference voltage source for both voltage detection circuits as shown in FIG. 13, not only the number of components but also the current consumption can be reduced for a circuit provided with separate reference voltage sources. 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-discharge state in which the voltage of the secondary battery has decreased, the life of the voltage of the secondary battery suddenly decreases along with the consumed energy. Therefore, making the charge / discharge control circuit function with the minimum current is a point of producing a rechargeable power supply having a long life.

FIG. 15 shows a circuit block of a charge / discharge control circuit when a secondary battery is used by connecting two batteries 71 and 72 in series. When the secondary battery is composed of a plurality of batteries as in the embodiment shown in FIG. 15, it is necessary to provide a circuit that independently detects the voltage of each battery and controls the charging / discharging voltage. In general, the voltage of a battery is determined by the constituent materials of the battery. Therefore, when a device that functions with a power supply requires a high voltage, the voltage is often increased by connecting batteries in series as shown in FIG. As shown in FIG. 15, the charge / discharge control circuit shown in FIG. 13 is connected to the batteries 71 and 72. The control circuit 79, which is a common circuit, receives signals from the comparators 75, 76, 77, and 78, and outputs a switch circuit control signal VS.

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

FIG. 16 shows an example of a reference voltage circuit that outputs the same constant voltage from + VB and −VB. This is a circuit in which another enhanced 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 of 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 point of each transistor. VR1 outputs a constant voltage Vref with respect to + VB. Further, VR2 outputs the same constant voltage Vref with respect to -VB. Therefore, the reference voltage circuit of FIG. 16 can output two constant voltages without increasing current consumption. If one reference voltage circuit as shown in FIG. 16 (there is only one current path between + VB and -VB) and VR1 and VR2 in FIG. 15 are formed, the secondary battery is constituted by a plurality of batteries. In this case, it can be formed without increasing the current consumption of the charge / discharge control circuit.

As described above, the present invention has a configuration in which one circuit serves as the reference voltage source, which previously required a number of comparator circuits for voltage detection. The charge / discharge control circuit of the present invention requires a plurality of comparator circuits due to its configuration, and furthermore, low 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 has a great effect.

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.

FIG. 17 is a circuit block diagram of Embodiment 1 of 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 voltage dividing resistor 1 of power supply voltage dividing means for dividing a power supply voltage, voltage detection circuits 2 and 3 for detecting two output voltages of the power supply voltage dividing means, and voltage detection circuits 2 and 3 respectively. And a control circuit 4 that outputs a final control signal VS in response to the output signal of.

The voltage detection circuits 2 and 3 are specifically formed of a reference voltage source 42 for the power supply terminal -VB and a comparator circuit 41 to which the output of the voltage dividing resistor is input as shown in FIG. 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 as a power supply. The power supply voltage division circuit 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit that detects overdischarge of a secondary battery as a power supply. In the case of the present invention, the power supply division circuits 1 input to each voltage detection circuit may be separately provided. In the case of FIG. 17, the power supply division circuit 1 is an example of a charge / discharge control circuit provided commonly to the voltage detection circuits. The control circuit 4 receives a signal relating to overcharge and overdischarge of the secondary battery from each of the voltage detection circuits 2 and 3, and outputs a signal VS for turning on or off the switch circuit of the power supply device.

For example, a case will be described in which a charging power supply is connected to a secondary battery connected between terminals -VB and + VB via a switch circuit, and the secondary battery is charged. In the charged state, the voltages -VB and + VB at both ends of the secondary battery gradually increase. When the secondary battery enters an overcharged state, the output signal of the overcharge voltage detection circuit 2 is inverted. The voltage for recognizing this overcharged state differs depending on the secondary battery. For example, in the case of a lithium ion battery, it is set to 4.3V. 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 up to 4.3 V from the division circuit of the voltage division circuit 1. The inverted signal output from the voltage detection circuit 2 is fed back to the voltage division 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. In response to the inverted output signal of the voltage detection circuit 2, the voltage division control transistor 175 is immediately turned on to further increase the divided voltage and operate so that the voltage detection circuit 2 can output the inverted signal stably. By turning on the voltage division control transistor 175, even if the voltage of the secondary battery fluctuates as low as 4.0 V, the voltage of the resistor R1 is at a level at which the voltage detection circuit 2 is sufficiently inverted.

As described above, in the overcharge detection circuit composed of the voltage division circuit 1 and the overcharge voltage detection circuit, after detecting overcharge, the overcharge detection voltage is reset to a low value by the detection signal. This makes it possible to perform stable overcharge detection. After resetting to a low value, the control circuit 4 outputs a signal VS for turning off the switch circuit. 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 inherent in the lithium ion battery. That is, the voltage is reduced by the voltage drop due to the internal resistance. However, before that, the overcharge detection voltage has been reduced and reset from 4.3 V to 4.0 V, so that the output of the voltage detection circuit 2 continues to detect the overcharge. Therefore, the reduced voltage 0.3V (4.3V-4.0V) for resetting the overcharge needs to be set larger than the voltage drop due to the internal resistance of the secondary battery during charging. Generally, the difference voltage between the initial setting voltage and the resetting voltage is between 0.2V and 0.5V. When the voltage is set to 0.5 V or more, the overcharge range is widened, and the use range in a normal state is narrowed. That is, the life is shortened.

FIG. 18 is a diagram showing signal timings of each circuit. The overcharge detection voltage a is reduced and reset to 4.2 V while the secondary battery is charged to the overcharge voltage 4.3 V. A split voltage control transistor 175 is provided to reduce 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 4.3 V, the output of the voltage detection circuit 2 is inverted from + VB to -VB. The voltage of −VB is input to the voltage division control transistor 175. The voltage division control transistor 175 turns on, the division ratio of the bleeder resistance changes, and the voltage at the overcharge detection point is reset to a low value from 4.3 V to 4.2 V. The output signal Vs of the control circuit 4 changes from + VB to 0 V after the time Δt has been reset and outputs a signal for changing the switch circuit from ON to OFF. In order to form Δt, the output of the voltage detection circuit 2 can be shifted by a delay circuit to delay the signal.

As described above, the overcharge detection has been described. Even in overdischarge, stable operation can be achieved by using the same configuration. In the case of overdischarge, the reset level is set to increase in the opposite direction to overcharge.

Hereinafter, a second embodiment of the means 2 of the present invention will be described with reference to the drawings.

FIG. 19 is a circuit block diagram of Embodiment 2 of 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 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 voltage detection circuits 2 and 3 respectively. And the control circuit 4 that outputs a final control signal VB based on 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 formed of a reference voltage source 42 for the power supply terminal -VB and a comparator circuit 41 for inputting the output of the voltage dividing resistor 1 as shown in FIG. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit. The voltage division resistor 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery as a power supply. The voltage division resistor 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit for detecting overdischarge of a secondary battery as a power supply. 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 division resistor 1 is an example of a charge / discharge control circuit provided commonly 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 receives signals from the respective delay circuits 191 and 192 regarding overcharge and overdischarge of the secondary battery, and outputs a signal VS for turning on or off the switch circuit of the power supply device. Therefore, the control circuit 4 is constituted by a logic circuit. Further, the switch circuit of the power supply device is turned on or off by the signal VS. However, even if there is a capacitance or a resistance component at the input terminal of the switch circuit, the signal VS needs to be changed within a predetermined time. 4, the output terminal VS needs to have low impedance. When the control circuit 4 is realized by, for example, a MOSFET (Metal-Oxide-Semiconductor-Field-Effect-Transistor), the number of transistor elements increases in order to form a logic circuit, and the final output stage decreases the impedance of the output terminal VS. Need to be bigger. Therefore, when the control circuit 4 turns ON or OFF the signal VS, a through current is consumed. Not only the control signal 4 but also the voltage detection circuits 2 and 3 generate a through current when the output is inverted. These through currents may lower the voltage of the secondary batteries connected in parallel.

The control circuit 4 receives the signals of the delay circuits 191 and 192 and determines the logic of the signal VS. However, if the logic of the delay circuits 191 and 192 is indeterminate at the time of initial battery connection, the signal VS output from the control circuit 4 does not become the logic that the voltage of the secondary battery is correctly detected, and the switch circuit 103 malfunctions. Resulting in. When these phenomena occur, charging or discharging is forcibly controlled even when a secondary battery having a normal voltage value is connected to the charge / discharge control circuit.

(4) The delay circuits 191 and 192 are provided to prevent these malfunctions. In other words, a time delay is created after the signal of the voltage detection circuit 2 or 3 is inverted, and a signal is input to the control circuit 4. Therefore, when a voltage is detected, a through current between the voltage detection circuit 2 or 3 and the control circuit 4 is reduced. To prevent them from occurring at the same time. In addition, since there is a time delay, for example, at the time of charging, the secondary battery becomes an overcharge voltage, and after the voltage detection circuit 3 operates, the charging of the secondary battery is continued until the signal VS of the control circuit 4 is inverted. Therefore, the detection operation becomes more reliable.

Furthermore, the delay circuit is configured to secure the logic at the time of initial power-on for a certain period. Specifically, as shown in FIG. 20, a CMOSFET inverter is formed between the power supply terminals + VB and -VB, and the 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, the capacitor 205 and the Pch transistor 203 are output until an inverted signal that changes from −VB to + VB is output to the output terminal VOUT. , A CR circuit is established and a delay occurs. In addition, even when the power is initially turned on (when the secondary battery is connected), the voltage of the output terminal VOUT is delayed by the capacitor 205 until it reaches the + VB voltage. That is, the -VB voltage is initially maintained for a certain period.

In FIG. 20, a delay is realized when the input terminal VIN changes from + VB to -VB. However, when a delay is required when the input terminal VIN changes from -VB to + VB, as shown in FIG. The capacitor 205 may be connected between the output terminal VOUT and the power supply terminal + VB. In order to realize a delay circuit, the same effect as that of the circuit of FIG. 20 can be obtained even if the delay circuit is configured by the constant current circuit 226, the Pch transistor 203, and the capacitor 205 as shown in FIG.

FIG. 22 shows a circuit for making a delay when the output terminal VOUT changes from + VB to -VB, and keeps -VB for a certain period at the time of initial power-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 configuration of the delay circuit, the timing of delay and the logic at the time of initial application can be freely set. Although the delay circuit is described by MOSFET for convenience, it is apparent that the delay circuit can be realized by other elements. Further, these delay circuits are merely examples, and the problem can be solved by using other circuits.

The charge / discharge control circuit according to the present invention is suitable for an integrated circuit provided on the same semiconductor substrate with less variation in the divided voltage of the voltage dividing resistor.

Hereinafter, a third embodiment of the means 2 of the present invention will be described 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 of the terminal -VBO 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. The terminal Ve newly prepared in the present invention is connected to the external terminal -VO of the power supply device. The power supply includes a voltage dividing resistor 1 of 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 voltage detection circuits 2 and 3 respectively. And the control circuit 4 that outputs the final control signal VS is connected in parallel with each other.

In the case of the present invention, a voltage dividing resistor for generating a divided voltage input to each voltage detection circuit may be separately provided. In the case of FIG. 25, the voltage division circuit 1 is an example of a charge / discharge control circuit provided commonly to each voltage detection circuit. The control circuit 4 receives from the voltage detection circuits 2 and 3 a signal relating to overcharge and overdischarge of the secondary battery and a signal of the terminal -VO of the power supply from Ve, and switches the power supply according to each signal. A signal VS for turning on or off the circuit is output. That is, since the control circuit 4 is configured by a logic circuit, and the power supply is a secondary battery, when the voltage of the secondary battery further decreases from the overdischarge state, the signal VS of the control circuit 4 becomes unstable. State. For example, when the output section of the control circuit 4 is configured by a C-MOS (Complementary-Metal-Oxide-Semiconductor) inverter, a voltage sufficient to operate the circuit is applied between + VB and -VB, and an input terminal is provided. If the same potential as -VB is applied to VIN, a voltage of -VB is output to the output terminal VS. 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 and discharging of the power supply device below the minimum operating voltage of the control circuit. In this case, the following inconvenience occurs.

That is, the secondary battery 101 is charged and discharged by the power supply device as shown in FIG. 2, and the switch circuit 103 is turned off to stop supplying energy to the external load. However, since the secondary battery 101 is connected to the charge / discharge control circuit 102, only the current consumed by the charge / discharge control circuit 102 is consumed, and a considerable amount of time has passed since the transition to the overdischarge state. After that, the secondary battery becomes lower than the minimum operating voltage of the control circuit 4, and the control signal VS shown in FIG. 25 becomes unstable. Once the power supply enters this state, even if charging is attempted from the primary power supply, the switch circuit is unstable and cannot be charged in the worst case. Therefore, in order to solve this, in the present invention, the output unit of the control circuit 4 in FIG. 25 is configured as shown in FIG. The power supply of the C-MOS 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.

端子 As shown in FIG. 24, the terminal + VB is connected to the + terminal of the secondary battery, the terminal −VB is connected to the − terminal of the secondary battery, and the terminal Ve is connected to the external terminal −VO of the power supply. When the power supply device is discharging, since the switch circuit 103 is ON in FIG. 24, the potentials of the terminal A and the terminal -VO become substantially equal. This is because in the output circuit of FIG. 26, the voltage of the secondary battery is applied between + VB and Ve, and the terminal -VB is applied with substantially the same potential as the terminal Ve. As a result, the output of the output terminal VS is controlled by the voltage of the terminal VIN, and performs the same operation as the conventional CMOS inverter. When the voltage of the secondary battery decreases and falls below the minimum operating voltage of the circuit in FIG. 26, the signal at the output terminal VS becomes unstable, but shows stable operation when charging from the primary power supply. When charging, a voltage higher than the voltage of the secondary battery is applied between the terminals + VO to -VO in FIG. At this time, since the + terminal B of the secondary battery and the external terminal + VO to which the + voltage of the charger is applied are common, the external terminal -VO is 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. 26, and the voltage difference between + VB and -VB is small, so that the Nch transistor 269 is turned ON and the C potential becomes the same as the potential of the terminal Ve, The signal at the output terminal VS becomes equal to + VB. That is, 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 potential + VB, and the control of the switch circuit is reliably performed.

When the voltage of the secondary battery (the voltage between + VB and -VB) is lower than the voltage of the charger (the voltage between + VBB and Ve), the C-MOS inverter at the output of the control circuit 4 turns on the Nch transistor 269. are doing. The threshold voltage (inversion voltage) of the inverter circuit 266 is Pc
The change can be made by the size of the h transistor or the Nch transistor or the like, and by setting this to be equal to or higher than the minimum operating voltage of the control circuit 4, the operation described so far is reliably performed.

Although the output section of the control circuit of the present invention is described in CMOS for convenience, it is apparent that other elements can be used. The problem can be solved even if another circuit is used as the circuit of the output unit. The charge / discharge control circuit according to the present invention is suitable for an integrated circuit provided on the same semiconductor substrate with less variation in the divided voltage of the voltage dividing resistor.

Hereinafter, a fourth embodiment of the invention 2 will be described with reference to the drawings.

FIG. 27 is a circuit block diagram of Embodiment 4 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 voltage dividing resistor 1 of power supply voltage dividing means for dividing a power supply voltage, voltage detection circuits 2 and 3 for detecting two output voltages of the power supply voltage dividing means, and voltage detection circuits 2 and 3 respectively. And a control circuit 4 that outputs a final control signal VS in response to the output signal of. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit. The voltage division resistor 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery as a power supply. The voltage division resistor 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit for detecting overdischarge of a secondary battery as a power supply. In the case of the present invention, the voltage dividing resistors 1 input to each voltage detection circuit may be separately provided. In the case of FIG. 27, the voltage dividing resistor 1 is an example of a charge / discharge control circuit provided commonly to the voltage detection circuits. The control circuit 4 receives a signal relating to overcharge and overdischarge of the secondary battery from each of the 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 that generates 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 a circuit that outputs a reference voltage VR that does not depend on a voltage change of the secondary battery from a connection point between the transistor 201 and the transistor 202. The transistor 201 is a depletion type MOS field effect transistor, and the transistor 202 is an enhancement type MOS field effect transistor. The transistors 201 and 202 are the same conductivity type N-type transistors. Both gate electrodes are connected to the reference voltage output terminal.

(4) In the case where the semiconductor integrated circuit constituting the charge / discharge control circuit is formed of a CMOS circuit, the charge / discharge control circuit is latched up when the power supply is reversely connected to the power supply. As a means for setting the output of the reference voltage circuit to the intermediate potential of the secondary battery when the latch-up occurs, an intermediate potential setting means is provided at the reference voltage output terminal VR. In the embodiment shown in FIG. 28, the intermediate divided output IN2 of the voltage dividing resistor is connected via a diode 283. The intermediate divided output IN2 is set to a substantially intermediate value between the secondary batteries + VB and -VB. Therefore, when the charge / discharge control circuit latches up, the reference voltage output becomes a value reduced by about 0.6 V which is the forward voltage of the diode 283 from the intermediate divided output IN2. Since this value is substantially an 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.

28. The embodiment shown in FIG. 28 is an example in which a means for setting the output of the reference voltage circuit of the voltage detection circuit to an intermediate potential is provided to prevent a malfunction of the switch circuit due to latch-up. Runaway can be prevented if the switch circuit is turned off by latch-up. Therefore, the switch circuit may be turned off when the output of the control circuit 4 is latched up.

The present invention is indispensable for a CMOS IC that malfunctions due to latch-up when a power supply is reversely connected.

Hereinafter, a fifth embodiment of the means 2 of the present invention will be described with reference to the drawings.

FIG. 29 is a circuit block diagram of Embodiment 5 of the charge / discharge control circuit in the means 2 of the present invention. 29, the external terminals -VO and + VO, the switch circuit 103, the current sensing resistor 104, the secondary battery 101, the reference voltage circuit 106, the transistor 107, the constant current source 108, the capacitor 109, and the high resistance 111 for pull-down are shown in FIG. Is the same as

The output of the comparator 21 changes from “H” to “L” when the current exceeds the current represented by the above-described equation (1), as in FIG. 30, turning off the transistor 107 and charging the capacitor 109 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 changes from “H” to “L”, and the switch circuit 103 is turned off. At this time, the comparator 22 has a latch function, and holds this state when the output of the comparator 22 becomes “L”.

(4) The latch function is released by the output of the comparator 21. FIG. 31 shows a circuit diagram of a comparator with a latch function. 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 becomes “H”. As a result, even if the voltage of the plus input terminal slightly fluctuates, the output of the comparator 22 with latch function is latched at "L".

Since the switch circuit 103 is turned off while the load is connected, the negative input terminal of the comparator 21 is pulled up to + VO by a load connected to an electronic device such as a video device, and the overcurrent state is maintained. Is done. (4) Thereafter, when the load is removed, the negative input voltage of the comparator 21 is lowered to “L” by the high-resistance pull-down resistor 111, so that the output of the comparator 21 becomes “H”. Since the latch release terminal 316 of the comparator 22 with the latch function is set to “H” by the output of “H”, the output of the comparator 22 with the latch function becomes “H” and the latch is released.

In FIG. 29, an overcurrent detection circuit includes a voltage detector for detecting a voltage between both ends of an overcurrent detection resistor 104 provided between the external terminal -VO and the switch circuit 103, and a voltage detector for detecting the voltage. A delay circuit for delaying the output of the delay circuit in time, and a voltage detection circuit with a latch-up function for detecting the voltage of 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 includes a constant current source 108, a capacitor 109, and a transistor 107. In the description so far, the charge / discharge control circuit 102 and the overcurrent detection circuit 105 have been described as being configured separately.

However, it can be said that the charge / discharge control circuit has both the charge / discharge control circuit 102 and the overcurrent detection circuit 105 described in the embodiment of the present invention.

FIG. 32 is a circuit block diagram showing Embodiment 1 of 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 are supplied as power. The power supply is connected to a voltage dividing resistor 1 of power supply voltage dividing means for dividing the power supply voltage, and a voltage detection circuit 2 for detecting the output voltage of the power supply voltage dividing means.

The voltage detection circuit 2 is formed of a reference voltage source 43 for the power supply terminal -VB and a comparator circuit 44 to which the output of the voltage dividing resistor 1 is input as shown in FIG. The voltage dividing resistor 1 and the voltage detecting circuit 2 constitute a circuit for detecting a sum voltage of a secondary battery as a 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 where the division voltage of the voltage division resistor 1 has little variation. It is also apparent that the present invention can be applied to the case of three or more secondary batteries connected in series. As described above, by detecting each of the sum voltages of the batteries constituted by the secondary batteries, it is possible to perform the optimal charge / discharge control even in the state where the voltage of each of the batteries has one-sided verification. Therefore, the life of the secondary battery can be improved.

Hereinafter, a second embodiment of the means 3 of the present invention will be described with reference to the drawings.

FIG. 33 is a circuit block diagram of a charge / discharge control circuit according to the second embodiment in the means 3 of the present invention. The voltage detection circuit 3 detects the overcharge detection voltage V1 of the secondary battery 6, and the voltage detection circuit 5 detects the overcharge detection voltage V2 of the secondary battery 7, and is output as an output signal VS by the control circuit 8. At the same time, the voltage of the secondary battery 6 is detected by the voltage detection circuit 2, and the detection voltage V3 is set to a voltage lower than the overcharge detection voltage V1. Similarly, the voltage of the secondary battery 7 is detected by the voltage detection circuit 4, 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 voltages V1 and V2 of the voltage detection circuits 3 and 5 are set to 4. 2V. However, if an abnormality occurs in the secondary battery 6 and its charging performance is significantly deteriorated, only the secondary battery 7 is charged, and the difference between the two voltage values increases. In order to prevent this, if the detection voltage V3 of the voltage detection circuit 2 is set to about 3.2 V, if the voltage of the secondary battery 6 does not exceed 3.2 V due to deterioration, the detection of the voltage detection circuit 5 The voltage V2 is set to a value lower than 4.2V, and when the voltage V2 is exceeded, the original detection voltage value is set to 4.2V. This setting is performed by the output signal of the voltage detection circuit 2.

Similarly, the deterioration of the secondary battery 7 is monitored by the output signal of the voltage detection circuit 4, and when the voltage of the secondary battery 7 does not exceed 3.2 V due to the deterioration, the detection voltage V1 of the voltage detection circuit 3 is increased. 4
. The voltage is set to a value lower than 2V, and when the voltage exceeds the value, the original detection voltage value is set to 4.2V. This setting is performed by the output signal of the voltage detection circuit 4.

In the description, 3.2 V and 4.2 V are used as examples, but these values depend on the battery characteristics and are not limited to these values. 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. By turning on or off the transistor 9, the overcharge detection voltage value V1 of the voltage detection circuit 3 is changed. Can be changed.

Similarly, the output of the voltage detection circuit 2 is used to detect the overcharge of the voltage detection circuit 5 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 voltage V2 can be changed.

Hereinafter, a third embodiment of the means 3 of the present invention will be described with reference to the drawings.

FIG. 36 is a block diagram showing a rechargeable power supply device of the present invention and a charge / discharge control circuit therefor. 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 the external terminals + 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 supply for charging is connected to an external terminal and the secondary battery 101 is charged from the power supply, when the voltage of the secondary battery 101 becomes equal to or higher than the overcharge voltage level, the signal of the voltage detection circuit 2 is output. Are inverted and input to the control circuit 3. A signal for turning off the switch circuit 5 is output from the control circuit 3 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 overdischarged. When the voltage drops below the voltage level, the signal of the voltage detection circuit 2 is inverted to a signal opposite to the normal voltage range. Then, a signal for turning off the switch circuit 5 is output from the control circuit 3 to stop the discharge. The normal voltage range refers to an intermediate state between the overcharge level and the overdischarge level.

In the rechargeable power supply described above, the voltage detection circuit 2, the control circuit 3, and the switch circuit 5 can be constituted by semiconductor integrated circuits arranged on the same substrate. FIG. 38 is a circuit diagram of an embodiment of the 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 minus terminal 34 of the secondary battery. In the switch circuit, an N-type insulated gate field effect transistor (hereinafter referred to as an N-type MISFET) 31 is provided between an external terminal -V and a minus terminal 34 of the secondary battery, and 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 V and the minus terminal 34 of the secondary battery, respectively. The gate electrodes 31G, 32G and 33G of the three N-type MISFETs are controlled by a control circuit.

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

(4) 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, and the transistor 32 is off. When an overdischarge state is caused by supplying power, the output signal of the voltage detection circuit is inverted, and a signal for turning off the switch circuit is output from the control circuit. That is, the transistors 31 and 32 are turned off, and only the transistor 33 is turned on.

In the normal state, it is possible to detect whether the battery is operating in the charging state or the discharging state by comparing the voltage between the external terminal -V and the minus terminal 34 of the secondary battery. The control circuit controls the impedance 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 charging or discharging.

In the switch circuit of FIG. 38 described above, only one transistor 31 flows through the battery. Therefore, in general, a transistor having a large current driving capability can be formed in half of the conventional transistor in order to reduce the voltage drop in the switch circuit. The 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 generally requires several A, while the current driving capability of the transistors 32 and 33 is as small as 1/1000 or less of the current driving capability. 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 case. The transistor area can be reduced to about half, and miniaturization can be facilitated. In addition, the substrate potential 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 configured by individual transistors, the operation thereof does not change.

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. Such a substrate having a single crystal silicon film provided over an insulating film is generally called an SOI substrate. A transistor having a cross-sectional view as shown in FIG. 39 is formed using an SOI substrate. That is, an N-type source region 53 and an N-type drain region 55 are provided on both sides of the channel formation region 54, and a gate electrode 57 is provided on the channel formation region 54 via a gate insulating film 56. With the transistor having the structure illustrated in FIG. 39, the potential of the channel formation region 54 which is also a substrate of the transistor can be formed electrically independently of a transistor provided over the same substrate. That is, since the substrate potentials of the transistors can be electrically separated from each other, a charge / discharge control IC having a switch circuit can be easily realized.

FIG. 40 is a plan view of a transistor in which the potential of a channel formation region which is a substrate is set to the same potential as the potential of a source region. An N-type source region 73, a drain region 72, and a channel formation region therebetween are formed in a single crystal silicon semiconductor film 71 provided on an insulation film, and a gate electrode 77 is formed on the channel formation region via a gate insulation film. Is provided. A P-type source region 74 is provided in part of the source region 73, and the potential of the source region 73 and the potential of the channel formation region are set to the same potential by the source electrode 75.

FIG. 41 is a cross-sectional view of FIG. 40 taken along the line A-A ′. A single crystal silicon semiconductor film 71 is provided over a 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 formation region 69, and an N-type drain region 62 are formed. A gate electrode 67 is provided on the channel formation region 69 with a gate insulating film 63 interposed therebetween. The P-type source region 64 and the N-type source region are connected to a source electrode 65. N-type drain region 62 is connected to drain electrode 66.

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

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

The charge / discharge control circuit of the present invention has an effect of reducing current consumption by adopting a configuration in which a voltage-dividing resistor of the overcharge and overdischarge detection circuit provided therein has a switching element for reducing current consumption. Have fruit. Further, a power supply device having a long life can be supplied by the charge / discharge control circuit, the secondary battery, and the switch circuit.

In addition, in the overdischarge state, the current consumption of the error amplifier of the overcharge detection circuit is cut, so that the power consumption of the battery in the overdischarge state can be reduced, and the battery can be prevented from being deteriorated. is there. Further, since the current consumption of the error amplifier of the overcharge detection circuit is cut, the power consumption of the battery in the overdischarge state can be reduced, and the battery can be prevented from being deteriorated.

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

In addition, by having a configuration that also serves as a reference voltage source for overcharge detection and overdischarge detection of a secondary battery provided inside, not only can the charge / discharge control circuit be configured with a small number of components and it can be made inexpensively, There is an effect that it is possible to reduce functionally important current consumption. The reduction of the current consumption of the charge / discharge control circuit has the effect of extending the life of the rechargeable power supply. Also, in the present invention, even when the secondary battery is formed by a plurality of batteries, since the reference voltage source for detecting the voltage of each battery is constituted by one circuit, the charge / discharge control circuit is similarly provided. Has the effect of reducing the current consumption and improving the life of the rechargeable power supply.

Also, the voltage dividing resistor for detecting the secondary battery voltage provided inside serves as both the overcharge pressure detection and the overdischarge voltage detection, thereby reducing the number of circuits connected in parallel to the secondary battery. This has the effect of reducing current consumption. Further, the present invention has an effect of improving the life of the secondary battery by reducing the current consumption of the charge / discharge control circuit. In addition, since the voltage dividing resistor is configured to be used for overcharging and overdischarging, when the charge / discharge control circuit is integrated, there is an effect that the chip size can be reduced and provided at a low cost.

As described above, as described above, in the charge / discharge control circuit, as soon as the voltage detection circuit detects overcharge or overdischarge, the detection signal is fed back to further overcharge or overdischarge the overcharge or overdischarge detection level. By resetting to detect erroneous operation, there is an effect of eliminating malfunction. Further, after resetting, switching the switch circuit between the secondary battery and the charging power supply has an effect of preventing unstable oscillation of the voltage detection circuit due to voltage fluctuation of the secondary battery due to impedance change of the switch circuit.

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

In the charge / discharge control circuit of the present invention, the voltage of the external terminal of the power supply device is input so that the voltage of the secondary battery serving as the power supply of the charge / discharge control circuit is equal to or less than the minimum operating voltage of the charge / discharge control circuit. Therefore, when the charger is connected, the switch circuit can be controlled, and a power supply device capable of performing reliable charging regardless of the voltage of the secondary battery can be supplied.

According to the present invention, as described above, in a charge / discharge control circuit composed of a CMOS IC, when a voltage opposite to a normal voltage is applied to the charge / discharge control circuit, the output of the control circuit turns off the switch circuit. Has an effect of preventing runaway of current to the secondary battery.

In addition, the charge / discharge control circuit of the present invention has an effect that the oscillation phenomenon at the time of overcurrent detection can be reliably prevented by providing the overcurrent detection circuit with a latch function. The charge / discharge control circuit of the present invention can supply a long-life power supply device by providing a voltage dividing resistor and a voltage detection circuit between terminals from which a sum voltage of two or more secondary batteries is output in series.

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

1 is a circuit block diagram of a charge / discharge control circuit according to a first embodiment of the present invention. It is a circuit block diagram of the conventional rechargeable power supply device. It is a circuit diagram of a voltage detector. FIG. 9 is a circuit block diagram of another embodiment of the charge / discharge control circuit of the present invention. FIG. 9 is a circuit block diagram of another embodiment of the charge / discharge control circuit of the present invention. FIG. 6 is a circuit diagram of a battery charge / discharge control circuit according to a second embodiment of the present invention. 4 is a circuit example of an error amplifier having a power ON / OFF function. FIG. 9 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. 9 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. 9 is a circuit block diagram of a charge / discharge control circuit according to a third embodiment of the present invention. FIG. 3 is a circuit diagram illustrating a buffer circuit. FIG. 9 is a circuit block diagram of a charge / discharge control circuit according to a fourth embodiment of the present invention. FIG. 3 is a circuit diagram of a reference voltage circuit. FIG. 3 is a circuit block diagram of a charge / discharge control circuit when the secondary battery is two batteries. It is a circuit diagram of VR1 and VR2 of FIG. FIG. 3 is a circuit block diagram of a charge / discharge control circuit according to a first embodiment in the means 2 of the present invention. FIG. 4 is a timing chart of signals of the charge / discharge control circuit of Embodiment 1 in the means 2 of the present invention. FIG. 9 is a circuit block diagram of a charge / discharge control circuit according to a second embodiment in the means 2 of the present invention. FIG. 9 is a circuit diagram of a delay circuit according to a second embodiment of the present invention. FIG. 9 is a circuit diagram of a delay circuit according to a second embodiment of the present invention. FIG. 9 is a circuit diagram of a delay circuit according to a second embodiment of the present invention. FIG. 9 is a circuit diagram of a delay circuit according to a second embodiment of the present invention. FIG. 13 is a circuit block diagram of a rechargeable power supply device according to a third embodiment in the means 2 of the present invention. FIG. 10 is a circuit block diagram of a charge / discharge control circuit according to a third embodiment in the means 2 of the present invention. It is an example of the control circuit output unit of the present invention. FIG. 13 is a circuit block diagram of a charge / discharge control circuit according to a fourth embodiment in the means 2 of the present invention. FIG. 13 is a circuit diagram of a reference voltage circuit according to a fourth embodiment in the means 2 of the present invention. FIG. 11 is a rechargeable control circuit diagram of a fifth embodiment in the means 2 of the present invention. It is a conventional charge type control circuit diagram. It is a circuit diagram of the comparator with a latch function of the present invention. FIG. 4 is a circuit block diagram of a charge / discharge control circuit according to a first embodiment in the means 3 of the present invention. FIG. 9 is a circuit block diagram of a charge / discharge control circuit according to a second embodiment in the means 3 of the present invention. It is a circuit diagram of a voltage detector. FIG. 13 is a circuit block diagram of another embodiment of the charge / discharge control circuit of Embodiment 2 in Means 3 of the present invention. FIG. 9 is a circuit block diagram of a third embodiment of the rechargeable power supply device and the charging / discharging control circuit unit 3 according to the present invention. It is a circuit block diagram of the conventional rechargeable power supply device. FIG. 4 is a circuit diagram of a switch circuit of a charge / discharge control circuit in means 3 of the present invention. It is sectional drawing of the transistor used for the charge / discharge control circuit in the means 3 of this invention. It is a top view of the transistor used for the charge / discharge control circuit in the means 3 of the present invention. FIG. 36 is a cross-sectional view of the transistor of FIG. 35, taken along the line AA ′. FIG. 4 is a circuit diagram of a switch circuit of a charge / discharge control circuit in means 3 of the present invention.

Explanation of reference numerals

DESCRIPTION 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 Over Output terminal of discharge detection circuit 17 Output terminal of overcharge detection circuit 18, 19 Battery 52, 53 Comparator circuit 21 Comparator 22 Comparator with latch function 23 Positive input terminal of comparator with latch function 24 Minus input terminal of comparator with latch function 25 With latch function Output terminal of comparator 26 Latch release signal input terminal of comparator with latch function 101 Secondary battery 102 Charge / discharge control circuit 103 Switch circuit 104 Current sense resistor 106 Reference voltage circuit 111 12 Battery 113, 114 Voltage division circuit 115, 116 Voltage detection circuit 117 Control circuit 118 Buffer circuit 175 Voltage division value control transistor 191, 192 Delay circuit 203 Pch transistor 204 Nch transistor 205 Capacity 226 Constant current circuit 266 Inverter circuit 267 Final output stage Pch transistor 268 Final output stage Nch transistor 269 Output control Nch transistor

Claims (4)

A voltage dividing circuit for dividing a voltage between a first power supply terminal and a second power supply terminal to which a voltage of a secondary battery as a power supply is supplied, and a voltage for detecting a divided voltage which is an output of the voltage dividing circuit A detection circuit, a first delay circuit for detecting that the power supply is overcharged and delaying the output signal when an output signal of the voltage detection circuit is inverted, and the power supply is overdischarged Detecting that the output signal of the voltage detection circuit is inverted, a second delay circuit for delaying the output signal, and input processing the signals from the first and second delay circuits, A control circuit including a logic circuit that outputs a signal for controlling charging / discharging of the power supply; the voltage dividing circuit; the voltage detecting circuit; the first and second delay circuits; A circuit includes the first power supply terminal and the second power supply A charge / discharge control circuit, which is connected in parallel between terminals. A secondary battery connected to an external power supply terminal via a switch circuit, and a charge / discharge control circuit connected in parallel with the secondary battery between a first power supply terminal and a second power supply terminal to control the switch circuit Wherein the charge / discharge control circuit detects a charge / discharge state of the secondary battery, and a voltage division circuit for dividing a voltage between a first power supply terminal and a second power supply terminal. And a first delay circuit for delaying the output signal when the output signal of the voltage detection circuit is inverted by detecting that the power supply is overcharged, and when the power supply is overcharged. A second delay circuit for delaying the output signal when an output signal of the voltage detection circuit is inverted upon detection of discharge, and input processing of the signals from the first and second delay circuits; To control the charging and discharging of the power supply A control circuit formed of a logic circuit that outputs a first signal, a voltage dividing circuit, the voltage detecting circuit, the first and second delay circuits, and the control circuit. A rechargeable power supply device connected in parallel between a power supply terminal and the second power supply terminal. 2. The charge / discharge control circuit according to claim 1, wherein the control circuit has a function of always outputting a signal for stopping charging / discharging of the power supply when the power supply is reversely connected. In a rechargeable power supply device including a secondary battery connected to an external power supply terminal via a switch circuit, and a charge / discharge control circuit connected in parallel with the secondary battery to control the switch circuit, the charge / discharge control 3. The circuit according to claim 2, wherein the charge / discharge control circuit has a function of outputting a signal for turning off the switch circuit when the secondary battery is connected to a circuit having a polarity opposite to a normal polarity. A rechargeable power supply as described.

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