WO2015063968A1

WO2015063968A1 - Battery pack, electronic device system, and electronic device

Info

Publication number: WO2015063968A1
Application number: PCT/JP2014/002937
Authority: WO
Inventors: 新平幸田; 亮介山本; 篤史川角
Original assignee: 三洋電機株式会社
Priority date: 2013-10-31
Filing date: 2014-06-03
Publication date: 2015-05-07

Abstract

This battery pack is provided with a first output terminal which outputs power from a secondary battery to a system circuit of an electronic device, a second output terminal which outputs power from the secondary battery to a clock circuit of the electronic device, a branch point which divides from the secondary battery into the first output terminal and the second output terminal, a first switch unit which is disposed between the branch point and the first output terminal and switches output from the first output terminal on and off, and a control unit which controls switching the first switch unit on and off. When the voltage of the secondary battery falls below a first voltage value, the control unit switches the first switch unit off and continues allowing output from the second output terminal, making it possible to continue outputting the power of the clock circuit of the electronic device from the battery pack for a long period of time, and thereby making it possible to eliminate a backup battery for the clock circuit and so make the electronic device smaller and lighter and to maintain the function of the clock circuit for a long period of time even when the remaining capacity of the battery pack has been reduced.

Description

Battery pack, electronic device system, and electronic device

The present invention relates to a battery pack technology that supplies power to both a system circuit of an electronic device and a clock circuit that generates a calendar time, and further maintains the function of the clock circuit for as long as possible when the remaining capacity decreases. It is about technology.

Conventional portable electronic devices such as notebook computers, digital cameras, and PDAs have a built-in clock circuit called RTC (Real Time Clock) that provides calendar time to the system. Normally, power is supplied from the battery pack serving as the system power source to the clock circuit, but the clock circuit needs to operate even when power cannot be supplied from the battery pack in order to generate calendar time. In particular, the battery pack may be removed from the portable electronic device for charging or the like. The battery pack may be used until the remaining capacity becomes zero. Therefore, as shown in FIG. 5, power is supplied to the timing circuit from a dedicated backup battery different from the battery pack.

As the backup battery, a primary battery such as a coin battery mounted on a circuit board is generally used. The backup battery also supplies power to the clock circuit memory. The memory of the timer circuit stores the calendar time used by the system, the setting of the wake-up time, the BIOS setup data, and the like. The time measuring circuit performs a time measuring operation for ticking time and periodically updates the calendar time stored in the memory of the time measuring circuit. The calendar time in the timer circuit memory is set and updated by synchronization with the user or the Internet clock in the network.

Since the memory of the clock circuit needs to erase the stored contents only by stopping the power, it is usually composed of a volatile memory such as SRAM. Therefore, when the computer cannot be started due to BIOS setup, the data stored in the timer circuit memory can be erased by removing the battery pack and the coin battery.

Since the coin battery cannot be removed unless the housing is opened, the user will not accidentally erase the time information or set-up data.

Patent Document 1 discloses that a portable electronic device having an RTC circuit as shown in FIG. 6 supplies a voltage to a memory and an RTC circuit via a regulator and a diode when a battery pack is mounted, and lithium via a regulator and a switch. Charge the battery. When the battery pack is not attached, voltage is supplied from the lithium battery to the memory and the RTC circuit via the switch. Thus, a technique is described that can continue power supply from a lithium battery as a backup battery to the RTC circuit for a long time.

JP 2004-180426 A

By the way, in recent portable electronic devices, in addition to keeping the clock circuit for a long time, miniaturization, weight reduction, and cost reduction are important issues. In order to solve this problem, it is indispensable to reduce the number of parts constituting the device and to reduce the size of each part.

However, the conventional configuration requires a backup battery such as a coin battery for supplying power to the timing circuit and continuing the operation of the RTC for a long time. Therefore, the portable electronic device is reduced in size, weight and cost. It had the problem of preventing Further, when the backup battery is removed, there is a problem that the operation of the timing circuit cannot be maintained for a long time.

The present invention solves the above-mentioned conventional problems, and by removing the backup battery for the clock circuit of the portable electronic device, the portable electronic device can be reduced in size, weight and cost, and the remaining battery pack can be realized. It is an object of the present invention to provide a battery pack that can maintain the function of a clock circuit for a long time even when the capacity is reduced.

In order to solve the conventional problems, a battery pack of the present invention includes a secondary battery, a first output terminal that outputs power from the secondary battery to a system circuit of an electronic device, and the electronic battery from the secondary battery. A second output terminal for outputting electric power to the timing circuit of the device, a branch point from the secondary battery to the first output terminal and the second output terminal, and between the branch point and the first output terminal, A first switch unit configured to turn on / off the output from the first output terminal; and a control unit configured to control the first switch unit to be turned on / off, wherein the voltage of the secondary battery is the first. When the voltage value becomes equal to or less than the voltage value, the first switch unit is turned OFF, and the output from the second output terminal is continued.

This configuration makes it possible to continuously output the power of the timing circuit of the portable electronic device from the battery pack for a long time.

According to the battery pack of the present invention, the backup battery for the timing circuit of the portable electronic device can be removed, and the electronic device can be reduced in size, weight and cost, and the time can be counted even when the remaining capacity of the battery pack is reduced. The function of the circuit can be maintained for a long time.

The battery pack of the present invention outputs a secondary battery, a first output terminal that outputs power from the secondary battery to a system circuit of an electronic device, and outputs power from the secondary battery to a timing circuit of the electronic device. A second output terminal, a branch point from the secondary battery to the first output terminal and the second output terminal, and an output from the first output terminal between the branch point and the first output terminal A first switch unit that turns on / off the first switch unit, and a control unit that controls ON / OFF of the first switch unit, wherein the control unit has a remaining capacity of the secondary battery equal to or less than a predetermined remaining capacity value At this time, the first switch unit is turned OFF, and the output from the second output terminal is continued.

An electronic device system according to the present invention includes an electronic device including the battery pack, a system circuit that operates with power from the first output terminal, and a timing circuit that operates with power from the second output terminal. It is equipped with.

In addition, the electronic device of the present invention inputs a system circuit, a timing circuit, a first input terminal for inputting power from the secondary battery to the system circuit, and inputs power from the secondary battery to the timing circuit. When the input voltage of the second input terminal and the secondary battery is equal to or lower than a predetermined voltage value, the input from the first input terminal is stopped, and after the input from the first input terminal is stopped, The input from the second input terminal is continued.

FIG. 1 is a block diagram of a battery pack and a portable electronic device having an output terminal for a timing circuit in an embodiment of the present invention. FIG. 2A is a relationship diagram between the discharge amount of the battery pack and the terminal voltage in the embodiment of the present invention, and FIG. 2B is the vicinity of the end of discharge in FIG. 2A (discharge amount is 90 (%) or more). FIG. FIG. 3A is a relationship diagram between the discharge amount of the battery pack and power in the embodiment of the present invention, and FIG. 3B is the vicinity of the discharge end in FIG. 3A (discharge amount is 90% or more). It is an enlarged view. FIG. 4 is a block diagram of another battery pack and a portable electronic device having an output terminal for a timing circuit in an embodiment of the present invention. FIG. 5 is a block diagram of a conventional battery pack and portable electronic device. FIG. 6 is a block diagram of another conventional battery pack and portable electronic device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

FIG. 1 is a block diagram of a battery pack 200 provided with an output terminal for a timer circuit and a portable electronic device 300 according to an embodiment of the present invention. And the battery pack 200 shown in FIG. 1 and the portable electronic device 300 are combined, and the electronic device system 100 is comprised.

Here, as the portable electronic device 300, various electronic devices such as a personal computer, a digital camera, and a PDA in which a clock circuit called an RTC (Real Time Clock) that provides a calendar time to the system is incorporated. In particular, in this embodiment, a small electronic device such as a laptop computer, a smartphone, or a tablet is employed.

The battery pack 200 includes a positive terminal 210, a time measuring terminal 220, information terminals 230 and 240, a temperature terminal 250, and a negative terminal 260 as connection terminals with the portable electronic device 300. Further, the battery pack 200 includes a secondary battery 201, a control unit 202, a double protection circuit 203, a current detection resistor 204 (current detection unit), a temperature sensor 205 (temperature detection unit), a fuse 206, a heater 207, two A branch point 208 is provided that divides the secondary battery 201 into a positive electrode terminal 210 and a time measuring terminal 220.

Between the branch point 208 and the positive terminal 210,

switching elements

211 and 212 are provided. In addition, a regulator 221 is provided between the branch point 208 and the time measuring terminal 220, and a reset circuit 222 is connected to the regulator 221. A grounded capacitor 223, a diode 224, and a grounded Zener diode 225 are disposed between the regulator 221 and the time measuring terminal 220.

The portable electronic device 300 includes a positive terminal 310, a time measuring terminal 320, information terminals 330 and 340, a temperature terminal 350, and a negative terminal 360. The battery pack 200 and the portable electronic device 300 include DC high-side

positive terminals

210 and 310 that supply power to the system circuit,

clock terminals

220 and 320 that supply power to the clock circuit, and an information terminal 230 for communication signals. , 240, 330, 340,

temperature terminals

250, 350 for battery pack temperature, and

negative terminals

260, 360 for power supply and communication signals.

In the battery pack 200, the positive electrode terminal 210 is connected to the positive electrode of the secondary battery 201 via a switching element 211 for discharging and a switching element 212 for charging. As the switching

elements

211 and 212, for example, n-channel FETs (Field Effect Transistors) are used.

The negative electrode terminal 260 is connected to the negative electrode of the secondary battery 201 via the current detection resistor 204, and is connected to the negative electrode from the positive electrode terminal 210 via the switching

elements

211 and 212, the secondary battery 201, and the current detection resistor 204. A current path to the terminal 260 is configured.

The current detection resistor 204 converts the charging current and discharging current of the secondary battery 201 into voltage values. A plurality of secondary batteries 201, for example, two secondary batteries 201 are connected in series as shown in FIG. The secondary battery 201 is a secondary battery such as a lithium ion secondary battery or a nickel hydride secondary battery. Note that the secondary battery 201 may be, for example, one, for example, a plurality of secondary batteries may be connected in parallel, or may be in a state where a combination of series and parallel is connected.

The temperature sensor 205 is a temperature sensor that detects the temperature of the secondary battery 201. The temperature of the secondary battery 201 is detected by a temperature sensor 205 and input to an analog / digital converter (not shown) in the control unit 202. Further, the terminal voltages V1 and V2 of the secondary battery 201 are read by a voltage detection circuit (not shown), respectively, and input to an analog / digital converter in the control unit 202. Furthermore, the current value of the current detected by the current detection resistor 204 is also input to the analog-digital converter in the control unit 202. The analog-digital converter converts each input value into a digital value and outputs the digital value to the control unit 202.

For example, the analog-digital converter represents the current value of the current detected by the current detection resistor 204, plus the current in the direction in which the secondary battery 201 is charged, and minus the current in the direction in which the secondary battery 201 is discharged. Shall.

The control unit 202 is, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing.
), A ROM (Read Only Memory) in which a predetermined control program is stored, a RAM (Random Access Memory) in which data is temporarily stored, peripheral circuits thereof, and the like. And the control part 202 performs charging / discharging control, remaining capacity detection, remaining time calculation, etc. by running the control program memorize | stored in ROM.

The charge / discharge control of the control unit 202 will be described. When the charging device is connected to the battery pack 200, the control unit 202 charges the secondary battery 201 using various charging methods such as constant current-constant voltage charging, trickle charging, and pulse charging. Then, for example, when the charging current flowing through the secondary battery 201 becomes equal to or less than the charge termination current value, the control unit 202 determines that the secondary battery 201 is fully charged and ends the charging.

In addition, the control unit 202 detects an abnormality outside the battery pack 200 such as a short circuit between the positive terminal 210 and the negative terminal 260 and an abnormal current from the portable electronic device 300 based on each input value from the analog-digital converter, An abnormality such as an abnormal temperature rise of the secondary battery 201 is detected. When the control unit 202 detects such an abnormality, the control unit 202 turns off the switching

elements

211 and 212 and performs a protection operation for protecting the secondary battery 201 from an abnormality such as overcurrent or overheating.

The remaining capacity detection of the control unit 202 will be described. The control unit 202 detects the remaining capacity RC of the secondary battery 201 by, for example, a current integration method. Specifically, the control unit 202 calculates the remaining capacity RC charged in the secondary battery 201 by integrating the current Ic detected by the current detection resistor 204 at a constant time interval (for example, 1 second). To do. In this case, since the current in the direction in which the secondary battery 201 is charged is positive and the current in the direction in which the secondary battery 201 is discharged is negative, by updating RC with RC ′ = RC + Ic × t, The remaining capacity RC of the secondary battery 201 is updated. Here, RC ′ represents the remaining capacity after update, and t represents a certain time interval.

In addition, when the full charge of the secondary battery 201 is detected by the charge / discharge control, the control unit 202 sets the predetermined full charge capacity value FCC of the secondary battery 201 as the current remaining capacity RC. Here, the control unit 202 may calculate the remaining capacity RC using a technique such as a voltage measurement method other than the current integration method.

The double protection circuit 203 inputs the terminal voltages V1 and V2 of the secondary battery 201 read by the voltage detection circuit, and heats the heater 207 when any of the terminal voltages V1 and V2 is an abnormal voltage. Then, the fuse 206 is blown. Thereby, the protection operation for protecting the secondary battery 201 from an abnormality such as overcurrent or overheating is performed.

The regulator 221 converts the outputs 8.4 to 4.0 (V) of the two secondary batteries 201 connected in series to the power 3.3 V for the RTC, which is a time measuring circuit, and supplies it to the time measuring terminal 220. Output. Since the regulator 221 is arranged between the branch point 208 and the time measuring terminal 220, even if the switching

elements

211 and 212 are turned off by the control of the control unit 202, the regulator 221 does not affect the RTC power. It can output continuously.

The positive terminal 210 has a constant power output [40 (W): 8.4 to 6.0 (V), 4.8 to 6.7 (A)], whereas the timing terminal 220 has a constant voltage output [3 .3 (V): 4 to 6 (μA), 13 to 20 (μW)].

The reset circuit 222 is connected between the secondary battery 201 and the branch point 208, and the output of the secondary battery 201 is a predetermined voltage, for example, 4.0 (V) (= 2.0 V × 2). When it becomes below, it determines that discharge is impossible when the remaining capacity of the secondary battery 201 is a predetermined value, for example, 50 (mAh) or less (when 1.3 V is set to 0 mAh), and the regulator 221 is turned off.

The diode 224 is disposed between wires connecting the regulator 221 and the time measuring terminal 220. As the diode 224, a Schottky diode having a small forward drop voltage Vf is used. When the battery pack 200 is connected to a charger (not shown), even if the timing terminal 220 is short-circuited with the positive terminal 210, the charging current is prevented from flowing into the regulator 221, and the charging current is positive. It flows only from 210 to the secondary battery 201.

Further, the Zener diode 225 is connected to a wiring connecting the diode 224 and the time measuring terminal 220 and is grounded. The resistor 226 is disposed between the wirings connecting the diode 224 and the time measuring terminal 220. The Zener diode 225 is a very general one such as a spec 5.6 (V) product. By arranging the Zener diode 225 and the resistor 226 in this way, the regulator 221 can be protected even if the time measuring terminal 220 is short-circuited with the positive terminal 210.

The portable electronic device 300 includes a control unit 301, a DC-DC converter 311, a timing circuit 321 called RTC, an information processing unit 331 that is a system circuit, and a charger IC 351.

The portable electronic device 300 inputs the power of the battery pack 200 input from the positive electrode terminal 310 to the DC-DC converter 311 and supplies it to the control unit 301. In addition, the portable electronic device 300 supplies the clock circuit 321 with the power for the clock circuit input from the clock terminal 320.

In addition, the portable electronic device 300 inputs the information signal of the battery pack 200 input from the information terminals 330 and 340 to the information processing unit 331. In addition, the portable electronic device 300 inputs temperature information of the battery pack 200 input from the temperature terminal 350 to the charger IC 351. And the portable electronic device 300 inputs an information signal and temperature information into the control part 301, and uses it as control information at the time of control of a system.

FIG. 2 is a relationship diagram between the discharge amount of the battery pack 200 and the terminal voltage in the embodiment of the present invention. 2A, the horizontal axis indicates the discharge amount (%) from the full charge of the battery pack 200 to the end of discharge, and the vertical axis indicates the terminal voltage (V) of the positive terminal 210 and the time measuring terminal 220. Moreover, FIG.2 (b) is an enlarged view of the discharge end vicinity (discharge amount 90% or more) of Fig.2 (a). In FIG. 2, the discharge amount and voltage discharge characteristics of the battery pack 200 are indicated by a dotted line, the terminal voltage of the positive terminal 210 is indicated by a solid line, and the terminal voltage of the time measuring terminal 220 is indicated by a broken line.

As shown in FIG. 1, the battery pack 200 includes two secondary batteries 201, which are lithium ion secondary batteries, connected in series. Therefore, when the battery pack 200 is fully charged, the voltage becomes 8.4 (V) (= 4.2 V × 2), and the voltage decreases as the discharge further proceeds.

The terminal voltage of the positive electrode terminal 210 is a voltage in accordance with the discharge characteristics of the battery pack 200 while the control unit 202 is turning on the switching

elements

211 and 212. Then, when the remaining capacity of the battery pack 200 is reduced and the voltage of the secondary battery 201 becomes 6.0 (V) (= 3.0 V × 2) or less, the control unit 202 turns off the switching

elements

211 and 212. Thus, the terminal voltage of the positive terminal 210 is 0 (V).

In the present specification, the voltage of the secondary battery 201 becomes 6.0 (V) (= 3.0 V × 2) which is the minimum output voltage of the positive electrode terminal 210 or less, and the control unit 202 outputs from the positive electrode terminal 210. It is defined as “End of discharge” when the power is stopped. Further, when the voltage of the secondary battery 201 is higher than 6.0 (V) (= 3.0 V × 2) and the control unit 202 stops the output from the positive terminal 210, it is referred to as “discharge stop”. Define. For example, when the voltage of the secondary battery 201 is 7.0 (V) and the control unit 202 stops discharging based on information from the portable electronic device 300, it is referred to as “discharging stop”.

The terminal voltage of the timing terminal 220 is that the output from the two secondary batteries 201 connected in series is stepped down to a predetermined voltage by the regulator 221 and output at a predetermined voltage, for example, 3.3 (V). It becomes. Then, when the reset circuit 222 turns off the regulator 221, the terminal voltage of the time measuring terminal 220 becomes 0 (V).

The output of the positive terminal 210 and the timing terminal 220 will be described with reference to FIG. In particular, the vicinity of the end of discharge, that is, the discharge amount of 90% or more will be described with reference to FIG.

As shown in FIG. 2 (a), from the full charge to the end of discharge, the positive terminal 210 outputs a voltage of 8.4 (V) to 6.0 (V) in accordance with the discharge characteristics of the battery pack 200. The terminal 220 outputs 3.3 (V).

As shown in FIG. 2B, near the end of the discharge, the control unit 202 determines that the voltage of the secondary battery 201 is 3.0 (V) or less, or the voltages of the two secondary batteries 201 connected in series are When it is detected that the voltage reaches 6.0 (V), the control unit 202 determines that the remaining capacity of the battery pack 200 has decreased to a predetermined value or less, turns off the switching

elements

211 and 212, and connects the terminals of the positive electrode terminal 210. The voltage is set to 0 (V).

When the user notices that the portable electronic device 300 cannot be used because the output from the positive electrode terminal 210 is lost, the output from the positive electrode terminal 210 can be resumed if charging is performed. However, in the case where charging is not performed, the timer circuit 321 of the portable electronic device 300 must continue to operate even when the output from the positive terminal 210 is stopped. Therefore, the time measuring terminal 220 continues to output terminal voltages of 3.3 (V) and 4 to 6 (μA).

Further, when the secondary battery 201 is overdischarged to an overdischarge prohibition voltage value (for example, 1.3 V) or less, the secondary battery 201 is deteriorated. Therefore, when the time measuring terminal 220 continues to output the terminal voltages 3.3 (V) and 4 to 6 (μA), the discharge characteristic of the battery pack 200 has a predetermined voltage, for example, FIG. When the voltage becomes 4.0 (V) or less as shown, the reset circuit 222 turns off the output from the regulator 221. As a result, the secondary battery 201 stops discharging, and the secondary battery 201 can be prevented from being overdischarged.

Since the operation of the timing circuit 321 has a low power of 13 to 20 (μW), the discharge characteristic of the secondary battery 201 is over two months from 6.0 (V) to 4.0 (V). Even after the electronic device 300 cannot be used, the timer circuit 321 can be operated for a long time.

Furthermore, in the battery pack 200 according to the embodiment of the present invention, not only the power to the system circuit of the portable electronic device 300 is stopped near the end of discharging, but also the power of the double protection circuit 203 is reduced to reduce the power of the portable electronic device The operating time of the 300 clock circuits 321 is extended.

FIG. 3 is a relational diagram between the discharge amount of the battery pack 200 and the power in the embodiment of the present invention. In FIG. 3A, the horizontal axis indicates the dischargeable amount (%) where the full charge of the battery pack 200 is 100 (%), and the vertical axis indicates the output power (W from the positive terminal 210 and the time measuring terminal 220). , ΜW) and the driving power (μW) of the double protection circuit 203. FIG. 3B is an enlarged view of the vicinity of the end of discharge in FIG. 3A (discharge amount is 90% or more). In FIG. 3, the output power from the positive terminal 210 is indicated by a solid line, the output power from the time measuring terminal 220 is indicated by a broken line, and the drive power of the double protection circuit 203 is indicated by a one-dot chain line.

The output from the positive terminal 210 is a constant power output [40 (W): 8.4 to 6.0 (V), 4.8 to drive the system circuit of the portable electronic device 300 from the time of full charge to the end of discharge. To 6.7 (A)]. The output from the timing terminal 220 is a constant voltage output [3.3 (V): 4 to 6 (μA), 13 to 20 (in order to drive the timing circuit 321 of the portable electronic device 300 from the time of full charge to the end of discharge. μW)].

The double protection circuit 203 always measures the terminal voltage of the secondary battery 201 of the battery pack 200. Further, the double protection circuit 203 monitors overcharge so that the secondary battery 201 is not overcharged. Monitoring of overcharging of the double protection circuit 203 is necessary near full charge, but not necessary near the end of discharge. Therefore, the double protection circuit 203 stops overcharge monitoring when the voltage is lower than a predetermined voltage that is not near full charge, and reduces drive power. The voltage at which the double protection circuit 203 stops monitoring overcharge is equal to or higher than the battery voltage of the secondary battery 201 that stops the output from the positive terminal 210, and the amount of discharge from the fully charged secondary battery 201 is 40. (%) Or more (remaining capacity is 60% or less).

For example, when the voltage at which the double protection circuit 203 stops monitoring overcharge is 7.0 (V) (= 3.5 V × 2), for example, the driving power of the double protection circuit 203 near full charge Is a constant current drive [10 (μA): 8.4 to 7.0 (V), 84 to 70 (μW) for measuring the terminal voltage of the secondary battery 201 of the overcharged battery pack 200 and monitoring overcharge. ]. Then, the driving power of the double protection circuit 203 near the end of discharging reduces the power of overcharge monitoring, and the constant current driving [5 (μA) only for measuring the terminal voltage of the secondary battery 201 of the overcharged battery pack 200. ): 7.0 to 4.0 (V), 35 to 20 (μW)].

The driving power of the double protection circuit 203 is about 1/500 of the output power from the positive terminal 210, but is more than four times the output power from the time measuring terminal 220. For this reason, by reducing the driving power of the double protection circuit 203 near the end of the discharge, it is possible to output from the time measuring terminal 220 for a long time more than twice with the reduced power, and to operate the time measuring circuit 321 for a longer time. It becomes possible.

According to such a configuration, the backup battery for the timing circuit of the portable electronic device can be removed, and the portable electronic device can be reduced in size, weight and cost, and the timing circuit can be used even when the remaining capacity of the battery pack is reduced. The function of can be maintained for a long time.

In this embodiment, the regulator 221 and the reset circuit 222 output the power for the timing circuit. However, the dual protection circuit may have a function of the regulator and the reset circuit. As shown in FIG. 4, the double protection circuit 503 of the battery pack 500 of the electronic device system 400 includes an output to which the time measuring terminal 220 is connected. The double protection circuit 503 steps down the output of the two secondary batteries 201 connected in series like a regulator and outputs the voltage. Then, when any voltage of the secondary battery 201 becomes 2.5 (V) or less, the output to the time measuring terminal 220 is stopped.

In this embodiment, the control unit 202 sets the voltage of the secondary battery 201 to 3.0 (V) or lower, or the voltage of the two secondary batteries 201 connected in series to 6.0 (V). When it is detected that the remaining capacity of the battery pack 200 has decreased to a predetermined value or less, the control unit 202 determines that the switching

elements

211 and 212 are turned off. The switching

elements

211 and 212 may be turned off when becomes below a predetermined value.

In the present embodiment, the electronic device system 100 is a combination of the battery pack 200 and the portable electronic device 300, but may be a combination of a battery pack and an electronic device that is not carried. In this case as well as the portable electronic device, even if the backup battery of the electronic device that is not carried is removed, the function of the timing circuit can be maintained for a long time even when the remaining capacity of the battery pack is reduced.

In the present embodiment, the time measuring terminal 220 corresponds to the constant power output [40 (W): 8.4 to 6.0 (V), 4.8 to 6.7 (A)] from the positive terminal 210. Constant voltage output [3.3 (V): 4 to 6 (μA), 13 to 20 (μW)] is a low-power output, but the system circuit of the portable electronic device 300 is a timing circuit 321. If the power is equal to or smaller than the output from the positive terminal 210, the output from the positive terminal 210 may be equal to or smaller than the output from the timing terminal 220.

In the present embodiment, the voltage of the battery pack 200 at which the reset circuit 222 turns off the output from the regulator 221 is set to 4.0 (V). (V) may be used. What is necessary is just to be lower than the minimum voltage value 6.0 (V) of the constant power output of the positive electrode terminal 210 and over discharge prohibition voltage value 2.6 (V) (= 1.3 V × 2).

In this embodiment, the output of the secondary battery 201 is stepped down by the regulator 221 and output from the timing terminal 220. However, the driving voltage of the timing circuit 321 of the portable electronic device 300 is the same as the output of the secondary battery 201. When the voltages are the same, the output of the secondary battery 201 may be directly output without using the regulator 221.

The battery pack according to the present invention removes the backup battery for the timing circuit of the portable electronic device, reduces the size and weight of the portable electronic device, reduces the cost, and reduces the remaining capacity of the battery pack. Since the function can be maintained for a long time, it is useful as a battery pack or the like that supplies both power to the system circuit of the portable electronic device and the clock circuit that generates the calendar time.

100, 400

Electronic device system

200, 500 Battery pack 201 Secondary battery 202

Control unit

203, 503 Double protection circuit 204 Current detection resistor 205 Temperature sensor 206 Fuse 207 Heater 208 Branch point 210

Positive electrode terminal

211, 212 Switching element 220 Timekeeping terminal 221 Regulator 222 Reset circuit 223 Capacitor 224 Diode 225 Zener diode 226 Resistor 230, 240 Information terminal 250 Temperature terminal 260 Negative electrode terminal 300 Portable electronic device 301 Control unit 310 Positive electrode terminal 311 DC-DC converter 320 Clock terminal 321 Clock circuit 330, 340 Information terminal 331 Information processing unit 350 Temperature terminal 351 Charger IC
360 Negative terminal

Claims

A secondary battery,
A first output terminal for outputting power from the secondary battery to a system circuit of an electronic device;
A second output terminal for outputting electric power from the secondary battery to the timing circuit of the electronic device;
A branch point from the secondary battery to the first output terminal and the second output terminal;
A first switch unit for turning ON / OFF the output from the first output terminal between the branch point and the first output terminal;
A control unit that controls ON / OFF of the first switch unit,
The control unit turns off the first switch unit and continues output from the second output terminal when the voltage of the secondary battery becomes equal to or lower than a first voltage value. .
The battery pack according to claim 1, further comprising a regulator between the branch point and the second output terminal for converting the output of the secondary battery into a low output for the timing circuit.
A second switch unit for turning off the output of the regulator;
The control unit turns off the output of the regulator by the second switch unit when the voltage of the secondary battery becomes equal to or lower than a second voltage value lower than the first voltage value. The battery pack according to claim 2.
The first voltage value is a lowest voltage value at which the first output terminal outputs constant power,
The battery pack according to claim 3, wherein the second voltage value is a voltage value higher than an overdischarge inhibition voltage value.
The double protection circuit stops monitoring overcharge when the remaining capacity of the secondary battery is a voltage value of 60% or less and a third voltage value of the first voltage value or more. The battery pack according to claim 1.
A secondary battery,
A first output terminal for outputting power from the secondary battery to a system circuit of an electronic device;
A second output terminal for outputting electric power from the secondary battery to the timing circuit of the electronic device;
A branch point from the secondary battery to the first output terminal and the second output terminal;
A first switch unit for turning ON / OFF the output from the first output terminal between the branch point and the first output terminal;
A control unit that controls ON / OFF of the first switch unit,
The control unit is configured to turn off the first switch unit and continue output from the second output terminal when the remaining capacity of the secondary battery becomes a predetermined remaining capacity value or less. pack.
The battery pack according to claim 6, further comprising a regulator for converting the output of the secondary battery to a low output for the timekeeping circuit between the branch point and the second output terminal.
A second switch unit for turning off the output of the regulator;
When the remaining capacity of the secondary battery is equal to or less than the predetermined remaining capacity value and the voltage of the secondary battery is equal to or less than the predetermined voltage value, the control unit causes the regulator to control the regulator. The battery pack according to claim 7, wherein the output of is turned off.
The predetermined remaining capacity value is a minimum remaining capacity value at which the first output terminal outputs constant power,
The battery pack according to claim 8, wherein the predetermined voltage value is a voltage value higher than an overdischarge inhibition voltage value.
The double protection circuit stops monitoring overcharge when the remaining capacity of the secondary battery is 60% or less and more than the predetermined remaining capacity. Battery pack.
The battery pack according to any one of claims 1 to 10,
An electronic device system comprising: an electronic device having a system circuit that operates with power from the first output terminal; and a timer circuit that operates with power from the second output terminal.
System circuit,
A clock circuit,
A first input terminal for inputting power from a secondary battery to the system circuit;
A second input terminal for inputting power from the secondary battery to the timing circuit;
When the input voltage of the secondary battery becomes a predetermined voltage value or less, the input from the first input terminal is stopped,
An electronic apparatus characterized in that the input from the second input terminal is continued even after the input from the first input terminal is stopped.