JP3231717B2 - Charge control circuit - Google Patents

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、リチウムイオン電
池等の充電制御回路に関し、定電流定電圧方式に好適な
充電制御回路に関する。[0001] 1. Field of the Invention [0002] The present invention relates to a charge control circuit for a lithium ion battery or the like, and more particularly to a charge control circuit suitable for a constant current and constant voltage system.

【０００２】[0002]

【従来の技術】近年、二次電池としてリチウムイオン電
池の販売が盛んに延びている。リチウムイオン電池は、
正極にＬｉＣｏＯ₂，負極にＣを使い、正極と負極とは
層状化合物になっており、充放電時はＬｉイオンがこの
間を出入りしながら移動する。Ｌｉイオン２次電池の端
子電圧が３．６ＶとＮｉ水素電池の１．２Ｖに比べて高
いのは、電解液に有機系の溶剤を使うためで、体積エネ
ルギー密度はＮｉ水素電池の約１．５倍の３００Ｗｈ／
ｌ，重量エネルギー密度は約２倍の約１２０Ｗｈ／ｋｇ
に達し、(1)大電流放電時に特性が劣化すること、(2)内
部インピーダンスが高いこと、(3)充電制御が定電流定
電圧方式であること、(4)Ｌｉイオン２次電池には材料
が違うコークス系グラファイト系の２種類があること、
という４つの特性を押さえる必要があるといわれてい
る。2. Description of the Related Art In recent years, sales of lithium-ion batteries as secondary batteries have been increasing actively. Lithium-ion batteries are
LiCoO ₂ is used for the positive electrode and C is used for the negative electrode. The positive electrode and the negative electrode are layered compounds, and during charging and discharging, Li ions move in and out of the gap. The reason why the terminal voltage of the Li-ion secondary battery is 3.6 V, which is higher than that of the Ni-hydrogen battery, which is 1.2 V, is because an organic solvent is used for the electrolytic solution, and the volume energy density is about 1. 5 times 300Wh /
1. Weight energy density is about 120Wh / kg, which is about twice as high
(1) that the characteristics deteriorate during high-current discharge, (2) that the internal impedance is high, (3) that the charge control is a constant-current constant-voltage method, and (4) that Li-ion secondary batteries There are two types of coke-based and graphite-based materials,
It is said that it is necessary to suppress these four characteristics.

【０００３】この充電制御が定電流定電圧方式であるこ
とに関し、Ｌｉイオン２次電池では、できるだけ充電電
圧を４．１Ｖまたは４．２Ｖに近づけることが、エネル
ギー容量を高めるカギとなり、これを越えると金属Ｌｉ
が析出して発火や発煙という課題につながる可能性がい
われている。このＬｉイオン２次電池の充電回路の従来
例を図面を参照して説明する。With respect to the fact that the charging control is of a constant current / constant voltage type, in a Li-ion secondary battery, setting the charging voltage as close as possible to 4.1 V or 4.2 V is a key to increasing the energy capacity, and exceeds this. And metal Li
It is said that it may lead to the problem of ignition and smoking. A conventional example of a charging circuit for this Li-ion secondary battery will be described with reference to the drawings.

【０００４】従来の充電回路の構成を、図６に示す。図
６において、充電電流供給部１から充電電流が供給さ
れ、充電制御回路２内の電流制限回路４で定電流源等に
より電流制限され、バッテリーの電池７に定電流を供給
して充電する。電池７の両端に接続された負荷回路１２
には、通信携帯機器の場合には送信部と受信部と信号処
理部とからなる周辺回路１４と周辺回路１４を制御する
ＣＰＵ１３とが備えられている。充電制御回路２には、
電流制限回路４と共に、電池７の電圧を検出する定電圧
充電制御回路３と、電池７の負側と接地電位とに接続さ
れて充電電流を流す抵抗器８の両端電圧を測定してＣＰ
Ｕ１３に満充電検出信号１１を出力する電圧検出回路
（１）５と、同様に抵抗器８の両端電圧を検出して電流
制限回路４に定電流充電用の制御信号を出力する電圧検
出回路（２）６とから構成されている。負荷回路１２の
ＣＰＵ１３は、電圧検出回路（１）５からの満充電検出
信号１１に従って電池７の満充電状態を検出して、充電
動作制御信号１５を充電制御回路２に供給することによ
り、充電動作を停止する。FIG. 6 shows a configuration of a conventional charging circuit. In FIG. 6, a charging current is supplied from a charging current supply unit 1, the current is limited by a constant current source or the like by a current limiting circuit 4 in a charging control circuit 2, and a constant current is supplied to a battery 7 of the battery to be charged. Load circuit 12 connected to both ends of battery 7
In the case of a communication portable device, a peripheral circuit 14 including a transmission unit, a reception unit, and a signal processing unit, and a CPU 13 for controlling the peripheral circuit 14 are provided. The charge control circuit 2 includes:
The constant voltage charging control circuit 3 for detecting the voltage of the battery 7 together with the current limiting circuit 4 and the voltage between both ends of the resistor 8 connected to the negative side of the battery 7 and the ground potential to flow the charging current are measured.
A voltage detection circuit (1) 5 that outputs a full charge detection signal 11 to U13, and a voltage detection circuit that similarly detects a voltage across the resistor 8 and outputs a control signal for constant current charging to the current limiting circuit 4 ( 2) and 6). The CPU 13 of the load circuit 12 detects the full charge state of the battery 7 in accordance with the full charge detection signal 11 from the voltage detection circuit (1) 5, and supplies a charge operation control signal 15 to the charge control circuit 2 to charge the battery. Stop operation.

【０００５】また、抵抗器８が図６の様に配置されてい
る場合、満充電検出を判断する電流は抵抗器８に発生す
る電圧をモニタしており、電池７への充電電流と負荷回
路１２への電流の合計を検出できる。図６の構成で、満
充電検出付近の充電電流の状態を、図７に示す。図７に
おいて、図７（ａ）には下部の「電池のみへ流れる充電
電流」と上部の「負荷電流（ＣＰＵ１３＋周辺回路１４
の電流）」とを加算した電流が抵抗器８に流れることを
示しており、図７（ｂ）には電圧検出回路（１）５から
の出力波形である満充電検出信号１１の状態図を示して
いる。図７において、満充電検出信号１１が”Ｈ”のと
きに充電制御回路２から充電電流を流している。電池７
への充電電流が満充電のしきい値以下で安定していた場
合でも、負荷回路１２への電流が増減するために、満充
電検出して充電完了すべき状態であっても、充電動作を
持続してしまい、負荷回路１２への電流と電池への充電
電流の合計が、満充電のしきい値を下回る為には、充電
時間が著しく延長したり、検出不可能となる問題があ
り、充電時間の正確性を確保する必要がある。When the resistor 8 is arranged as shown in FIG. 6, the current for judging the detection of the full charge monitors the voltage generated in the resistor 8, and the charging current to the battery 7 and the load circuit The sum of the currents to 12 can be detected. FIG. 7 shows the state of the charging current near the detection of the full charge in the configuration of FIG. In FIG. 7, FIG. 7 (a) shows the lower part “charging current flowing only to the battery” and the upper part “load current (CPU 13 + peripheral circuit 14).
FIG. 7B shows a state diagram of the full charge detection signal 11 which is an output waveform from the voltage detection circuit (1) 5. Is shown. In FIG. 7, when the full charge detection signal 11 is “H”, a charge current is flowing from the charge control circuit 2. Battery 7
Even if the charging current to the load circuit 12 is stable below the full charge threshold value, the charging operation is not performed even when the full charge is detected and the charging should be completed because the current to the load circuit 12 increases or decreases. In order for the sum of the current to the load circuit 12 and the charging current to the battery to fall below the full charge threshold, there is a problem that the charging time is significantly extended or undetectable, It is necessary to ensure the accuracy of the charging time.

【０００６】また、特開平８―３０７４９３号公報で
は、上記従来例での負荷回路１２に相当する回路が、携
帯電話機による充電中の着信による電池電圧の降下によ
り満充電検出の誤検出を引き起こすことを解決するもの
で、着信中は、強制的に満充電検出動作を行わなくする
ことにより、満充電誤検出を防止することが開示されて
いる。Also, in Japanese Patent Application Laid-Open No. 8-307493, a circuit corresponding to the load circuit 12 in the above-mentioned conventional example causes a false detection of full charge detection due to a drop in battery voltage due to an incoming call during charging by a portable telephone. It is disclosed that a full charge detection operation is forcibly not performed during an incoming call to prevent erroneous full charge detection.

【０００７】[0007]

【発明が解決しようとする課題】しかしながら、上述し
たように、定電流定電圧方式において満充電検出して充
電完了すべき状態であっても、充電動作を持続してしま
い、負荷回路と電池への充電電流の合計が、満充電のし
きい値を下回る為には、充電時間を著しく延長したり、
検出不可能となる問題があり、充電時間の正確性を確保
することができない。また、特開平８―３０７４９３号
公報による携帯電話機の着信中には充電動作をオフにす
ることでは、その着信中に電池を消耗してしまって、そ
の後携帯電話機として充電電流供給部から切り離したな
らば、満充電状態で充電電流供給部と切り離すことが要
求されている問題を解決できない。However, as described above, the charging operation is continued even when the full charge is detected and the charging should be completed in the constant current / constant voltage method, and the load circuit and the battery are connected. In order for the total charging current to fall below the full charge threshold, the charging time may be significantly extended,
There is a problem that detection becomes impossible, and it is not possible to ensure the accuracy of the charging time. Also, if the charging operation is turned off during an incoming call of a mobile phone according to Japanese Patent Application Laid-Open No. 8-307493, the battery is consumed during the incoming call, and then the mobile phone is disconnected from the charging current supply unit. For example, it is not possible to solve the problem that it is required to disconnect the battery from the charging current supply unit in the fully charged state.

【０００８】本発明は、満充電検出の誤検出を無くし、
充電が完了してもよい電池の充電状態にもかかわらずま
だ充電動作を行っているという、著しい充電時間の延長
を防止することができ、電池に接続した負荷の負荷変動
があっても安定した電圧を供給できることを課題とす
る。The present invention eliminates erroneous detection of full charge detection,
Charging may be completed.The charging operation is still performed in spite of the charging state of the battery, which can prevent a remarkable extension of the charging time, and is stable even if there is a load fluctuation of the load connected to the battery. An object is to supply a voltage.

【０００９】[0009]

【課題を解決するための手段】本発明は、電池に充電電
流を供給する充電電流供給部と、前記電池に直列に接続
された第１の抵抗器と、一端が前記第１の抵抗器に接続
され、他端が前記充電電流供給部の接地電位に接続され
た第２の抵抗器と、前記第１の抵抗器の両端電圧を検出
する第１の電圧検出回路と、前記第２の抵抗器の両端電
圧を検出する第２の電圧検出回路と、前記第１の抵抗器
に並列に接続され、前記電池の満充電状態を検出する時
以外はオンするスイッチ素子と、前記第２の電圧検出回
路の検出信号に基づいて前記電池の充電電流を制御する
電流制御回路と、前記スイッチ素子がオフである時に前
記第１の電圧検出回路の検出信号に基づいて前記電池の
満充電状態を検出し、前記充電電流供給部からの充電電
流をオフする制御回路とを備えたことを特徴としてい
る。SUMMARY OF THE INVENTION The present invention provides a battery for charging a battery.
Connected to the battery in series with the battery
Connected first resistor and one end connected to the first resistor
And the other end is connected to the ground potential of the charging current supply unit.
The second resistor and the voltage across the first resistor.
A first voltage detection circuit that operates, and a voltage across both ends of the second resistor.
A second voltage detection circuit for detecting pressure, and the first resistor
To detect the full charge state of the battery
And the second voltage detection circuit
Control the charging current of the battery based on a road detection signal
The current control circuit and the switch element when the switch element is off;
The battery voltage of the battery is determined based on a detection signal of the first voltage detection circuit.
A full charge state is detected, and charging power from the charging current supply unit is detected.
And a control circuit for turning off the flow.
You .

【００１０】[0010]

【００１１】[0011]

【００１２】[0012]

【００１３】[0013]

【００１４】本発明は、具体的に図１を参照しつつ説明
すれば、電池７が満充電に達する過程で、充電制御回路
２は定電流充電から定電圧充電に切り替えるように制御
を行い、満充電に近づき充電電流がある一定値以下にな
ることを抵抗器８に発生する電圧により読み取り、ある
電圧に達しているかどうか判断することで、満充電の検
出を行っている。抵抗器９では、負荷回路１２で消費す
る電流と電池への充電電流の合計をモニタし、抵抗器８
では電池への充電電流のみをモニタすることで、負荷回
路１２の負荷に影響なく、満充電の検出をする事ができ
る。The present invention will be described in detail with reference to FIG. 1. In the process where the battery 7 reaches a full charge, the charge control circuit 2 performs control to switch from constant current charge to constant voltage charge. The full charge is detected by reading from the voltage generated in the resistor 8 that the charge current becomes less than a certain value as the charge approaches the full charge and judges whether the voltage has reached a certain voltage. The resistor 9 monitors the sum of the current consumed by the load circuit 12 and the charging current to the battery.
By monitoring only the charging current to the battery, full charge can be detected without affecting the load of the load circuit 12.

【００１５】また、充電していない時、即ち負荷回路１
２が電池７より電源を供給して、負荷回路１２が動作し
ている場合、負荷回路１２の動作をより安定にする為に
は、負荷回路１２へ供給する電圧がより安定しているこ
とが望ましいことから、負荷回路１２と電池７間のイン
ピーダンスをより低くする目的で、図４に示すように抵
抗器８に並列にＳＷ１０を構成し、負荷回路１２により
安定した電圧を供給することができる。When the battery is not charged, that is, the load circuit 1
2 supplies power from the battery 7 and operates the load circuit 12, in order to make the operation of the load circuit 12 more stable, the voltage supplied to the load circuit 12 must be more stable. Because it is desirable, for the purpose of lowering the impedance between the load circuit 12 and the battery 7, the SW 10 can be configured in parallel with the resistor 8 as shown in FIG. .

【００１６】[0016]

【発明の実施の形態】本発明による実施形態について、
図面を参照しつつ詳細に説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described.
This will be described in detail with reference to the drawings.

【００１７】図１は、本発明の充電制御回路の参考例を
示すブロック図である。図１において、充電電流供給部
１から充電電流が供給され、充電制御回路２内の電流制
御回路４で定電流源及び定電圧源等により電流・電圧が
制限され、バッテリーの代表的なリチウムイオン電池７
に定電流・定電圧を供給して充電する。電池７とこれに
シリーズに接続された抵抗器８との両端に接続された負
荷回路１２には、通信携帯機器の場合には送信部と受信
部と信号処理部、音声処理部等とからなる周辺回路１４
と周辺回路１４を制御するＣＰＵ１３とが備えられてい
る。FIG. 1 shows a reference example of the charge control circuit of the present invention .
FIG . In FIG. 1, a charging current is supplied from a charging current supply unit 1, and a current / voltage is limited by a constant current source and a constant voltage source in a current control circuit 4 in a charge control circuit 2. Lithium ion battery 7
Supply constant current and constant voltage to the battery to charge. The load circuit 12 connected to both ends of the battery 7 and the resistor 8 connected in series to the battery 7 includes a transmission unit, a reception unit, a signal processing unit, a voice processing unit, and the like in the case of a communication portable device. Peripheral circuit 14
And a CPU 13 for controlling the peripheral circuit 14.

【００１８】また、充電制御回路２には、電流制限回路
４と共に、電池７の電圧を検出する定電圧充電制御回路
３と、電池７の負側とシリーズに接続され負荷回路１２
に流す負荷電流に従って両端電圧値が変化する抵抗器８
の両端電圧を測定してＣＰＵ１３に満充電検出信号１１
を出力する電圧検出回路（１）５と、抵抗器８と接地電
位間接続した抵抗器９の両端電圧を検出して電流制限回
路４に定電流・定電圧用の制御信号を出力する電圧検出
回路（２）６とから構成されている。The charging control circuit 2 includes a current limiting circuit 4, a constant voltage charging control circuit 3 for detecting the voltage of the battery 7, and a load circuit 12 connected in series with the negative side of the battery 7.
8 whose voltage value changes according to the load current flowing through the resistor 8
Of the full charge detection signal 11
And a voltage detection circuit that detects a voltage across a resistor 9 connected between the resistor 8 and the ground potential and outputs a control signal for a constant current and a constant voltage to the current limiting circuit 4. And a circuit (2) 6.

【００１９】また、負荷回路１２のＣＰＵ１３は、電圧
検出回路（１）５からの満充電検出信号１１に従って、
電池７の満充電状態を検出して、充電動作制御信号１５
を充電制御回路２に供給することにより、充電動作をオ
ン・オフする。The CPU 13 of the load circuit 12 responds to the full charge detection signal 11 from the voltage detection circuit (1) 5
A full charge state of the battery 7 is detected, and a charge operation control signal 15
Is supplied to the charge control circuit 2 to turn on / off the charging operation.

【００２０】また、充電電流供給部１より供給される電
源が、充電制御回路２へ入力され、電流制限回路４を経
て電池７へ送られ、電池７を充電している。リチウムイ
オン電池７の充電は、図２に示すようにまず定電流充電
を行い、電池電圧がある一定電圧まで達すると（ｔ
１）、定電圧充電に切り替わり、徐々に充電電流が減少
し、点線で示すある充電電流以下で満充電となり、充電
を終了するような充電動作を行っている。The power supplied from the charging current supply unit 1 is input to the charging control circuit 2, sent to the battery 7 via the current limiting circuit 4, and charges the battery 7. As shown in FIG. 2, the lithium-ion battery 7 is charged at a constant current, and when the battery voltage reaches a certain voltage (t)
1) Switching to constant-voltage charging, the charging current gradually decreases, the battery is fully charged below a certain charging current indicated by a dotted line, and a charging operation is performed to terminate charging.

【００２１】定電流充電を制御する目的として、充電制
御回路２から出力された電流を抵抗器９で電圧に変換
し、電圧検出回路（２）６を経て、電流制限回路４を制
御するように構成されている。また、定電圧充電を制御
する目的として、リチウムイオン電池７の電圧を充電制
御回路２の中の定電圧充電制御回路３に取り込み、電流
制限回路４を制御することで、電池電圧を一定に保つよ
うに制御している。For the purpose of controlling the constant current charging, the current output from the charging control circuit 2 is converted into a voltage by the resistor 9 and the current limiting circuit 4 is controlled via the voltage detecting circuit (2) 6. It is configured. Further, for the purpose of controlling the constant voltage charging, the voltage of the lithium ion battery 7 is taken into the constant voltage charging control circuit 3 in the charging control circuit 2 and the current limiting circuit 4 is controlled to keep the battery voltage constant. Control.

【００２２】満充電を検出する回路は、電池７への充電
電流を抵抗器８でその両端電圧に変換し、図３のように
しきい値Ｖｔｈ以下の電圧で、電圧検出回路（１）５か
らの満充電検出信号１１を“Ｌ”→“Ｈ”レベルに変化
するように構成されている。満充電検出信号１１は、負
荷回路１２の構成要素の１つであるＣＰＵ１３へ送ら
れ、ＣＰＵ１３は、ある決まった周期で満充電検出回路
１１のレベルを監視し、“Ｌ”→“Ｈ”レベルを確認す
ると、電池の充電が完了したことを認識し、充電動作制
御信号１５を使って充電動作を停止する役目をしてい
る。また、満充電検出回路１１のレベルが“Ｌ”レベル
を確認すると、電池の充電が必要なことを認識し、充電
制御回路２の動作を開始する。A circuit for detecting full charge converts a charging current to the battery 7 into a voltage between both ends by a resistor 8, and outputs a voltage equal to or lower than a threshold value Vth from the voltage detecting circuit (1) 5 as shown in FIG. Is changed from “L” to “H” level. The full charge detection signal 11 is sent to the CPU 13 which is one of the components of the load circuit 12, and the CPU 13 monitors the level of the full charge detection circuit 11 at a predetermined cycle, and changes from "L" to "H" level. When it is confirmed that the charging of the battery has been completed, the charging operation control signal 15 is used to stop the charging operation. When the level of the full charge detection circuit 11 confirms the “L” level, it recognizes that the battery needs to be charged, and starts the operation of the charge control circuit 2.

【００２３】ここで、満充電とは、２次電池を充電する
際、その電池が蓄積可能なエネルギーを全て外部電源か
ら供給された結果を示すもので、化学的には正負の電極
に介在する化学変換媒質が当該電池の仕様特性として定
められた値に変化した状態を示している。また、本２次
電池７については、電池７が所定の飽和電圧に至り且つ
定電圧充電駆動により充電電流が所定のしきい値電流以
下に下がった状態を示している。従って、本充電制御回
路では、満充電検出作用とともに、満充電に至らなくて
も、充電制御回路としても動作するものである。The term "full charge" as used herein refers to the result of supplying all the energy that can be stored in a secondary battery from an external power supply when the secondary battery is charged, and is chemically interposed between positive and negative electrodes. This shows a state in which the chemical conversion medium has changed to a value determined as a specification characteristic of the battery. The secondary battery 7 shows a state in which the battery 7 has reached a predetermined saturation voltage and the charging current has dropped to a predetermined threshold current or less due to the constant voltage charging drive. Therefore, the present charge control circuit operates as a charge control circuit even if full charge is not reached, together with the full charge detection operation.

【００２４】次に、図１の参考例の動作について図２、
図３を参照して説明する。図１に示す構成をもった充電
制御回路で充電すると、図２のように、電池７の電圧が
ある一定値に満たない時は、抵抗器９、電圧検出回路
（２）６、及び電流制限回路４によって定電流制御を行
う。また、電池７の電圧がある一定値付近になると、定
電圧充電制御回路３の働きで、電流制限回路４に電流減
少を働きかけ、充電電流が徐々に減少する。充電電流が
ある一定の充電電流以下、即ち抵抗器８に発生する電圧
があるしきい値電圧Ｖth以下となると、電圧検出回路
（１）５は、ある電圧以下になった事を検出し、図３に
示すように満充電検出信号１１を“Ｌ”→“Ｈ”にレベ
ルを変化させ、出力をする。ＣＰＵ１３は、ある一定の
周期で満充電検出信号１１のレベルを確認しており、
“Ｈ”を認識すると充電動作制御信号１５により充電制
御回路２へ、充電動作の停止を指示し、充電が完了す
る。 Next, the operation of the reference example of FIG. 1 will be described with reference to FIG.
This will be described with reference to FIG . When charging is performed by the charging control circuit having the configuration shown in FIG. 1, when the voltage of the battery 7 is less than a certain value as shown in FIG. 2, a resistor 9, a voltage detection circuit (2) 6, and a current limiter are provided. The circuit 4 controls the constant current. Also, when the voltage of the battery 7 becomes close to a certain value, the constant voltage charging control circuit 3 acts on the current limiting circuit 4 to decrease the current, and the charging current gradually decreases. When the charging current is lower than a certain charging current, that is, when the voltage generated in the resistor 8 becomes lower than a certain threshold voltage Vth, the voltage detecting circuit (1) 5 detects that the voltage has become lower than a certain voltage. As shown in FIG. 3, the level of the full charge detection signal 11 is changed from “L” to “H” and output. The CPU 13 confirms the level of the full charge detection signal 11 at a certain period,
And recognizing the "H" to a more charging control circuit 2 to the charging operation control signal 15 instructs the stop of the charging operation, the charging is completed.

【００２５】図４は本発明の一実施形態の構成を示すブ
ロック図である。本実施形態では図１の構成に対して抵
抗器８の両端に接続されたＳＷ１０が追加されている。
ＳＷ１０はＣＰＵ１３によってＯＮ／ＯＦＦが制御され
る。その他の構成は図１と同様であるので説明を省略す
る。ＳＷ１０がＯＦＦの場合には、図１と同様な動作を
し、ＳＷ１０がＯＮの場合には、電圧検出回路（１）５
の動作をＯＦＦとして、満充電検出信号１１の制御信号
を出力せず、ＣＰＵ１３による充電制御回路２への制御
もＯＦＦしてしまう。ＣＰＵ１３はこのＳＷ１０への制
御信号を一定間隔で出力する。FIG . 4 is a block diagram showing the configuration of an embodiment of the present invention.
It is a lock figure. In the present embodiment, the configuration shown in FIG.
The SW 10 connected to both ends of the anti-arm 8 is added.
SW10 is ON / OFF controlled by CPU13
You. Other configurations are the same as those in FIG.
You . When SW10 is OFF, the same operation as in FIG.
When the switch SW10 is ON, the voltage detection circuit (1) 5
Is turned off, the control signal of the full charge detection signal 11 is not output, and the control of the charge control circuit 2 by the CPU 13 is also turned off. The CPU 13 outputs a control signal to the SW 10 at regular intervals.

【００２６】図５に示す様に、ＣＰＵ１３による満充電
検出動作をする場合にのみＳＷ１０をＯＦＦし、抵抗器
８に充電電流分だけの電圧を発生させ、満充電検出信号
１１のレベルの確認を行う。満充電検出動作以外の場合
は、負荷回路１２に供給する電源電圧の変動を抑える為
に、ＳＷ１０をＯＮさせる制御をする。As shown in FIG. 5, only when the CPU 13 performs the full charge detection operation, the switch 10 is turned off, a voltage corresponding to the charge current is generated in the resistor 8, and the level of the full charge detection signal 11 is confirmed. Do. In cases other than the full charge detection operation, control is performed to turn on the SW 10 in order to suppress fluctuations in the power supply voltage supplied to the load circuit 12.

【００２７】このＣＰＵ１３の満充電検出動作時間を制
限し、通常の状態の場合には、負荷回路１２側からみた
電源回路は、抵抗器８がショウトされて、電池７だけと
なり、電源インピーダンスが低下し、負荷回路１２の負
荷状態が変化した場合でも、電池７の電圧に従って、電
源電圧が一定となり、負荷回路１２の種々の動作を安定
にすることができる。The operation time of the CPU 13 for detecting the full charge is limited, and in a normal state, the power supply circuit viewed from the load circuit 12 side has only the battery 7 with the resistor 8 shorted, and the power supply impedance is reduced. However, even when the load state of the load circuit 12 changes, the power supply voltage becomes constant in accordance with the voltage of the battery 7, and various operations of the load circuit 12 can be stabilized.

【００２８】尚、上記実施形態では、主に電池をリチウ
ムイオン２次電池の満充電制御回路について説明した
が、２次電池は他のニッケルカドミウム２次電池であっ
ても、ニッケル水素電池であってもよく、また、満充電
ばかりでなく、通常の充電制御回路においても適用でき
るものである。In the above embodiment, the battery is mainly described as a full charge control circuit for a lithium ion secondary battery. However, the secondary battery may be another nickel cadmium secondary battery or a nickel hydrogen battery. Alternatively, the present invention can be applied not only to full charge but also to a normal charge control circuit.

【００２９】[0029]

【発明の効果】本発明によれば、第１の効果として、定
電流充電中は、充電制御回路から出力される電流で制限
をかける為、抵抗器９に発生する電流をモニタし、更に
電池に流れる充電電流のみをモニタ可能な抵抗器８によ
って、満充電検出する際、負荷回路１２の負荷変動して
も、満充電検出信号１１の出力レベルに影響されない
為、満充電検出の誤検出を無くし、充電が完了しても良
い電池の充電状態にもかかわらずまだ充電動作を行って
いるという、著しい充電時間の延長を防止することがで
きる。According to the present invention, as a first effect, during the constant current charging, the current generated in the resistor 9 is monitored because the current output from the charge control circuit is limited. When the full charge is detected by the resistor 8 that can monitor only the charge current flowing through the load circuit 12, even if the load of the load circuit 12 fluctuates, the output level of the full charge detection signal 11 is not affected. Thus, it is possible to prevent a remarkable extension of the charging time in which the charging operation is still performed despite the charging state of the battery, which may be completed.

【００３０】また、第２の効果として、図４にあるＳＷ
１０を、図５の様な制御をＣＰＵ１３で行うことで、第
１の効果である著しい充電時間の延長の防止に加え、Ｃ
ＰＵ１３と周辺回路１４で構成される負荷回路１２と電
池間のインピーダンスを減少でき、ＣＰＵ１３や周辺回
路１４の負荷変動があっても安定した電圧を供給するこ
とができる。As a second effect, the SW shown in FIG.
5 is controlled by the CPU 13 as shown in FIG. 5, and in addition to the first effect of preventing the remarkable extension of the charging time,
The impedance between the battery and the load circuit 12 composed of the PU 13 and the peripheral circuit 14 can be reduced, and a stable voltage can be supplied even when the load of the CPU 13 and the peripheral circuit 14 fluctuates.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の参考例を示すブロック図である。FIG. 1 is a block diagram showing a reference example of the present invention.

【図２】図１の参考例の充電動作を示すグラフである。FIG. 2 is a graph showing a charging operation of the reference example of FIG.

【図３】図１の参考例の満充電検出信号の変化を示すグ
ラフである。FIG. 3 is a graph showing a change of a full charge detection signal of the reference example of FIG . 1 ;

【図４】本発明の充電制御回路の一実施形態の構成を示
すブロック図である。FIG. 4 shows a configuration of an embodiment of a charge control circuit of the present invention.
It is to block diagram.

【図５】図４の実施形態のＳＷ１０のＯＮ／ＯＦＦとＣ
ＰＵ１３の処理との関係を示すタイミングチャートであ
る。FIG. 5 shows ON / OFF of SW10 and C of the embodiment in FIG . 4;
6 is a timing chart illustrating a relationship with processing of a PU 13 ;

【図６】従来例の充電制御回路を示すブロック図であ
る。FIG. 6 is a block diagram showing a conventional charge control circuit .

【図７】図６の充電制御回路の動作を示すグラフであ
る。FIG. 7 is a graph showing an operation of the charge control circuit of FIG . 6 ;

【符号の説明】[Explanation of symbols]

１ 充電電流供給部 ２ 充電制御回路 ３ 定電圧充電制御回路 ４ 電流制限回路 ５ 電圧検出回路（１） ６ 電圧検出回路（２） ７ 電池 ８、９ 抵抗器 １０ ＳＷ（スイッチ） １１ 満充電検出信号 １２ 負荷回路 １３ ＣＰＵ １４ 周辺回路 １５ 充電動作制御信号DESCRIPTION OF SYMBOLS 1 Charge current supply part 2 Charge control circuit 3 Constant voltage charge control circuit 4 Current limiting circuit 5 Voltage detection circuit (1) 6 Voltage detection circuit (2) 7 Battery 8 , 9 resistor 10 SW (switch) 11 Full charge detection signal 12 load circuit 13 CPU 14 peripheral circuit 15 charge operation control signal

Claims (3)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 電池に充電電流を供給する充電電流供給
部と、前記電池に直列に接続された第１の抵抗器と、一
端が前記第１の抵抗器に接続され、他端が前記充電電流
供給部の接地電位に接続された第２の抵抗器と、前記第
１の抵抗器の両端電圧を検出する第１の電圧検出回路
と、前記第２の抵抗器の両端電圧を検出する第２の電圧
検出回路と、前記第１の抵抗器に並列に接続され、前記
電池の満充電状態を検出する時以外はオンするスイッチ
素子と、前記第２の電圧検出回路の検出信号に基づいて
前記電池の充電電流を制御する電流制御回路と、前記ス
イッチ素子がオフである時に前記第１の電圧検出回路の
検出信号に基づいて前記電池の満充電状態を検出し、前
記充電電流供給部からの充電電流をオフする制御回路と
を備えたことを特徴とする充電制御回路。1. A charging current supply for supplying a charging current to a battery.
A first resistor connected in series with the battery;
One end is connected to the first resistor, and the other end is the charging current.
A second resistor connected to the ground potential of the supply,
A first voltage detection circuit for detecting a voltage between both ends of the first resistor
And a second voltage for detecting a voltage across the second resistor.
A detection circuit, connected in parallel to the first resistor,
Switch that turns on except when detecting the full charge state of the battery
Based on an element and a detection signal of the second voltage detection circuit.
A current control circuit for controlling a charging current of the battery;
When the switch element is off, the first voltage detection circuit
Detecting a full charge state of the battery based on the detection signal;
A control circuit for turning off the charging current from the charging current supply unit;
Charge control circuit comprising the. 【請求項２】 前記電池はリチウムイオン電池であるこ
とを特徴とする請求項１に記載の充電制御回路。2. The battery according to claim 1, wherein the battery is a lithium ion battery.
The charge control circuit according to claim 1, wherein: 【請求項３】 前記電流制御回路は、前記電池の電圧が
所定値までは定電流充電を行い、所定値になると定電圧
充電を行うことを特徴とする請求項１に記載の充電制御
回路。3. The current control circuit according to claim 1 , wherein the voltage of the battery is
Constant current charging is performed up to the specified value,
The charging control circuit according to claim 1, wherein the charging is performed .