JP2007124740A - Charging circuit, electronic apparatus, and method of controlling current of charging circuit - Google Patents

Charging circuit, electronic apparatus, and method of controlling current of charging circuit Download PDF

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JP2007124740A
JP2007124740A JP2005309903A JP2005309903A JP2007124740A JP 2007124740 A JP2007124740 A JP 2007124740A JP 2005309903 A JP2005309903 A JP 2005309903A JP 2005309903 A JP2005309903 A JP 2005309903A JP 2007124740 A JP2007124740 A JP 2007124740A
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charging circuit
battery
absolute value
current
charging
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JP4544130B2 (en
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Makio Kobayashi
牧夫 小林
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NEC Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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    • Y02E60/10—Energy storage using batteries

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging circuit which can accurately suppress the heat generation of a charge current control FET, in its turn, thereby accurately suppressing the heat generation of a device itself, and to provide an electronic device with that charging circuit. <P>SOLUTION: The charging circuit performs the charge by the constant voltage supply from an external power source, with at least one or more batteries connected in parallel. This detects the absolute value of a load current and compares the absolute value with specified threshold. When the absolute value is larger than the threshold as the results of comparison, it controls the system to cut off at least one or more batteries from the charging circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、外部電源から定電圧給電される定電流充電タイプの充電回路、電子装置、及び充電回路の電流制御方法に関する。   The present invention relates to a constant current charging type charging circuit, an electronic device, and a current control method for the charging circuit that are supplied with constant voltage from an external power source.

従来技術として、外部電源から定電圧給電される定電流充電タイプの充電回路の構成例を図５に示し、以下に説明する。   As a conventional technique, a configuration example of a constant current charging type charging circuit that is supplied with a constant voltage from an external power supply is shown in FIG. 5 and will be described below.

図５において、外部から端子１へ定電圧化された電流が供給される。この電流はダイオード２を介して充電電流制御部（Field Effect Transistor：電界効果トランジスタ／以下、充電電流制御ＦＥＴという）３へ供給される。以下、充電電流制御ＦＥＴ３はｎチャンネルタイプとして説明する。   In FIG. 5, a constant voltage current is supplied from the outside to the terminal 1. This current is supplied to a charging current control unit (Field Effect Transistor / hereinafter referred to as a charging current control FET) 3 through a diode 2. Hereinafter, the charge current control FET 3 will be described as an n-channel type.

制御部７は、電流検出器４からの信号により充電電流を検出する。制御部７は、ソースとドレイン間に流れる電流値、すなわち電流検出器４からの信号を検出し、検出した信号からソースとドレイン間に流れる電流があらかじめ決められた一定電流値になるように充電電流制御ＦＥＴ３のゲート電圧を変化調整する。すなわちこれが定電流充電タイプの動作である。また、電流検出器４は、この検出器の両端の電位差は無い構成とする。   The control unit 7 detects a charging current based on a signal from the current detector 4. The control unit 7 detects a current value flowing between the source and the drain, that is, a signal from the current detector 4, and charges the detected signal so that the current flowing between the source and the drain becomes a predetermined constant current value. The gate voltage of the current control FET 3 is changed and adjusted. That is, this is a constant current charge type operation. Further, the current detector 4 is configured such that there is no potential difference between both ends of the detector.

外部から端子１へ給電される定電圧化された電流は、負荷側に流れ込む電流ＩＬと、電池側に流れ込む電流ＩＢとに分流し、電流ＩＢは電池６の充電に供される。電池６は電流ＩＢにより充電され、電池電圧ｂが上昇する。   The constant-voltage current fed from the outside to the terminal 1 is divided into a current IL flowing into the load side and a current IB flowing into the battery side, and the current IB is used for charging the battery 6. The battery 6 is charged by the current IB, and the battery voltage b rises.

このような従来の充電回路の構成の場合、充電電流制御ＦＥＴ３により電流ＩＬと電流ＩＢの合計電流は定電流化されているため、負荷の電流ＩＬが大きい場合は、相対的に電池充電の電流ＩＢが減少する。すなわち電池電圧ｂはゆるやかに上昇し、充電電流制御ＦＥＴ３のドレインとソース間の電位差aは、図２においてＡに示すように、ゆるやかに減少することになる。   In the case of such a conventional charging circuit configuration, the total current of the current IL and the current IB is made constant by the charging current control FET 3, so that when the load current IL is large, the battery charging current is relatively large. IB decreases. That is, the battery voltage b gradually increases, and the potential difference a between the drain and source of the charging current control FET 3 gradually decreases as indicated by A in FIG.

このとき、図２に示すように充電電流制御ＦＥＴ３の両端の電位差ａが大きい時間が多いため、図３に示すようにＦＥＴ３の発熱は大きく温度上昇も激しい。従って、充電回路部分は高温となり、この充電回路を備えた電子装置の筐体表面も高温となり易く、装置の使用者へ不快感や不安感を与えるという問題があった。   At this time, as shown in FIG. 2, since the potential difference a between both ends of the charging current control FET 3 is large, the heat generation of the FET 3 is large and the temperature rises rapidly as shown in FIG. Therefore, the charging circuit portion becomes high temperature, and the surface of the casing of the electronic device equipped with this charging circuit is likely to become high temperature, which causes a problem that the user of the device is uncomfortable and uneasy.

従来技術例として、複数の動作モードに最適な充電制御を行うと共に、ＡＣアダプタの容量を超えそうなときに、小電流充電あるいは充電停止して電圧ドロップの発生を防止できる「バッテリ制御装置」がある（例えば、特許文献１参照）。また、別の従来技術例として、外部電源の大型化ならびに機器の使い勝手の悪化を招くことなく、内蔵した複数組の電池を最適に充電することができる「電池可動電子機器およびその充電制御方法」がある（例えば、特許文献２参照）。
特開平０７−２４１０４７号公報 特許第２７７８７７２号公報 As an example of the prior art, there is a “battery control device” that performs optimal charging control for a plurality of operation modes and can prevent a voltage drop by charging with a small current or stopping charging when the capacity of the AC adapter is exceeded. Yes (see, for example, Patent Document 1). Also, as another prior art example, a “battery movable electronic device and its charge control method” that can optimally charge a plurality of built-in batteries without increasing the size of an external power source and deteriorating the usability of the device. (See, for example, Patent Document 2).
Japanese Patent Laid-Open No. 07-2441047 Japanese Patent No. 2777872

しかしながら、上記特許文献１記載の発明は、電圧ドロップにより負荷に流れる電流を二次的に検出するものであり、一般的にはユーザ自身が市場で購入したＡＣアダプタを使用する場合もあり、ＡＣアダプタは個々のばらつきも大きいので、電圧ドロップの値の測定では負荷電流の検出の正確性は低くなり、正確に発熱を抑えることはできない。
一方、上記特許文献２記載の発明は、負荷電流を検出して電池容量を切り替える機能を有していないので、例えば２つの電池が並列に接続されている場合、一方の電池が充電されず、ユーザの利便性が低いという問題がある。 However, the invention described in Patent Document 1 is for secondary detection of the current flowing through the load due to voltage drop, and in general, the user himself may use an AC adapter purchased in the market. Since adapters vary widely from one adapter to another, the accuracy of load current detection is low when measuring voltage drop values, and heat generation cannot be suppressed accurately.
On the other hand, since the invention described in Patent Document 2 does not have a function of switching the battery capacity by detecting the load current, for example, when two batteries are connected in parallel, one battery is not charged, There is a problem that user convenience is low.

以上のことから、負荷電流について正確に絶対値を検出し、適切に電池容量を切り替えることにより、正確に発熱を抑えることができる充電回路が望まれる。   From the above, there is a demand for a charging circuit that can accurately suppress heat generation by accurately detecting the absolute value of the load current and switching the battery capacity appropriately.

本発明は、上記事情に鑑みてなされたものであり、複数の電池を並列に接続した充電回路において、検出した負荷電流ＩＬの絶対値に応じて、適切に電池容量を切り替えることにより、充電電流制御ＦＥＴの発熱を正確に抑え、ひいては装置自体の発熱をも正確に抑えることが可能な充電回路、その充電回路を備えた電子装置、及びその充電回路の電流制御方法を提供することを目的とする。   The present invention has been made in view of the above circumstances, and in a charging circuit in which a plurality of batteries are connected in parallel, by appropriately switching the battery capacity according to the absolute value of the detected load current IL, the charging current is It is an object of the present invention to provide a charging circuit capable of accurately suppressing heat generation of a control FET and, in turn, accurately suppressing heat generation of the device itself, an electronic device including the charging circuit, and a current control method for the charging circuit. To do.

かかる目的を達成するために、請求項１記載の発明は、少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路であって、負荷電流の絶対値を検出し、絶対値と所定の閾値とを比較し、比較の結果、絶対値が閾値より大きい場合、少なくとも１以上の電池を充電回路から切り離すように制御することを特徴とする。   In order to achieve such an object, the invention described in claim 1 is a charging circuit in which at least one battery is connected in parallel and charging is performed by constant voltage power supply from an external power source, and the absolute value of the load current is determined. It detects, compares an absolute value with a predetermined threshold value, and when the absolute value is larger than the threshold value as a result of the comparison, control is performed such that at least one battery is disconnected from the charging circuit.

請求項２記載の発明は、少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路であって、電池に対応して設けられたスイッチ手段と、負荷電流の絶対値を検出する負荷電流検出手段と、絶対値と所定の閾値とを比較し、比較の結果、絶対値が閾値より大きい場合、少なくとも１以上の電池を充電回路から切り離すようにスイッチ手段を制御する制御手段と、を有することを特徴とする。   The invention according to claim 2 is a charging circuit in which at least one battery is connected in parallel and charging is performed by constant voltage power supply from an external power source, and a switch means provided corresponding to the battery, a load current, A load current detecting means for detecting an absolute value of the battery, and comparing the absolute value with a predetermined threshold value, and if the result of the comparison is that the absolute value is greater than the threshold value, the switch means is configured to disconnect at least one battery from the charging circuit. Control means for controlling.

請求項３記載の発明は、請求項１又は２記載の発明において、比較の結果、絶対値が閾値に満たない場合、少なくとも１以上の電池を充電回路に接続するように制御することを特徴とする。   The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, when the absolute value is less than the threshold value as a result of the comparison, at least one battery is controlled to be connected to the charging circuit. To do.

請求項４記載の発明は、請求項１から３のいずれか１項に記載の充電回路を有することを特徴とする。   According to a fourth aspect of the present invention, the charging circuit according to any one of the first to third aspects is provided.

請求項５記載の発明は、少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路の電流制御方法であって、負荷電流の絶対値を検出し、絶対値と所定の閾値とを比較し、比較の結果、絶対値が閾値より大きい場合、少なくとも１以上の電池を充電回路から切り離すように制御することを特徴とする。   The invention according to claim 5 is a current control method of a charging circuit in which at least one battery is connected in parallel and charging is performed by constant voltage power supply from an external power source, and the absolute value of the load current is detected and absolute A value is compared with a predetermined threshold value, and when the absolute value is larger than the threshold value as a result of the comparison, at least one battery is controlled to be disconnected from the charging circuit.

請求項６記載の発明は、少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路の電流制御方法であって、負荷電流の絶対値を検出する負荷電流検出ステップと、絶対値と所定の閾値とを比較し、比較の結果、絶対値が閾値より大きい場合、少なくとも１以上の電池を充電回路から切り離すように、電池に対応して設けられたスイッチ手段を制御する制御ステップと、を有することを特徴とする。   The invention according to claim 6 is a current control method for a charging circuit in which at least one or more batteries are connected in parallel, and charging is performed by constant voltage power supply from an external power source, and the load current detects the absolute value of the load current. Switch means provided corresponding to the battery so as to disconnect the at least one battery from the charging circuit when the absolute value is larger than the threshold value as a result of the comparison between the detection step and the absolute value and the predetermined threshold value And a control step for controlling.

請求項７記載の発明は、請求項５又は６記載の発明において、制御ステップにて、比較の結果、絶対値が閾値に満たない場合、少なくとも１以上の電池を充電回路に接続するように制御することを特徴とする。   The invention according to claim 7 is the control according to claim 5 or 6, wherein, in the control step, if the absolute value is less than the threshold value as a result of the comparison, at least one battery is connected to the charging circuit. It is characterized by doing.

本発明によれば、充電電流制御ＦＥＴの発熱を正確に抑え、ひいては装置自体の発熱をも正確に抑えることが可能となる。   According to the present invention, it is possible to accurately suppress the heat generation of the charging current control FET, and thus to accurately suppress the heat generation of the device itself.

以下、本発明を実施するための最良の形態について添付図面を参照して詳細に説明する。   The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

本発明は、携帯端末等の電子装置に使用される充電回路である。また、本発明は、複数の電池を並列に接続し、外部電源から定電圧給電される定電流タイプの充電回路であり、あらかじめ決められた負荷電流ＩＬの大きさに応じて電池の一つもしくは一部の電池容量のみを接続して充電することにより、電池容量を変更することができる構成である。この構成では、充電中でも充電電流制御ＦＥＴ３の温度上昇を減少せしめることが可能であり、ひいては装置自体の筐体表面温度の上昇を抑えることができる。   The present invention is a charging circuit used in an electronic device such as a portable terminal. Further, the present invention is a constant current type charging circuit in which a plurality of batteries are connected in parallel and supplied with a constant voltage from an external power source, and either one of the batteries or a battery depending on a predetermined load current IL. The battery capacity can be changed by connecting and charging only a part of the battery capacity. With this configuration, it is possible to reduce the temperature rise of the charging current control FET 3 even during charging, and as a result, it is possible to suppress an increase in the housing surface temperature of the device itself.

図１において、制御部７により制御されるスイッチ８は、複数の電池が並列に構成されたうちの一部の電池６−２を充電回路から切り離し、充電する電池容量を減少せしめる。このように負荷容量に応じて電池容量を減少させることができる構成とすれば、充電電流制御ＦＥＴ３の両端の電位差aは急速に減少し、充電電流制御ＦＥＴ３の発熱量すなわち温度上昇を抑えることができる。   In FIG. 1, the switch 8 controlled by the control unit 7 disconnects some of the batteries 6-2 among a plurality of batteries configured in parallel from the charging circuit, and reduces the battery capacity to be charged. If the battery capacity can be reduced according to the load capacity in this way, the potential difference a between both ends of the charging current control FET 3 decreases rapidly, and the amount of heat generated by the charging current control FET 3, that is, the temperature rise can be suppressed. it can.

本発明によれば、負荷電流により充電する電池容量を減少せしめているので、電池電圧が比較的急速に上昇し、充電電流制御ＦＥＴ３のドレインとソース間の電位差ａが急速に減少することから、充電電流制御ＦＥＴ３の発熱を抑え、ひいては装置自体の発熱をも正確に抑えることが可能となる。   According to the present invention, since the battery capacity to be charged is reduced by the load current, the battery voltage rises relatively quickly, and the potential difference a between the drain and source of the charging current control FET 3 rapidly decreases. It is possible to suppress the heat generation of the charging current control FET 3 and to accurately suppress the heat generation of the device itself.

図１は、本発明の一実施例である充電回路の構成を示す図である。また、本実施例では、図１に示す充電回路を備える電子装置を、携帯電話等の携帯端末装置とする。なお、既に上記にて従来構成の図５を用いて各構成を説明しており、図１においても同様の説明であるので省略する。図１において、上記従来構成の図５と異なる部分のみ説明する。   FIG. 1 is a diagram showing a configuration of a charging circuit according to an embodiment of the present invention. In this embodiment, an electronic device including the charging circuit shown in FIG. 1 is a mobile terminal device such as a mobile phone. Note that each configuration has already been described above with reference to FIG. 5 of the conventional configuration, and the description is omitted in FIG. In FIG. 1, only the parts different from FIG. 5 of the conventional configuration will be described.

図１において、電池は電池６−１と電池６−２の２つが並列に接続されている。電池６−１と電池６−２とを合わせた電池容量は、携帯端末に必要とされる電池容量と同等とする。すなわち、従来構成と比較すれば、電池６−１と電池６−２とを合わせた電池容量は、従来構成である図５の電池６と同じ電池容量である。   In FIG. 1, two batteries, a battery 6-1 and a battery 6-2, are connected in parallel. The total battery capacity of the battery 6-1 and the battery 6-2 is equivalent to the battery capacity required for the mobile terminal. That is, as compared with the conventional configuration, the combined battery capacity of the battery 6-1 and the battery 6-2 is the same battery capacity as the battery 6 of FIG.

電流ＩＢは、それぞれ電流ＩＢ−１と電流ＩＢ−２に分流する。更に電池６−２には電流ＩＢ−２が電池６−２に流れ込まないようにスイッチ８を設けている。すなわち電池６−２はスイッチ８の動作により充電回路から切り離されることができる。このスイッチ８は、制御部７の制御により、接続／非接続（以下、ＯＮ／ＯＦＦと記す）の動作が可能である。   The current IB is divided into a current IB-1 and a current IB-2, respectively. Further, the battery 6-2 is provided with a switch 8 so that the current IB-2 does not flow into the battery 6-2. That is, the battery 6-2 can be disconnected from the charging circuit by the operation of the switch 8. The switch 8 can be connected / disconnected (hereinafter referred to as ON / OFF) under the control of the control unit 7.

負荷５に流れ込む負荷電流ＩＬは、負荷電流検出器９により検出される。負荷電流検出器９は、正確に負荷電流ＩＬの絶対値を検出する。これは、従来技術（例えば特許文献１）のように、電圧ドロップによる２次的な検出方法であると、検出の正確性が低くなり、発熱の危険性があり、Product Liability（ＰＬ）の問題になりかねない。本実施例では、この負荷電流検出器９により正確に負荷電流ＩＬの絶対値を検出できるため、正確に電池容量を切り替え、正確に発熱を抑えることができる。   The load current IL flowing into the load 5 is detected by the load current detector 9. The load current detector 9 accurately detects the absolute value of the load current IL. This is a secondary detection method based on voltage drop as in the prior art (for example, Patent Document 1), the detection accuracy is low, there is a risk of heat generation, and there is a problem of Product Liability (PL). It can be. In this embodiment, since the load current detector 9 can accurately detect the absolute value of the load current IL, the battery capacity can be switched accurately and heat generation can be suppressed accurately.

制御部７は、負荷電流検出器９から負荷５に流れ込む負荷電流ＩＬの絶対値を受け取った後、この絶対値と、予め決められた閾値Ｉｔｈとを比較する。制御部７は、比較の結果、負荷電流ＩＬの絶対値が所定の閾値Ｉｔｈ未満であると判断した場合、スイッチ８をＯＮとし、電池６−２の電池へ充電されるように制御する。すなわち、合計の電池容量は図５で説明した従来構成と同等である。一方、負荷電流ＩＬの絶対値が所定の閾値Ｉｔｈよりも大きいと判断した場合、制御部７は、スイッチ８をＯＦＦとし、電池６−２には電流が流れないように（充電されないように）制御する。   After receiving the absolute value of the load current IL flowing into the load 5 from the load current detector 9, the control unit 7 compares this absolute value with a predetermined threshold value Ith. When it is determined as a result of the comparison that the absolute value of the load current IL is less than the predetermined threshold value Ith, the control unit 7 turns on the switch 8 and controls the battery 6-2 to be charged. That is, the total battery capacity is equivalent to the conventional configuration described in FIG. On the other hand, when it is determined that the absolute value of the load current IL is larger than the predetermined threshold value Ith, the control unit 7 turns off the switch 8 so that no current flows through the battery 6-2 (so as not to be charged). Control.

ここで、負荷電流ＩＬがあらかじめ決められた閾値Ｉｔｈよりも大きく、スイッチ８をＯＦＦしたときの動作を詳述する。
充電電流ＩＢは、電池６−２へは流れずに全て電池６−１へ流れ込み、電池電圧ｂは急速に上昇する。よって、図２において、Ｂに示す通り充電電流制御ＦＥＴ３のドレインとソース間の電位差ａは、従来構成のときのＡに比較して急速に減少する。すなわち端子１へは外部から定電圧給電されるため、充電電流制御ＦＥＴ３のドレイン側は一定電圧である一方、ソース側は電池電圧ｂと同等なので、電位差ａは急速に減少することになる。 Here, the operation when the load current IL is larger than the predetermined threshold value Ith and the switch 8 is turned off will be described in detail.
The charging current IB does not flow to the battery 6-2 but flows all into the battery 6-1, and the battery voltage b rises rapidly. Therefore, in FIG. 2, as shown by B, the potential difference a between the drain and the source of the charging current control FET 3 is rapidly reduced as compared with A in the conventional configuration. That is, since a constant voltage is supplied to the terminal 1 from the outside, the drain side of the charging current control FET 3 is a constant voltage, while the source side is equivalent to the battery voltage b, so the potential difference a rapidly decreases.

充電電流制御ＦＥＴ３の発熱はドレインとソース間に流れる電流と、ドレインとソース間の電位差ａの両方に比例する。本実施例では定電流タイプの充電回路を対象としており、定電流タイプの充電回路ではいかなる電池容量と負荷電流ＩＬであってもドレインとソース間の電流は一定である。従って、ＦＥＴ３の発熱へ影響するのはドレインとソース間の電位差ａである。従って、電位差ａが急速に減少するために、図３に示すＦＥＴ３の発熱量はＢに示すように、従来構成のＡに比較して低いという効果を得ることができる。   The heat generation of the charging current control FET 3 is proportional to both the current flowing between the drain and the source and the potential difference a between the drain and the source. This embodiment is intended for a constant current type charging circuit. In the constant current type charging circuit, the current between the drain and the source is constant regardless of the battery capacity and the load current IL. Therefore, it is the potential difference a between the drain and the source that affects the heat generation of the FET 3. Accordingly, since the potential difference a rapidly decreases, an effect that the heat generation amount of the FET 3 shown in FIG. 3 is lower than that of A of the conventional configuration as shown in B can be obtained.

一方、負荷電流ＩＬがあらかじめ決められた閾値Ｉｔｈよりも低い場合について説明する。
端子１へ給電される電流は負荷電流ＩＬが小さいのでほとんど電池充電電流ＩＢへ供される。ここで、電池６−１と電池６−２との合計の電池容量の充電が必要となるが、充電電流ＩＢが大きいので電池電圧ｂの上昇もはやく、ＦＥＴの電位差ａも急速に小さくなり発熱量は小さい。従って、負荷電流ＩＬがあらかじめ決められた閾値Ｉｔｈよりも低いときにはスイッチ８をＯＮとしても発熱量は小さいので問題ない。また、スイッチ８をＯＮとすることにより、電池６−１と電池６−２の両方の電池に十分充電ができるので利便性も高いというメリットがある。 On the other hand, a case where the load current IL is lower than a predetermined threshold value Ith will be described.
The current supplied to the terminal 1 is almost supplied to the battery charging current IB because the load current IL is small. Here, charging of the total battery capacity of the battery 6-1 and the battery 6-2 is required. However, since the charging current IB is large, the battery voltage b is no longer increased, and the potential difference a of the FET is rapidly decreased to generate heat. The amount is small. Therefore, when the load current IL is lower than the predetermined threshold value Ith, there is no problem because the amount of heat generated is small even if the switch 8 is turned on. Further, by setting the switch 8 to ON, both the battery 6-1 and the battery 6-2 can be sufficiently charged, so that there is an advantage that convenience is high.

次に、本実施例の充電回路の動作について、図４のフローチャートを参照して説明する。
まず、負荷電流ＩＬの閾値Ｉｔｈを制御部７の記憶部（図示せず）へあらかじめ記憶させ、適時読み出しできる状態とする（ステップＳ１）。制御部７は、負荷電流検出器９から信号線１０の信号により負荷電流ＩＬの絶対値を受け取り（ステップＳ２）、所定の負荷電流ＩＬの閾値Ｉｔｈを記憶部から読み出し、負荷電流ＩＬの絶対値と比較する（ステップＳ３）。比較の結果、負荷電流ＩＬの絶対値が閾値Ｉｔｈよりも大きい場合は（ステップＳ３／ＹＥＳ）、制御部７は、スイッチ８をＯＦＦに制御する（ステップＳ４）。一方、負荷電流ＩＬの絶対値が閾値Ｉｔｈに満たない場合は（ステップＳ３／ＮＯ）、スイッチ８をＯＮに制御する（ステップＳ５）。以降は、負荷電流ＩＬの変化と閾値Ｉｔｈの関係を比較するため、ステップＳ４及びステップＳ５の後、ステップＳ２の負荷電流ＩＬの検出を繰り返す。 Next, the operation of the charging circuit of this embodiment will be described with reference to the flowchart of FIG.
First, the threshold value Ith of the load current IL is stored in advance in a storage unit (not shown) of the control unit 7 so that it can be read out in a timely manner (step S1). The control unit 7 receives the absolute value of the load current IL from the signal of the signal line 10 from the load current detector 9 (step S2), reads the threshold Ith of the predetermined load current IL from the storage unit, and calculates the absolute value of the load current IL. (Step S3). As a result of the comparison, when the absolute value of the load current IL is larger than the threshold value Ith (step S3 / YES), the control unit 7 controls the switch 8 to be OFF (step S4). On the other hand, when the absolute value of the load current IL is less than the threshold value Ith (step S3 / NO), the switch 8 is controlled to be ON (step S5). Thereafter, in order to compare the relationship between the change in the load current IL and the threshold value Ith, the detection of the load current IL in step S2 is repeated after step S4 and step S5.

以上説明したように、本実施例の充電回路によれば、負荷電流の絶対値を検出し、閾値との比較結果に基づいて、充電する電池容量を減少せしめているので、電池電圧が比較的急速に上昇し充電電流制御ＦＥＴ３のドレインとソース間の電位差ａが急速に減少することから、ＦＥＴ３の発熱を抑えることができる。また、携帯端末装置自体の発熱をも抑えることが可能となる。   As described above, according to the charging circuit of this embodiment, the absolute value of the load current is detected, and the battery capacity to be charged is reduced based on the comparison result with the threshold value. Since the potential difference a between the drain and source of the charging current control FET 3 rapidly increases and rapidly decreases, the heat generation of the FET 3 can be suppressed. In addition, it is possible to suppress the heat generation of the mobile terminal device itself.

上記実施例１では、図１において、あらかじめ決められた閾値Ｉｔｈより負荷電流ＩＬが大きい場合、制御部７がスイッチ８をＯＦＦ制御することにより、電池６−２を充電回路から切り離すようにしたが、別の実施例として、図１において、６−１にもスイッチを設け、スイッチ８に対する制御と同様にＯＦＦ制御し、全ての電池（図１では６−１及び６−２）を切り離すようにしてもよい。なお、携帯端末の一例である携帯電話では、負荷にバースト動作をする無線部を有しており、急激な負荷変動による無線特性劣化を防ぐために小容量でも電池を充電回路すなわち無線部への給電回路に接続するのが普通である。よって、このような場合は実施例１の制御を用いるのがよい。   In the first embodiment, when the load current IL is larger than the predetermined threshold value Ith in FIG. 1, the control unit 7 controls the switch 8 to be turned off to disconnect the battery 6-2 from the charging circuit. As another example, in FIG. 1, a switch is also provided in 6-1 and OFF control is performed similarly to the control for the switch 8, so that all the batteries (6-1 and 6-2 in FIG. 1) are disconnected. May be. Note that a mobile phone, which is an example of a mobile terminal, has a wireless unit that performs a burst operation on the load, and the battery is supplied to the charging circuit, that is, the wireless unit even with a small capacity in order to prevent deterioration of wireless characteristics due to sudden load fluctuation Usually connected to a circuit. Therefore, in such a case, it is better to use the control of the first embodiment.

以上、本発明の実施例について説明したが、上記実施例に限定されるものではなく、その要旨を逸脱しない範囲において種々の変形が可能である。   As mentioned above, although the Example of this invention was described, it is not limited to the said Example, A various deformation | transformation is possible in the range which does not deviate from the summary.

本発明は、外部から定電供給される定電流タイプの充電回路全般及びその充電回路を備える電子装置全般に適用できる。   The present invention can be applied to all constant current type charging circuits supplied with constant power from the outside and to all electronic devices including the charging circuit.

本発明の実施例である充電回路の構成を示す図である。It is a figure which shows the structure of the charging circuit which is an Example of this invention. 時間と電位差との関係を示すグラフである。It is a graph which shows the relationship between time and an electric potential difference. 時間と発熱量との関係を示すグラフである。It is a graph which shows the relationship between time and the emitted-heat amount. 本発明の実施例である充電回路の動作を示すフローチャートである。It is a flowchart which shows operation | movement of the charging circuit which is an Example of this invention. 従来の充電回路の構成を示す図である。It is a figure which shows the structure of the conventional charging circuit.

符号の説明Explanation of symbols

１ 端子
２ ダイオード
３ 充電電流制御ＦＥＴ
４ 電流検出器
５ 負荷
６、６−１、６−２ 電池
７ 制御部
８ スイッチ
９ 負荷電流検出器
ＩＬ、ＩＢ 電流 1 terminal 2 diode 3 charge current control FET
4 Current detector 5 Load 6, 6-1, 6-2 Battery 7 Control unit 8 Switch 9 Load current detector IL, IB Current

Claims (7)

少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路であって、
負荷電流の絶対値を検出し、該絶対値と所定の閾値とを比較し、該比較の結果、該絶対値が該閾値より大きい場合、前記少なくとも１以上の電池を前記充電回路から切り離すように制御することを特徴とする充電回路。 A charging circuit in which at least one battery is connected in parallel and is charged by constant voltage power supply from an external power source,
An absolute value of the load current is detected, the absolute value is compared with a predetermined threshold value, and if the absolute value is larger than the threshold value as a result of the comparison, the at least one battery is disconnected from the charging circuit. A charging circuit that is controlled. 少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路であって、
前記電池に対応して設けられたスイッチ手段と、
負荷電流の絶対値を検出する負荷電流検出手段と、
該絶対値と所定の閾値とを比較し、該比較の結果、該絶対値が該閾値より大きい場合、前記少なくとも１以上の電池を前記充電回路から切り離すように前記スイッチ手段を制御する制御手段と、
を有することを特徴とする充電回路。 A charging circuit in which at least one battery is connected in parallel and is charged by constant voltage power supply from an external power source,
Switch means provided corresponding to the battery;
Load current detection means for detecting the absolute value of the load current;
Control means for comparing the absolute value with a predetermined threshold value and, if the absolute value is greater than the threshold value as a result of the comparison, controlling the switch means to disconnect the at least one battery from the charging circuit; ,
A charging circuit comprising: 前記比較の結果、前記絶対値が前記閾値に満たない場合、前記少なくとも１以上の電池を前記充電回路に接続するように制御することを特徴とする請求項１又は２記載の充電回路。   3. The charging circuit according to claim 1, wherein when the absolute value is less than the threshold value as a result of the comparison, the charging circuit is controlled to connect the at least one battery to the charging circuit. 請求項１から３のいずれか１項に記載の充電回路を有することを特徴とする電子装置。   An electronic device comprising the charging circuit according to claim 1. 少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路の電流制御方法であって、
負荷電流の絶対値を検出し、該絶対値と所定の閾値とを比較し、該比較の結果、該絶対値が該閾値より大きい場合、前記少なくとも１以上の電池を前記充電回路から切り離すように制御することを特徴とする充電回路の電流制御方法。 A current control method for a charging circuit in which at least one battery is connected in parallel and charging is performed by constant voltage power supply from an external power source,
An absolute value of the load current is detected, the absolute value is compared with a predetermined threshold value, and if the absolute value is larger than the threshold value as a result of the comparison, the at least one battery is disconnected from the charging circuit. A method for controlling a current of a charging circuit, characterized by comprising: 少なくとも１以上の電池が並列に接続され、外部電源からの定電圧給電により充電を行う充電回路の電流制御方法であって、
負荷電流の絶対値を検出する負荷電流検出ステップと、
該絶対値と所定の閾値とを比較し、該比較の結果、該絶対値が該閾値より大きい場合、前記少なくとも１以上の電池を前記充電回路から切り離すように、前記電池に対応して設けられたスイッチ手段を制御する制御ステップと、
を有することを特徴とする充電回路の電流制御方法。 A current control method for a charging circuit in which at least one battery is connected in parallel and charging is performed by constant voltage power supply from an external power source,
A load current detection step for detecting an absolute value of the load current;
The absolute value is compared with a predetermined threshold value, and if the absolute value is larger than the threshold value as a result of the comparison, the at least one battery is provided corresponding to the battery so as to be disconnected from the charging circuit. A control step for controlling the switch means,
A current control method for a charging circuit, comprising: 前記制御ステップにて、前記比較の結果、前記絶対値が前記閾値に満たない場合、前記少なくとも１以上の電池を前記充電回路に接続するように制御することを特徴とする請求項５又は６記載の充電回路の電流制御方法。   7. The control step, wherein, as a result of the comparison, if the absolute value is less than the threshold value, control is performed so that the at least one battery is connected to the charging circuit. Current control method for the charging circuit.
JP2005309903A 2005-10-25 2005-10-25 Charging circuit, electronic device, and current control method for charging circuit Expired - Fee Related JP4544130B2 (en)

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CN107611509A (en) * 2017-07-21 2018-01-19 深圳天珑无线科技有限公司 A kind of intelligent terminal and its charging method and the device with store function
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