JPH0610780B2 - Power supply circuit - Google Patents
Power supply circuitInfo
- Publication number
- JPH0610780B2 JPH0610780B2 JP63216632A JP21663288A JPH0610780B2 JP H0610780 B2 JPH0610780 B2 JP H0610780B2 JP 63216632 A JP63216632 A JP 63216632A JP 21663288 A JP21663288 A JP 21663288A JP H0610780 B2 JPH0610780 B2 JP H0610780B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- battery
- transistor
- resistor
- voltage comparator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000003990 capacitor Substances 0.000 claims description 17
- 239000004973 liquid crystal related substance Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Landscapes
- Television Receiver Circuits (AREA)
- Control Of Electrical Variables (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は可搬型液晶テレビジョン受像機内の内蔵電池を
有する電子機器の電源回路に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for an electronic device having a built-in battery in a portable liquid crystal television receiver.
従来の技術 近年、可搬型液晶テレビジョン受像機はメーカー数社か
ら発売され、今後さらにその市場は拡大するものと予想
される。ところで、現在、可搬型液晶テレビジョン受像
機等の可搬型の電子機器は、充電式バッテリーや乾電池
などを内蔵電池として内蔵する方式のものがほとんどで
あるが、このような内蔵電池を使用して機器を駆動でき
る時間は、連続動作で１ないし２時間程度である。そこ
でさらに長時間に亘って機器を使用できるように例えば
乾電池又は充電式バッテリーを備えた外部電池ケースを
可搬型液晶テレビジョン受像機の本体に接続して用いる
ことも多い。なお、このような電子機器は、上記のよう
な電池にて駆動させる以外にも、家庭用電源からＡＣア
ダプタを介し、あるいはカーバッテリーを用いて電源を
供給できるようになっている。そして電子機器の電源回
路は、ＡＣアダプタ，カーバッテリーが接続されたとき
に、それぞれの電源用に回路が切り換えられる。一方、
内蔵電池に充電する場合には、例えばＡＣアダプタを接
続した状態で、電源スイッチ（図示せず）をオフ兼充電
側にすることが充電可能となる。2. Description of the Related Art In recent years, portable liquid crystal television receivers have been released by several manufacturers, and it is expected that the market will further expand in the future. By the way, at present, most portable electronic devices such as a portable liquid crystal television receiver have a built-in battery such as a rechargeable battery or a dry battery as a built-in battery. The device can be driven for about 1 to 2 hours in continuous operation. Therefore, an external battery case equipped with, for example, a dry battery or a rechargeable battery is often connected to the main body of a portable liquid crystal television receiver so that the device can be used for a longer period of time. In addition to the above-described battery-driven electronic equipment, it is possible to supply power from a household power supply via an AC adapter or a car battery. Then, the power supply circuit of the electronic device is switched for each power supply when the AC adapter and the car battery are connected. on the other hand,
When the built-in battery is charged, it is possible to charge the battery by turning the power switch (not shown) to the off / charging side with the AC adapter connected, for example.
発明が解決しようとする課題 上記従来の電子機器に内蔵電池である充電式バッテリー
が内蔵されている場合、この内蔵電池に外部電池を電源
として充電することも可能である。外部電池からの充電
も可能であることは、使用者にとって外部電池を電子機
器に接続し、電源スイッチをオン状態として機器を動作
させている場合には、何ら問題はないが、機器の動作を
オフ状態とするつもりで電源スイッチをオフ側に切り換
えたときに、本来は専用の充電器であるＡＣアダプタか
ら充電すべきものが、外部電池から充電され、知らない
間に外部電池である乾電池又は充電電池が放電状態にな
る。その結果、その後に外部電池を電源として使用しよ
うとしたときに使用できないといった不都合が生じる。
この外部電池から内部電池への充電による不都合は、例
えば外部電池ケースに使用状態を選択するためのスイッ
チを新たに設けることにより解決することが可能であ
る。しかしながら外部電池ケースに新たなスイッチを設
けることによるコスト的な問題、さらには、外部電池ケ
ースと電子機器本体のそれぞれに設けられた２つのスイ
ッチを操作するわずらわしさ、また使用者がスイッチを
それぞれの動作状態に応じて切り換えるのを忘れたとき
の不都合を考慮すると万全の対策であるとは言えない。Problems to be Solved by the Invention When a rechargeable battery, which is a built-in battery, is built in the above conventional electronic device, the built-in battery can be charged using an external battery as a power source. It is also possible to charge from an external battery, which means that there is no problem if the user connects the external battery to an electronic device and operates the device with the power switch on, but When the power switch is switched to the off side with the intention of turning it off, what should be charged from the AC adapter, which is originally a dedicated charger, is charged from the external battery, and without knowing, it is a dry battery or an external battery. The battery is discharged. As a result, there arises a disadvantage that the external battery cannot be used when the battery is subsequently used as a power source.
The inconvenience caused by charging the external battery to the internal battery can be solved by, for example, newly providing a switch for selecting a usage state in the external battery case. However, the cost problem of providing a new switch in the external battery case, and the inconvenience of operating two switches provided in the external battery case and the electronic device body, and the user having to switch each switch Considering the inconvenience when forgetting to switch depending on the operating state, it cannot be said to be a complete countermeasure.
課題を解決するための手段 上記目的を達成するために本発明の電源回路は、電池の
一端に第１のトランジスタのエミッタを接続し、この第
１のトランジスタのエミッタ・コレクタ間に第１の抵抗
を、エミッタ・ベース間に第２の抵抗を、ベース・コレ
クタ間にコンデンサを接続し、前記電池の両端電圧を抵
抗分割して得た電圧を電圧比較器の反転入力端子に供給
し、前記電池の他端に第３の抵抗を介して前記電圧比較
器の非反転入力端子を接続し、前記電圧比較器の出力に
第２のトランジスタのベースを結合し、この第２のトラ
ンジスタのコレクタに前記第１のトランジスタのベース
を結合しかつ、エミッタを前記電池の他端に接続すると
ともに、前記第１のトランジスタのコレクタに第１の出
力端子を、前記電圧比較器の非反転入力端子に第２の出
力端子をそれぞれ接続し、前記電圧比較器は、第１，第
２の出力端子間に負荷が接続された場合に第３の抵抗に
流れる電流による電圧降下を検出するように構成し、負
荷のインピーダンスが所定値より小さい場合、前記電圧
降下が所定値より大なるとき前記電圧比較器により前記
第１、第２のトランジスタをオン状態として前記第１、
第２の出力端子間の電圧を所定電圧以上とし、負荷のイ
ンピーダンスが所定値より大きい場合、前記電圧降下が
所定値より小なるとき前記電圧比較器により前記第１、
第２のトランジスタをオフ状態として前記第１、第２の
出力端子間の電圧を前記所定電圧以下とするような構成
にした。Means for Solving the Problems In order to achieve the above object, the power supply circuit of the present invention connects an emitter of a first transistor to one end of a battery, and connects a first resistor between an emitter and a collector of the first transistor. , A second resistor is connected between the emitter and the base, and a capacitor is connected between the base and the collector, and the voltage obtained by resistance-dividing the voltage across the battery is supplied to the inverting input terminal of the voltage comparator. Is connected to the non-inverting input terminal of the voltage comparator through a third resistor, the output of the voltage comparator is coupled to the base of the second transistor, and the collector of the second transistor is connected to the non-inverting input terminal of the voltage comparator. The base of the first transistor is coupled and the emitter is connected to the other end of the battery, and the first output terminal is the collector of the first transistor and the non-inverting input terminal of the voltage comparator. Second output terminals are connected to each other, and the voltage comparator is configured to detect a voltage drop due to a current flowing through the third resistance when a load is connected between the first and second output terminals. When the impedance of the load is smaller than a predetermined value and the voltage drop is larger than a predetermined value, the first and second transistors are turned on by the voltage comparator, and the first and second transistors are turned on.
When the voltage between the second output terminals is equal to or higher than a predetermined voltage and the impedance of the load is higher than a predetermined value, when the voltage drop is lower than the predetermined value, the voltage comparator causes the first,
The second transistor is turned off, and the voltage between the first and second output terminals is set to be equal to or lower than the predetermined voltage.
作用 上記構成により、出力端子間に接続された負荷が所定の
インピーダンスより小さいとき負荷への電力供給を遮断
することにより、出力端子間に接続され得る電子機器，
内蔵電池の負荷のうち、内蔵電池が接続された場合には
外部電池からの充電経路が遮断され、外部電池から内蔵
電池に充電が行われる不都合が防止される。Action With the above configuration, when the load connected between the output terminals is smaller than a predetermined impedance, the power supply to the load is cut off, so that the electronic device can be connected between the output terminals,
In the load of the built-in battery, when the built-in battery is connected, the charging path from the external battery is blocked, and the inconvenience of charging the built-in battery from the external battery is prevented.
実施例 以下、本発明の実施例の電源回路について説明する。な
お本実施例においては、可搬型液晶テレビジョン受像機
の外部電池ケースに設ける電源回路について説明する。Embodiment Hereinafter, a power supply circuit according to an embodiment of the present invention will be described. In this embodiment, a power supply circuit provided in an external battery case of a portable liquid crystal television receiver will be described.
第１図は本発明の第１の実施例における電源回路の回路
図である。第１図において、１は外部電池ケース（図示
せず）の収納された外部電池、２，３，４は外部電池１
の両端電圧を分割する分割抵抗、５は抵抗３，４の両端
電圧、ひいては電圧比較器６の反転入力端子(-)への入
力電圧を一定値に維持するためのツェナーダイオードで
ある。７はスイッチングトランジスタで、電圧比較器６
の出力に電流制限用抵抗８を介して接続されている。９
は出力トランジスタで、エミッタ・コレクタ間に抵抗１
０，エミッタ・ベース間に抵抗１１，ベース・コレクタ
間にコンデンサ１２が接続され、さらにエミッタが外部
電池１の正極側に、ベースが抵抗１３を介してトランジ
スタ７のコレクタに接続され、そして、コレクタが出力
端子Ｖ１に接続されている。また、他方の出力端子Ｖ２
と外部電池１の負極側との間には抵抗１４が接続され、
この抵抗１４と出力端子Ｖ２との接続点に、電圧比較器
６の非反転入力端子(+)が接続される。FIG. 1 is a circuit diagram of a power supply circuit according to the first embodiment of the present invention. In FIG. 1, 1 is an external battery in which an external battery case (not shown) is housed, and 2, 3 and 4 are external batteries 1
5 is a Zener diode for maintaining the voltage across the resistors 3, 4 and the input voltage to the inverting input terminal (-) of the voltage comparator 6 at a constant value. 7 is a switching transistor, which is a voltage comparator 6
Is connected to the output of the device through a current limiting resistor 8. 9
Is an output transistor, with a resistor 1 between the emitter and collector
0, a resistor 11 between the emitter and the base, a capacitor 12 between the base and the collector, an emitter connected to the positive electrode side of the external battery 1, a base connected to the collector of the transistor 7 through the resistor 13, and a collector. Is connected to the output terminal V 1 . The other output terminal V 2
A resistor 14 is connected between the negative electrode side of the external battery 1 and
The non-inverting input terminal (+) of the voltage comparator 6 is connected to the connection point between the resistor 14 and the output terminal V 2 .
上記構成について以下にその動作を説明する。The operation of the above configuration will be described below.
まず、出力端子Ｖ１，Ｖ２間に負荷すなわちテレビジョ
ン受像機ないしテレビジョン受像機に内蔵されている内
蔵電池である充電電池が接続されていない無負荷状態で
は、抵抗１４に電流が流れないために、電圧比較器６の
出力はローレベルとなり、トランジスタ７がオフにな
り、トランジスタ７のコレクタ・エミッタ間に電流が流
れないため、抵抗１１による電位降下が生じずトランジ
スタ９もオフ状態となる。First, in a no-load state in which a load, that is, a television receiver or a rechargeable battery built in the television receiver is not connected between the output terminals V 1 and V 2 , no current flows through the resistor 14. Therefore, the output of the voltage comparator 6 becomes low level, the transistor 7 is turned off, and no current flows between the collector and emitter of the transistor 7, so that the potential drop due to the resistor 11 does not occur and the transistor 9 is also turned off. .
次に、出力端子Ｖ１，Ｖ２間に上述のような負荷を接続
すると、電池１の正極からオフ状態のトランジスタ９に
接続された抵抗１０ないし抵抗１１及びコンデンサ１２
の直列回路、そして負荷を経て抵抗１４から電池１の負
極側に電流の流れるループがコンデンサ１２の充放電に
ともなって構成される。ここで、負荷としては前述のよ
うに、例えばテレビジョン受像機のように比較的インピ
ーダンスの小さいつまり負荷の重いものがあれば、また
一方では内蔵電池のように比較的インピーダンスの大き
いつまり負荷の軽いものでもある。このような負荷のイ
ンピーダンスの差異は、回路ループの流れる電流の大き
さの差異となり、ひいては抵抗１４の電圧降下の差異を
生ずる。Next, when the above-mentioned load is connected between the output terminals V 1 and V 2 , the resistors 10 to 11 and the capacitor 12 connected from the positive electrode of the battery 1 to the transistor 9 in the off state.
A loop in which a current flows from the resistor 14 to the negative electrode side of the battery 1 via the series circuit and the load is formed as the capacitor 12 is charged and discharged. Here, as described above, if the load has a relatively small impedance, that is, a heavy load, such as a television receiver, on the other hand, the load has a relatively large impedance, that is, a light load, such as a built-in battery. It is also a thing. Such a difference in the impedance of the load causes a difference in the magnitude of the current flowing through the circuit loop, which in turn causes a difference in the voltage drop across the resistor 14.
本実施例においては、抵抗１４の両端電圧ＶＲは、電圧
比較器６の非反転入力端子に供給されており、電池１の
両端電圧を抵抗分割して得られる電圧Ｖ−と比較され
る。とくに電圧Ｖ−は、負荷がテレビジョン受像機であ
るが、受像機内蔵電池であるかを判別するために、これ
らの負荷を接続することによって抵抗１４に発生する電
圧のほぼ中間の電圧に設定されている。In this embodiment, end-to-end voltage V R of the resistor 14 is supplied to the non-inverting input terminal of the voltage comparator 6, the voltage obtained by resistance-dividing a voltage across the battery 1 V - is compared to. In particular, the voltage V - is set to a voltage approximately in the middle of the voltage generated in the resistor 14 by connecting these loads in order to determine whether the load is the television receiver and the battery is a receiver built-in battery. Has been done.
したがって、出力端子Ｖ１，Ｖ２間にインピーダンスの
小さいテレビジョン受像機が負荷として接続された場
合、負荷電流ひいては抵抗１４に流れる電流が大きくな
り、抵抗１４の電位差つまり電圧比較器６の反転入力端
子(-)と非反転入力端子(+)との電位差が大きくなり電圧
比較器６の出力はハイレベルとなる。よってトランジス
タ７はオン状態となり、そしてトランジスタ９がオン状
態に設定される。その結果、出力端子Ｖ１，Ｖ２間の電
圧が所定電圧である9.6Ｖ以上となり継続して電池１か
ら出力端子Ｖ１，Ｖ２間に接続された負荷に電力が供給
される。Therefore, when a television receiver having a low impedance is connected between the output terminals V 1 and V 2 as a load, the load current and thus the current flowing through the resistor 14 increase, and the potential difference of the resistor 14, that is, the inverting input of the voltage comparator 6. The potential difference between the terminal (-) and the non-inverting input terminal (+) becomes large, and the output of the voltage comparator 6 becomes high level. Therefore, the transistor 7 is turned on, and the transistor 9 is set to the on state. As a result, the voltage between the output terminals V 1 and V 2 becomes equal to or higher than the predetermined voltage of 9.6 V, and power is continuously supplied from the battery 1 to the load connected between the output terminals V 1 and V 2 .
一方、出力端子Ｖ１，Ｖ２間にインピーダンスの大きい
受像機の内蔵電池が負荷として接続された場合、負荷電
流ひいては抵抗１４に流れる電流が小さくなり抵抗１４
の電位差つまり電圧比較器６の反転入力端子(-)と非反
転入力端子(+)との電位差が小さくなり電圧比較器６の
出力はローレベルとなる。これにより、トランジスタ７
はオフ状態に保持され、よって、トランジスタ９もオフ
状態となり、コンデンサ１２の充放電にもとづくループ
も開かれる。その結果、内蔵電池のインピーダンスは抵
抗１０の値より小さいため、内蔵電池の両端に充電に必
要な所定電圧9.6Ｖが印加されないので内蔵電池は充電
状態とはならない。よって出力端子Ｖ１，Ｖ２間の電圧
が所定電圧9.6Ｖ未満となることで電池１からの受像機
の内蔵電池への充電が発生することはなくなる。なお、
コンデンサ１２に蓄積された電荷は、抵抗１０の抵抗値
Ｒ１０、抵抗１１の抵抗値Ｒ１１とコンデンサ１２の容
量Ｃにもとづき(R10+R11)×Ｃの時定数で放電される
が、放電直後にテレビジョン受像機がオン状態にされた
場合に、コンデンサ１２が十分に放電されておらず、コ
ンデンサ１２が放電状態である場合、この放電電流によ
りトランジスタ９のベース・エミッタ間が逆バイアスさ
れておりその結果テレビジョン受像機をオン状態にする
ことができないという不都合がないよう留意する必要が
ある。On the other hand, when the built-in battery of the receiver having a large impedance is connected as a load between the output terminals V 1 and V 2 , the load current and thus the current flowing through the resistor 14 becomes small, and
Of the voltage comparator 6, that is, the potential difference between the inverting input terminal (-) and the non-inverting input terminal (+) of the voltage comparator 6 becomes small, and the output of the voltage comparator 6 becomes low level. As a result, the transistor 7
Is held in the off state, so that the transistor 9 is also turned off and the loop based on the charging and discharging of the capacitor 12 is also opened. As a result, since the impedance of the built-in battery is smaller than the value of the resistance 10, the predetermined voltage 9.6V required for charging is not applied to both ends of the built-in battery, so that the built-in battery does not enter the charged state. Therefore, when the voltage between the output terminals V 1 and V 2 becomes less than the predetermined voltage of 9.6V, charging of the built-in battery of the image receiver from the battery 1 will not occur. In addition,
The electric charge accumulated in the capacitor 12 is discharged with a time constant of (R 10 + R 11 ) × C based on the resistance value R 10 of the resistor 10 , the resistance value R 11 of the resistor 11 and the capacitance C of the capacitor 12, When the television receiver is turned on immediately after discharge and the capacitor 12 is not sufficiently discharged and the capacitor 12 is in the discharge state, this discharge current causes a reverse bias between the base and emitter of the transistor 9. Therefore, it is necessary to pay attention so that there is no inconvenience that the television receiver cannot be turned on.
なお、本実施例では1.2Ｖの充電電池を８個直列につな
ぐことで、9.6Ｖの外部電池としているが電圧の値は他
の値でもよいことは言うまでもない。また外部電池は充
電電池以外の電池でも同様の効果を得られる。In this embodiment, eight 1.2 V rechargeable batteries are connected in series to form an external battery of 9.6 V, but it goes without saying that the voltage value may be another value. The same effect can be obtained by using an external battery other than a rechargeable battery.
第２図は本発明の第２の実施例における電源回路であ
る。第２図において、第１図に示した実施例と違ってい
る点を説明する。１５は第２の電圧比較器、１６は出力
トランジスタ、１７はドライブトランジスタ、１８〜２
２はバイアス抵抗である。この構成において、テレビジ
ョン受像機の内蔵電池である充電電池が空になっていた
場合、バッテリーケースと内蔵電池を内蔵したテレビジ
ョン受像機を接続し、テレビジョン受像機の電源スイッ
チをテレビジョン受像機の内蔵電池と接続したときに
は、出力端子Ｖ１は、空の内蔵電池に接続されているた
め低い電圧に固定される。すなわち、コンデンサ１２は
十分充電された状態であるのでスイッチをテレビ受像機
の外部電池側（テレビセットをオンした状態である）に
したとき前述のようにコンデンサ１２の放電電流でトラ
ンジスタ９のベース・エミッタ間が逆バイアスされるの
でテレビジョン受像機が起動できなくなる可能性があ
る。これらを改善するのが第２図の電源回路である。FIG. 2 shows a power supply circuit according to the second embodiment of the present invention. In FIG. 2, the difference from the embodiment shown in FIG. 1 will be described. 15 is a second voltage comparator, 16 is an output transistor, 17 is a drive transistor, and 18 to 2
2 is a bias resistor. In this configuration, if the rechargeable battery, which is the built-in battery of the television receiver, is empty, connect the battery case and the television receiver with the built-in battery, and then turn the power switch of the television receiver on. When connected to the internal battery of the machine, the output terminal V 1 is fixed to a low voltage because it is connected to an empty internal battery. That is, since the capacitor 12 is fully charged, when the switch is set to the external battery side of the TV receiver (the TV set is turned on), the discharge current of the capacitor 12 causes the base of the transistor 9 Since the emitters are reverse-biased, the television receiver may not start. The power supply circuit of FIG. 2 improves these.
すなわちテレビジョン受像機の電源スイッチをテレビジ
ョン受像機の内蔵電池側からテレビジョン受像機の外部
電池側（オフ→オン）に切り換えたとき、一瞬スイッチ
回路はオープンになる。つまり、端子Ｖ１はテレビジョ
ン受像機は内蔵電池に接続されているが、一瞬オープン
の状態になり、その後テレビジョン受像機の外部電池側
に接続される。このときＶ１端子電圧はローレベルから
ハイレベルに変化する、この変化を抵抗２０とコンデン
サ２３の回路と抵抗２１，２２の回路で検出する。すな
わちコンデンサ２３が接続されている回路はＶ１端子が
ローレベルからハイレベルに変化しても抵抗２０
（R20）とコンデンサ２３(C2)の形成する時定数でゆっ
くりと立上る。つまり、コンデンサの端子電圧、すなわ
ち第２の電圧比較器の反転入力端子(-)の電圧はゆっく
りと上昇し、抵抗２１，２２からなる回路は瞬間的に立
上る。つまり抵抗２２の端子電圧すなわち第２の電圧比
較器１５の非反転入力端子(+)の電圧は瞬時に上昇す
る。この間に電圧比較器１５の両入力端子（＋，−）に
加わる電圧が逆転し、電圧比較器１５の出力がハイレベ
ルになり、トランジスタ１６，１７をオンさせる。よっ
てトランジスタ１６がトランジスタ９のエミッタ・コレ
クタ間を短絡するのでテレビジョン受像機を起動でき
る。したがって内蔵電池が空のときにおいてもスイッチ
をテレビジョン受像機の外部電池側（スイッチオン）に
切り換えれば起動することになる。That is, when the power switch of the television receiver is switched from the built-in battery side of the television receiver to the external battery side of the television receiver (OFF → ON), the switch circuit is momentarily opened. In other words, the terminal V 1 is connected to the built-in battery of the television receiver, but is in an open state for a moment, and then connected to the external battery side of the television receiver. At this time, the V 1 terminal voltage changes from the low level to the high level, and this change is detected by the circuit of the resistor 20 and the capacitor 23 and the circuit of the resistors 21 and 22. That is, the circuit to which the capacitor 23 is connected has the resistance 20 even if the V 1 terminal changes from low level to high level.
It rises slowly with the time constant formed by (R 20 ) and the capacitor 23 (C 2 ). That is, the terminal voltage of the capacitor, that is, the voltage at the inverting input terminal (-) of the second voltage comparator rises slowly, and the circuit composed of the resistors 21 and 22 instantaneously rises. That is, the terminal voltage of the resistor 22, that is, the voltage of the non-inverting input terminal (+) of the second voltage comparator 15 instantly rises. During this time, the voltage applied to both input terminals (+,-) of the voltage comparator 15 is reversed, the output of the voltage comparator 15 becomes high level, and the transistors 16 and 17 are turned on. Therefore, the transistor 16 short-circuits the emitter and the collector of the transistor 9, so that the television receiver can be started. Therefore, even when the built-in battery is empty, it can be started by switching the switch to the external battery side (switch on) of the television receiver.
発明の効果 以上のように本発明は電源回路に接続される負荷のイン
ピーダンスに対応する電流の大小によって出力をオン・
オフすることが出来るとともに、その起動のスムーズに
行うことが出来る。その結果、外部の充電電池から電子
機器の内蔵充電電池への充電することを防止でき、信頼
性の高い電源回路を実現できる。As described above, according to the present invention, the output is turned on depending on the magnitude of the current corresponding to the impedance of the load connected to the power supply circuit.
It can be turned off and can be activated smoothly. As a result, it is possible to prevent the external rechargeable battery from charging the built-in rechargeable battery of the electronic device, and it is possible to realize a highly reliable power supply circuit.
第１図は本発明の第１の実施例における電源回路の回路
図、第２図は本発明の第２の実施例における電源回路の
回路図である。 １……外部電池、６……電圧比較器、７，９……トラン
ジスタ、１０，１１，１４……抵抗、１２……コンデン
サ、Ｖ１，Ｖ２……出力端子。1 is a circuit diagram of a power supply circuit according to a first embodiment of the present invention, and FIG. 2 is a circuit diagram of a power supply circuit according to a second embodiment of the present invention. 1 ... External battery, 6 ... Voltage comparator, 7, 9 ... Transistor, 10, 11, 14 ... Resistor, 12 ... Capacitor, V 1 , V 2 ... Output terminal.
Claims (1)
タを接続し、この第１のトランジスタのエミッタ・コレ
クタ間に第１の抵抗を、エミッタ・ベース間に第２の抵
抗を、ベース・コレクタ間にコンデンサをそれぞれ接続
し、前記電池の両端電圧を抵抗分割して得た電圧を電圧
比較器の反転入力端子に供給し、前記電池の他端に第３
の抵抗を介して前記電圧比較器の非反転入力端子を接続
し、前記電圧比較器の出力に第２のトランジスタのベー
スを結合し、この第２のトランジスタのコレクタに前記
第１のトランジスタのベースを結合しかつエミッタを前
記電池の他端に接続するとともに、前記第１のトランジ
スタのコレクタに第１の出力端子を、前記電圧比較器の
非反転入力端子に第２の出力端子をそれぞれ接続し、前
記電圧比較器は、第１，第２の出力端子間に負荷が接続
された場合に第３の抵抗に流れる電流による電圧降下を
検出するように構成し、負荷のインピーダンスが所定値
より小さい場合、前記電圧降下が所定値より大なるとき
前記電圧比較器により前記第１、第２のトランジスタを
オン状態として前記第１、第２の出力端子間の電圧を所
定電圧以上とし、負荷のインピーダンスが所定値より大
きい場合、前記電圧降下が所定値より小なるとき前記電
圧比較器により前記第１、第２のトランジスタをオフ状
態として前記第１、第２の出力端子間の電圧を前記所定
電圧以下とする電源回路。1. An emitter of a first transistor is connected to one end of a battery, a first resistor is provided between the emitter and collector of the first transistor, a second resistor is provided between the emitter and base, and a base collector. A capacitor is connected between them, and a voltage obtained by dividing the voltage across the battery by resistance division is supplied to the inverting input terminal of the voltage comparator, and a third voltage is applied to the other end of the battery.
The non-inverting input terminal of the voltage comparator is connected through the resistor of the second comparator, the base of the second transistor is coupled to the output of the voltage comparator, and the collector of the second transistor is connected to the base of the first transistor. And an emitter connected to the other end of the battery, a collector of the first transistor connected to the first output terminal, and a non-inverting input terminal of the voltage comparator connected to the second output terminal. The voltage comparator is configured to detect a voltage drop due to a current flowing through the third resistance when a load is connected between the first and second output terminals, and the impedance of the load is smaller than a predetermined value. In this case, when the voltage drop is larger than a predetermined value, the voltage comparator turns on the first and second transistors to set the voltage between the first and second output terminals to a predetermined voltage or more, When the impedance of the load is larger than a predetermined value, and when the voltage drop is smaller than a predetermined value, the voltage comparator turns off the first and second transistors to change the voltage between the first and second output terminals. A power supply circuit having the predetermined voltage or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63216632A JPH0610780B2 (en) | 1988-08-31 | 1988-08-31 | Power supply circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63216632A JPH0610780B2 (en) | 1988-08-31 | 1988-08-31 | Power supply circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0264808A JPH0264808A (en) | 1990-03-05 |
| JPH0610780B2 true JPH0610780B2 (en) | 1994-02-09 |
Family
ID=16691477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63216632A Expired - Lifetime JPH0610780B2 (en) | 1988-08-31 | 1988-08-31 | Power supply circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0610780B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9946269B2 (en) | 2013-03-13 | 2018-04-17 | Continental Automotive Gmbh | Method for operating a switch valve that opens and closes a fluid line fed by a filter and feeding an intake pipe |
-
1988
- 1988-08-31 JP JP63216632A patent/JPH0610780B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9946269B2 (en) | 2013-03-13 | 2018-04-17 | Continental Automotive Gmbh | Method for operating a switch valve that opens and closes a fluid line fed by a filter and feeding an intake pipe |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0264808A (en) | 1990-03-05 |
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