JP2007181290A - Power supply circuit and activation method of the same - Google Patents

Power supply circuit and activation method of the same Download PDF

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JP2007181290A
JP2007181290A JP2005375713A JP2005375713A JP2007181290A JP 2007181290 A JP2007181290 A JP 2007181290A JP 2005375713 A JP2005375713 A JP 2005375713A JP 2005375713 A JP2005375713 A JP 2005375713A JP 2007181290 A JP2007181290 A JP 2007181290A
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JP4961739B2 (en
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Yoichi Takano
陽一 高野
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Mitsumi Electric Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply circuit and its activation method for stabilizing the input voltage, outputting stabilized output voltage and preventing excess current from being generated during start-up. <P>SOLUTION: In the power supply circuit for stabilizing the input voltage and outputting the stabilized output voltage, an output current is limited to a first current, if the output voltage is a predetermined voltage or less smaller than a fixed voltage; and the output current is limited to a second current or less, if the output voltage is larger than the predetermined voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は電源回路及びその起動方法に係り、特に、入力電圧を安定化した出力電圧を出力する電源回路及びその起動方法に関する。   The present invention relates to a power supply circuit and a starting method thereof, and more particularly, to a power supply circuit that outputs an output voltage in which an input voltage is stabilized and a starting method thereof.

シリーズレギュレータなどの電源回路の立ち上げ時にはラッシュ電流が発生する。ラッシュ電流は、電源に接続されたキャパシタ成分へのチャージアップを急速に行なうことにより発生する過大電流である。ラッシュ電流が大きい場合、ＵＳＢやＤＣ／ＤＣコンバータから電源の供給を受けている場合、それらの電流供給能力により起動できない場合が生じる。   A rush current is generated when a power circuit such as a series regulator is started up. The rush current is an excessive current generated by rapidly charging up the capacitor component connected to the power source. When the rush current is large, when power is supplied from a USB or a DC / DC converter, it may be impossible to start up due to the current supply capability.

したがって、ラッシュ電流を抑制するために、起動時に電流制限回路により過大電流を制限した電源回路が提案されている（特許文献１参照）。
特開平１０−２７１６８０号公報 Therefore, in order to suppress the rush current, a power supply circuit in which an excessive current is limited by a current limiting circuit at the time of startup has been proposed (see Patent Document 1).
Japanese Patent Laid-Open No. 10-271680

しかるに、従来の電源回路では起動後、出力電圧−出力電流の特性をフの字特性など所望の特性にすることはできなかった。   However, in the conventional power supply circuit, the output voltage-output current characteristic cannot be changed to a desired characteristic such as a U-shaped characteristic after startup.

本発明は上記の点に鑑みてなされたもので、起動時の過大電流の発生を防止できるかつ、起動後、出力電圧−出力電流の特性を所望の特性とすることができる電源回路及びその起動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 points, and a power supply circuit capable of preventing the generation of an excessive current at the start and capable of setting the output voltage-output current characteristic to a desired characteristic after the start and the start thereof It aims to provide a method.

本発明は、入力電圧を安定化した出力電圧を出力する電源回路において、出力電圧が一定の電圧より小さい所定の電圧以下では出力電流を定電流に制御し、出力電圧が所定の電圧より大きい電圧では出力電流を電流−電圧特性を所望の特性となるように制御する電流制御回路（１１４）を有することを特徴とする。   The present invention relates to a power supply circuit that outputs an output voltage in which an input voltage is stabilized. The output current is controlled to a constant current when the output voltage is lower than a predetermined voltage lower than a certain voltage, and the output voltage is larger than the predetermined voltage. Then, it has a current control circuit (114) for controlling the output current so that the current-voltage characteristic becomes a desired characteristic.

電流制御回路（１１４）は、出力電流に対する出力電圧の特性を所望の特性に制御する特性制御回路（１３２）と、出力電圧が所定の電圧範囲で出力電流を定電流に制御する定電流制御回路（１３１）と、出力電圧を検出する電圧検出回路（１３５）と、電圧検出回路（１３５）の検出結果に応じて特性制御回路（１３２）及び定電流制御回路（１３１）の動作を切り替える切替回路（１３６、１３７、１３８）とを有することを特徴とする。   The current control circuit (114) includes a characteristic control circuit (132) that controls the characteristic of the output voltage with respect to the output current to a desired characteristic, and a constant current control circuit that controls the output current to a constant current within a predetermined voltage range. (131), a voltage detection circuit (135) for detecting the output voltage, and a switching circuit for switching the operation of the characteristic control circuit (132) and the constant current control circuit (131) according to the detection result of the voltage detection circuit (135) (136, 137, 138).

特性制御回路（１３２）は、出力電流に対する出力電圧の特性をフの字特性に制御することを特徴とする。   The characteristic control circuit (132) is characterized in that the characteristic of the output voltage with respect to the output current is controlled to a U-shaped characteristic.

出力電流により充電されるキャパシタが接続されており、定電流制御回路（１３１）はキャパシタにラッシュ電流が発生しない程度の定電流を供給することを特徴とする。   A capacitor charged by the output current is connected, and the constant current control circuit (131) supplies a constant current that does not generate a rush current to the capacitor.

なお、上記参照符号は、あくまでも参考であり、これによって、特許請求の範囲の記載が限定されるものではない。   In addition, the said reference code is a reference to the last, and description of a claim is not limited by this.

本発明によれば、出力電圧が一定の電圧より小さい所定の電圧以下では出力電流を定電流に制御し、出力電圧が所定の電圧より大きい電圧では出力電流を電流−電圧特性が所望の特性となるように制御することにより、起動時に出力端子に接続されたキャパシタを比較的小さな電流でチャージアップすることができるため、キャパシタのチャージアップに伴うラッシュ電流の発生を防止できる。よって、出力端子にラッシュ電流を低減するために容量の大きなキャパシタを接続する必要はなくなる。また、起動後は、フの字特性で出力電流Ｉoutを制御でき、負荷電流の増大に対応できる。   According to the present invention, the output current is controlled to a constant current when the output voltage is equal to or lower than a predetermined voltage lower than a certain voltage, and the current-voltage characteristic is a desired characteristic when the output voltage is higher than the predetermined voltage. By controlling in such a manner, the capacitor connected to the output terminal can be charged up with a relatively small current at the time of startup, so that it is possible to prevent the generation of a rush current accompanying the charge-up of the capacitor. Therefore, it is not necessary to connect a capacitor having a large capacity to reduce the rush current at the output terminal. Further, after the start-up, the output current Iout can be controlled with the U-shaped characteristic, and the load current can be increased.

図１は本発明の一実施例の回路構成図を示す。   FIG. 1 is a circuit diagram showing an embodiment of the present invention.

本実施例の電源回路１００は、いわゆる、シリーズレギュレータを構成しており、出力検出回路１１１、誤差アンプ１１２、基準電源回路１１３、電流制御回路１１４、制御トランジスタＭ８を含む構成とされている。   The power supply circuit 100 of this embodiment forms a so-called series regulator, and includes an output detection circuit 111, an error amplifier 112, a reference power supply circuit 113, a current control circuit 114, and a control transistor M8.

出力検出回路１１１は、抵抗Ｒ３と抵抗Ｒ４とを直列に接続した直列回路を出力端子Ｔoutと接地端子Ｔgndとの間に接続した構成とされている。出力検出回路１１１は、出力端子Ｔoutから出力される出力電圧Ｖoutを抵抗Ｒ３及び抵抗Ｒ４で分圧した検出電圧Ｖsを誤差アンプ１１２の非反転入力端子に供給する。   The output detection circuit 111 has a configuration in which a series circuit in which a resistor R3 and a resistor R4 are connected in series is connected between the output terminal Tout and the ground terminal Tgnd. The output detection circuit 111 supplies a detection voltage Vs obtained by dividing the output voltage Vout output from the output terminal Tout by the resistors R3 and R4 to the non-inverting input terminal of the error amplifier 112.

基準電源回路１１３は、基準電圧生成回路１２１、バイアス回路１２２から構成されている。基準電圧生成回路１２１とバイアス回路１２２は、直列に接続され、入力端子Ｔinと接地端子Ｔgndとの間に接続されており、基準電圧Ｖrefを発生する。   The reference power supply circuit 113 includes a reference voltage generation circuit 121 and a bias circuit 122. The reference voltage generation circuit 121 and the bias circuit 122 are connected in series and are connected between the input terminal Tin and the ground terminal Tgnd, and generate the reference voltage Vref.

バイアス回路１２２には、コントロール端子Ｔcが接続されている。コントロール端子Ｔcには、コントロール信号が供給されている。バイアス回路１２２は、コントロール端子Ｔcに供給されるコントロール信号がハイレベルのときに基準電圧生成回路１２１をバイアスする。   A control terminal Tc is connected to the bias circuit 122. A control signal is supplied to the control terminal Tc. The bias circuit 122 biases the reference voltage generation circuit 121 when the control signal supplied to the control terminal Tc is at a high level.

基準電圧生成回路１２１は、バイアス回路１２２によりバイアスされたときに基準電圧Ｖrefを生成する。バイアス回路１２２は、コントロール端子Ｔcに供給されるコントロール信号がローレベルのときには基準電圧生成回路１２１へのバイアスを停止する。基準電圧生成回路１２１は、バイアス回路１２２によるバイアスが停止されている状態では基準電圧Ｖrefを０Ｖとする。   The reference voltage generation circuit 121 generates a reference voltage Vref when biased by the bias circuit 122. The bias circuit 122 stops the bias to the reference voltage generation circuit 121 when the control signal supplied to the control terminal Tc is at a low level. The reference voltage generation circuit 121 sets the reference voltage Vref to 0 V when the bias by the bias circuit 122 is stopped.

誤差アンプ１１２は、反転入力端子に基準電源回路１１３から基準電圧Ｖrefが供給され、非反転入力端子に出力検出回路１１１から検出電圧Ｖsが供給されている。誤差アンプ１１２は、基準電圧Ｖrefと検出電圧Ｖsとの差分に応じた電圧を制御トランジスタＭ８のゲートに供給する。   In the error amplifier 112, the reference voltage Vref is supplied from the reference power supply circuit 113 to the inverting input terminal, and the detection voltage Vs is supplied from the output detection circuit 111 to the non-inverting input terminal. The error amplifier 112 supplies a voltage corresponding to the difference between the reference voltage Vref and the detection voltage Vs to the gate of the control transistor M8.

制御トランジスタＭ８は、ソース−ドレインが入力端子Ｔinと出力端子Ｔoutとの間に接続され、ゲートに誤差アンプ１１２の出力が供給されている。制御トランジスタＭ８は、誤差アンプ１１２の出力に応じて入力端子Ｔinから出力端子Ｔoutに供給される電流が制御され、出力電圧Ｖoutが一定となるように制御される。   The control transistor M8 has a source-drain connected between the input terminal Tin and the output terminal Tout, and a gate supplied with the output of the error amplifier 112. The control transistor M8 is controlled such that the current supplied from the input terminal Tin to the output terminal Tout is controlled according to the output of the error amplifier 112, and the output voltage Vout is constant.

電流制御回路１１４は、定電流制御回路１３１、電圧−電流特性制御回路１３２、電流制限回路１３３、出力制御回路１３４、電圧検出回路１３５、インバータ１３６、スイッチ回路１３７、１３８から構成されている。   The current control circuit 114 includes a constant current control circuit 131, a voltage-current characteristic control circuit 132, a current limiting circuit 133, an output control circuit 134, a voltage detection circuit 135, an inverter 136, and switch circuits 137 and 138.

定電流制御回路１３１は、トランジスタＭ１、Ｍ２、Ｍ３から構成されており、出力電流Ｉoutが一定になるように出力制御回路１３４を制御する。   The constant current control circuit 131 includes transistors M1, M2, and M3, and controls the output control circuit 134 so that the output current Iout is constant.

電圧−電流特性制御回路１３２は、トランジスタＭ４〜Ｍ６から構成されており、出力電圧Ｖoutに対する出力電流Ｉoutの特性がフの字特性となるように出力制御回路１３４を制御する。   The voltage-current characteristic control circuit 132 includes transistors M4 to M6, and controls the output control circuit 134 so that the characteristic of the output current Iout with respect to the output voltage Vout becomes a U-shaped characteristic.

電流制限回路１３３は、トランジスタＭ１１、Ｍ１２、抵抗Ｒ２から構成されており、入力電流が制限電流を越えないように出力制御回路１３４を制御する。   The current limit circuit 133 includes transistors M11 and M12 and a resistor R2, and controls the output control circuit 134 so that the input current does not exceed the limit current.

出力制御回路１３４は、トランジスタＭ７、抵抗Ｒ１から構成されており、定電流制御回路１３１、電圧−電流特性制御回路１３２、電流制限回路１３３により、制御トランジスタＭ８のゲート電位を制御する。   The output control circuit 134 includes a transistor M7 and a resistor R1. The constant current control circuit 131, the voltage-current characteristic control circuit 132, and the current limit circuit 133 control the gate potential of the control transistor M8.

電圧検出回路１３５は、出力端子Ｔoutと接地端子Ｔgndとの間に接続されている。電圧検出回路１３５は、いわゆる、ヒステリシス特性を有しており、出力電圧Ｖoutが立ち上がってから出力電圧Ｖoutが閾値電圧Ｖth1に前までは出力をローレベルとし、出力電圧Ｖoutが閾値電圧Ｖth1に達すると出力をハイレベルとし、出力電圧Ｖoutが閾値電圧Ｖth1に達した後は出力電圧Ｖoutが閾値電圧Ｖth2以下になるまで出力をハイレベルに維持し、閾値電圧Ｖth2以下になると出力をローレベルとする。電圧検出回路１３５の出力は、インバータ１３６及びスイッチ回路１３７に供給されている。   The voltage detection circuit 135 is connected between the output terminal Tout and the ground terminal Tgnd. The voltage detection circuit 135 has a so-called hysteresis characteristic. When the output voltage Vout rises to the threshold voltage Vth1 before the output voltage Vout rises, the output is set to a low level, and the output voltage Vout reaches the threshold voltage Vth1. The output is set to the high level, and after the output voltage Vout reaches the threshold voltage Vth1, the output is maintained at the high level until the output voltage Vout becomes the threshold voltage Vth2 or less. When the output voltage Vout becomes the threshold voltage Vth2 or less, the output is set to the low level. The output of the voltage detection circuit 135 is supplied to the inverter 136 and the switch circuit 137.

インバータ１３６は、電圧検出回路１３５の出力を反転する。インバータ１３６の出力は、スイッチ回路１３８に供給されている。   Inverter 136 inverts the output of voltage detection circuit 135. The output of the inverter 136 is supplied to the switch circuit 138.

スイッチ回路１３７は、ｎチャネルＭＯＳトランジスタから構成されており、ソース−ドレイン間が定電流制御回路１３１と接地との間に接続されている。スイッチ回路１３７は、電圧検出回路１３５の出力がローレベルのとき、すなわち、出力電圧Ｖoutが閾値電圧Ｖth以下のときにはオフし、定電流制御回路１３１を構成するトランジスタＭ１、Ｍ２を動作可能な状態とし、出力電流Ｉoutが一定電流となるように制御トランジスタＭ８を制御する。また、スイッチ回路１３７は、電圧検出回路１３５の出力がハイレベルのとき、すなわち、出力電圧Ｖoutが閾値電圧Ｖthを超えたときにはオンし、定電流制御回路１３１を構成するトランジスタＭ１、Ｍ２を非動作状態とし、出力電流Ｉoutの定電流制御を停止する。   The switch circuit 137 is composed of an n-channel MOS transistor, and the source and drain are connected between the constant current control circuit 131 and the ground. The switch circuit 137 is turned off when the output of the voltage detection circuit 135 is at a low level, that is, when the output voltage Vout is equal to or lower than the threshold voltage Vth, so that the transistors M1 and M2 constituting the constant current control circuit 131 are operable. The control transistor M8 is controlled so that the output current Iout becomes a constant current. The switch circuit 137 is turned on when the output of the voltage detection circuit 135 is at a high level, that is, when the output voltage Vout exceeds the threshold voltage Vth, and the transistors M1 and M2 constituting the constant current control circuit 131 are not operated. And the constant current control of the output current Iout is stopped.

さらに、スイッチ回路１３８は、ｎチャネルＭＯＳトランジスタから構成されており、ソース−ドレイン間が電圧−電流特性制御回路１３２と接地との間に接続されている。スイッチ回路１３８は、インバータ１３６の出力がローレベルのとき、すなわち、出力電圧Ｖoutが閾値電圧Ｖth以下のときにはオフし、電圧−電流特性制御回路１３２を構成するトランジスタＭ４、Ｍ５を動作可能な状態とし、出力電圧Ｖoutに対する出力電流Ｉoutの特性がフの字が特性となるように制御トランジスタＭ８を制御する。また、スイッチ回路１３８は、インバータ１３６の出力がハイレベルのとき、すなわち、出力電圧Ｖoutが閾値電圧Ｖthを超えたときにはオンし、電圧−電流特性制御回路１３２を構成するトランジスタＭ４、Ｍ５を非動作状態とし、電圧−電流特性制御回路１３２による制御トランジスタＭ８の制御を停止する。   Further, the switch circuit 138 is composed of an n-channel MOS transistor, and the source and drain are connected between the voltage-current characteristic control circuit 132 and the ground. The switch circuit 138 is turned off when the output of the inverter 136 is at a low level, that is, when the output voltage Vout is equal to or lower than the threshold voltage Vth, so that the transistors M4 and M5 constituting the voltage-current characteristic control circuit 132 are operable. Then, the control transistor M8 is controlled so that the characteristic of the output current Iout with respect to the output voltage Vout becomes the character “F”. The switch circuit 138 is turned on when the output of the inverter 136 is at a high level, that is, when the output voltage Vout exceeds the threshold voltage Vth, and the transistors M4 and M5 constituting the voltage-current characteristic control circuit 132 are not operated. Then, control of the control transistor M8 by the voltage-current characteristic control circuit 132 is stopped.

〔動作〕
図２は本発明の一実施例の動作説明図を示す。図２（Ａ）はコントロール端子Ｔcに供給されるコントロール信号、図２（Ｂ）は入力端子Ｔinから入力される入力電流Ｉin、図２（Ｃ）は出力端子Ｔoutから出力される出力電圧Ｖoutの波形を示している。 [Operation]
FIG. 2 is a diagram for explaining the operation of an embodiment of the present invention. 2A shows the control signal supplied to the control terminal Tc, FIG. 2B shows the input current Iin inputted from the input terminal Tin, and FIG. 2C shows the output voltage Vout outputted from the output terminal Tout. The waveform is shown.

時刻ｔ１で、図２（Ａ）に示すようにコントロール端子Ｔcに供給されるコントロール信号がローレベルからハイレベルに立ち上がると、誤差アンプ１１２の出力が増加して、制御トランジスタＭ８を通して出力端子Ｔoutに電流が供給される。これによって、図２（Ｂ）に示すように入力電流Ｉinが増加する。   At time t1, as shown in FIG. 2A, when the control signal supplied to the control terminal Tc rises from the low level to the high level, the output of the error amplifier 112 increases and passes through the control transistor M8 to the output terminal Tout. Current is supplied. As a result, the input current Iin increases as shown in FIG.

このとき、出力電圧Ｖoutは閾値電圧Ｖth1以下であるので、定電流制御回路１３１が動作状態なり、電圧−電流特性制御回路１３２は非動作状態となる。よって、図２（Ｂ）に示す入力電流Ｉinは、時刻ｔ２で、定電流制御回路１３１で設定されている定電流に達し、保持される。   At this time, since the output voltage Vout is equal to or lower than the threshold voltage Vth1, the constant current control circuit 131 is in an operating state, and the voltage-current characteristic control circuit 132 is in a non-operating state. Therefore, the input current Iin shown in FIG. 2B reaches the constant current set by the constant current control circuit 131 and is held at time t2.

よって、出力端子Ｔoutに接続されたキャパシタが定電流制御回路１３１で設定されている比較的低い電流でチャージアップされる。よって、キャパシタのチャージアップに伴うラッシュ電流の発生を防止できる。   Therefore, the capacitor connected to the output terminal Tout is charged up with a relatively low current set by the constant current control circuit 131. Therefore, it is possible to prevent the generation of a rush current accompanying the charge-up of the capacitor.

時刻ｔ３で出力電圧Ｖoutが閾値電圧Ｖth1に達すると、定電流制御回路１３１が非動作状態となり、電圧−電流特性制御回路１３２が動作状態となる。これによって、電圧−電流特性制御回路１３２によって出力電流Ｉoutがフの字特性で制御される。これによって、図２（Ｂ）に示すように入力電流Ｉinは、出力端子Ｔoutに接続される負荷の状態に応じた電流を供給するようになる。   When the output voltage Vout reaches the threshold voltage Vth1 at time t3, the constant current control circuit 131 becomes non-operational and the voltage-current characteristic control circuit 132 becomes operational. As a result, the output current Iout is controlled by the voltage-current characteristic control circuit 132 with the U-shaped characteristic. As a result, as shown in FIG. 2B, the input current Iin supplies a current corresponding to the state of the load connected to the output terminal Tout.

図３は本発明の一実施例の出力電圧−出力電流特性を示す図である。   FIG. 3 is a graph showing output voltage-output current characteristics of one embodiment of the present invention.

本実施例によれば、起動時、出力電圧Ｖoutが閾値電圧Ｖth1以下の状態では、定電流制御回路１３１が動作状態となり、電圧−電流特性制御回路１３２が非動作状態となるので、出力電流Ｉoutは定電流Ｉ0となるように制御される。出力端子Ｔoutに接続されたキャパシタはこの定電流Ｉ0によりチャージアップされる。定電流Ｉ0は、キャパシタのチャージアップに伴うラッシュ電流の発生しない、比較的小さい値に設定されている。   According to the present embodiment, when the output voltage Vout is less than or equal to the threshold voltage Vth1 at startup, the constant current control circuit 131 is in an operating state and the voltage-current characteristic control circuit 132 is in a non-operating state. Is controlled to have a constant current I0. The capacitor connected to the output terminal Tout is charged up by this constant current I0. The constant current I0 is set to a relatively small value that does not generate a rush current accompanying the charge-up of the capacitor.

出力電圧Ｖoutが閾値電圧Ｖth1になると、定電流制御回路１３１が非動作状態となり、電圧−電流特性制御回路１３２が動作状態となるので、出力電流Ｉoutは電圧−電流特性制御回路１３２によりフの字特性で制御される。なお、閾値Ｖth1で電流制御回路１３１から電圧−電流特性制御回路１３２のフの字特性に切り換わるときには、閾値Ｖth1から出力電圧Ｖout0までの電位差が小さいため、電流は図３に示すように完全なフの字特性で変化することはなく、わずかな電流増加で所定の出力電圧Ｖout0に達することになる。   When the output voltage Vout becomes the threshold voltage Vth1, the constant current control circuit 131 becomes non-operating and the voltage-current characteristic control circuit 132 becomes active, so that the output current Iout is Controlled by characteristics. When switching from the current control circuit 131 to the U-shaped characteristic of the voltage-current characteristic control circuit 132 at the threshold Vth1, since the potential difference from the threshold Vth1 to the output voltage Vout0 is small, the current is completely as shown in FIG. There is no change in the U-shaped characteristic, and the predetermined output voltage Vout0 is reached with a slight increase in current.

これにより、出力電圧Ｖoutが閾値電圧Ｖth1に達した後には、負荷に供給される出力電流Ｉoutが増加した場合でも、電流はフの字特性で制御されるため、出力電流Ｉoutをフの字特性で増加させることが可能となる。   As a result, after the output voltage Vout reaches the threshold voltage Vth1, even if the output current Iout supplied to the load increases, the current is controlled by the F-characteristic. It becomes possible to increase by.

なお、電流制限回路１３３は、出力電流Ｉoutに制限をかけている。   Note that the current limiting circuit 133 limits the output current Iout.

本実施例によれば、起動時にチャージアップによるラッシュ電流の発生を防止できる。よって、出力端子Ｔoutにラッシュ電流を低減するために容量の大きなキャパシタを接続する必要はなくなる。また、起動後は、フの字特性で出力電流Ｉoutを制御でき、負荷電流の増大に対応できる。   According to this embodiment, it is possible to prevent the generation of a rush current due to charge-up at the time of startup. Therefore, it is not necessary to connect a capacitor with a large capacity to reduce the rush current to the output terminal Tout. In addition, after the start-up, the output current Iout can be controlled with the U-shaped characteristic, and the load current can be increased.

なお、本実施例では、起動後、電圧−電流特性をフの字特性とした例について説明したが、起動後の電圧−電流特性はフの字特性に限定されるものではなく、所望の特性に設定することができる。   In the present embodiment, the example in which the voltage-current characteristic is a U-shaped characteristic after startup has been described. However, the voltage-current characteristic after startup is not limited to the U-shaped characteristic, and a desired characteristic. Can be set to

本発明の一実施例の回路構成図である。It is a circuit block diagram of one Example of this invention. 本発明の一実施例の動作説明図である。It is operation | movement explanatory drawing of one Example of this invention. 本発明の一実施例の出力電圧−出力電流特性を示す図である。It is a figure which shows the output voltage-output current characteristic of one Example of this invention.

符号の説明Explanation of symbols

１００ 電源回路
１１１ 出力検出回路、１１２ 誤差アンプ、１１３ 基準電源回路
１１４ 電流制御回路、Ｍ８ 制御トランジスタ
１２１ 基準電圧生成回路、１２２ バイアス回路
１３１ 定電流制御回路、１３２ 電圧−電流特性制御回路、１３３ 電流制限回路
１３４ 出力制御回路、１３５ 電圧検出回路、１３６ インバータ
１３７、１３８ スイッチ回路 DESCRIPTION OF SYMBOLS 100 Power supply circuit 111 Output detection circuit, 112 Error amplifier, 113 Reference power supply circuit 114 Current control circuit, M8 control transistor 121 Reference voltage generation circuit, 122 Bias circuit 131 Constant current control circuit, 132 Voltage-current characteristic control circuit, 133 Current limit Circuit 134 Output control circuit, 135 Voltage detection circuit, 136 Inverter 137, 138 Switch circuit

Claims (6)

入力電圧を安定化した出力電圧を出力する電源回路において、
前記出力電圧が前記一定の電圧より小さい所定の電圧以下では出力電流を定電流に制御し、前記出力電圧が前記所定の電圧より大きい電圧では前記出力電流を所望の電流−電圧特性となるように制御する電流制御回路を有することを特徴とする電源回路。 In the power supply circuit that outputs the output voltage with the input voltage stabilized,
The output current is controlled to be a constant current when the output voltage is less than or equal to a predetermined voltage smaller than the constant voltage, and the output current has a desired current-voltage characteristic when the output voltage is larger than the predetermined voltage. A power supply circuit comprising a current control circuit for controlling. 前記電流制御回路は、前記出力電流に対する前記出力電圧の特性を前記所望の特性に制御する特性制御回路と、
前記出力電圧が所定の電圧範囲で出力電流を一定に制限する電流制限回路と、
前記出力電圧を検出する電圧検出回路と、
前記電圧検出回路の検出結果に応じて前記特性制御回路及び前記定電流制御回路の動作を切り替える切替回路とを有することを特徴とする請求項１記載の電源回路。 The current control circuit is configured to control a characteristic of the output voltage with respect to the output current to the desired characteristic;
A current limiting circuit for limiting the output current to be constant within a predetermined voltage range of the output voltage;
A voltage detection circuit for detecting the output voltage;
The power supply circuit according to claim 1, further comprising: a switching circuit that switches operations of the characteristic control circuit and the constant current control circuit according to a detection result of the voltage detection circuit. 前記特性制御回路は、前記出力電流に対する前記出力電圧の特性をフの字特性に制御することを特徴とする請求項２記載の電源回路。 The power supply circuit according to claim 2, wherein the characteristic control circuit controls a characteristic of the output voltage with respect to the output current to a U-shaped characteristic. 前記出力電流により充電されるキャパシタが接続されており、
前記電流制限回路は、前記キャパシタにラッシュ電流が発生しない程度の定電流を供給することを特徴とする請求項２記載の電源回路。 A capacitor charged by the output current is connected,
The power supply circuit according to claim 2, wherein the current limiting circuit supplies a constant current that does not generate a rush current to the capacitor. 出力電圧を一定の電圧に安定化させる電源回路の起動方法において、
前記出力電圧が前記一定の電圧より小さい所定の電圧以下では出力電流を定電流に制御し、前記出力電圧が前記所定の電圧より大きい電圧では前記出力電流を所望の電流−電圧特性となるように制御することを特徴とする電源回路の起動方法。 In the startup method of the power supply circuit that stabilizes the output voltage to a constant voltage,
The output current is controlled to be a constant current when the output voltage is less than or equal to a predetermined voltage smaller than the constant voltage, and the output current has a desired current-voltage characteristic when the output voltage is larger than the predetermined voltage. A method of starting a power supply circuit, comprising: controlling the power supply circuit. 前記出力電流に対する前記出力電圧の特性をフの字特性に制御し、
前記所定の電圧より小さい電圧のときに、前記出力電流を前記定電流に制御することを特徴とする請求項５記載の電源回路の起動方法。 Control the characteristics of the output voltage with respect to the output current to a U-shaped characteristic,
6. The method according to claim 5, wherein the output current is controlled to the constant current when the voltage is lower than the predetermined voltage.
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