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JP2013025510A - Constant voltage circuit - Google Patents

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JP2013025510A
JP2013025510A JP2011158651A JP2011158651A JP2013025510A JP 2013025510 A JP2013025510 A JP 2013025510A JP 2011158651 A JP2011158651 A JP 2011158651A JP 2011158651 A JP2011158651 A JP 2011158651A JP 2013025510 A JP2013025510 A JP 2013025510A
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voltage
resistor
output
circuit
shunt regulator
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JP5669208B2 (en
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Takashige Watanabe
恭成 渡辺
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Nichicon Corp
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Abstract

【課題】出力電流にかかわらず、一定の出力電圧を負荷に供給することができる定電圧回路を提供する。
【解決手段】直列接続された各抵抗に印加される電圧が出力電圧の増減に応じて変化する主分圧抵抗回路Ｒ1、Ｒ2と、主分圧抵抗回路Ｒ1、Ｒ2の分圧点（点ｅ）にリファレンス端子が接続された主シャントレギュレータＩＣ1と、主シャントレギュレータＩＣ1のカソードに流れ込む電流ＩKに応じて電圧降下を生じさせる電圧降下用抵抗ＲBと、電圧降下用抵抗ＲBの電圧降下の減少に応じて出力電圧ＶOUTを上昇させる一方、電圧降下の増加に応じて出力電圧ＶOUTを降下させる出力電圧補正部２と、を備え、主シャントレギュレータＩＣ1のカソードに流れ込む電流ＩKは、出力電流の増加分だけ減少する一方、出力電流の減少分だけ増加することを特徴とする。
【選択図】図１A constant voltage circuit capable of supplying a constant output voltage to a load irrespective of an output current is provided.
The main voltage dividing resistor circuits R 1 and R 2 in which the voltage applied to each resistor connected in series changes according to the increase or decrease of the output voltage, and the voltage dividing of the main voltage dividing resistor circuits R 1 and R 2 . point (point e) main shunt regulator IC 1 the reference terminal is connected to a resistor R B for the voltage drop causes a voltage drop according to the current I K flows to the cathode of the main shunt regulator IC 1, a voltage drop An output voltage correction unit 2 that raises the output voltage V OUT according to a decrease in the voltage drop of the resistor R B , while lowering the output voltage V OUT according to an increase in the voltage drop, of the main shunt regulator IC 1 The current I K flowing into the cathode is characterized in that it decreases by the increase in output current, while it increases by the decrease in output current.
[Selection] Figure 1

Description

本発明は、定電圧回路に関し、特に出力電流に応じて出力電圧を補正することができる定電圧回路に関する。   The present invention relates to a constant voltage circuit, and more particularly to a constant voltage circuit capable of correcting an output voltage according to an output current.

従来から、図３に示すように、基準電圧を発生させる基準電圧発生回路１２と、分圧抵抗回路からなる出力電圧検出部１３と、基準電圧発生回路１２で生成された基準電圧および出力電圧検出部１３で分圧して得られた電圧を差動増幅する差動増幅回路１４と、差動増幅回路１４で得られた信号により制御される出力トランジスタ１５と、出力電圧ＶOUTを補正するための出力電圧補正部１６と、を備えた定電圧回路１１が知られている（例えば、特許文献１参照）。 Conventionally, as shown in FIG. 3, a reference voltage generation circuit 12 for generating a reference voltage, an output voltage detection unit 13 including a voltage dividing resistor circuit, and a reference voltage and an output voltage detection generated by the reference voltage generation circuit 12 A differential amplifying circuit 14 for differentially amplifying the voltage obtained by dividing by the unit 13; an output transistor 15 controlled by a signal obtained by the differential amplifying circuit 14; and for correcting the output voltage V OUT A constant voltage circuit 11 including an output voltage correction unit 16 is known (see, for example, Patent Document 1).

出力電圧補正部１６は、出力トランジスタ１５と出力電圧検出部１３との間に設けられた出力電圧補正用の抵抗１７と、出力トランジスタ１５の出力電流ＩOUTに応じた電流を出力するＰＭＯＳトランジスタ１８と、ＰＭＯＳトランジスタ１８の出力電流に応じた電流を抵抗１７に流すためのカレントミラー回路を形成するＮＭＯＳトランジスタ１９、２０とを含んでいる。 The output voltage correction unit 16 includes an output voltage correction resistor 17 provided between the output transistor 15 and the output voltage detection unit 13, and a PMOS transistor 18 that outputs a current corresponding to the output current I OUT of the output transistor 15. And NMOS transistors 19 and 20 forming a current mirror circuit for causing a current corresponding to the output current of the PMOS transistor 18 to flow through the resistor 17.

かかる構成の定電圧回路１１では、出力電流ＩOUTの増加に起因して出力電圧ＶOUTが低下した場合であっても、低下した出力電圧ＶOUTを抵抗１７の両端に発生した電圧の分だけ上昇させることができる。したがって、この定電圧回路１１によれば、一定の出力電圧ＶOUTを出力することができる。 In the constant voltage circuit 11 having such a configuration, even when the output voltage V OUT is reduced due to the increase in the output current I OUT , the reduced output voltage V OUT is equivalent to the voltage generated across the resistor 17. Can be raised. Therefore, according to the constant voltage circuit 11, a constant output voltage V OUT can be output.

特開２００２−９１５８０号公報JP 2002-91580 A

ところで、出力電流ＩOUTが増加した場合、定電圧回路１１と負荷２１との間の配線パターンやハーネスにおける電圧降下の影響が大きくなり、負荷２１に供給される電圧は出力電圧ＶOUTよりも低くなる場合がある。しかしながら、従来の定電圧回路１１では、この点について何ら考慮されていなかった。 By the way, when the output current I OUT increases, the influence of the voltage drop in the wiring pattern and the harness between the constant voltage circuit 11 and the load 21 increases, and the voltage supplied to the load 21 is lower than the output voltage V OUT. There is a case. However, the conventional constant voltage circuit 11 does not consider this point at all.

なお、出力電圧検出部１３を負荷２１の近傍に設け、出力電流ＩOUTの変化を直接モニタリングすることで、定電圧回路１１と負荷２１との間の配線パターン等における電圧降下の影響を小さくすることも考えられるが、その場合は、出力電圧検出部１３と差動増幅回路１４との間の配線パターンが長くなり、ノイズの影響を受けやすくなるという新たな問題が生じてしまう。 The output voltage detection unit 13 is provided near the load 21 and the change in the output current I OUT is directly monitored, thereby reducing the influence of the voltage drop in the wiring pattern between the constant voltage circuit 11 and the load 21. In this case, however, the wiring pattern between the output voltage detection unit 13 and the differential amplifier circuit 14 becomes long, which causes a new problem of being easily affected by noise.

また、従来の定電圧回路１１は、カレントミラー回路を形成する複数のＰＭＯＳトランジスタおよびＮＭＯＳトランジスタ等で構成された差動増幅回路１４や出力電圧補正部１６を備えているため、部品点数が多くなり、コストの増大を招くおそれがあった。   In addition, the conventional constant voltage circuit 11 includes the differential amplifier circuit 14 and the output voltage correction unit 16 configured by a plurality of PMOS transistors and NMOS transistors forming a current mirror circuit, so that the number of components increases. The cost may increase.

本発明は上記事情に鑑みてなされたものであって、その課題とするところは、出力電流にかかわらず、一定の電圧を負荷に供給することができる定電圧回路を提供することにある。   The present invention has been made in view of the above circumstances, and an object thereof is to provide a constant voltage circuit capable of supplying a constant voltage to a load regardless of an output current.

上記課題を解決するために、本発明に係る定電圧回路は、入力端に印加される直流電圧を一定の出力電圧に変換して出力端から出力させる定電圧回路において、直列接続された各抵抗に印加される電圧が出力電圧の増減に応じて変化する主分圧抵抗回路と、前記主分圧抵抗回路の分圧点にリファレンス端子が接続された主シャントレギュレータと、主シャントレギュレータのカソードに流れ込む電流に応じて電圧降下を生じさせる電圧降下用抵抗と、電圧降下用抵抗の電圧降下の減少に応じて出力電圧を上昇させる一方、電圧降下の増加に応じて出力電圧を降下させる出力電圧補正部とを備え、主シャントレギュレータのカソードに流れ込む電流は、出力電流の増加分だけ減少する一方、出力電流の減少分だけ増加することを特徴とする。   In order to solve the above-described problems, a constant voltage circuit according to the present invention is a constant voltage circuit that converts a DC voltage applied to an input terminal into a constant output voltage and outputs the voltage from the output terminal. The main voltage dividing resistor circuit in which the voltage applied to the output voltage changes according to the increase or decrease of the output voltage, the main shunt regulator having a reference terminal connected to the voltage dividing point of the main voltage dividing resistor circuit, A voltage drop resistor that causes a voltage drop according to the flowing current, and an output voltage correction that increases the output voltage according to a decrease in the voltage drop of the voltage drop resistor, while dropping the output voltage as the voltage drop increases The current flowing into the cathode of the main shunt regulator is reduced by an increase in the output current, while increasing by an increase in the output current.

この構成によれば、主シャントレギュレータのカソードに流れ込む電流に応じて電圧降下を生じさせる電圧降下用抵抗と、該電圧降下用抵抗の電圧降下の減少に応じて出力電圧を上昇させる一方、電圧降下の増加に応じて出力電圧を降下させるように出力電圧を補正する出力電圧補正部とを備えている。このため、出力電流が増加した場合に、主シャントレギュレータのカソードに流れ込む電流が減少し、電圧降下用抵抗の電圧降下が減少することによって、出力電圧を上昇させて、出力電流が増加する直前の出力電圧よりも大きな出力電圧を出力することができる。したがって、この構成によれば、配線パターンやハーネスでの電圧降下に合わせて出力電圧を上昇させることで、出力電流にかかわらず一定の電圧を負荷に供給することができる。   According to this configuration, the voltage drop resistor that causes a voltage drop according to the current flowing into the cathode of the main shunt regulator, and the output voltage is raised according to the decrease in the voltage drop of the voltage drop resistor, while the voltage drop And an output voltage correction unit that corrects the output voltage so as to decrease the output voltage according to the increase in the output voltage. For this reason, when the output current increases, the current flowing into the cathode of the main shunt regulator decreases, and the voltage drop of the voltage drop resistor decreases, so that the output voltage is increased and the output current increases immediately before the increase. An output voltage larger than the output voltage can be output. Therefore, according to this configuration, it is possible to supply a constant voltage to the load regardless of the output current by increasing the output voltage in accordance with the voltage drop in the wiring pattern or the harness.

また、この構成によれば、出力電流が減少した場合（例えば、負荷が軽い場合）に、主シャントレギュレータのカソードに流れ込む電流が増加し、電圧降下用抵抗の電圧降下が増加することによって、出力電圧を降下させて、出力電流が減少する直前の出力電圧よりも小さな出力電圧を出力することができる。したがって、この構成によれば、消費電力を低減することができる。   In addition, according to this configuration, when the output current decreases (for example, when the load is light), the current flowing into the cathode of the main shunt regulator increases, and the voltage drop of the voltage drop resistor increases, so that the output It is possible to output an output voltage smaller than the output voltage immediately before the output current is decreased by decreasing the voltage. Therefore, according to this configuration, power consumption can be reduced.

さらに、この構成によれば、従来の定電圧回路のように出力電流の変化をモニタリングする必要がなくなるため、ノイズの影響を低減することができる。   Furthermore, according to this configuration, it is not necessary to monitor the change in the output current as in the conventional constant voltage circuit, so that the influence of noise can be reduced.

また、本発明に係る定電圧回路は、出力電圧補正部が、アノード端子が主シャントレギュレータのアノード端子に接続された補正用シャントレギュレータと、補正用シャントレギュレータのリファレンス端子が接続された抵抗分圧点を含む補正用分圧抵抗回路とを有し、主分圧抵抗回路は、出力端と主シャントレギュレータのリファレンス端子との間に接続された第１抵抗と、主シャントレギュレータのリファレンス端子と補正用分圧抵抗回路の一端との間に接続された第２抵抗とを有し、電圧降下用抵抗は、一端が主シャントレギュレータおよび補正用シャントレギュレータのアノード端子に接続され、かつ他端が補正用分圧抵抗回路の他端に接続されていることが好ましい。   In the constant voltage circuit according to the present invention, the output voltage correction unit includes a correction shunt regulator in which the anode terminal is connected to the anode terminal of the main shunt regulator, and a resistance voltage divider in which the reference terminal of the correction shunt regulator is connected. And a voltage dividing resistor circuit for correction including a point. The main voltage dividing resistor circuit includes a first resistor connected between the output terminal and the reference terminal of the main shunt regulator, and a reference terminal of the main shunt regulator and the correction. And a second resistor connected between one end of the voltage dividing resistor circuit, and one end of the voltage drop resistor is connected to the anode terminal of the main shunt regulator and the correction shunt regulator, and the other end is corrected. It is preferable to be connected to the other end of the voltage dividing resistor circuit.

この構成によれば、部品点数を減らすことができ、コストを低減することができる。   According to this configuration, the number of parts can be reduced, and the cost can be reduced.

また、本発明に係る定電圧回路は、補正用分圧抵抗回路が、補正用シャントレギュレータのリファレンス端子とカソード端子との間に接続された第３抵抗と、補正用シャントレギュレータのリファレンス端子と電圧降下用抵抗との間に接続された第４抵抗とを有することが好ましい。   In the constant voltage circuit according to the present invention, the correction voltage dividing resistor circuit includes a third resistor connected between the reference terminal and the cathode terminal of the correction shunt regulator, and the reference terminal and the voltage of the correction shunt regulator. It is preferable to have a fourth resistor connected between the descent resistor.

本発明によれば、出力電流の増加にかかわらず一定の電圧を負荷に供給可能な定電圧回路を提供することができる。   According to the present invention, it is possible to provide a constant voltage circuit capable of supplying a constant voltage to a load regardless of an increase in output current.

本発明に係る定電圧回路の回路図である。1 is a circuit diagram of a constant voltage circuit according to the present invention. 本発明に係る定電圧回路の使用例を示す回路図である。It is a circuit diagram which shows the usage example of the constant voltage circuit which concerns on this invention. 従来の定電圧回路の回路図である。It is a circuit diagram of the conventional constant voltage circuit.

以下、添付図面を参照して、本発明に係る定電圧回路の好ましい実施形態について説明する。   Hereinafter, preferred embodiments of a constant voltage circuit according to the present invention will be described with reference to the accompanying drawings.

［定電圧回路の構成］
図１に、本発明の一実施形態に係る定電圧回路１を示す。同図に示すように、本実施形態に係る定電圧回路１は、シャントレギュレータＩＣ1（本発明の「主シャントレギュレータ」に相当）と、入力端３において直流電源５に直列接続された入力抵抗ＲAと、直列接続された第１抵抗Ｒ1および第２抵抗Ｒ2からなる第１分圧抵抗回路（本発明の「主分圧抵抗回路」に相当）と、シャントレギュレータＩＣ1のカソード電流ＩKに応じた電圧降下を生じさせる電圧降下用抵抗ＲBと、電圧降下用抵抗ＲBの電圧降下に応じて出力電圧ＶOUTを補正する出力電圧補正部２とを備えている。なお、図１において、定電圧回路１の出力端４と負荷６との間に接続されている疑似抵抗ＲCは、実際に接続されている抵抗ではなく、配線パターンやハーネス等の抵抗を疑似的に表現したものである。 [Configuration of constant voltage circuit]
FIG. 1 shows a constant voltage circuit 1 according to an embodiment of the present invention. As shown in the figure, the constant voltage circuit 1 according to this embodiment includes a shunt regulator IC 1 (corresponding to a “main shunt regulator” of the present invention) and an input resistor connected in series to a DC power source 5 at an input terminal 3. R A , a first voltage dividing resistor circuit (corresponding to a “main voltage dividing resistor circuit” of the present invention) composed of a first resistor R 1 and a second resistor R 2 connected in series, and a cathode current of the shunt regulator IC 1 A voltage drop resistor R B that causes a voltage drop according to I K and an output voltage correction unit 2 that corrects the output voltage V OUT according to the voltage drop of the voltage drop resistor R B are provided. In FIG. 1, the pseudo resistance R C connected between the output terminal 4 of the constant voltage circuit 1 and the load 6 is not a resistance actually connected but a resistance such as a wiring pattern or a harness. It is an expression.

出力電圧補正部２は、本発明の「補正用シャントレギュレータ」に相当するシャントレギュレータＩＣ2と、直列接続された第３抵抗Ｒ3および第４抵抗Ｒ4からなる第２分圧抵抗回路（本発明の「補正用分圧抵抗回路」に相当）とを含んでいる。出力電圧補正部２は、具体的には後述するが、電圧降下用抵抗ＲBにおける電圧降下の減少に応じて出力電圧ＶOUTを上昇させる一方、電圧降下用抵抗ＲBにおける電圧降下の増加に応じて出力電圧ＶOUTを降下させる。 The output voltage correction unit 2 includes a shunt regulator IC 2 corresponding to the “correction shunt regulator” of the present invention, and a second voltage-dividing resistor circuit (this book) including a third resistor R 3 and a fourth resistor R 4 connected in series. Equivalent to the “dividing resistor circuit for correction” of the invention. The output voltage correction unit 2 is specifically described below while increasing the output voltage V OUT in response to the decrease of the voltage drop in the voltage drop across resistor R B, the increase of the voltage drop in the voltage drop across resistor R B Accordingly, the output voltage V OUT is decreased.

シャントレギュレータＩＣ1は、アノード端子がシャントレギュレータＩＣ2のアノード端子と電圧降下用抵抗ＲBの一端との接続点（点ａ）に接続され、カソード端子が入力抵抗ＲAの他端に接続され、かつリファレンス端子が第１分圧抵抗回路の分圧点（点ｅ；第１抵抗Ｒ1と第２抵抗Ｒ2との接続点）に接続されている。シャントレギュレータＩＣ1は、アノード端子とリファレンス端子との電位差に応じてカソード電流ＩKを制御する。 Shunt regulator IC 1 ', an anode terminal connected to a connection point between one end of the anode terminal and the voltage drop across resistor R B of the shunt regulator IC 2 (point a), the cathode terminal is connected to the other end of the input resistor R A The reference terminal is connected to a voltage dividing point (point e; connection point between the first resistor R 1 and the second resistor R 2 ) of the first voltage dividing resistor circuit. The shunt regulator IC 1 controls the cathode current I K according to the potential difference between the anode terminal and the reference terminal.

シャントレギュレータＩＣ2は、アノード端子が点ａに接続され、カソード端子が第２分圧抵抗回路の一端（点ｄ）に接続され、かつリファレンス端子が第２分圧抵抗回路の抵抗分圧点（点ｃ；第３抵抗Ｒ3と第４抵抗Ｒ4との接続点）に接続されている。シャントレギュレータＩＣ2は、シャントレギュレータＩＣ1と同様に、アノード端子とリファレンス端子との電位差に応じてカソード電流を制御する。 The shunt regulator IC 2 has an anode terminal connected to the point a, a cathode terminal connected to one end (point d) of the second voltage dividing resistor circuit, and a reference terminal connected to the resistance voltage dividing point of the second voltage dividing resistor circuit ( Point c; connection point between third resistor R 3 and fourth resistor R 4 ). Similar to the shunt regulator IC 1 , the shunt regulator IC 2 controls the cathode current according to the potential difference between the anode terminal and the reference terminal.

第１分圧抵抗回路と第２分圧抵抗回路とは直列接続されており、第１分圧抵抗回路の一端（点ｆ）は出力端４に接続され、第２分圧抵抗回路の他端は電圧降下用抵抗ＲBの他端に接続されている（点ｂ）。このため、シャントレギュレータＩＣ1のリファレンス端子には、出力電圧ＶOUTを第１抵抗Ｒ1と第２〜第４抵抗Ｒ2〜Ｒ4とにより分圧した電圧が入力される。 The first voltage dividing resistor circuit and the second voltage dividing resistor circuit are connected in series, one end (point f) of the first voltage dividing resistor circuit is connected to the output terminal 4, and the other end of the second voltage dividing resistor circuit. It is connected to the other end of the voltage drop across the resistor R B (point b). Therefore, a voltage obtained by dividing the output voltage V OUT by the first resistor R 1 and the second to fourth resistors R 2 to R 4 is input to the reference terminal of the shunt regulator IC 1 .

［定電圧回路の動作］
次に、出力電流ＩOUTが増加した場合における定電圧回路１の動作について具体的に説明する。本具体例においては、入力抵抗ＲAの抵抗値を１Ω、電圧降下用抵抗ＲBの抵抗値を１０ｍΩ、第１抵抗Ｒ1の抵抗値を４０ｋΩ、第２〜第４抵抗Ｒ2〜Ｒ4の各抵抗値を１０ｋΩとし、初期状態において、直流電源５から１０Ｖの入力電圧が供給され、５Ｖの出力電圧ＶOUTが出力されているものとする。また、点ａ〜ｆにおける各電位は点ｂを基準に考えるものとする。 [Operation of constant voltage circuit]
Next, the operation of the constant voltage circuit 1 when the output current I OUT increases will be specifically described. In this example, 1 [Omega the resistance of the input resistor R A, 10 m [Omega the resistance value of the voltage drop across the resistor R B, 40 k.OMEGA a first resistance value of the resistor R 1, the second to fourth resistor R 2 to R 4 In the initial state, an input voltage of 10 V is supplied from the DC power source 5 and an output voltage V OUT of 5 V is output. Each potential at points a to f is considered with reference to point b.

かかる定電圧回路１において何らかの要因で出力電流ＩOUTが１Ａ増加すると、入力抵抗ＲAを流れる入力電流ＩINは実質的に一定（５Ａ）であるため、シャントレギュレータＩＣ1のカソード電流ＩKが１Ａ減少する。 When the output current I OUT increases by 1 A for some reason in the constant voltage circuit 1, the input current I IN flowing through the input resistor RA is substantially constant (5 A). Therefore, the cathode current I K of the shunt regulator IC 1 is Decrease by 1A.

シャントレギュレータＩＣ1のカソード電流ＩKが１Ａ減少すると、電圧降下用抵抗ＲBの電圧降下は１０ｍＶ減少し、電圧降下用抵抗ＲBの一端（点ａ）の電位は１０ｍＶ降下する。 When the cathode current I K of the shunt regulator IC 1 decreases by 1 A, the voltage drop of the voltage drop resistor R B decreases by 10 mV, and the potential at one end (point a) of the voltage drop resistor R B drops by 10 mV.

電圧降下用抵抗ＲBの一端（点ａ）の電位が１０ｍＶ降下すると、シャントレギュレータＩＣ2はアノード端子とリファレンス端子との電位差を基準電圧に一致させるために、第２分圧抵抗回路の抵抗分圧点（点ｃ）の電位を１０ｍＶ降下させる。 When the potential of one end (point a) of the voltage drop across resistor R B is 10mV drop, shunt regulator IC 2 in order to match the potential difference between the anode terminal and the reference terminal to the reference voltage, the resistance of the second voltage divider resistor circuit The potential at the pressure point (point c) is lowered by 10 mV.

第２分圧抵抗回路を構成する第３抵抗Ｒ3と第４抵抗Ｒ4には同一の電流が流れているので、第３抵抗Ｒ3と第４抵抗Ｒ4との抵抗値の比（１：１）により、第２分圧抵抗回路の抵抗分圧点（点ｃ）の電位が１０ｍＶ降下すると、第２分圧抵抗回路の一端（点ｄ）の電位も１０ｍＶ降下する。 Since the same current flows through the third resistor R 3 and the fourth resistor R 4 constituting the second voltage dividing resistor circuit, the ratio of the resistance values of the third resistor R 3 and the fourth resistor R 4 (1 1), when the potential of the resistance voltage dividing point (point c) of the second voltage dividing resistor circuit drops by 10 mV, the potential of one end (point d) of the second voltage dividing resistor circuit also drops by 10 mV.

第２分圧抵抗回路の一端（点ｄ）の電位が１０ｍＶ降下すると、シャントレギュレータＩＣ1はアノード端子とリファレンス端子との電位差を基準電圧に一致させるために、第１分圧抵抗回路の分圧点（点ｅ）の電位を１０ｍＶ上昇させる。 When the potential at one end (point d) of the second voltage dividing resistor circuit drops by 10 mV, the shunt regulator IC 1 causes the voltage dividing of the first voltage dividing resistor circuit to match the potential difference between the anode terminal and the reference terminal with the reference voltage. The potential at the point (point e) is increased by 10 mV.

第１分圧抵抗回路を構成する第１抵抗Ｒ1と第２抵抗Ｒ2には同一の電流が流れているので、第１抵抗Ｒ1と第２抵抗Ｒ2との抵抗値の比（４：１）により、第１分圧抵抗回路の分圧点（点ｅ）の電位が１０ｍＶ上昇すると、第１分圧抵抗回路の一端（点ｆ）の電位は４０ｍＶ上昇する。これにより、出力端４の電位も４０ｍＶ上昇し、出力電圧ＶOUTが４０ｍＶ上昇する。 Since the same current flows through the first resistor R 1 and the second resistor R 2 constituting the first voltage dividing resistor circuit, the ratio of the resistance values of the first resistor R 1 and the second resistor R 2 (4 1), when the potential at the voltage dividing point (point e) of the first voltage dividing resistor circuit is increased by 10 mV, the potential at one end (point f) of the first voltage dividing resistor circuit is increased by 40 mV. As a result, the potential of the output terminal 4 also increases by 40 mV, and the output voltage V OUT increases by 40 mV.

上記のように、本実施形態に係る定電圧回路１では、第１抵抗Ｒ1と第２抵抗Ｒ2との抵抗値の比を調整することにより、出力端４の電位の上昇量（上記具体例では４０ｍＶ）を調整することができる。このため、本実施形態に係る定電圧回路１では、出力端４の電位の上昇量が、配線パターンやハーネスにおける電圧降下（疑似抵抗ＲCにおける電圧降下）と同程度になるように、第１抵抗Ｒ1と第２抵抗Ｒ2との抵抗値の比を調整することで、出力電流ＩOUTにかかわらず一定の電圧を負荷６に供給することができる。 As described above, the constant voltage circuit 1 according to the present embodiment adjusts the ratio of the resistance values of the first resistor R 1 and the second resistor R 2 , thereby increasing the amount of increase in the potential of the output terminal 4 (the above specific example). In the example, 40 mV) can be adjusted. For this reason, in the constant voltage circuit 1 according to the present embodiment, the first voltage is increased so that the amount of increase in the potential of the output terminal 4 is approximately the same as the voltage drop in the wiring pattern or the harness (voltage drop in the pseudo resistance RC ). A constant voltage can be supplied to the load 6 regardless of the output current I OUT by adjusting the ratio of the resistance values of the resistor R 1 and the second resistor R 2 .

また、本実施形態に係る定電圧回路１によれば、出力電流ＩOUTが減少した場合、電圧降下用抵抗ＲBの電圧降下に応じて出力端４の電位を降下させることができるので、一定の電圧を負荷６に供給することができ、さらに消費電力を低減することもできる。 Further, according to the constant-voltage circuit 1 according to the present embodiment, when the output current I OUT is decreased, it is possible to lower the potential at the output terminal 4 in accordance with the voltage drop of the voltage drop across resistor R B, a constant Can be supplied to the load 6, and the power consumption can also be reduced.

さらに、本実施形態に係る定電圧回路１によれば、従来の定電圧回路１１のように出力電流ＩOUTの変化をモニタリングする必要がなくなるため、ノイズの影響を低減することができる。 Furthermore, according to the constant voltage circuit 1 according to the present embodiment, it is not necessary to monitor the change in the output current I OUT as in the conventional constant voltage circuit 11, so that the influence of noise can be reduced.

さらに、本実施形態に係る定電圧回路１によれば、従来の定電圧回路１１と比べて部品点数を減らすことができるので、コストを低減することができる。   Furthermore, according to the constant voltage circuit 1 according to the present embodiment, the number of parts can be reduced as compared with the conventional constant voltage circuit 11, and thus the cost can be reduced.

以上、本発明に係る定電圧回路の好ましい実施形態について説明したが、本発明は上記実施形態の構成に限定されるものではない。   The preferred embodiment of the constant voltage circuit according to the present invention has been described above, but the present invention is not limited to the configuration of the above embodiment.

例えば、上記各抵抗ＲA、ＲB、Ｒ1〜Ｒ4の抵抗値は、配線パターンや負荷６の状態に応じて任意に設定することができる。設定手順の一例としては、まず、第２抵抗Ｒ2に発生させたい電圧を決定し、シャントレギュレータＩＣ1およびシャントレギュレータＩＣ2の基準電圧に基づいて、電圧降下用抵抗ＲB、第３抵抗Ｒ3および第４抵抗Ｒ4の抵抗値を設定する。次に、出力端４の電位の上昇量を決定し、その上昇量に合わせて第１抵抗Ｒ1と第２抵抗Ｒ2の抵抗値を設定する。そして、出力させたい最大の出力電圧ＶOUTに合わせて入力抵抗ＲAの抵抗値を設定すればよい。 For example, the resistance values of the resistors R A , R B , and R 1 to R 4 can be arbitrarily set according to the wiring pattern and the state of the load 6. As an example of the setting procedure, first, a voltage to be generated in the second resistor R 2 is determined, and the voltage drop resistor R B and the third resistor R are determined based on the reference voltages of the shunt regulator IC 1 and the shunt regulator IC 2. 3 and the resistance value of the fourth resistor R 4 are set. Next, the amount of increase in the potential of the output terminal 4 is determined, and the resistance values of the first resistor R 1 and the second resistor R 2 are set according to the amount of increase. Then, the resistance value of the input resistor RA may be set in accordance with the maximum output voltage V OUT desired to be output.

なお、上記各抵抗ＲA、ＲB、Ｒ1〜Ｒ4の数および位置は用途に応じて任意に変更することができる。例えば、第３抵抗Ｒ3を削除してもよい。 Each of the above resistor R A, R B, number and position of R 1 to R 4 may be arbitrarily changed depending on the application. For example, the third resistor R 3 may be omitted.

さらに、上記実施形態に係る定電圧回路１は、出力電圧補正部２をシャントレギュレータＩＣ2および第２分圧抵抗回路によって構成しているが、電圧降下用抵抗ＲBの電圧降下に応じて出力端４の電位を補正することができるのであれば、他の部品や回路等によって構成してもよい。 Further, the constant voltage circuit 1 according to the embodiment described above, the output voltage correction unit 2 has been configured by the shunt regulator IC 2 and the second voltage divider resistor circuit in accordance with the voltage drop of the voltage drop across resistor R B Output As long as the potential of the end 4 can be corrected, it may be constituted by other parts, circuits, or the like.

また、図２に示すように、トランスにより１次側と２次側とが絶縁された回路においても、主シャントレギュレータＩＣ1に直列接続されたフォトカプラの発光ダイオードＰＣ1を接続してもよい。ここで、ＲDは発光ダイオードＰＣ1をオフ状態とするときに安定して発光ダイオードＰＣ1をオフ状態に保つための抵抗であり、ＲEは発光ダイオードＰＣ1の入力電流制限抵抗である。かかる構成の定電圧回路１’によれば、フォトカプラのフォトトランジスタＰＣ2が接続された１次側回路（例えば、フィードバック端子を備えたスイッチング制御回路）に出力電圧ＶOUTの変化をフィードバックすることができる。 Further, as shown in FIG. 2, even in a circuit where the primary side and the secondary side are insulated by a transformer, the photocoupler light emitting diode PC 1 connected in series to the main shunt regulator IC 1 may be connected. . Here, R D is the resistance for keeping stably turned off light-emitting diode PC 1 when the light-emitting diode PC 1 in an off state, R E is an input current-limiting resistor of a light-emitting diode PC 1. According to the constant voltage circuit 1 ′ having such a configuration, a change in the output voltage V OUT is fed back to a primary circuit (for example, a switching control circuit having a feedback terminal) to which the phototransistor PC 2 of the photocoupler is connected. Can do.

１、１’ 定電圧回路
２ 出力電圧補正部
３ 入力端
４ 出力端
５ 直流電源
６ 負荷
ＩＣ1 主シャントレギュレータ
ＩＣ2 補正用シャントレギュレータ
ＲA 入力抵抗
ＲB 電圧降下用抵抗
ＲC 疑似抵抗
ＲD 電流検出用抵抗
Ｒ1 第１抵抗
Ｒ2 第２抵抗
Ｒ3 第３抵抗
Ｒ4 第４抵抗 1, 1 ′ constant voltage circuit 2 output voltage correction unit 3 input terminal 4 output terminal 5 DC power supply 6 load IC 1 main shunt regulator IC 2 correction shunt regulator R A input resistance R B voltage drop resistance R C pseudo resistance R D Current detection resistor R 1 First resistor R 2 Second resistor R 3 Third resistor R 4 Fourth resistor

Claims (3)

入力端に印加される直流電圧を一定の出力電圧に変換して出力端から出力させる定電圧回路において、
直列接続された各抵抗に印加される電圧が出力電圧の増減に応じて変化する主分圧抵抗回路と、
前記主分圧抵抗回路の分圧点にリファレンス端子が接続された主シャントレギュレータと、
前記主シャントレギュレータのカソードに流れ込む電流に応じて電圧降下を生じさせる電圧降下用抵抗と、
前記電圧降下用抵抗の電圧降下の減少に応じて前記出力電圧を上昇させる一方、前記電圧降下の増加に応じて前記出力電圧を降下させる出力電圧補正部と、
を備え、
前記主シャントレギュレータのカソードに流れ込む電流は、出力電流の増加分だけ減少する一方、出力電流の減少分だけ増加することを特徴とする定電圧回路。 In the constant voltage circuit that converts the DC voltage applied to the input terminal to a constant output voltage and outputs it from the output terminal,
A main voltage dividing resistor circuit in which the voltage applied to each resistor connected in series changes according to the increase or decrease of the output voltage;
A main shunt regulator having a reference terminal connected to a voltage dividing point of the main voltage dividing resistor circuit;
A voltage drop resistor that causes a voltage drop in response to the current flowing into the cathode of the main shunt regulator;
An output voltage correction unit that raises the output voltage in response to a decrease in the voltage drop of the voltage drop resistor, and drops the output voltage in response to an increase in the voltage drop;
With
The constant voltage circuit characterized in that the current flowing into the cathode of the main shunt regulator decreases by an increase in the output current, and increases by an decrease in the output current. 前記出力電圧補正部は、アノード端子が前記主シャントレギュレータのアノード端子に接続された補正用シャントレギュレータと、前記補正用シャントレギュレータのリファレンス端子が接続された抵抗分圧点を含む補正用分圧抵抗回路とを有し、
前記主分圧抵抗回路は、前記出力端と前記主シャントレギュレータのリファレンス端子との間に接続された第１抵抗と、前記主シャントレギュレータのリファレンス端子と前記補正用分圧抵抗回路の一端との間に接続された第２抵抗とを有し、
前記電圧降下用抵抗は、一端が前記主シャントレギュレータおよび前記補正用シャントレギュレータのアノード端子に接続され、かつ他端が前記補正用分圧抵抗回路の他端に接続されていることを特徴とする請求項１に記載の定電圧回路。 The output voltage correction unit includes a correction shunt regulator having an anode terminal connected to the anode terminal of the main shunt regulator, and a correction voltage dividing resistor including a resistance voltage dividing point to which a reference terminal of the correction shunt regulator is connected. Circuit and
The main voltage dividing resistor circuit includes a first resistor connected between the output terminal and a reference terminal of the main shunt regulator, a reference terminal of the main shunt regulator, and one end of the correction voltage dividing resistor circuit. A second resistor connected in between,
The voltage drop resistor has one end connected to the anode terminal of the main shunt regulator and the correction shunt regulator, and the other end connected to the other end of the correction voltage dividing resistor circuit. The constant voltage circuit according to claim 1. 前記補正用分圧抵抗回路は、前記補正用シャントレギュレータのリファレンス端子とカソード端子との間に接続された第３抵抗と、前記補正用シャントレギュレータのリファレンス端子と前記電圧降下用抵抗との間に接続された第４抵抗とを有することを特徴とする請求項２に記載の定電圧回路。   The correction voltage dividing resistor circuit includes a third resistor connected between a reference terminal and a cathode terminal of the correction shunt regulator, and a reference terminal of the correction shunt regulator and the voltage drop resistor. The constant voltage circuit according to claim 2, further comprising a fourth resistor connected thereto.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11259154A (en) * 1998-03-13 1999-09-24 Fujitsu Denso Ltd Dual tracking circuit
JP2002091580A (en) * 2000-09-20 2002-03-29 Ricoh Co Ltd Stabilized power supply circuit
JP2008165466A (en) * 2006-12-28 2008-07-17 Sanyo Electric Co Ltd Shunt circuit
JP2010136595A (en) * 2008-12-08 2010-06-17 Nec Lighting Ltd Current detecting circuit and power supply circuit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11259154A (en) * 1998-03-13 1999-09-24 Fujitsu Denso Ltd Dual tracking circuit
JP2002091580A (en) * 2000-09-20 2002-03-29 Ricoh Co Ltd Stabilized power supply circuit
JP2008165466A (en) * 2006-12-28 2008-07-17 Sanyo Electric Co Ltd Shunt circuit
JP2010136595A (en) * 2008-12-08 2010-06-17 Nec Lighting Ltd Current detecting circuit and power supply circuit

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