JP2007164259A - Constant current device - Google Patents
Constant current device Download PDFInfo
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- JP2007164259A JP2007164259A JP2005356152A JP2005356152A JP2007164259A JP 2007164259 A JP2007164259 A JP 2007164259A JP 2005356152 A JP2005356152 A JP 2005356152A JP 2005356152 A JP2005356152 A JP 2005356152A JP 2007164259 A JP2007164259 A JP 2007164259A
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本発明は、レーザーダイオードなどの電流駆動型素子の駆動に好適な定電流装置に関し、特にその電流値設定に関するものである。 The present invention relates to a constant current device suitable for driving a current-driven element such as a laser diode, and more particularly to setting a current value thereof.
レーザーダイオードなど電流値により動作態様が決まる電流駆動型素子の駆動に使用する、図４の１１に示すような定電流回路（特許文献１）において、電流値Ｉｏ１は、
Ｉｏ１＝Ｖｒｏ／Ｒｓ２という式より決定される。電圧電流変換素子Ｑ２に流れる電流を状況に応じて調整することは、電圧電流変換素子Ｑ２への入力電圧Ｖｒｏを調整するか、検出抵抗Ｒｓ２の抵抗値を変更することにより実現できる。
It is determined from the equation I o1 = Vro / Rs2. Adjustment of the current flowing through the voltage-current conversion element Q2 according to the situation can be realized by adjusting the input voltage Vro to the voltage-current conversion element Q2 or changing the resistance value of the detection resistor Rs2.
しかし、入力電圧Ｖｒｏで変更する場合、たとえば１０ｍＡの電流と１００ｍＡの電流の双方を得るように設定する必要があるとき、１０ｍＡ用の入力信号電圧とその１０倍の１００ｍＡ用の入力信号電圧双方に対応するよう大幅に入力電圧Ｖｒｏを調整しなければならず、可変幅が広い場合には高い精度の電流値設定が困難である。 However, when the input voltage Vro is changed, for example, when it is necessary to set both the 10 mA current and the 100 mA current, the input signal voltage for 10 mA and the input signal voltage for 100 mA, which is 10 times as much, are used. The input voltage Vro must be significantly adjusted to cope with this, and when the variable width is wide, it is difficult to set the current value with high accuracy.
他の手法として、抵抗Ｒｓ２を可変抵抗とし、入力信号を可変させる手法がある。しかし、摺動部を持つ可変抵抗を使用することは信頼性を損なううえ、摺動部分の接触精度が不安定であるため、可変幅が広い場合には高い精度の電流値設定が困難である。また、固定抵抗とスイッチを組み合わせ、設定する手法も考えられるが、ノイズ電圧密度が設定する抵抗により異なるため、設定レンジによりノイズレベルが変動するという問題がある。 As another method, there is a method in which the resistor Rs2 is a variable resistor and the input signal is varied. However, using a variable resistor with a sliding part impairs reliability, and the contact accuracy of the sliding part is unstable, so it is difficult to set a highly accurate current value when the variable width is wide. . A method of combining and setting a fixed resistor and a switch is also conceivable, but there is a problem that the noise level varies depending on the set range because the noise voltage density varies depending on the set resistor.
本発明には、このような状況のもとでなされたもので、可変幅の広い、高い精度の電流値設定が可能な定電流装置を提供することを課題とするものである。 The present invention has been made under such circumstances, and an object of the present invention is to provide a constant current device having a wide variable width and capable of setting a current value with high accuracy.
前記課題を解決するため、本発明では定電流装置を次の（１）ないし（４）のとおりに構成する。 In order to solve the above problems, in the present invention, the constant current device is configured as follows (1) to (4).
（１）スイッチと抵抗を直列接続した直列回路をｎ個並列に接続した直並列回路と、前記直並列回路と直列に接続した電圧電流変換素子と、前記直並列回路と前記電圧電流変換素子の共通接続点に接続された一方の入力端および制御信号を入力する他方の入力端を有し、出力端が前記電圧電流変換素子の入力端に接続されたオペアンプとを備えた定電流装置であって、
前記直列回路の各抵抗の抵抗値の比を、１：１／２：１／４…１／２ｎ−１とした定電流装置。
(1) A series-parallel circuit in which n series circuits each having a switch and a resistor connected in series are connected in parallel, a voltage-current conversion element connected in series with the series-parallel circuit, the series-parallel circuit, and the voltage-current conversion element A constant current device including one input terminal connected to a common connection point and the other input terminal for inputting a control signal, and an output terminal connected to the input terminal of the voltage-current conversion element. And
A constant current device in which the ratio of the resistance values of the resistors of the series circuit is 1: 1/2: 1/4 ... 1/2 n-1 .
（２）前記（１）に記載の定電流装置において、
前記直並列回路の各スイッチをバイナリコーデッドディシマルにしたがいオン，オフする定電流装置。
(2) In the constant current device according to (1),
A constant current device that turns on and off each switch of the series-parallel circuit according to binary coded decimal.
（３）前記（１）に記載の定電流装置において、
前記直並列回路の各スイッチをロータリーディジタルコードＤＩＰスイッチとした定電流装置。
(3) In the constant current device according to (1),
A constant current device in which each switch of the series-parallel circuit is a rotary digital code DIP switch.
（４）前記（１）ないし（３）のいずれかに記載の定電流装置において、
前記直並列回路に並列に抵抗を接続した定電流装置。
(4) In the constant current device according to any one of (1) to (3),
A constant current device in which a resistor is connected in parallel to the series-parallel circuit.
本発明によれば、可変幅の広い、高い精度の電流値設定が可能な定電流装置を提供することができる。 According to the present invention, it is possible to provide a constant current device having a wide variable width and capable of setting a current value with high accuracy.
以下本発明を実施するための最良の形態を実施例により詳しく説明する。 Hereinafter, the best mode for carrying out the present invention will be described in detail by way of examples.
図１は、実施例１である“定電流装置”の構成を示す図である。図示のように、出力段の電圧電流変換素子Ｆ１であるＦＥＴのソース（トランジスタではエミッタ）側に検出抵抗を接続し、この抵抗に生じる電位差を入力段のオペアンプＯＰ１にフィードバックすることで一定の電流が得られる。これは電流が交流となっても同じである。負荷は、図４の回路１１と同様に、ＦＥＴのドレインと電源（不図示）の間に接続される。
FIG. 1 is a diagram illustrating a configuration of a “constant current device” according to the first embodiment. As shown in the figure, a detection resistor is connected to the source (emitter in the transistor) side of the FET which is the voltage-current conversion element F1 in the output stage, and the potential difference generated in this resistor is fed back to the operational amplifier OP1 in the input stage, thereby providing a constant current. Is obtained. This is the same even if the current becomes alternating current. The load is connected between the drain of the FET and a power source (not shown), as in the
前記検出抵抗を図示のように、スイッチと抵抗を直列接続した直列回路ｎ個を並列に配列する形で形成する。それぞれの抵抗Ｒ１，Ｒ２．Ｒ４，Ｒ８…の抵抗値は１：１／２：１／４：１／８…：１／２ｎ−１の比率に設定する。 As shown in the figure, the detection resistor is formed in a form in which n series circuits each having a switch and a resistor connected in series are arranged in parallel. Each resistor R1, R2. R4, R8 ... resistance of 1: 1/2: 1/4: 1/8 ...: set to 1/2 n-1 ratio.
このとき比率１の抵抗値をＲとすると、それぞれの抵抗の抵抗値はＲ、Ｒ／２、Ｒ／４、Ｒ／８、…となる。そして抵抗に接続したスイッチＳ１，Ｓ２，Ｓ４，Ｓ８…をバイナリコーデッドディシマルにしたがいＯＮ／ＯＦＦを切り替える。
At this time, if the resistance value of the
バイナリコードとスイッチのＯＮ／ＯＦＦの関係について図２の表１に示す。スイッチのＯＮ／ＯＦＦによって決まる合成抵抗は図２の表１の最下段のようになる。 The relationship between the binary code and the switch ON / OFF is shown in Table 1 of FIG. The combined resistance determined by the ON / OFF of the switch is as shown in the lowermost part of Table 1 in FIG.
本定電流装置では、この合成抵抗に生じる電圧降下を検出し入力電圧と等しくなるように制御されるため、電流値ＩはＩ＝Ｖ・ｎ／Ｒで与えられる。すなわち表１のスイッチの組み合わせにより電流値は図２の表２のようになる。すなわちＶ／Ｒで決まる一定値間隔の電流値を４段階以内で設定するには２個の、８段階以内で設定するには３個の、１６段階以内で設定するには４個の抵抗があればよい。すなわち、２ｎ段階で設定するために、ｎ個の「抵抗＋スイッチ」の組み合わせで実現できる。これは、市販のロータリーディジタルコードＤＩＰスイッチを使用すれば、大きな実装面積を要させずに、容易に実現できる。 In this constant current device, since the voltage drop generated in the combined resistance is detected and controlled to be equal to the input voltage, the current value I is given by I = V · n / R. That is, the current value is as shown in Table 2 of FIG. That is, two resistors are used to set the current value at a constant value determined by V / R within 4 steps, 3 are set within 8 steps, and 4 resistors are set within 16 steps. I just need it. In other words, since it is set in 2 n stages, it can be realized by a combination of n “resistors + switches”. This can be easily realized without using a large mounting area by using a commercially available rotary digital code DIP switch.
なお、図２の表では、初期値がゼロに設定されるが、これを何らかの値に設定するには、図３に示すとおり、スイッチと抵抗の直並列回路に並列に抵抗Ｒ０を挿入すればよい。 In the table of FIG. 2, the initial value is set to zero, but in order to set this to some value, a resistor R0 is inserted in parallel with a series-parallel circuit of a switch and a resistor as shown in FIG. Good.
さらに、このスイッチにリレーなど電気的にバイナリコードで制御できる素子を使用すれば、パソコンで制御可能な定電流源を作ることができるうえ、各抵抗が比で設定されるため、集積化にも適している。 In addition, if a device such as a relay that can be electrically controlled by a binary code is used for this switch, a constant current source that can be controlled by a personal computer can be created, and each resistor is set in a ratio, so integration is also possible. Is suitable.
また、それぞれの抵抗にＲと同じ値のものを使用し、各段階の数だけ並列に接続してもよい。この場合、同じ品種ロットが揃った抵抗を使うことができ、ばらつきを抑えることができる。 Alternatively, each resistor having the same value as R may be used and connected in parallel by the number of stages. In this case, resistors having the same product lot can be used, and variations can be suppressed.
以上説明したように，本実施例によれば、可変幅の広い、高い精度の電流値設定が可能な定電流装置を提供することができる。 As described above, according to this embodiment, it is possible to provide a constant current device having a wide variable width and capable of setting a current value with high accuracy.
なお、実施例１は、負荷をＦＥＴのドレインと電源の間に接続する例であるが、図４の回路２１Ａと同様に、ＦＥＴのソースと接地間に接続する形で実施することができる。この場合は、検出抵抗は図４の回路２１Ａと同様に、ＦＥＴのドレインと電源の間に接続することになる。 The first embodiment is an example in which the load is connected between the drain of the FET and the power source, but can be implemented by connecting the source between the FET and the ground in the same manner as the circuit 21A in FIG. In this case, the detection resistor is connected between the drain of the FET and the power supply, similarly to the circuit 21A of FIG.
Ｆ１ 電圧電流変換素子（ＦＥＴ）
ＯＰ１ オペアンプ
Ｒ１…Ｒ８ 抵抗
Ｓ１…Ｓ８ スイッチ
F1 Voltage-to-current converter (FET)
OP1 operational amplifier R1 ... R8 resistor S1 ... S8 switch
Claims (4)
前記直列回路の各抵抗の抵抗値の比を、１：１／２：１／４…１／２ｎ−１としたことを特徴とする定電流装置。 A series-parallel circuit in which n series circuits in which switches and resistors are connected in series are connected in parallel, a voltage-current conversion element connected in series with the series-parallel circuit, and a common connection point between the series-parallel circuit and the voltage-current conversion element A constant current device comprising: one input terminal connected to the other end; and the other input terminal for inputting a control signal; and an operational amplifier connected to the input terminal of the voltage-current conversion element.
A constant current device characterized in that a ratio of resistance values of the resistors of the series circuit is set to 1: 1/2: 1/4 ... 1/2 n-1 .
前記直並列回路の各スイッチをバイナリコーデッドディシマルにしたがいオン，オフすることを特徴とする定電流装置。 The constant current device according to claim 1,
A constant current device, wherein each switch of the series-parallel circuit is turned on and off in accordance with binary coded decimal.
前記直並列回路の各スイッチをロータリーディジタルコードＤＩＰスイッチとしたことを特徴とする定電流装置。 The constant current device according to claim 1,
A constant current device characterized in that each switch of the series-parallel circuit is a rotary digital code DIP switch.
前記直並列回路に並列に抵抗を接続したことを特徴とする定電流装置。 The constant current device according to any one of claims 1 to 3,
A constant current device comprising a resistor connected in parallel to the series-parallel circuit.
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| JP2005356152A JP2007164259A (en) | 2005-12-09 | 2005-12-09 | Constant current device |
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| JP2005356152A JP2007164259A (en) | 2005-12-09 | 2005-12-09 | Constant current device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2018097476A (en) * | 2016-12-09 | 2018-06-21 | ローム株式会社 | Reference current generation circuit, semiconductor integrated circuit, vehicle |
| CN109782835A (en) * | 2018-12-27 | 2019-05-21 | 湖南银河电气有限公司 | A kind of wide-range and the DC current source and processing method of closed-loop control |
-
2005
- 2005-12-09 JP JP2005356152A patent/JP2007164259A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2018097476A (en) * | 2016-12-09 | 2018-06-21 | ローム株式会社 | Reference current generation circuit, semiconductor integrated circuit, vehicle |
| CN109782835A (en) * | 2018-12-27 | 2019-05-21 | 湖南银河电气有限公司 | A kind of wide-range and the DC current source and processing method of closed-loop control |
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