JPH06113441A - Current detection circuit - Google Patents
Current detection circuitInfo
- Publication number
- JPH06113441A JPH06113441A JP25603392A JP25603392A JPH06113441A JP H06113441 A JPH06113441 A JP H06113441A JP 25603392 A JP25603392 A JP 25603392A JP 25603392 A JP25603392 A JP 25603392A JP H06113441 A JPH06113441 A JP H06113441A
- Authority
- JP
- Japan
- Prior art keywords
- transistor
- current detection
- output transistor
- output
- power supply
- 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.)
- Pending
Links
Landscapes
- Emergency Protection Circuit Devices (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、電流検出回路に関
し、特に電流検出値の高精度化をはかった回路に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current detection circuit, and more particularly to a circuit with a highly accurate current detection value.
【０００２】[0002]
【従来の技術】従来、この種の電流検出回路は図３に示
すように、出力用トランジスタＴ1 のドレイン・ソース
間に接続した抵抗Ｒ2 とＭＯＳＦＥＴＴ3 との直列回路
の中間点ａをコンパレータｄの第１の入力に接続し、電
流検出用基準電圧Ｖ2 をコンパレータｄの第２の入力に
接続した構成となっており、昇圧回路９が昇圧動作し出
力用トランジスタＴ1 がオンし、ＭＯＳＦＥＴＴ3 がオ
ンした状態で出力電圧Ｖout が低下しＶcc−ＶA ＞Ｖ2
となったとき、電流を検出する動作となっていた。（但
し、Ｖccは、電源電圧，Ｖa はＡ点の電圧） 2. Description of the Related Art Conventionally, as shown in FIG. 3, a current detecting circuit of this type has a comparator for detecting an intermediate point a of a series circuit of a resistor R 2 connected between a drain and a source of an output transistor T 1 and a MOSFET T 3. It has a configuration in which it is connected to the first input of d and the current detection reference voltage V 2 is connected to the second input of the comparator d. The booster circuit 9 performs a boosting operation to turn on the output transistor T 1 . With the MOSFET T 3 turned on, the output voltage V out drops and V cc -V A > V 2
When, the current was detected. (However, V cc is the power supply voltage and V a is the voltage at point A)
【発明が解決しようとする課題】ところで、上記の従来
の電流検出回路は電流検出用基準電圧Ｖ2 を作る基準電
源ｈの特性は、出力用トランジスタＴ1 と昇圧回路ａの
特性に対応して同方向に変動するものではない。In the conventional current detection circuit described above, the characteristic of the reference power source h for producing the reference voltage V 2 for current detection corresponds to the characteristics of the output transistor T 1 and the booster circuit a. It does not change in the same direction.
【０００３】すなわち、製造ロットのバラツキにより出
力用トランジスタＴ1 のＯＮ抵抗が大きめになった時、
負荷Ｃに流れる電流がある一定値になるには出力電圧Ｖ
outは低めになり、したがって、Ａ点の電圧ＶA も低く
なるが、それに応じて電源ｈ（すなわち、電流検出用基
準電圧Ｖ2 ）が低くなるものではない。また、温度特性
により出力トランジスタＴ1 のＯＮ抵抗が大きくなる場
合もまた、同様である。That is, when the ON resistance of the output transistor T 1 becomes large due to variations in manufacturing lots,
In order for the current flowing through the load C to reach a certain value, the output voltage V
out becomes low, and therefore the voltage V A at the point A also decreases, but the power supply h (that is, the current detection reference voltage V 2 ) does not decrease accordingly. The same applies when the ON resistance of the output transistor T 1 increases due to temperature characteristics.
【０００４】したがって、製造のバラツキや温度特性に
より出力用トランジスタＴ1 や、昇圧回路の特性が変動
すると検出する電流値が変動するという欠点があった。Therefore, there has been a drawback that the detected current value fluctuates when the characteristics of the output transistor T 1 and the booster circuit fluctuate due to manufacturing variations and temperature characteristics.
【０００５】[0005]
【課題を解決するための手段】この発明の電流検出回路
は、電源の一方に一端を接続し、他端が負荷を介して電
源の他方に接続された出力用トランジスタの電流が所定
値以上であることを検出する回路であって、前記電源の
一方に対して、安定化した電圧を有する安定化電源と、
一端を前記電源の一方に接続し、他端が抵抗を介して前
記安定化電源に接続された前記出力用トランジスタに特
性相似な電流検出用トランジスタとを有し、前記出力用
トランジスタの制御端子を前記電流検出用トランジスタ
の制御端子を接続し、コンパレータの第１の入力端子を
前記出力端子トランジスタの他端に接続し、第２の入力
端子を、前記電流検出用トランジスタの他端に接続した
構成となっている。The current detection circuit of the present invention has one end connected to one of the power supplies, and the other end connected to the other of the power supplies through the load, if the current of the output transistor is a predetermined value or more. A circuit for detecting that there is a stabilized power supply having a stabilized voltage with respect to one of the power supplies,
One end is connected to one of the power supplies, and the other end has a current detection transistor characteristically similar to the output transistor connected to the stabilized power supply through a resistor, and a control terminal of the output transistor is provided. A configuration in which a control terminal of the current detection transistor is connected, a first input terminal of a comparator is connected to the other end of the output terminal transistor, and a second input terminal is connected to the other end of the current detection transistor. Has become.
【０００６】なお、明細書で用いる特性相似なトランジ
スタとは少なくともＯＮ抵抗の温度変化率が近似し、同
じ制御端子電圧における電流の関係が、比例関係にある
ものをいう。Note that a transistor having similar characteristics used in the specification means a transistor in which at least the rate of change in temperature of the ON resistance is approximate and the current relations at the same control terminal voltage are proportional.
【０００７】[0007]
【作用】上記の構成によると電流検出用基準電圧である
電流検出用トランジスタの他端の電圧が、出力用トラン
ジスタの特性変動によって生ずる出力用トランジスタの
他端の電圧の変動と同方向に変動するので電流検出値の
精度が向上する。According to the above structure, the voltage at the other end of the current detecting transistor, which is the current detecting reference voltage, changes in the same direction as the change in the voltage at the other end of the output transistor caused by the characteristic change of the output transistor. Therefore, the accuracy of the current detection value is improved.
【０００８】[0008]
【実施例】以下、この発明について図面を参照して説明
する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
【０００９】図１はこの発明の一実施例の回路図であ
る。図においてＴ1 は出力用ＭＯＳトランジスタ、Ｔ2
は出力用トランジスタＴ1 に１／ｎに相似なＭＯＳＦＥ
Ｔでなる電流検出用トランジスタ、Ｒ1 は抵抗、Ｖ1 は
安定化電源ｈ1 の電圧、Ｖccは電源電圧、Ｖout は出力
電圧、ａは昇圧回路、ｂは遅延回路、ｃは負荷、ｄはコ
ンパレータ、ｅは電流検出用基準電圧発生回路、ＶINは
制御入力端子電圧、ｆはＡＮＤゲート、ｇは電流検出信
号である。FIG. 1 is a circuit diagram of an embodiment of the present invention. In the figure, T 1 is an output MOS transistor, T 2
Is a MOSFE similar to 1 / n to the output transistor T 1.
T is a current detecting transistor, R 1 is a resistor, V 1 is the voltage of the stabilized power supply h 1 , V cc is the power supply voltage, V out is the output voltage, a is a booster circuit, b is a delay circuit, c is a load, d is a comparator, e is a reference voltage generating circuit for current detection, V IN is a control input terminal voltage, f is an AND gate, and g is a current detection signal.
【００１０】次に上記の実施例の動作について説明す
る。Next, the operation of the above embodiment will be described.
【００１１】制御入力端子ＩＮに出力用トランジスタＴ
1 のオン信号が入力されると、昇圧回路ａの出力電圧が
昇圧し、出力用トランジスタＴ1 と電流検出用トランジ
スタオン抵抗と抵抗Ｒ1 による安定化電源の電圧Ｖ1 の
分割により発生させることで出力用トランジスタＴ1 と
昇圧回路ａの特性変動と同方向上に変動する電流検出用
基準電圧Ｖccが発生し、電流検出精度が向上する。なお
電流検出値の調製は、ＭＯＳＦＥＴ2 の大きさ、抵抗Ｒ
2 の値によって調整可能となる。An output transistor T is connected to the control input terminal IN.
When the ON signal of 1 is input, the output voltage of the booster circuit a is boosted and generated by dividing the voltage V 1 of the stabilized power supply by the output transistor T 1 , the current detection transistor ON resistance and the resistance R 1. Then, the current detection reference voltage V cc which fluctuates in the same direction as the characteristic fluctuation of the output transistor T 1 and the booster circuit a is generated, and the current detection accuracy is improved. The current detection value is adjusted by the size of the MOSFET 2 and the resistance R
It becomes adjustable by the value of 2 .
【００１２】[0012]
【実施例２】図２は、この発明の第２の実施例の回路図
である。[Embodiment 2] FIG. 2 is a circuit diagram of a second embodiment of the present invention.
【００１３】実施例は、ＧＮＤ基準で回路構成し、出力
用トランジスタＴ1 と電流検出用トランジスタＴ2 のゲ
ート電圧を入力信号で直接制御すること以外第１の実施
例と同じであるため、同一参照符号を付して、その説明
を省略する。The embodiment is the same as the first embodiment except that the circuit is constructed based on the GND standard and the gate voltages of the output transistor T 1 and the current detection transistor T 2 are directly controlled by the input signal. The reference numerals are given and the description thereof is omitted.
【００１４】この実施例でも、第１の実施例と同様で、
出力用トランジスタＴ1 の特性変動と制御入力端子電圧
ＶINの変動と同方向に変動する電流検出用基準電圧Ｖcc
が発生し電流検出値が安定化する。Also in this embodiment, as in the first embodiment,
A current detection reference voltage V cc that fluctuates in the same direction as the characteristic fluctuation of the output transistor T 1 and the fluctuation of the control input terminal voltage V IN.
Occurs and the current detection value stabilizes.
【００１５】以上第１、第２の実施例における出力用ト
ランジスタＴ1 に特性相似な電流検出用トランジスタＴ
2 は同一チップ、または同一ウェーハに同時に作り込む
ことで簡単に作ることができる。As described above, the current detecting transistor T having a characteristic similar to that of the output transistor T 1 in the first and second embodiments.
2 can be easily made by simultaneously making them on the same chip or the same wafer.
【００１６】たとえば、チャンネル長は同一で、チャン
ネル巾を、異ならせることで実現できる。For example, the channel length can be the same and the channel width can be different.
【００１７】また、出力用トランジスタＴ1 は多数の同
一エレメントの集合として形成し、電流検出用トランジ
スタＴ2 は１個または少数で形成することでも実現でき
る。Further, the output transistor T 1 may be formed as a set of many same elements, and the current detection transistor T 2 may be formed by one or a small number.
【００１８】上記の実施例はＮチャンネルＭＯＳ型トラ
ンジスタを用いたものであるが、ＰチャンネルＭＯＳ型
トランジスタの場合も同様に実施できる。Although the above-described embodiment uses the N-channel MOS type transistor, the same can be applied to the case of the P-channel MOS type transistor.
【００１９】バイポーラトランジスタ、その他のタイプ
のトランジスタであっても同様に実施できる。A bipolar transistor and other types of transistors can be similarly implemented.
【００２０】[0020]
【発明の効果】以上説明したように、この発明は負荷ド
ライブ用出力トランジスタに流れる電流を検出する回路
において、コンパレータの第１の入力を出力用トランジ
スタの負荷ドライブ用端子に接続し、第２の入力を安定
した電源に出力用トランジスタと特性相似なトランジス
タと抵抗を直列接続したその中間点に接続したので、出
力用トランジスタの特性変動と同方向に変動する電流検
出用基準電圧が発生し、電流検出精度が向上する。As described above, according to the present invention, in the circuit for detecting the current flowing through the load driving output transistor, the first input of the comparator is connected to the load driving terminal of the output transistor, and the second input is connected. Since the input was connected to the stable power supply at the midpoint of the series connection of the output transistor and the transistor with similar characteristics to the output transistor, a reference voltage for current detection that fluctuates in the same direction as the characteristic fluctuation of the output transistor is generated, The detection accuracy is improved.
【図１】 この発明の第１実施例の回路図である。FIG. 1 is a circuit diagram of a first embodiment of the present invention.
【図２】 この発明の第２実施例の回路図である。FIG. 2 is a circuit diagram of a second embodiment of the present invention.
【図３】 従来の回路図である。FIG. 3 is a conventional circuit diagram.
Ｔ1 出力用トランジスタ Ｔ2 出力用トランジスタと特性相似な電流検出用トラ
ンジスタ ａ 昇圧回路 ｂ 遅延回路 ｃ 負荷 ｄ コンペレータ ｅ 電流検出用基準電圧発生回路 ｆ ＡＮＤゲート ｇ 電流検出信号 Ｖcc 電源電圧 Ｖ1 安定化電源電圧 ＩＮ 制御入力端子 Ｖout 出力電圧 Ｖoc 電流検出用基準電圧 ＶA 電流検出信号T 1 output transistor T 2 output transistor characteristics similar to current detection transistor a Boost circuit b Delay circuit c Load d Comparator e Current detection reference voltage generation circuit f AND gate g Current detection signal V cc Power supply voltage V 1 stable Power supply voltage IN control input terminal V out output voltage V oc current detection reference voltage VA current detection signal
Claims (2)
を介して電源の他方に接続される出力用トランジスタの
電流が所定値以上であることを検出する回路であって、 前記電源の一方に対して安定化した電圧を有する安定化
電源と、 一端が前記電源の一方に接続され他端が抵抗を介して前
記安定化電源に接続される前記出力用トランジスタに特
性相似な電流検出用トランジスタとを有し、 前記出力用トランジスタの制御端子に前記電流検出用ト
ランジスタの制御端子を接続し、 コンパレータの第１入力端子を前記出力用トランジスタ
の他端に接続し、第２の入力端子を前記電流検出用トラ
ンジスタの他端に接続したことを特徴とする電流検出回
路。1. A circuit for detecting that a current of an output transistor, one end of which is connected to one side of a power source and the other end of which is connected to the other side of the power source through a load, is a predetermined value or more, A regulated power supply having a regulated voltage for one side, and a current detection characteristic of the output transistor whose one end is connected to one side of the power source and whose other end is connected to the stabilized power source through a resistor And a control transistor of the current detection transistor is connected to the control terminal of the output transistor, a first input terminal of the comparator is connected to the other end of the output transistor, and a second input terminal Is connected to the other end of the current detection transistor.
トランジスタが同一半導体チップに形成されたことを特
徴とする請求項１に記載の電流検出回路。2. The current detection circuit according to claim 1, wherein the output transistor and the current detection transistor are formed on the same semiconductor chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25603392A JPH06113441A (en) | 1992-09-25 | 1992-09-25 | Current detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25603392A JPH06113441A (en) | 1992-09-25 | 1992-09-25 | Current detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06113441A true JPH06113441A (en) | 1994-04-22 |
Family
ID=17286989
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25603392A Pending JPH06113441A (en) | 1992-09-25 | 1992-09-25 | Current detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06113441A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0819164A (en) * | 1994-06-29 | 1996-01-19 | Mitsubishi Electric Corp | Semi-conductor device |
| KR100423103B1 (en) * | 2000-07-24 | 2004-03-16 | 야자키 소교 가부시키가이샤 | Semiconductor switching device with function for vibrating current, thereby shutting down over-current |
-
1992
- 1992-09-25 JP JP25603392A patent/JPH06113441A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0819164A (en) * | 1994-06-29 | 1996-01-19 | Mitsubishi Electric Corp | Semi-conductor device |
| KR100423103B1 (en) * | 2000-07-24 | 2004-03-16 | 야자키 소교 가부시키가이샤 | Semiconductor switching device with function for vibrating current, thereby shutting down over-current |
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