JPS61117613A - Constant voltage power supply circuit with current limit - Google Patents
Constant voltage power supply circuit with current limitInfo
- Publication number
- JPS61117613A JPS61117613A JP23889484A JP23889484A JPS61117613A JP S61117613 A JPS61117613 A JP S61117613A JP 23889484 A JP23889484 A JP 23889484A JP 23889484 A JP23889484 A JP 23889484A JP S61117613 A JPS61117613 A JP S61117613A
- Authority
- JP
- Japan
- Prior art keywords
- current
- transistor
- main
- main control
- output
- 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
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
- G05F1/569—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection
- G05F1/573—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection with overcurrent detector
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Automation & Control Theory (AREA)
- Continuous-Control Power Sources That Use Transistors (AREA)
Abstract
Description
本発明は、出力電圧を基準電圧と比較してトランジスタ
のベース電流を塙整することにより出力電圧を定電圧と
し、かつ出力電流の過電流の制限機能を有する電流制限
付定電圧電源回路に間する。The present invention provides a constant voltage power supply circuit with a current limit that makes the output voltage a constant voltage by adjusting the base current of the transistor by comparing the output voltage with a reference voltage, and has a function of limiting overcurrent of the output current. do.
電流制限付定電圧回路としては従来第２図に示す方式の
ものが知られている。この回路は、入力端子１と出力端
子の間にコレクタ、エミッタによって接続された主トラ
ンジスタ３のベース電流を、出力電圧検出抵抗４６５に
よって分圧された電圧と基準電圧６とを比較する誤差増
幅ｎ７の出力により出力端子の電圧が高いときには小さ
くし、逆の場合は大きくすることによって一定の出力電
圧を得るものである。この回路Ｊ、：おいて出力電流と
して過電流が流れるのを制限するために、主トランジス
タ３に直列に電流検出抵抗８を接続し、出力電流、すな
わちトランジスタ３のエミッタ電流が増加して抵抗８の
電圧降下が副トランジスタ９の導通に必要なＶＯに達す
ると、トランジスタ９がＲ１１ＩＩシて主トランジスタ
３のベース電流を制限し、その結果主トランジスタ３の
エミッタ電流が制限されイ、シかしこの方式においては
主電流が抵抗８を通過するため、抵抗８の消費電力が大
きく、また電流制限値がＩＡを超える場合には抵抗８の
抵抗値が１Ω以下となって大形になる。従ってこの回路
をＩＣ化する場合、チップサイズの増大、抵抗精度等に
問題が生ずる。As a current limiting constant voltage circuit, one of the type shown in FIG. 2 is conventionally known. This circuit has an error amplification n7 that compares the base current of the main transistor 3 connected between the input terminal 1 and the output terminal by the collector and emitter with the voltage divided by the output voltage detection resistor 465 and the reference voltage 6. A constant output voltage is obtained by decreasing the output voltage when the voltage at the output terminal is high, and increasing it in the opposite case. In order to limit the flow of overcurrent as an output current in this circuit J, a current detection resistor 8 is connected in series with the main transistor 3, so that the output current, that is, the emitter current of the transistor 3 increases, and When the voltage drop reaches VO, which is necessary for the conduction of the secondary transistor 9, the transistor 9 limits the base current of the main transistor 3 through R11II, and as a result, the emitter current of the main transistor 3 is limited. Since the main current passes through the resistor 8, the power consumption of the resistor 8 is large, and if the current limit value exceeds IA, the resistance value of the resistor 8 becomes 1Ω or less, resulting in a large size. Therefore, when this circuit is integrated into an IC, problems arise such as increase in chip size and resistance accuracy.
本発明は、この問題点を解決するため主制限トランジス
タの直列に電流検出抵抗を接続することなく主制御トラ
ンジスタの過電流を制限することのできる電流１ｌｌＩ
ＩＩｌ付定電圧電源回路を提供することを目的とする。In order to solve this problem, the present invention provides a current 1llI which can limit the overcurrent of the main control transistor without connecting a current detection resistor in series with the main limiting transistor.
The purpose of the present invention is to provide a constant voltage power supply circuit with IIl.
本発明によれば、定電圧電源回路の主制御トランジスタ
とカレントミラー回路を構成するトランジスタによって
出力電流に比例した小電流を発生する回路とその小電流
の値の増大に対応して主制御トランジスタのベース電流
を制限する回路とを備えることによって上記の目的が達
成されろ。According to the present invention, a circuit generates a small current proportional to an output current by a main control transistor of a constant voltage power supply circuit and a transistor constituting a current mirror circuit, and a main control transistor is The above object is achieved by providing a base current limiting circuit.
第１図は本発明の一実施例を示し、第２図お場合と同様
入力端子ｌに非安定電圧が入力された場合、主制御トラ
ンジスタ３のベース電流が出力端子２の電位に対応して
誤差増幅器７によって調整されて、出力端子２より安定
化された電圧が出力される。第２図と興なり電流検出抵
抗８は接続されず、主トランジスタ３とエミッタ５ベー
スがそれぞれ同電位となるように接続された電流検出用
トランジスタ１１はカレントミラー回路を構成する。
ここで、トランジスタ１１のエミッタ面積をトランジス
タ３のエミッタ面積の１ノー（ｍａ１）にすると、他の
トランジスタの特性が同一の場合、トランジスタ１１の
エミッタ電流は主トランジスタ３のエミッタ電流の１７
＠となる。またトランジスタ１１と入力端子ｌの間に接
続されるトランジスタ１２が同一の特性のトランジスタ
１３とカレントミラー回路を構成しており、トランジス
タ１３のコレクタ電流は主トランジスタ３の出力電流の
ｌ／閤となる。従って出力電流が増加するにつれてトラ
ンジスタ１３のコレクタ電流もそれに比例して増加する
。そしてトランジスタ１３のコレクタと大地間に挿入さ
れた抵抗１４の電位降下分が、誤差増幅器７の出力側に
接続された電流制限トランジスタ１５を轟通させるＶａ
ｔに達すると、トランジスタ１５により主トランジスタ
３のベース電流を制限し、その結果主電流が制限される
。このように、主電流の制限がその１ノーの小さな１！
流を検知することによって行われるので、従来のような
大消費電力、小抵抗の電流検出用抵抗が必要でなくなり
、特にＩＣ化を行う場合に大きな利点を提供するもので
ある。
カレントミラー回路によって生ずる主電流に比例した小
電流を検知して主制御トランジスタのベース電流を調整
する回路は上の実施例に限定されろことはなく、電流制
限トランジスタを用いないで例えば演算増幅器を用いて
もよい。FIG. 1 shows an embodiment of the present invention, in which when an unstable voltage is input to the input terminal l as in the case of FIG. 2, the base current of the main control transistor 3 corresponds to the potential of the output terminal 2. A stabilized voltage is output from the output terminal 2 after being adjusted by the error amplifier 7 . As shown in FIG. 2, the current detection resistor 8 is not connected, and the current detection transistor 11, in which the main transistor 3 and the base of the emitter 5 are connected so that they are at the same potential, constitutes a current mirror circuit. Here, if the emitter area of the transistor 11 is set to 1 (ma1) of the emitter area of the transistor 3, the emitter current of the transistor 11 will be 17 times the emitter current of the main transistor 3 when the characteristics of the other transistors are the same.
Becomes @. Further, the transistor 12 connected between the transistor 11 and the input terminal 1 constitutes a current mirror circuit with the transistor 13 having the same characteristics, and the collector current of the transistor 13 becomes 1/min of the output current of the main transistor 3. . Therefore, as the output current increases, the collector current of transistor 13 also increases proportionally. Then, the potential drop of the resistor 14 inserted between the collector of the transistor 13 and the ground causes the current limiting transistor 15 connected to the output side of the error amplifier 7 to conduct Va.
When t is reached, the base current of the main transistor 3 is limited by the transistor 15, so that the main current is limited. In this way, the main current limit is that 1 no small 1!
Since this is carried out by detecting the current, there is no need for a current detection resistor with large power consumption and small resistance as in the past, which provides a great advantage especially when integrated circuits are implemented. The circuit that adjusts the base current of the main control transistor by detecting a small current proportional to the main current generated by the current mirror circuit is not limited to the above embodiment, and can be implemented by using, for example, an operational amplifier without using a current limiting transistor. May be used.
本発明は、定電圧電源回路の主制御トランジスタ電流に
比例した小さい電流をカレントミラー回路を用いて発生
させ、その電流を検知して主電流の制限を行うようにし
たもので、従来のような主トランジスタに直列接続の大
消費電力、小砥坑値の電流検出用抵抗が不必要になり、
特に回路のＩＣ化に際して大きな効果が得られる。The present invention uses a current mirror circuit to generate a small current proportional to the main control transistor current of a constant voltage power supply circuit, and detects this current to limit the main current. Eliminates the need for a current detection resistor with high power consumption and a small grindstone value connected in series with the main transistor.
Particularly, great effects can be obtained when converting a circuit into an IC.
１！Ｓ１図は本発明の一実施例の回路図、第２図は従来
例の回路図である。
ｌ二人力端子、２：出力端子、３：主制御トランジスタ
、４．５：電圧検出抵抗、６；基準電圧、？ｌｔ差増幅
器、１ｉｉｔ流検出トランジスタ、１５：電流制限トラ
ンジスタ。1! FIG. S1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional example. l Two-power terminal, 2: Output terminal, 3: Main control transistor, 4.5: Voltage detection resistor, 6: Reference voltage, ? lt difference amplifier, 1iit current detection transistor, 15: current limit transistor.
Claims (1)
のベース電流を調整することにより出力電圧を定電圧と
するものにおいて、主制御トランジスタとカレントミラ
ー回路を構成するトランジスタによって出力電流に比例
した小電流を発生する回路と該小電流の値の増大に対応
して主制御トランジスタのベース電流を制限する回路を
備えたことを特徴とする電流制限付定電圧電源回路。1) In a device that makes the output voltage constant by comparing the output voltage with a reference voltage and adjusting the base current of the main control transistor, a small 1. A constant voltage power supply circuit with current limitation, comprising a circuit that generates a current and a circuit that limits the base current of a main control transistor in response to an increase in the value of the small current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23889484A JPS61117613A (en) | 1984-11-13 | 1984-11-13 | Constant voltage power supply circuit with current limit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23889484A JPS61117613A (en) | 1984-11-13 | 1984-11-13 | Constant voltage power supply circuit with current limit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61117613A true JPS61117613A (en) | 1986-06-05 |
Family
ID=17036847
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23889484A Pending JPS61117613A (en) | 1984-11-13 | 1984-11-13 | Constant voltage power supply circuit with current limit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61117613A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5045942A (en) * | 1987-11-18 | 1991-09-03 | Nec Corporation | Digital video communication system having a network clock source |
| EP0476440A2 (en) * | 1990-09-18 | 1992-03-25 | National Semiconductor Corporation | Transient protected isolator output stage |
| US5355078A (en) * | 1992-07-31 | 1994-10-11 | Sharp Kabushiki Kaisha | Semiconductor integrated circuit for a stabilized power supply circuit |
-
1984
- 1984-11-13 JP JP23889484A patent/JPS61117613A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5045942A (en) * | 1987-11-18 | 1991-09-03 | Nec Corporation | Digital video communication system having a network clock source |
| EP0476440A2 (en) * | 1990-09-18 | 1992-03-25 | National Semiconductor Corporation | Transient protected isolator output stage |
| US5355078A (en) * | 1992-07-31 | 1994-10-11 | Sharp Kabushiki Kaisha | Semiconductor integrated circuit for a stabilized power supply circuit |
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