JPH02281308A - Dropper type constant voltage circuit - Google Patents
Dropper type constant voltage circuitInfo
- Publication number
- JPH02281308A JPH02281308A JP10412289A JP10412289A JPH02281308A JP H02281308 A JPH02281308 A JP H02281308A JP 10412289 A JP10412289 A JP 10412289A JP 10412289 A JP10412289 A JP 10412289A JP H02281308 A JPH02281308 A JP H02281308A
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- base
- output
- transistor
- dividing
- 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.)
- Granted
Links
- 238000010586 diagram Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
Landscapes
- Continuous-Control Power Sources That Use Transistors (AREA)
Abstract
Description
【発明の詳細な説明】
（発明の技術分野）
本発明は半導体集積回路等に適用されるドロッパ型定電
圧回路に係り、特に過電流保護に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a dropper type constant voltage circuit applied to semiconductor integrated circuits and the like, and particularly relates to overcurrent protection.
（従来技術とその問題点）
第１図、第２図は従来回路図及びその出力特性図で図中
Ｑ１はドロッパ用主トランジスタ％Ｑ２は制御用トラン
ジスタ、Ｑ、は補助トランジスタ、Ｒ５は抵抗、Ｒ１、
Ｒ３は出力電圧検出用抵抗、ＡＭＰは差動増巾器である
。この回路動作は出力電圧ｖ０が上昇すると増巾器ＡＭ
Ｐの出力が低下しトランジスタＱ、を介して主トランジ
スタＱ、のベース電流を制限することにより出力電圧Ｖ
。を−定値に保つ、又、出力電流Ｉ。が増加すると主ト
ランジスタＱ１のベース電流が増加し、その電流が制御
用トランジスタＱ２を介して抵抗Ｒ１を流れるので、抵
抗Ｒ１で発生する電圧が増加する。(Prior art and its problems) Figures 1 and 2 are conventional circuit diagrams and their output characteristic diagrams. In the figures, Q1 is the main transistor for the dropper. R1,
R3 is an output voltage detection resistor, and AMP is a differential amplifier. This circuit operation is such that when the output voltage v0 increases, the amplifier AM
By limiting the base current of the main transistor Q, through the transistor Q, the output voltage of P decreases, and the output voltage V
. - Keep the output current I at a constant value. When the current increases, the base current of the main transistor Q1 increases, and this current flows through the resistor R1 via the control transistor Q2, so that the voltage generated at the resistor R1 increases.
しかし、その電圧が補助トランジスタＱ、のベス電圧（
約０．７Ｖ）に達すると、トランジスタＱ３をオンさせ
、トランジスタＱ２のベース電流を吸い込むことによっ
てトランジスタＱ２をオフさせる方向に働き、その結果
として電流は第２図の如く制限され、垂下特性を示すが
、主トランジスタ−Ｑ１には過電流が流れ続け、好まし
くない状態となる。又、この特性を改善するには複雑な
制御回路を必要としていた。However, that voltage is the base voltage of the auxiliary transistor Q (
When the voltage reaches approximately 0.7 V), it turns on transistor Q3 and sucks the base current of transistor Q2, thereby turning off transistor Q2. As a result, the current is limited as shown in Figure 2, and exhibits a drooping characteristic. However, overcurrent continues to flow through the main transistor Q1, resulting in an unfavorable state. Moreover, to improve this characteristic, a complicated control circuit was required.
（発明の目的）
本発明は垂下運転時の過電流を防止した電源回路の提供
を目的とするものである。(Objective of the Invention) An object of the present invention is to provide a power supply circuit that prevents overcurrent during drooping operation.
（発明の構成と作用）
本発明は、入力電源の一端に接続された主トランジスタ
と、前記主トランジスタのベースと前記入力電源の他端
に接続された制御用トランジスタ及び抵抗の直列回路と
、出力電圧と基準電圧を比較して、前記制御用トランジ
スタを制御する増巾器を備えたドロッパ盟定電圧回路に
おいて、出力電圧を検出する分圧抵抗と、前記制御用ト
ランジスタのベースとアー°ス間にエミッタ、コレクタ
が接続され、ベースが前記分圧抵抗の分割点に接続され
た補助トランジスタと、前記分割点に給電する補助電源
と、前記分割点とアース間に接続された定電圧素子を備
えたことを特徴とする。(Structure and operation of the invention) The present invention comprises a main transistor connected to one end of the input power source, a series circuit of a control transistor and a resistor connected to the base of the main transistor and the other end of the input power source, and an output power source. In a dropper constant voltage circuit equipped with an amplifier that controls the control transistor by comparing a voltage with a reference voltage, a voltage dividing resistor that detects the output voltage and a voltage between the base of the control transistor and ground. an auxiliary transistor having an emitter and a collector connected to the voltage dividing resistor, and a base connected to the dividing point of the voltage dividing resistor; an auxiliary power supply supplying power to the dividing point; and a constant voltage element connected between the dividing point and ground. It is characterized by:
第３図は本発明の一実施例回路図、−第４図はその動作
説明図で、従来例と同一符号は同等部分を示す、第３図
において、Ａは本発明の要部回路を構成する過電流保護
回路、Ｂは従来回路に相当する主回路、Ｃは補助電源で
ある。保護回路ＡにおいてＱ、は入力電源のアース端と
制御用トランジスタＱ２のベース間にコレクタ・エミッ
タが接続されたＰＮＰ型トランジスタで、そのベースは
出力検出用分圧抵抗Ｒ１、Ｒ１の分割点Ｐに接続されて
いる。ＤＩは前記分割点Ｐとアース間に接続されたダイ
オード或はツェナーダイオード等の定電圧素子、次にＣ
は前記分割点Ｐに給電する補助電源でＶ ｒ ｅ ｆ
＊は電圧源、Ｒ１、Ｒａは任意の基準電圧を形成する抵
抗、Ｑ６は増巾用トランジスタである。以下図面により
動作を説明する。Fig. 3 is a circuit diagram of an embodiment of the present invention, - Fig. 4 is an explanatory diagram of its operation, and the same symbols as in the conventional example indicate equivalent parts. In Fig. 3, A constitutes the main circuit of the present invention. B is a main circuit corresponding to a conventional circuit, and C is an auxiliary power supply. In protection circuit A, Q is a PNP transistor whose collector-emitter is connected between the ground terminal of the input power supply and the base of the control transistor Q2, and its base is connected to the dividing point P between the output detection voltage dividing resistors R1 and R1. It is connected. DI is a constant voltage element such as a diode or Zener diode connected between the dividing point P and the ground, and then C
is the auxiliary power supply that supplies power to the dividing point P, and V r e f
* is a voltage source, R1 and Ra are resistors that form an arbitrary reference voltage, and Q6 is an amplification transistor. The operation will be explained below with reference to the drawings.
今、出力電流Ｉｏｕｔが増加すると、差動増巾器Ａ ｍ
ｐ 、が働きトランジスタＱ２のベース電圧は上昇す
るが、その電圧がＶ Ｆ （ＤＩ）＋ Ｖ ＲＭ（Ｑ４
）に達すると、トランジスタＱ！のベースは、その電圧
でクランプされるので、抵抗Ｒ１を流れる電流Ｉ□は、
（１）式で示される。Now, when the output current Iout increases, the differential amplifier A m
p acts and the base voltage of transistor Q2 rises, but this voltage becomes V F (DI) + V RM (Q4
), the transistor Q! Since the base of is clamped at that voltage, the current I□ flowing through resistor R1 is
It is shown by equation (1).
ｆｌｉｔ、、Ｖａｇ（Ｑｚ）、Ｙｅｌｌ（Ｑ４）は、ト
ランジスタＱ！、
Ｑ、のベース・エミッタ間電圧、Ｖｐ（ＤＩ）はダイオ
ード−Ｄｌの正方向電圧である。flit, , Vag (Qz), and Yell (Q4) are transistors Q! , Q, the base-emitter voltage Vp(DI) is the positive direction voltage of the diode -Dl.
一方出力′電流１０．．は（２）式で示される。On the other hand, the output 'current 10. ．． is shown by equation (2).
にｌ
従って出力電流Ｉ ｍｍ＆は第４図の（Ｂ）部に示す如
く、出力の電圧電流特性は垂下領域に入り、出力電圧は
低下する０次に、更に負荷抵抗が小さくなり、出力電圧
が下がり、Ｐ点の電位がＶ Ｆ（ＤＩ）Ｒ＋
される。Therefore, as shown in part (B) of Fig. 4, the output current Imm& is as shown in part (B) of Fig. 4. The potential at point P is V F(DI)R+ .
従って、出力電流■６．、は第４図（Ｃ）部に示す如く
、出力電圧電流特性はフの字領域に入る。Therefore, the output current ■6. As shown in part (C) of FIG. 4, the output voltage and current characteristics fall into the fold-back region.
更に出力電圧が下り、Ｐ点の電位が（５）式に示す値に
なると
Ｒ＋％
その電圧にクランプされる。従って出力電流１．、。When the output voltage further decreases and the potential at point P reaches the value shown in equation (5), it is clamped to that voltage. Therefore, the output current is 1. ,.
は
Ｒ，％
Ｒ＋
となり第４図（ｄ）に示すようにクランプされる、この
ため主トランジスタＱ、の過電流が制限されるため、主
トランジスタＱ１を過電流から保護できる。なお、第４
図において、（Ａ）は定電圧領域、（Ｂ）は定電流垂下
領域、（Ｃ）はフの字領域、（Ｄ）は出力電流クランプ
領域、Ｉａは垂下領域での電流値、Ｖａは垂下領域から
フの字領域へ変る時の出力電圧、■、は残留電流値であ
る。becomes R,% R+ and is clamped as shown in FIG. 4(d). Therefore, the overcurrent of the main transistor Q is limited, and the main transistor Q1 can be protected from overcurrent. In addition, the fourth
In the figure, (A) is the constant voltage region, (B) is the constant current droop region, (C) is the foldback region, (D) is the output current clamp region, Ia is the current value in the droop region, and Va is the droop. The output voltage when changing from the fold-back area to the fold-back area, ■ is the residual current value.
以上の如く本発明回路によれば簡単な回路で、特性の良
い過電流保護回路を提供出来るもので、その効果は大き
い。As described above, according to the circuit of the present invention, an overcurrent protection circuit with good characteristics can be provided with a simple circuit, and its effects are significant.
第１図、第２図は従来回路図、及びその出力特性図、第
３図は本実回路の１実施例、第４図はその特性図である
。
Ｅｉ・・・電源、Ｑ、・・・主トランジスタ−Ｑ２・・
・制御用トランジスター、Ｑｓ・Ｑ４・Ｑ５・・・補助
トランジスター％Ｒ１〜Ｒ７・・・抵抗、Ａ、、１ ・
・・差動増巾器、Ｖ Ｐ ＩＩ ｒ ｒ、Ｖ、。
、２・・・基準電圧電源、Ｄｌ・・・定電圧素子Ａ・・
・過電流保護回路部、Ｂ・・・主回路部Ｃ・・・補助電
源である。1 and 2 are conventional circuit diagrams and their output characteristic diagrams, FIG. 3 is an embodiment of the present actual circuit, and FIG. 4 is its characteristic diagram. Ei...power supply, Q,...main transistor -Q2...
・Control transistor, Qs・Q4・Q5...Auxiliary transistor %R1~R7...Resistance, A,,1 ・
...Differential amplifier, V P II r r, V,. , 2... Reference voltage power supply, Dl... Constant voltage element A...
- Overcurrent protection circuit section, B...Main circuit section C...Auxiliary power supply.
Claims (1)
トランジスタのベースと前記入力電源の他端に接続され
た制御用トランジスタ及び抵抗の直列回路と、出力電圧
と基準電圧を比較して、前記制御用トランジスタを制御
する増巾器を備えたドロッパ型定電圧回路において、出
力電圧を検出する分圧抵抗と、前記制御用トランジスタ
のベースとアース間にエミッタ、コレクタが接続され、
ベースが前記分圧抵抗の分割点に接続された補助トラン
ジスタと、前記分割点に給電する補助電源と、前記分割
点とアース間に接続された定電圧素子を備えたことを特
徴とするドロッパ型定電圧回路。A main transistor connected to one end of the input power supply, a series circuit of a control transistor and a resistor connected to the base of the main transistor and the other end of the input power supply, compare the output voltage with a reference voltage, and perform the control. In a dropper type constant voltage circuit equipped with an amplifier for controlling a control transistor, an emitter and a collector are connected between a voltage dividing resistor for detecting an output voltage and a base and ground of the control transistor,
A dropper type characterized in that it includes an auxiliary transistor whose base is connected to the dividing point of the voltage dividing resistor, an auxiliary power source that supplies power to the dividing point, and a constant voltage element connected between the dividing point and ground. Constant voltage circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10412289A JP2802937B2 (en) | 1989-04-24 | 1989-04-24 | Dropper type constant voltage circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10412289A JP2802937B2 (en) | 1989-04-24 | 1989-04-24 | Dropper type constant voltage circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02281308A true JPH02281308A (en) | 1990-11-19 |
| JP2802937B2 JP2802937B2 (en) | 1998-09-24 |
Family
ID=14372321
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10412289A Expired - Fee Related JP2802937B2 (en) | 1989-04-24 | 1989-04-24 | Dropper type constant voltage circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2802937B2 (en) |
-
1989
- 1989-04-24 JP JP10412289A patent/JP2802937B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2802937B2 (en) | 1998-09-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |