JPH06213941A - External power supply voltage detection circuit - Google Patents
External power supply voltage detection circuitInfo
- Publication number
- JPH06213941A JPH06213941A JP474693A JP474693A JPH06213941A JP H06213941 A JPH06213941 A JP H06213941A JP 474693 A JP474693 A JP 474693A JP 474693 A JP474693 A JP 474693A JP H06213941 A JPH06213941 A JP H06213941A
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- power supply
- external power
- circuit
- supply voltage
- 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.)
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- Electronic Switches (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
(57)【要約】
【目的】 抵抗分割比の変化に対しても安定して動作す
る外部電源電圧検知回路を提供する。
【構成】 コンパレータ１５は、定電圧生成回路１１に
よって生成される外部電源電圧より所定電圧分だけ低い
電圧ａが殆ど一定の電圧ｂより大きい場合にスイッチン
グ素子１４をオンにする電圧ｇを出力する。抵抗１６
は、スイッチング素子１４がオンになると外部電源電圧
を所定の比で分割して外部電源電圧に比例した電圧ｄを
出力する。コンパレータ１７はダイオード１３の順方向
電圧ｅと電圧ｄとを比較して、外部電源電圧が低下して
所定電圧に至って電圧ｄが電圧ｅより低くなると“０"
になる電圧ｆを出力する。こうして、電圧ｅが安定して
いる領域において電圧ｄが電圧ｅに等しくなるようにし
て、抵抗１６の分割比が変化してもコンパレータ１７は
安定して動作するようにする。
(57) [Abstract] [Purpose] To provide an external power supply voltage detection circuit that operates stably even when the resistance division ratio changes. The comparator 15 outputs a voltage g for turning on the switching element 14 when a voltage a lower by a predetermined voltage than the external power supply voltage generated by the constant voltage generation circuit 11 is larger than a substantially constant voltage b. Resistance 16
When the switching element 14 is turned on, the external power supply voltage is divided at a predetermined ratio and a voltage d proportional to the external power supply voltage is output. The comparator 17 compares the forward voltage e of the diode 13 with the voltage d, and when the external power supply voltage decreases to a predetermined voltage and the voltage d becomes lower than the voltage e, “0”.
The voltage f becomes In this way, the voltage d is made equal to the voltage e in the region where the voltage e is stable, so that the comparator 17 operates stably even if the division ratio of the resistor 16 changes.
Description
【０００１】[0001]
【産業上の利用分野】この発明は、外部電源電圧が所定
電圧に至ったことを検知する外部電源電圧検知回路に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external power supply voltage detection circuit for detecting that an external power supply voltage has reached a predetermined voltage.
【０００２】[0002]
【従来の技術】集積度の向上に伴って高機能化が急速に
進んでいる集積回路装置では、外部電源電圧の変化を検
出する必要が多々ある。例えば、揮発性半導体記憶装置
を使用して電池でその記憶内容を保持するようなシステ
ムの場合には、その電池の電圧が低下すると記憶内容が
壊れる可能性がある。そこで、電池の電圧が所定値まで
低下した場合に揮発性半導体記憶装置を非動作状態にす
るために、電池の電圧が上記所定値まで低下したことを
検知するための外部電源電圧検知回路が必要となる。2. Description of the Related Art In an integrated circuit device, which has been rapidly improved in function with the increase in the degree of integration, it is often necessary to detect a change in an external power supply voltage. For example, in the case of a system in which a volatile semiconductor memory device is used to hold the stored contents in a battery, the stored contents may be destroyed when the voltage of the battery drops. Therefore, an external power supply voltage detection circuit is required to detect that the voltage of the battery has dropped to the above specified value in order to put the volatile semiconductor memory device into the inoperative state when the voltage of the battery has dropped to the specified value. Becomes
【０００３】従来から使用されている外部電源電圧検知
回路の一例を図５に示す。この外部電源電圧検知回路の
回路構成は、定電圧生成回路１と、この定電圧生成回路
１に制御される定電流源２と、定電流源２からの電流を
受けるダイオード３と、このダイオード３の順方向電圧
ｅと抵抗４で分割して得られた電圧ｄとを比較するコン
パレータ５とからなる。FIG. 5 shows an example of an external power supply voltage detection circuit which has been conventionally used. The circuit configuration of the external power supply voltage detection circuit is as follows: a constant voltage generation circuit 1, a constant current source 2 controlled by the constant voltage generation circuit 1, a diode 3 that receives a current from the constant current source 2, and the diode 3 Of the forward voltage e and the voltage d obtained by dividing the voltage with the resistor 4 are compared with each other.
【０００４】図６に示すように、上記ダイオード３の順
方向電圧ｅは外部電源電圧ＶＣＣが十分高い領域では外
部電源電圧ＶＣＣに関係なく一定値を呈するのに対し
て、電圧ｄは外部電源電圧ＶＣＣに比例する。ここで、
図６において、上記電圧ｄの直線と電圧ｅの曲線とが所
定電圧“ＶＣＣ0"で交差するように抵抗４の分割比を設
定する。そうすると、電圧ｄが電圧ｅを越えると、コン
パレータ５の出力電圧ｆが外部電源電圧ＶＣＣと同じ電
圧を呈するようになる。したがって、コンパレータ５の
出力電圧ｆが“０"になるのを監視することによって、
外部電源電圧ＶＣＣが上記電圧“ＶＣＣ0"に至ったこと
を検知できるのである。As shown in FIG. 6, the forward voltage e of the diode 3 has a constant value in a region where the external power supply voltage VCC is sufficiently high regardless of the external power supply voltage VCC, whereas the voltage d is the external power supply voltage. Proportional to VCC. here,
In FIG. 6, the division ratio of the resistor 4 is set so that the straight line of the voltage d and the curve of the voltage e intersect at a predetermined voltage "VCC 0 ". Then, when the voltage d exceeds the voltage e, the output voltage f of the comparator 5 becomes the same voltage as the external power supply voltage VCC. Therefore, by monitoring that the output voltage f of the comparator 5 becomes "0",
It is possible to detect that the external power supply voltage VCC has reached the voltage "VCC 0 ".
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、上記従
来の外部電源電圧検知回路においては次ぎのような問題
がある。すなわち、検知すべき電圧(上記電圧ｄの直線
と電圧ｅの曲線とが交差する上記所定電圧“ＶＣＣ0")
が低い場合(この場合の電圧をｄ1とする)には、抵抗４
の分割比に誤差が生ずると上記電圧ｄ1の直線と電圧ｅ
の曲線とが交差しない場合が生じ、その場合には電圧検
知回路が誤動作するという問題がある。However, the conventional external power supply voltage detection circuit described above has the following problems. That is, the voltage to be detected (the predetermined voltage "VCC 0 " where the straight line of the voltage d and the curve of the voltage e intersect).
Is low (the voltage in this case is d1), the resistance 4
If an error occurs in the division ratio of, the straight line of the voltage d1 and the voltage e
In some cases, the curve does not intersect with the curve, and in that case, the voltage detection circuit malfunctions.
【０００６】この問題は、上記外部電源電圧ＶＣＣが
“０"の範囲から電圧ｄが外部電源電圧ＶＣＣに比例す
ることに原因がある。This problem is caused by the fact that the voltage d is proportional to the external power supply voltage VCC from the range of the external power supply voltage VCC "0".
【０００７】そこで、この発明の目的は、抵抗分割比の
変化に対しても安定して動作する外部電源電圧検知回路
を提供することにある。Therefore, an object of the present invention is to provide an external power supply voltage detection circuit which operates stably even when the resistance division ratio changes.
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するた
め、第１の発明は、基準電圧生成回路によって外部電源
電圧に基づいて生成された基準電圧と比例電圧生成回路
によって生成された外部電源電圧に比例する比例電圧と
を比較する電圧比較回路を有して、上記電圧比較回路の
比較結果に基づいて外部電源電圧が所定電圧に至ったこ
とを検知する外部電源電圧検知回路において、上記比例
電圧生成回路の状態を動作状態と非動作状態とに切り換
えるスイッチング回路と、外部電源電圧が所定電圧より
高くなると上記スイッチング回路を駆動して上記比例電
圧生成回路の状態を動作状態側に切り換えるスイッチン
グ回路駆動手段を備えたことを特徴としている。In order to achieve the above object, a first invention is a reference voltage generated by a reference voltage generation circuit based on an external power supply voltage and an external power supply voltage generated by a proportional voltage generation circuit. In the external power supply voltage detection circuit for detecting that the external power supply voltage has reached a predetermined voltage based on the comparison result of the voltage comparison circuit, the proportional voltage A switching circuit that switches the state of the generating circuit between an operating state and a non-operating state, and a switching circuit drive that drives the switching circuit when the external power supply voltage becomes higher than a predetermined voltage to switch the state of the proportional voltage generating circuit to the operating state side. It is characterized by having means.
【０００９】また、第２の発明は、第１の発明の外部電
源電圧検知回路において、外部電源電圧より所定電圧分
だけ低い第１の電圧と所定値を有する第２の電圧を生成
する定電圧生成手段を備えると共に、上記スイッチング
回路駆動手段は、上記定電圧生成回路によって生成され
る上記第１の電圧と第２の電圧とを比較して記第１の電
圧が第２の電圧より高い場合に上記スイッチング回路を
駆動して上記比例電圧生成回路の状態を動作状態側に切
り換える信号を出力するコンパレータで構成されたこと
を特徴としている。According to a second aspect of the invention, in the external power supply voltage detection circuit of the first invention, a constant voltage for generating a first voltage lower than the external power supply voltage by a predetermined voltage and a second voltage having a predetermined value. When the switching circuit driving means is provided with a generating means and compares the first voltage and the second voltage generated by the constant voltage generating circuit, the first voltage is higher than the second voltage. And a comparator for outputting a signal for driving the switching circuit to switch the state of the proportional voltage generating circuit to the operating state side.
【００１０】また、第３の発明は、第２の発明の外部電
源電圧検知回路であって、上記定電圧生成手段は、上記
外部電源電圧より所定電圧分だけ低い第１の電圧を生成
する金属酸化膜半導体電界効果トランジスタ(ＭＯＳＦ
ＥＴ)を縦続接続した回路と、上記所定値を有する第２
の電圧を生成するセルフバイアス回路で構成されたこと
を特徴としている。A third aspect of the present invention is the external power supply voltage detection circuit according to the second aspect of the invention, wherein the constant voltage generating means generates a first voltage that is lower than the external power supply voltage by a predetermined voltage. Oxide film semiconductor field effect transistor (MOSF
ET) in cascade connection, and a second circuit having the above-mentioned predetermined value
It is characterized in that it is configured by a self-bias circuit that generates the voltage.
【００１１】また、第４の発明は、第１乃至第３の何れ
か一つの発明の外部電源電圧検知回路であって、上記基
準電圧生成回路はダイオードと定電流源で構成され、上
記比例電圧生成回路は外部電源電圧を比例配分する抵抗
で構成されたことを特徴としている。A fourth aspect of the present invention is the external power supply voltage detection circuit according to any one of the first to third aspects of the invention, wherein the reference voltage generation circuit comprises a diode and a constant current source, and the proportional voltage The generation circuit is characterized by being composed of resistors that proportionally distribute the external power supply voltage.
【００１２】[0012]
【作用】第１の発明では、外部電源電圧が所定電圧より
も高い場合には、スイッチング回路駆動手段によって駆
動されたスイッチング回路によって比例電圧生成回路の
状態が動作状態側に切り換えられる。その結果、上記比
例電圧生成回路から出力される外部電源電圧に比例する
比例電圧は外部電源電圧が上記所定電圧よりも高い場合
に生成されることになり、必然的に上記比例電圧は基準
電圧の安定した領域において上記基準電圧と同じ電圧と
なる。したがって、上記比例電圧生成回路によって設定
される上記比例電圧における比例定数が大きく変化して
も、電圧比較回路によって基準電圧と上記比例電圧とが
安定して比較される。According to the first aspect of the present invention, when the external power supply voltage is higher than the predetermined voltage, the switching circuit driven by the switching circuit driving means switches the state of the proportional voltage generating circuit to the operating state side. As a result, a proportional voltage proportional to the external power supply voltage output from the proportional voltage generation circuit is generated when the external power supply voltage is higher than the predetermined voltage, and the proportional voltage is necessarily the reference voltage. The voltage is the same as the reference voltage in the stable region. Therefore, even if the proportional constant in the proportional voltage set by the proportional voltage generation circuit changes significantly, the voltage comparison circuit stably compares the reference voltage with the proportional voltage.
【００１３】また、第２の発明では、定電圧生成手段に
よって、外部電源電圧より所定電圧分だけ低い第１の電
圧と所定値を有する第２の電圧が生成される。そうする
と、上記スイッチング回路駆動手段であるコンパレータ
によって、上記第１の電圧と第２の電圧とが比較されて
上記第１の電圧が第２の電圧よりも高い場合には上記ス
イッチング回路を駆動する信号が出力される。こうし
て、上記比例電圧生成回路から出力される外部電源電圧
に比例する比例電圧は外部電源電圧が上記所定電圧より
も十分高い場合に生成される。Further, in the second invention, the constant voltage generating means generates the first voltage lower than the external power supply voltage by the predetermined voltage and the second voltage having the predetermined value. Then, the comparator, which is the switching circuit driving means, compares the first voltage and the second voltage, and when the first voltage is higher than the second voltage, a signal for driving the switching circuit. Is output. Thus, the proportional voltage proportional to the external power supply voltage output from the proportional voltage generation circuit is generated when the external power supply voltage is sufficiently higher than the predetermined voltage.
【００１４】また、第３の発明では、上記定電圧生成手
段を構成するＭＯＳＦＥＴを縦続接続した回路によって
外部電源電圧より所定電圧分だけ低い上記第１の電圧が
生成される。さらに、上記定電圧生成手段を構成するセ
ルフバイアス回路によって上記所定値を有する第２の電
圧が生成される。こうして生成された上記第１の電圧と
第２の電圧とが上記コンパレータによって比較されて、
上記第１の電圧が第２の電圧よりも高い場合に上記スイ
ッチング回路を駆動する信号が出力される。In the third aspect of the invention, the first voltage lower than the external power supply voltage by a predetermined voltage is generated by the circuit in which the MOSFETs constituting the constant voltage generating means are connected in cascade. Further, the self-bias circuit that constitutes the constant voltage generating means generates the second voltage having the predetermined value. The first voltage and the second voltage thus generated are compared by the comparator,
A signal for driving the switching circuit is output when the first voltage is higher than the second voltage.
【００１５】また、第４の発明では、定電流源からダイ
オードへの順方向電圧が基準電圧として出力され、外部
電源電圧を比例配分する抵抗によって上記外部電源電圧
に比例する上記比例電圧が出力される。こうして生成さ
れた上記基準電圧と比例電圧とが上記電圧比較回路によ
って比較され、その比較結果に基づいて外部電源電圧が
所定電圧に至ったことが検知される。In the fourth invention, the forward voltage from the constant current source to the diode is output as the reference voltage, and the proportional voltage proportional to the external power supply voltage is output by the resistor for proportionally distributing the external power supply voltage. It The reference voltage thus generated and the proportional voltage are compared by the voltage comparison circuit, and it is detected that the external power supply voltage has reached the predetermined voltage based on the comparison result.
【００１６】[0016]
【実施例】以下、この発明を図示の実施例により詳細に
説明する。図１は本実施例の外部電源電圧検知回路を電
池の電圧検知回路に適用した場合における回路図であ
る。この電池電圧検知回路は、定電圧生成回路１１と、
この定電圧生成回路１１に制御される定電流源１２と、
この定電流源１２からの電流が入力されるダイオード１
３と、定電圧生成回路１１によって生成された電圧ａと
電圧ｂとを比較するコンパレータ１５と、このコンパレ
ータ１５からの出力電圧ｇが制御端子に入力されるスイ
ッチイング素子１４と、抵抗１６と、ダイオード１３の
順方向電圧ｅと抵抗１６の分割比で決まる電圧ｄとを比
較するコンパレータ１７から構成される。The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a circuit diagram when the external power supply voltage detection circuit of this embodiment is applied to a battery voltage detection circuit. This battery voltage detection circuit includes a constant voltage generation circuit 11,
A constant current source 12 controlled by the constant voltage generation circuit 11,
Diode 1 to which current from this constant current source 12 is input
3, a comparator 15 for comparing the voltage a and the voltage b generated by the constant voltage generation circuit 11, a switching element 14 to which the output voltage g from the comparator 15 is input to the control terminal, a resistor 16, and It is composed of a comparator 17 for comparing the forward voltage e of the diode 13 and the voltage d determined by the division ratio of the resistor 16.
【００１７】図２は、図１における定電圧生成回路１１
の具体例であり、セルフバイアス回路２１とＭＯＳＦＥ
Ｔを縦続接続した回路２２とで構成されている。図３
は、上記コンパレータ１７によってダイオード１３の順
方向電圧ｅと比較される外部電源電圧ＶＣＣに比例した
電圧ｄの生成系における各電圧ａ,電圧ｂ,電圧ｃ,電圧
ｄおよび電圧ｇと外部電源電圧ＶＣＣとの関係を示す図
である。また、図４は、コンパレータ１７によって電圧
ｅと電圧ｄとを比較する際における各電圧ｄ,電圧ｅお
よび電圧ｆと外部電源電圧ＶＣＣとの関係を示す図であ
る。FIG. 2 shows the constant voltage generating circuit 11 shown in FIG.
Of the self-bias circuit 21 and the MOSFE.
And a circuit 22 in which Ts are connected in cascade. Figure 3
Is the voltage a, the voltage b, the voltage c, the voltage d and the voltage g in the generation system of the voltage d proportional to the external power supply voltage VCC which is compared with the forward voltage e of the diode 13 by the comparator 17 and the external power supply voltage VCC. It is a figure which shows the relationship with. Further, FIG. 4 is a diagram showing a relationship between each voltage d, voltage e and voltage f, and external power supply voltage VCC when the comparator 17 compares the voltage e and the voltage d.
【００１８】以下、図１乃至図４に従って、上記構成の
電池電圧検知回路の動作について説明する。図３に示す
ように、上記セルフバイアス回路２１で生成される電圧
ｂは殆ど一定の電圧であり、ＭＯＳＦＥＴを縦続接続し
た回路２２で生成される電圧ａと電圧ｃは外部電源電圧
ＶＣＣより“Ｖth"分だけ低い電圧となる。したがっ
て、上記電圧ａおよび電圧ｃは外部電源電圧ＶＣＣが
“Ｖth"より低い範囲ではグランドレベルである。The operation of the battery voltage detection circuit having the above configuration will be described below with reference to FIGS. As shown in FIG. 3, the voltage b generated by the self-bias circuit 21 is almost constant, and the voltage a and the voltage c generated by the circuit 22 in which the MOSFETs are connected in cascade are "Vth" from the external power supply voltage VCC. "It will be a low voltage. Therefore, the voltage a and the voltage c are at the ground level in the range where the external power supply voltage VCC is lower than "Vth".
【００１９】上記電圧ａがクランドレベルである場合に
は電圧ａは電圧ｂより低いので、コンパレータ１５の出
力電圧ｇのレベルは“Ｈ"となってスイッチイング素子
１４は“オフ"となる。その結果、抵抗１６によって分
割される電圧ｄは“０"となるのである。When the voltage a is at the ground level, the voltage a is lower than the voltage b, so the level of the output voltage g of the comparator 15 is "H" and the switching element 14 is "off". As a result, the voltage d divided by the resistor 16 becomes "0".
【００２０】これに対して、上記電圧ａが電圧ｂより高
くなると、コンパレータ１５の出力電圧ｇのレベルは
“Ｌ"となってスイッチイング素子１４は“オン"とな
る。そして、上記電圧ｄは抵抗１６の分割比で決まる値
に設定されるのである。On the other hand, when the voltage a becomes higher than the voltage b, the level of the output voltage g of the comparator 15 becomes "L" and the switching element 14 becomes "on". The voltage d is set to a value determined by the division ratio of the resistor 16.
【００２１】その結果、図４に示すように、上記外部電
源電圧ＶＣＣに比例する電圧ｄはダイオード１３の順方
向電圧ｅの曲線部近傍から立ち上がることになり、電圧
ｅの曲線と電圧ｄの直線とは電圧ｅの安定領域で確実に
交差することになる。したがって、コンパレータ１７か
らの出力電圧ｆによって確実に外部電源電圧ＶＣＣの低
下を検知できるのである。As a result, as shown in FIG. 4, the voltage d proportional to the external power supply voltage VCC rises near the curve portion of the forward voltage e of the diode 13, and the curve of the voltage e and the straight line of the voltage d. And will definitely cross in the stable region of the voltage e. Therefore, the output voltage f from the comparator 17 can reliably detect the decrease in the external power supply voltage VCC.
【００２２】このように、本実施例では、上記定電圧生
成回路１１をセルフバイアス回路２１とＭＯＳＦＥＴを
縦続接続した回路２２とで構成する。そして、セルフバ
イアス回路２１からの大略一定の電圧ｂとＭＯＳＦＥＴ
を縦続接続した回路２２からの外部電源電圧ＶＣＣより
“Ｖth"分だけ低い電圧ａとをコンパレータ１５で比較
し、このコンパレータ１５からの出力電圧ｇによって抵
抗１６に接続されたスイッチング素子１４のオン/オフ
を制御するようにしている。こうすることによって、電
圧ａが電圧ｂより大きくなると電圧ｄが抵抗１６の分割
比で設定されるようになる。As described above, in this embodiment, the constant voltage generating circuit 11 is composed of the self-bias circuit 21 and the circuit 22 in which MOSFETs are connected in cascade. Then, the substantially constant voltage b from the self-bias circuit 21 and the MOSFET
The comparator 15 compares a voltage a lower by “Vth” than the external power supply voltage VCC from the circuit 22 connected in series with each other, and the output voltage g from the comparator 15 turns on / off the switching element 14 connected to the resistor 16. I'm trying to control the off. By doing so, when the voltage a becomes larger than the voltage b, the voltage d is set by the division ratio of the resistor 16.
【００２３】したがって、本実施例によれば、外部電源
電圧ＶＣＣが所定電圧を越えてから外部電源電圧ＶＣＣ
に比例する電圧ｄが設定されることになり、ダイオード
１３の順方向電圧ｅの曲線と電圧ｄの直線とが電圧ｅの
安定領域で確実に交差して電池電圧検知回路は安定して
動作する。Therefore, according to this embodiment, the external power supply voltage VCC exceeds the predetermined voltage before the external power supply voltage VCC is exceeded.
Since the voltage d proportional to the voltage d is set, the curve of the forward voltage e of the diode 13 and the straight line of the voltage d surely intersect in the stable region of the voltage e, and the battery voltage detection circuit operates stably. .
【００２４】その際に、上記スイッチング素子１４の電
流駆動能力は抵抗１６の分割に影響を与えないように大
きな値にしておく必要がある。また、上記定電圧生成回
路１１を構成するＭＯＳＦＥＴを縦続接続した回路２２
におけるＭＯＳＦＥＴを更にもう１個縦積みすると、電
圧ａや電圧ｃの値は外部電源電圧ＶＣＣから“２×Ｖt
h"分だけ下がった電圧値となる。したがって、電圧ａの
直線と電圧ｂの曲線とが交差する位置の電圧を高くする
ことが可能となり、その結果抵抗１６の分割比で決まる
電圧ｄをより高い外部電源電圧ＶＣＣで活性化できるよ
うになる。At this time, the current driving capability of the switching element 14 must be set to a large value so as not to affect the division of the resistor 16. Further, a circuit 22 in which MOSFETs forming the constant voltage generating circuit 11 are cascade-connected.
If one more MOSFET is vertically stacked, the values of the voltage a and the voltage c will be “2 × Vt” from the external power supply voltage VCC.
The voltage value decreases by h ". Therefore, it is possible to increase the voltage at the position where the straight line of the voltage a and the curve of the voltage b intersect, and as a result, the voltage d determined by the division ratio of the resistor 16 is increased. It can be activated by a high external power supply voltage VCC.
【００２５】本実施例における電池電圧検知回路は、２
個のコンパレータ１５,１７と１個のスイッチング素子
１４で形成でき、しかもいずれもＭＯＳＦＥＴで構成で
きるので面積の増加は僅かで済む。The battery voltage detection circuit in this embodiment has two
Since the comparators 15 and 17 and the switching element 14 can be formed, and both can be formed by MOSFETs, the area can be slightly increased.
【００２６】[0026]
【発明の効果】以上より明らかなように、第１の発明の
外部電源電圧検知回路は、外部電源電圧が所定電圧より
高くなると、スイッチング回路駆動手段によってスイッ
チング回路を駆動して、電圧比較回路で基準電圧と比較
される外部電源電圧に比例する比例電圧を生成する比例
電圧生成回路の状態を動作状態に切り換えるので、上記
比例電圧生成回路によって生成される上記比例電圧は外
部電源電圧が所定電圧よりも高い場合に生成されること
になる。したがって、必然的に上記電圧比較回路は上記
基準電圧が十分安定している領域で動作することにな
り、上記比例電圧における比例定数の変化に対しても安
定して動作できる。As is apparent from the above, in the external power supply voltage detection circuit of the first invention, when the external power supply voltage becomes higher than the predetermined voltage, the switching circuit driving means drives the switching circuit to cause the voltage comparison circuit to operate. Since the state of the proportional voltage generation circuit that generates a proportional voltage proportional to the external power supply voltage that is compared with the reference voltage is switched to the operating state, the proportional voltage generated by the proportional voltage generation circuit is the external power supply voltage higher than the predetermined voltage. Will also be generated if high. Therefore, the voltage comparison circuit inevitably operates in a region where the reference voltage is sufficiently stable, and can stably operate even when the proportional constant changes in the proportional voltage.
【００２７】また、第２の発明の外部電源電圧検知回路
は、上記スイッチング回路駆動手段を、定電圧生成回路
によって生成される外部電源電圧より所定電圧分だけ低
い第１の電圧と所定値を有する第２の電圧とを比較し
て、上記第１の電圧が第２の電圧より高い場合に上記ス
イッチング回路を駆動して上記比例電圧生成回路の状態
を動作状態側に切り換える信号を出力するコンパレータ
で構成したので、外部電源電圧検知回路を容易に形成で
きる。In the external power supply voltage detection circuit of the second invention, the switching circuit driving means has a first voltage and a predetermined value which are lower than the external power supply voltage generated by the constant voltage generation circuit by a predetermined voltage. A comparator that compares the second voltage and outputs a signal that drives the switching circuit to switch the state of the proportional voltage generation circuit to the operating state side when the first voltage is higher than the second voltage. Since it is configured, the external power supply voltage detection circuit can be easily formed.
【００２８】また、第３の発明の外部電源電圧検知回路
は、上記定電圧生成手段を、ＭＯＳＦＥＴを縦続接続し
てなる上記第１の電圧を生成する回路と上記第２の電圧
を生成するセルフバイアス回路とで構成したので、外部
電源電圧検知回路を更に容易に形成できる。Also, in the external power supply voltage detecting circuit of the third invention, the constant voltage generating means is a circuit for generating the first voltage, which is formed by cascading MOSFETs, and a self voltage generating circuit for generating the second voltage. Since it is configured with the bias circuit, the external power supply voltage detection circuit can be formed more easily.
【００２９】また、第４の発明の外部電源電圧検知回路
は、上記基準電圧生成回路をダイオードと定電流源で構
成し、上記比例電圧生成回路を外部電源電圧を比例配分
する抵抗で構成したので、外部電源電圧検知回路を具体
的に形成できる。In the external power supply voltage detection circuit of the fourth invention, the reference voltage generation circuit is composed of a diode and a constant current source, and the proportional voltage generation circuit is composed of resistors for proportionally distributing the external power supply voltage. The external power supply voltage detection circuit can be specifically formed.
【図１】この発明の外部電源電圧検知回路が適用された
電池電圧検知回路の回路図である。FIG. 1 is a circuit diagram of a battery voltage detection circuit to which an external power supply voltage detection circuit of the present invention is applied.
【図２】図１における定電圧生成回路１１の具体的な回
路図である。2 is a specific circuit diagram of a constant voltage generation circuit 11 in FIG.
【図３】図１における外部電源電圧に比例する電圧ｄの
生成系における各電圧と外部電源電圧との関係を示す図
である。FIG. 3 is a diagram showing the relationship between each voltage in the generation system of the voltage d proportional to the external power supply voltage in FIG. 1 and the external power supply voltage.
【図４】図１におけるコンパレータに係る各電圧と外部
電源電圧との関係を示す図である。FIG. 4 is a diagram showing a relationship between each voltage related to the comparator in FIG. 1 and an external power supply voltage.
【図５】従来の外部電源電圧検知回路が適用された電池
電圧検知回路の回路図である。FIG. 5 is a circuit diagram of a battery voltage detection circuit to which a conventional external power supply voltage detection circuit is applied.
【図６】図５におけるコンパレータに係る各電圧と外部
電源電圧との関係を示す図である。6 is a diagram showing a relationship between each voltage related to the comparator in FIG. 5 and an external power supply voltage.
１１…定電圧生成回路、 １２…定電流源１
２、１４…スイッチング素子、 １５,１７…
コンパレータ、１６…抵抗、 ２
１…セルフバイアス回路、２２…ＭＯＳＦＥＴの縦続接
続回路。11 ... Constant voltage generation circuit, 12 ... Constant current source 1
2, 14 ... Switching element, 15, 17 ...
Comparator, 16 ... Resistance, 2
1 ... Self-bias circuit, 22 ... Cascade connection circuit of MOSFET.
Claims (4)
に基づいて生成された基準電圧と比例電圧生成回路によ
って生成された外部電源電圧に比例する比例電圧とを比
較する電圧比較回路を有して、上記電圧比較回路の比較
結果に基づいて外部電源電圧が所定電圧に至ったことを
検知する外部電源電圧検知回路において、 上記比例電圧生成回路の状態を動作状態と非動作状態と
に切り換えるスイッチング回路と、 外部電源電圧が所定電圧より高くなると上記スイッチン
グ回路を駆動して、上記比例電圧生成回路の状態を動作
状態側に切り換えるスイッチング回路駆動手段を備えた
ことを特徴とする外部電源電圧検知回路。1. A voltage comparison circuit for comparing a reference voltage generated by a reference voltage generation circuit based on an external power supply voltage with a proportional voltage proportional to the external power supply voltage generated by a proportional voltage generation circuit, In an external power supply voltage detection circuit that detects that the external power supply voltage has reached a predetermined voltage based on the comparison result of the voltage comparison circuit, a switching circuit that switches the state of the proportional voltage generation circuit between an operating state and a non-operating state. An external power supply voltage detection circuit comprising switching circuit driving means for driving the switching circuit when the external power supply voltage becomes higher than a predetermined voltage to switch the state of the proportional voltage generation circuit to the operating state side.
において、 外部電源電圧より所定電圧分だけ低い第１の電圧と所定
値を有する第２の電圧を生成する定電圧生成手段を備え
ると共に、 上記スイッチング回路駆動手段は、上記定電圧生成回路
によって生成される上記第１の電圧と第２の電圧とを比
較して、上記第１の電圧が第２の電圧より高い場合に上
記スイッチング回路を駆動して上記比例電圧生成回路の
状態を動作状態側に切り換える信号を出力するコンパレ
ータで構成されたことを特徴とする外部電源電圧検知回
路。2. The external power supply voltage detection circuit according to claim 1, further comprising a constant voltage generation means for generating a first voltage lower than the external power supply voltage by a predetermined voltage and a second voltage having a predetermined value. The switching circuit driving means compares the first voltage and the second voltage generated by the constant voltage generating circuit and, when the first voltage is higher than the second voltage, the switching circuit An external power supply voltage detection circuit comprising a comparator for driving a signal to switch a state of the proportional voltage generation circuit to an operating state side.
であって、 上記定電圧生成手段は、上記外部電源電圧より所定電圧
分だけ低い第１の電圧を生成する金属酸化膜半導体電界
効果トランジスタを縦続接続した回路と、上記所定値を
有する第２の電圧を生成するセルフバイアス回路で構成
されたことを特徴とする外部電源電圧検知回路。3. The external power supply voltage detection circuit according to claim 2, wherein the constant voltage generation means generates a first voltage lower by a predetermined voltage than the external power supply voltage. An external power supply voltage detection circuit comprising a circuit in which transistors are connected in cascade and a self-bias circuit which generates a second voltage having the above-mentioned predetermined value.
載の外部電源電圧検知回路であって、 上記基準電圧生成回路はダイオードと定電流源で構成さ
れ、 上記比例電圧生成回路は、外部電源電圧を比例配分する
抵抗で構成されたことを特徴とする外部電源電圧検知回
路。4. The external power supply voltage detection circuit according to claim 1, wherein the reference voltage generation circuit includes a diode and a constant current source, and the proportional voltage generation circuit includes: An external power supply voltage detection circuit comprising a resistor for proportionally distributing the external power supply voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP474693A JPH06213941A (en) | 1993-01-14 | 1993-01-14 | External power supply voltage detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP474693A JPH06213941A (en) | 1993-01-14 | 1993-01-14 | External power supply voltage detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06213941A true JPH06213941A (en) | 1994-08-05 |
Family
ID=11592487
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP474693A Pending JPH06213941A (en) | 1993-01-14 | 1993-01-14 | External power supply voltage detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06213941A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007121088A (en) * | 2005-10-27 | 2007-05-17 | Sanyo Electric Co Ltd | Low voltage detection circuit |
| CN101783664A (en) * | 2009-01-13 | 2010-07-21 | 精工电子有限公司 | Power supply voltage monitoring circuit and electronic circuit including the power supply voltage monitoring circuit |
| KR20220081073A (en) * | 2020-12-08 | 2022-06-15 | 현대모비스 주식회사 | Tracker voltage monitoring circuit and method |
-
1993
- 1993-01-14 JP JP474693A patent/JPH06213941A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007121088A (en) * | 2005-10-27 | 2007-05-17 | Sanyo Electric Co Ltd | Low voltage detection circuit |
| CN101783664A (en) * | 2009-01-13 | 2010-07-21 | 精工电子有限公司 | Power supply voltage monitoring circuit and electronic circuit including the power supply voltage monitoring circuit |
| JP2010166184A (en) * | 2009-01-13 | 2010-07-29 | Seiko Instruments Inc | Power supply voltage monitoring circuit, and electronic circuit including the power supply voltage monitoring circuit |
| US8604821B2 (en) | 2009-01-13 | 2013-12-10 | Seiko Instruments Inc. | Power supply voltage monitoring circuit and electronic circuit including the power supply voltage monitoring circuit |
| KR101372795B1 (en) * | 2009-01-13 | 2014-03-10 | 세이코 인스트루 가부시키가이샤 | Power supply voltage monitoring circuit and electronic circuit including the power supply voltage monitoring circuit |
| KR20220081073A (en) * | 2020-12-08 | 2022-06-15 | 현대모비스 주식회사 | Tracker voltage monitoring circuit and method |
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