JPH0351903A - Power-on reset monitor circuit - Google Patents

Power-on reset monitor circuit

Info

Publication number
JPH0351903A
JPH0351903A JP1187699A JP18769989A JPH0351903A JP H0351903 A JPH0351903 A JP H0351903A JP 1187699 A JP1187699 A JP 1187699A JP 18769989 A JP18769989 A JP 18769989A JP H0351903 A JPH0351903 A JP H0351903A
Authority
JP
Japan
Prior art keywords
power
reset
circuit
output
signal
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
Application number
JP1187699A
Other languages
Japanese (ja)
Inventor
Susumu Yokose
横瀬 晋
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Ibaraki Ltd
Original Assignee
NEC Ibaraki Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NEC Ibaraki Ltd filed Critical NEC Ibaraki Ltd
Priority to JP1187699A priority Critical patent/JPH0351903A/en
Publication of JPH0351903A publication Critical patent/JPH0351903A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE:To prevent the malfunctions due to the variance of the rise-up time of a power supply by using the 1st and 2nd diodes, a pnp type transistor TR, and an npn type TR. CONSTITUTION:When the power voltage Vcc1 rises up and reaches a prescribed level in a power-on reset circuit 1, a reset signal V1 rises up after a fixed time. A reset signal V2 performs the same action in accordance with the power voltage Vcc2. When both reset signals V1 and V2 are set at H levels, no current flows to both diodes D1 and D2. Thus a pnp type TR Q1 and an npn type TR Q2 are not turned on and therefore an output signal V3 is set at an H level. As a result, both circuits 1 can output continuously the signals showing the reset states until they output the reset signals to release the reset states even though an error produced between both rise-up times of the power voltage when the power is supplied to both circuits 1.

Description

【発明の詳細な説明】 (産業上の利用分野) 本発明は、デジタル電子装置の電源が投入された直後に
おける該デジタル電子装置の出力信号の論理状態を予め
定められた初期状態にする回路に関し、特にそれぞれ別
々の電源から給電さ11.62つのデジタル回路を接続
してなる電子装置に備えられ、該2つのデジタル回路の
出力を監視し、該出力が共に所定の初期論理状態になっ
たときだけに電源投入後の初期設定が正しく行われたと
判定して、所定の論理状態のパワーオンリセット信号を
生成するパワーオンリセッ■・監視回路に関する.(従
来の技術) 第5図は従来のパワーオンリセット監視回路を示す回路
図である.本図のパワーオンリセット監視回路は、異な
る電源からそれぞれ電力を給電される2つのデジタル回
路7a及び8aにそれぞれ備えられているパワーオンリ
セット回1i1とAND回路Zl,Z2と抵抗RIO,
Rllとからなっている.パワーオンリセヅト回路1は
電源が立ち上がってから一定時間Tだけ遅れて立ち上が
るリセッ1〜信号を出力する.図において、4は接続さ
れた前記デジタル回路間の出力端子、5.6は交流電圧
より直流電圧をつくり出す安定化電源、9は交流入力端
子である. 次に第5図の回路の動作を第6図のタイムチャートを用
いて説明する。ここで前記デジタル回路7 a + 8
 aは正常状態のときに出力の論理値が“L”、アラー
ム状態のとき出力の論理値が“H”というインターフェ
ースであり、デジタル回路7aと8aとを含んでなるデ
ジタル電子装置の出力論理値は出力端子4に現われる.
交流入力端子9に交流電圧VAcが供給されると安定化
電源5,6が直流電圧Vccl , Vcc2を発生す
るが、直流電圧■cc1,vcc2の立ち上がりに時間
差を生じる場合がある.まず交流電圧VACが供給され
るとある時間を置いて直流電圧Vcclが立ち上がり、
その直流電圧V c c 1がVHの電圧に達してから
一定時間Tを経てパワーオンリセット信号■1{“し”
の状態でリセット、“H”の状態でリセット解除}が立
ち上がり、その後に直流電圧Vcc2が立ち上がりvH
に達するとその時点から一定時間Tだけ経過するとパワ
ーオンリセット信号V2(″L”の状態でリセット、“
H”の状態でリセット解除)が立ち上がる.以上の事は
第6図に示してある.V5は、電源電圧Vcclが立ち
上がると同時に抵抗RIOによって″H”になり、次に
電源電圧Vcc2が立ち上がりVt.に達するとAND
回路Z2の内部のトランジスタが動作して“L”になる
.パワーオンリセ・yト信号V2が立ち上がる時点以降
のVsの状態は、ANDriil路Z2のパワーオンリ
セット信号V2でない入力測の信号に左右される.出力
端子4の信号V4はパワーオンリセット信号V1と前記
V%の論理積であるから第6図に示す様な信号となり、
第6図の斜線部ではパワーオンリセット信号■2はリセ
ヅト解除を示していないのにもかかわらず誤ってアラー
ム状態を示す. (発明が解決しようとする課題) 前述した異なる電源から給電されてそれぞれパワーオン
リセット回路を備える従来のパワーオンリセット監視回
路においては、それぞれの電源の立ち上がるまでの時間
にばらつきがあると、そのばらつきによっては一方のパ
ワーオンリセット信号がリセット解除になっていない時
に誤ってアラーム状態を示してしまう.この様に、従来
のパワーオンリセット監視回路には解決すべき課題があ
った。
DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a circuit that sets the logic state of an output signal of a digital electronic device to a predetermined initial state immediately after the power of the digital electronic device is turned on. , especially provided in an electronic device consisting of two connected digital circuits, each powered from a separate power source, which monitors the outputs of the two digital circuits and when both of the outputs reach a predetermined initial logic state. This invention relates to a power-on reset/monitoring circuit that determines that the initial settings after power-on have been performed correctly and generates a power-on reset signal with a predetermined logic state. (Prior Art) Figure 5 is a circuit diagram showing a conventional power-on reset monitoring circuit. The power-on reset monitoring circuit in this figure includes a power-on reset circuit 1i1, an AND circuit Zl, Z2, a resistor RIO,
It consists of Rll. The power-on reset circuit 1 outputs a reset 1 signal that rises with a delay of a certain time T after the power is turned on. In the figure, 4 is an output terminal between the connected digital circuits, 5.6 is a stabilized power supply that generates DC voltage from AC voltage, and 9 is an AC input terminal. Next, the operation of the circuit shown in FIG. 5 will be explained using the time chart shown in FIG. Here, the digital circuit 7 a + 8
a is an interface whose output logical value is "L" in a normal state and "H" in an alarm state, and is an output logical value of a digital electronic device including digital circuits 7a and 8a. appears at output terminal 4.
When an AC voltage VAc is supplied to the AC input terminal 9, the stabilized power supplies 5 and 6 generate DC voltages Vccl and Vcc2, but there may be a time difference in the rise of the DC voltages cc1 and vcc2. First, when AC voltage VAC is supplied, DC voltage Vccl rises after a certain period of time.
After a certain period of time T has passed since the DC voltage V c c 1 reaches the voltage VH, the power-on reset signal ■ 1 {“S”
Reset in the “H” state, reset release in the “H” state} rises, and then the DC voltage Vcc2 rises to vH
When a certain period of time T has elapsed from that point, the power-on reset signal V2 (resets in the "L" state, "
The above is shown in Figure 6. V5 is set to "H" by the resistor RIO at the same time as the power supply voltage Vccl rises, and then the power supply voltage Vcc2 rises and Vt AND when it reaches .
The transistor inside circuit Z2 operates and becomes "L". The state of Vs after the power-on reset signal V2 rises depends on the input signal other than the power-on reset signal V2 on the ANDriil path Z2. Since the signal V4 at the output terminal 4 is the AND of the power-on reset signal V1 and the above-mentioned V%, it becomes a signal as shown in FIG.
In the shaded area in Figure 6, the power-on reset signal ■2 erroneously indicates an alarm state even though it does not indicate reset cancellation. (Problem to be Solved by the Invention) In the conventional power-on reset monitoring circuit that is supplied with power from the different power supplies mentioned above and each has a power-on reset circuit, if there is variation in the time it takes for each power supply to start up, the variation In some cases, an alarm state may be erroneously indicated when one power-on reset signal is not released from reset. As described above, the conventional power-on reset monitoring circuit has problems that need to be solved.

(課題を解決するための手段) 前述した課題を解決するために本発明が提供する手段は
、電源電圧が立ち上がる時点からある時間をおいて立ち
上がる論理状@”o″′でリセットを示し論理状態″1
″でリセット解除を示すリセγト信号を出力する第1の
パワーオンリセット回路と、前記第1のパワーオンリセ
ット回路と同様の機能を持つ第2のパワーオンリセット
回路と、第1のパワーオンリセット回路の出力端子にカ
ソードが接続してある第1のダイオードと、第2のパワ
ーオンリセット回路の出力端子にカソードが接続してあ
り前記第1のダイオードのアノードにアノードが接続し
てある第2のダイオードと、導通状態に応じてコレクタ
に出力電流を生ずるpnp型のトランジスタと、前記第
1のダイオードのアノードと前記pnp型のトランジス
タのベースとの間に接続してある第1の抵抗と、導通状
?に応じてコレクタ電圧の論理状態を“O′又は″1″
にするnpn型のトランジスタと、前記npn型のトラ
ンジスタのコレクタと前記npn型のトランジスタのベ
ースとの間に接続してある第2の抵抗と、第1の電源と
前記npn型のトランジスタのコレクタとの間に接続し
てある第3の抵抗とが備えてあり、前記第1のパワーオ
ンリセット回路は第1の電源から電力の供給を受け、前
記第2のパワーオンリセット回路は第2の電源から電力
の供給を受け、前記pnp型のトランジスタのエミッタ
は前記第1の電源に接続してあり、前記npn型のトラ
ンジスタのエミッタは接地してあることを特徴とする. (実施例) 次に実施到を挙げて本発明を詳しく説明する.第1図は
本発明の実施例の回路図であり、lはパワーオンリセッ
ト回路、2は出力端子、D1,D2はダイオード、Rl
,R2,R3は抵抗、Q1はpnp型のトランジスタ、
Q2はnpn型のトランジスタ、vcc1■V c c
 2は電源であり、第2図はその動作タイムチャートを
示す図である.また、第3図は本発明の回路を利用した
デジタル電子装置の例を示す回路図であり、3は第1図
実施例のパワーオンリセット監視回路、4は出力端子、
5.6は安定化電源、7.8はデジタル回路、9は交流
入力端子、R10.R11は抵抗、Z1z2はAND回
路であり、第4図はその動作タイムチャートである. 以下に第1図の本発明のパワーオンリセット監視回路の
動作を第2図の動作タイムチャートに従って説明する。
(Means for Solving the Problems) The means provided by the present invention to solve the above-mentioned problems is a logic state that indicates a reset with a logic state @"o"' that rises after a certain period of time after the power supply voltage rises. ″1
a first power-on reset circuit that outputs a reset signal indicating release of reset at ``, a second power-on reset circuit having the same function as the first power-on reset circuit, and a first power-on reset circuit that outputs a reset signal indicating release of reset at a first diode having a cathode connected to the output terminal of the reset circuit; and a second diode having a cathode connected to the output terminal of the second power-on reset circuit and an anode connected to the anode of the first diode. a pnp-type transistor that generates an output current in the collector depending on the conduction state; and a first resistor connected between the anode of the first diode and the base of the pnp-type transistor. , the logic state of the collector voltage is set to “O’ or “1” depending on the conduction state?
a second resistor connected between a collector of the npn transistor and a base of the npn transistor; a first power supply and a collector of the npn transistor; the first power-on reset circuit receives power from the first power source, and the second power-on reset circuit receives power from the second power source. The emitter of the pnp transistor is connected to the first power source, and the emitter of the npn transistor is grounded. (Example) Next, the present invention will be explained in detail by citing examples of implementation. FIG. 1 is a circuit diagram of an embodiment of the present invention, l is a power-on reset circuit, 2 is an output terminal, D1, D2 are diodes, Rl
, R2, R3 are resistors, Q1 is a pnp type transistor,
Q2 is an npn type transistor, vcc1■V c c
2 is a power supply, and FIG. 2 is a diagram showing its operation time chart. 3 is a circuit diagram showing an example of a digital electronic device using the circuit of the present invention, 3 is the power-on reset monitoring circuit of the embodiment in FIG. 1, 4 is an output terminal,
5.6 is a stabilized power supply, 7.8 is a digital circuit, 9 is an AC input terminal, R10. R11 is a resistor, Z1z2 is an AND circuit, and FIG. 4 is an operation time chart thereof. The operation of the power-on reset monitoring circuit of the present invention shown in FIG. 1 will be explained below according to the operation time chart shown in FIG. 2.

電源電圧Vcclが立ち上がりV.に達するとリセット
信号■,はその時点から一定時間Tの経過後に立ち上が
る.リセ・yト信号v2も電源電圧Vcc2に応じて同
様に動作をする6電源電圧Vcclが立ち上がるまでは
,電源電圧V c c 2を含めてリセット信号Vl,
V2、出力信号v3とも“L”である.リセット信号■
2が立ち上がる直前までの間はリセット信号v+,tた
はV2が“L”であるので、Vcclからpnp型のト
ランジスタQ1のエミッタ、ベース、抵抗R1、ダイオ
ードD1またはダイオードD2.パワーオンリセット回
路1、接地の経路で電流が流れ、前記pnp型のトラン
ジスタQ1がONとなってそのpnp型のトランジスタ
Q1のエミッタからコレクタに電流が流れ、抵抗R2を
経てnpn型のトランジスタQ2のベースに前記電流が
流れ込み、その電流によって前記npn型のトランジス
タQ2がONL、電源Vcclより抵抗R3、npn型
のトランジスタQ2のコレクタ、エミッタ、接地の経路
で電流が流れるので、出力端子2の信号は“L”である
.ところが、リセット信号V2が“H”になる時点では
、ダイオードD1及びD2には電流が流れなくなりpn
p型のトランジスタQ1はONにならず、それによりn
pn型のトランジスタQ2もONにならないので、出力
信号v3 “H”となる。この様に、出力信号■)はリ
セ・yト信号v1及びv2がいずれも″H″になるまで
“H”にはならない. 次に第1図の回路を利用したデジタル電子装置の例とし
て挙げた第3図を参照して第1図の実施例を一層詳しく
説明する。このデジタル電子装置はデジタル回路7及び
8を備えている.第4図に示す動作夕・fムチャートに
従って説明する.交流入力端子9に交流電圧VAcが印
加されると、安定化電源5,6によって直流電圧Vea
l . VCC2が発生するがそれら2つの直涜電圧V
 cc j .V cc 2の立ち上がりまでの時間に
は一般に差がある。デジタル回路8にはパワーオンリセ
ット回路がなくデジタル回路7には第1図実施例のパワ
ーオンリセット監視回路3があるので、そのリセット信
号V,と他の信号との時間関係は第4図に示す様なタイ
ムチャートになることは第2図に示したパワーオンリセ
ット監視回路の動作タイムチャートから明らかである.
出力端子4に出力される出力信号V4は、リセット信号
V,が立ち上がるとAND回路z2の出力に左右される
ので“H″または“L″のどちらになるかは不定である
が、リセット信号V,が“L”の間はAND回路z1に
よって″し”に保持される. (発明の効果) 以上に説明した様に、本発明6こよh,ば異なる電源か
ら電力供給を受ける2つのパワーオンリセット回路から
1つのパワーオンリセット信号をつくる場合、それら2
つのパワーオンリセット回路に電力を供給する2つの電
源の電圧の立ち上がりに時間的ずれがあっても、両方の
パワーオンリセット回路がリセットを解除するリセット
信号をそれぞれ出力するまでリセッ1・を示す信号を出
力し続けることができる.したがって、従来のパワーオ
ンリセット監視回路で解決が待たれていた課題は本発明
により解決された。
When the power supply voltage Vccl rises, V. When reaching , the reset signal ■ rises after a certain period of time T has elapsed from that point. The reset signal v2 also operates in the same way according to the power supply voltage Vcc2.6 Until the power supply voltage Vccl rises, the reset signal Vl, including the power supply voltage Vcc2,
Both V2 and output signal v3 are "L". Reset signal ■
Since the reset signal v+, t or V2 is "L" until just before the voltage rises from Vccl to the emitter and base of the pnp transistor Q1, the resistor R1, the diode D1 or the diode D2. In the power-on reset circuit 1, current flows through the grounded path, turning on the pnp transistor Q1, causing current to flow from the emitter of the pnp transistor Q1 to the collector, and passing through the resistor R2 to the npn transistor Q2. The current flows into the base, and the current flows through the npn transistor Q2 ONL, and the current flows from the power supply Vccl through the resistor R3, the collector of the npn transistor Q2, the emitter, and the ground, so the signal at the output terminal 2 is It is “L”. However, when the reset signal V2 becomes "H", no current flows through the diodes D1 and D2, and pn
The p-type transistor Q1 does not turn on, so that the n
Since the pn type transistor Q2 is also not turned on, the output signal v3 becomes "H". In this way, the output signal (2) does not go to "H" until both reset signals v1 and v2 go to "H". Next, the embodiment of FIG. 1 will be described in more detail with reference to FIG. 3, which is given as an example of a digital electronic device using the circuit of FIG. This digital electronic device is equipped with digital circuits 7 and 8. This will be explained according to the operation/frequency chart shown in Figure 4. When AC voltage VAc is applied to AC input terminal 9, DC voltage Vea is increased by stabilized power supplies 5 and 6.
l. VCC2 is generated, but these two direct voltages V
cc j. There is generally a difference in the time it takes for V cc 2 to rise. Since the digital circuit 8 has no power-on reset circuit and the digital circuit 7 has the power-on reset monitoring circuit 3 of the embodiment shown in FIG. 1, the time relationship between the reset signal V and other signals is shown in FIG. It is clear from the operation time chart of the power-on reset monitoring circuit shown in Figure 2 that the time chart shown in the figure will be used.
The output signal V4 outputted to the output terminal 4 depends on the output of the AND circuit z2 when the reset signal V rises, so it is uncertain whether it will be "H" or "L", but the reset signal V , is held at "L" by the AND circuit z1. (Effects of the Invention) As explained above, the sixth aspect of the present invention is that when one power-on reset signal is generated from two power-on reset circuits that receive power from different power sources, those two
Even if there is a time lag in the rise of the voltages of the two power supplies that supply power to one power-on reset circuit, the signal indicating reset 1 until both power-on reset circuits each output a reset signal to release the reset. can continue to be output. Therefore, the present invention has solved the problems that had been awaited in the conventional power-on reset monitoring circuit.

【図面の簡単な説明】[Brief explanation of drawings]

Claims (1)

【特許請求の範囲】[Claims] 電源電圧が立ち上がる時点からある時間をおいて立ち上
がる論理状態“0”でリセットを示し論理状態“1”で
リセット解除を示すリセット信号を出力する第1のパワ
ーオンリセット回路と、前記第1のパワーオンリセット
回路と同様の機能を有する第2のパワーオンリセット回
路と、第1のパワーオンリセット回路の出力端子にカソ
ードが接続してある第1のダイオードと、第2のパワー
オンリセット回路の出力端子にカソードが接続してあり
前記第1のダイオードのアノードにアノードが接続して
ある第2のダイオードと、導通状態に応じてコレクタに
出力電流を生ずるpnp型のトランジスタと、前記第1
のダイオードのアノードと前記pnp型のトランジスタ
のベースとの間に接続してある第1の抵抗と、導通状態
に応じてコレクタ電圧の論理状態を“0”又は“1”に
するnpn型のトランジスタと、前記pnp型のトラン
ジスタのコレクタと前記npn型のトランジスタのベー
スとの間に接続してある第2の抵抗と、第1の電源と前
記npn型のトランジスタのコレクタとの間に接続して
ある第3の抵抗とが備えてあり、前記第1のパワーオン
リセット回路は第1の電源から電力の供給を受け、前記
第2のパワーオンリセット回路は第2の電源から電力の
供給を受け、前記pnp型のトランジスタのエミッタは
前記第1の電源に接続してあり、前記npn型のトラン
ジスタのエミッタは接地してあることを特徴とするパワ
ーオンリセット監視回路。
a first power-on reset circuit that outputs a reset signal that indicates a reset when the logic state is "0" and indicates that the reset is canceled when the logic state is "1"; a second power-on reset circuit having the same function as the power-on reset circuit; a first diode whose cathode is connected to the output terminal of the first power-on reset circuit; and an output of the second power-on reset circuit. a second diode having a cathode connected to its terminal and an anode connected to the anode of the first diode; a pnp transistor that generates an output current in its collector depending on the conduction state;
a first resistor connected between the anode of the diode and the base of the pnp transistor, and an npn transistor whose collector voltage has a logic state of "0" or "1" depending on the conduction state. a second resistor connected between the collector of the pnp transistor and the base of the npn transistor; and a second resistor connected between the first power supply and the collector of the npn transistor. a third resistor, the first power-on reset circuit receives power from a first power source, and the second power-on reset circuit receives power from a second power source. . A power-on reset monitoring circuit, wherein an emitter of the pnp transistor is connected to the first power source, and an emitter of the npn transistor is grounded.
JP1187699A 1989-07-19 1989-07-19 Power-on reset monitor circuit Pending JPH0351903A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP1187699A JPH0351903A (en) 1989-07-19 1989-07-19 Power-on reset monitor circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1187699A JPH0351903A (en) 1989-07-19 1989-07-19 Power-on reset monitor circuit

Publications (1)

Publication Number Publication Date
JPH0351903A true JPH0351903A (en) 1991-03-06

Family

ID=16210610

Family Applications (1)

Application Number Title Priority Date Filing Date
JP1187699A Pending JPH0351903A (en) 1989-07-19 1989-07-19 Power-on reset monitor circuit

Country Status (1)

Country Link
JP (1) JPH0351903A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001060858A (en) * 1999-07-14 2001-03-06 Fairchild Semiconductor Corp Power on reset circuit for system having two power supplies

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6361823B2 (en) * 1980-04-17 1988-11-30

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6361823B2 (en) * 1980-04-17 1988-11-30

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001060858A (en) * 1999-07-14 2001-03-06 Fairchild Semiconductor Corp Power on reset circuit for system having two power supplies

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