JPS63147745U - - Google Patents
Info
- Publication number
- JPS63147745U JPS63147745U JP3911787U JP3911787U JPS63147745U JP S63147745 U JPS63147745 U JP S63147745U JP 3911787 U JP3911787 U JP 3911787U JP 3911787 U JP3911787 U JP 3911787U JP S63147745 U JPS63147745 U JP S63147745U
- Authority
- JP
- Japan
- Prior art keywords
- level
- determination level
- power supply
- supply voltage
- microcomputer
- 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
- 230000001934 delay Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 4
Landscapes
- Techniques For Improving Reliability Of Storages (AREA)
Description
第１図は本考案の一実施例を示す回路図、第２
図はその信号波形図、第３図は従来例を示す回路
図、第４図はその信号波形図、第５図はフローチ
ヤートである。
１１……比較器、１２……トランジスタ、１３
……オンデイレータイマ回路、１４……比較器、
１５……トランジスタ、１６……負帰還抵抗、２
０……マイクロコンピユータ、３０……バツクア
ツプＲＡＭ。
Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
3 is a circuit diagram showing a conventional example, FIG. 4 is a signal waveform diagram, and FIG. 5 is a flowchart. 11...Comparator, 12...Transistor, 13
...On-delay timer circuit, 14...Comparator,
15...Transistor, 16...Negative feedback resistor, 2
0...Microcomputer, 30...Backup RAM.
Claims (1)
果に応じたレベルの信号を出力する第１の比較回
路を備えて、電源電圧が第１の判定レベル以下に
なつたときに対応する第１の比較回路の出力信号
の変化を割込み信号としてマイクロコンピユータ
によりバツクアツプＲＡＭへの読み書きを禁止す
ると共に、電源電圧の立上がりのみを遅延させる
オンデイレータイマ回路と、このオンデイレータ
イマ回路を介して入力される電源電圧を第２の判
定レベルと比較して比較結果に応じたレベルの信
号を出力する第２の比較回路とを備えて、電源電
圧が第２の判定レベル以下になつたときに対応す
る第２の比較回路の出力信号の変化をリセツト信
号としてマイクロコンピユータを停止させるよう
にした車載マイクロコンピユータのメモリ保護装
置において、前記第２の比較回路の出力に応じて
、前記第２の判定レベルを変化させて、電源電圧
が第２の判定レベル以下となつたときに第２の判
定レベルを第１の判定レベルより高くし、電源電
圧が第２の判定レベルを越えたときに第２の判定
レベルを第１の判定レベルより低くする第２の判
定レベルの切換手段を設けたことを特徴とする車
載マイクロコンピユータのメモリ保護装置。 a first comparison circuit that compares the power supply voltage with a first determination level and outputs a signal at a level according to the comparison result; A change in the output signal of the comparison circuit is used as an interrupt signal to prohibit the microcomputer from reading or writing to the backup RAM, and an on-delay timer circuit that delays only the rise of the power supply voltage is input via the on-delay timer circuit. and a second comparison circuit that compares the power supply voltage to a second determination level and outputs a signal at a level according to the comparison result, and responds when the power supply voltage falls below the second determination level. In the memory protection device for an on-vehicle microcomputer, the microcomputer is stopped by using a change in the output signal of a second comparator circuit as a reset signal. When the power supply voltage is below the second determination level, the second determination level is set higher than the first determination level, and when the power supply voltage exceeds the second determination level, the second determination level is set higher than the first determination level. 1. A memory protection device for a vehicle-mounted microcomputer, characterized in that a second judgment level switching means is provided for setting the judgment level lower than the first judgment level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3911787U JPH0435959Y2 (en) | 1987-03-19 | 1987-03-19 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3911787U JPH0435959Y2 (en) | 1987-03-19 | 1987-03-19 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63147745U true JPS63147745U (en) | 1988-09-29 |
| JPH0435959Y2 JPH0435959Y2 (en) | 1992-08-25 |
Family
ID=30851994
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3911787U Expired JPH0435959Y2 (en) | 1987-03-19 | 1987-03-19 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0435959Y2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014048070A (en) * | 2012-08-29 | 2014-03-17 | Denso Corp | Electronic control device |
-
1987
- 1987-03-19 JP JP3911787U patent/JPH0435959Y2/ja not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014048070A (en) * | 2012-08-29 | 2014-03-17 | Denso Corp | Electronic control device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0435959Y2 (en) | 1992-08-25 |
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