JPH0280400U - - Google Patents
Info
- Publication number
- JPH0280400U JPH0280400U JP15888288U JP15888288U JPH0280400U JP H0280400 U JPH0280400 U JP H0280400U JP 15888288 U JP15888288 U JP 15888288U JP 15888288 U JP15888288 U JP 15888288U JP H0280400 U JPH0280400 U JP H0280400U
- Authority
- JP
- Japan
- Prior art keywords
- ram
- power supply
- cpu
- switching element
- malfunction
- 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
- 230000007257 malfunction Effects 0.000 claims 2
- 238000001514 detection method Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 2
Landscapes
- Power Sources (AREA)
- Static Random-Access Memory (AREA)
Description
第１図は本考案のＲＡＭデータ防護回路の一実
施例を示す回路図、第２図は従来のＲＡＭデータ
防護回路を示す回路図である。
１……ＣＰＵ、４……ＲＡＭ、５……制御信号
線、６……主電源、８……バツクアツプ電源、１
０……プルアツプ抵抗、１１……トランジスタ、
１４……定電圧ダイオード。
FIG. 1 is a circuit diagram showing an embodiment of the RAM data protection circuit of the present invention, and FIG. 2 is a circuit diagram showing a conventional RAM data protection circuit. 1...CPU, 4...RAM, 5...Control signal line, 6...Main power supply, 8...Backup power supply, 1
0...Pull-up resistor, 11...Transistor,
14... Constant voltage diode.
Claims (1)
によるＣＰＵの誤動作に基づく誤アクセスから防
護するためのＲＡＭデータ防護回路であつて、 上記ＣＰＵからＲＡＭのチツプセレクト端子に
ローレベルの選択信号を送る制御信号線に介設さ
れたスイツチング素子と、上記ＣＰＵを誤動作さ
せる上記電源電圧の一定量の低下を検出して、上
記スイツチング素子の制御入力端子にこのスイツ
チング素子をオフにする信号を出力する電圧検出
回路と、上記ＲＡＭのチツプセレクト端子にプル
アツプ抵抗を介してハイレベルの一定電圧を印加
するバツクアツプ電源を備えたＲＡＭデータ防護
回路。[Claims for Utility Model Registration] A RAM data protection circuit for protecting data stored in a RAM from erroneous access due to malfunction of a CPU due to a drop in power supply voltage, which connects the CPU to a chip select terminal of the RAM. A switching element interposed in a control signal line that sends a low-level selection signal detects a certain amount of drop in the power supply voltage that causes the CPU to malfunction, and sends a control input terminal of the switching element to turn off the switching element. A RAM data protection circuit comprising: a voltage detection circuit that outputs a signal to set the RAM; and a backup power supply that applies a constant high-level voltage to the chip select terminal of the RAM via a pull-up resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15888288U JPH0280400U (en) | 1988-12-06 | 1988-12-06 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15888288U JPH0280400U (en) | 1988-12-06 | 1988-12-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0280400U true JPH0280400U (en) | 1990-06-20 |
Family
ID=31439613
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15888288U Pending JPH0280400U (en) | 1988-12-06 | 1988-12-06 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0280400U (en) |
-
1988
- 1988-12-06 JP JP15888288U patent/JPH0280400U/ja active Pending
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