JPS57172595A - Memory protecting circuit - Google Patents

Memory protecting circuit

Info

Publication number
JPS57172595A
JPS57172595A JP56056628A JP5662881A JPS57172595A JP S57172595 A JPS57172595 A JP S57172595A JP 56056628 A JP56056628 A JP 56056628A JP 5662881 A JP5662881 A JP 5662881A JP S57172595 A JPS57172595 A JP S57172595A
Authority
JP
Japan
Prior art keywords
circuit
memory
reference value
power supply
power 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.)
Pending
Application number
JP56056628A
Other languages
Japanese (ja)
Inventor
Shingo Yamaguchi
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.)
Ricoh Co Ltd
Original Assignee
Ricoh Co 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 Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to JP56056628A priority Critical patent/JPS57172595A/en
Publication of JPS57172595A publication Critical patent/JPS57172595A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE: To enable with a simple circuit to prevent memory contents from being destroyed when turn on an electric power supply or the power supply is turned off, by making the selection line of a memory circuit unselected when a power voltage is lower than a reference value.
CONSTITUTION: A power-on resetting circuit A which generates a reset signal when a power supply is turned on and has a time constant depending upon a resistance R3 and a capacitor C1 is provided and the memory protecting circuit of a memory circuit 2 which is powered down by a battery BA is provided with a detecting circuit which detects a power voltage Vcc exceeding a prescribed reference value. Then when the power voltage Vcc is lower than the reference value, the capacitor C1 is discharged and at the same time, the selection line of the memory circuit 2 is made unselected. For example, a circuit which includes a microcomputer 1, a Zener diode ZD, etc., as shown in the figure is used to perform said operation.
COPYRIGHT: (C)1982,JPO&Japio
JP56056628A 1981-04-15 1981-04-15 Memory protecting circuit Pending JPS57172595A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP56056628A JPS57172595A (en) 1981-04-15 1981-04-15 Memory protecting circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP56056628A JPS57172595A (en) 1981-04-15 1981-04-15 Memory protecting circuit

Publications (1)

Publication Number Publication Date
JPS57172595A true JPS57172595A (en) 1982-10-23

Family

ID=13032561

Family Applications (1)

Application Number Title Priority Date Filing Date
JP56056628A Pending JPS57172595A (en) 1981-04-15 1981-04-15 Memory protecting circuit

Country Status (1)

Country Link
JP (1) JPS57172595A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59202526A (en) * 1983-04-30 1984-11-16 Minolta Camera Co Ltd Voltage drop protecting circuit of control circuit
JPH0314150A (en) * 1989-06-13 1991-01-22 Hitachi Maxell Ltd Memory card
KR100231139B1 (en) * 1996-08-28 1999-11-15 문정환 Reset signal generating circuit
JP2008075795A (en) * 2006-09-22 2008-04-03 Japan Aviation Electronics Industry Ltd Sucker sheet

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52116027A (en) * 1976-03-25 1977-09-29 Casio Comput Co Ltd Memory protection circuit in small size electronic devices
JPS5531133B2 (en) * 1976-08-04 1980-08-15
JPS5627734B2 (en) * 1973-02-22 1981-06-26

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5627734B2 (en) * 1973-02-22 1981-06-26
JPS52116027A (en) * 1976-03-25 1977-09-29 Casio Comput Co Ltd Memory protection circuit in small size electronic devices
JPS5531133B2 (en) * 1976-08-04 1980-08-15

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59202526A (en) * 1983-04-30 1984-11-16 Minolta Camera Co Ltd Voltage drop protecting circuit of control circuit
JPH0314150A (en) * 1989-06-13 1991-01-22 Hitachi Maxell Ltd Memory card
KR100231139B1 (en) * 1996-08-28 1999-11-15 문정환 Reset signal generating circuit
JP2008075795A (en) * 2006-09-22 2008-04-03 Japan Aviation Electronics Industry Ltd Sucker sheet

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