Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!world!jon_sree From: jon_sree@world.std.com (Jon Sreekanth) Newsgroups: sci.electronics Subject: Re: HELP! non-volatile memory needed Message-ID: Date: 19 Jun 91 16:04:50 GMT References: <1991Jun14.173237.22353@cbnewsm.att.com> Sender: jon_sree@world.std.com (Jon Sreekanth) Organization: The World Lines: 31 In-Reply-To: ses@mhuxu.ATT.COM's message of 14 Jun 91 17: 32:37 GMT In article <1991Jun14.173237.22353@cbnewsm.att.com> ses@mhuxu.ATT.COM (attt-smith, stephen) writes: I need a byte or block programmable non-volatile memory source to hold 512 bytes. The total current draw must be less than 75mA. In the non-operating state there can be no power. The application is for programmed memory dialing from a telephone which may not have any internal or external power when it is not being used. The program memory is to consist of 18 numbers of 15 digits. Not sure what you mean by "byte or block programmable". If you anticipate infrequent programming, you can use a serial or byte-wide EEPROM. Serial EEPROM's are very cheap, 1K bit 93C46 is an 8 pin serial EEPROM, shift in address, shift out 16 bits of data at a time. (~$1.50) I think you get upto 4K bits in the same package, but don't know the part number. Standard byte-wide EEPROMs are made in the same pinout as EPROM's, and start with 28XX; so a 2K byte chip would be 28C16. Being CMOS parts, they draw well under 75ma. For frequent updates, there are two choices (apart from taking a standard RAM and doing your own battery backup). One is the so-called non-volatile RAM's from Dallas Semi, and others, which have their own internal lithium battery. They have SRAM speed read and write, but hold data automatically on powerdown. The other option is the new flash RAM's, but I've never used them myself. / Jon Sreekanth Assabet Valley Microsystems Fax and PC products 346 Lincoln St #722, Marlboro, MA 01752 508-562-0722 jon_sree@world.std.com