The FM25L256B combines 256 kilobit nonvolatile F-RAM with an industry-standard serial peripheral interface (SPI) that is pin-compatible with comparable EEPROMs.

A direct hardware replacement for EEPROM, only superior, the device reads and writes at bus speeds of up to 25MHz, operates from 2.7 to 3.6 volts over the industrial temperature range (-40 degrees C to +85 degrees C), and is available in a green 8-pin SOIC or DFN package.

F-RAM offers three distinct benefits in advanced metering designs:

  • NoDelay™ reads/writes:  F-RAM writes data at bus speed, eliminating the need for a complicated data backup system in the event of power loss.
  • Virtually unlimited endurance:  F-RAM collects data for an unlimited period without wearing out. In an electric meter F-RAM can be written every second for the life of a meter.  No other nonvolatile memory offers this capability.  Less advanced designs that exclude F-RAM can only afford to write the data when power is failing because alternative memory products wear out quickly if they are written too often.
  • Low power consumption:  F-RAM devices are RAMs and do not require charge pumps and are, therefore, orders of magnitude lower in power during write cycles than floating gate devices such as flash and EEPROM.  During battery-powered data collection, F-RAM devices offer the lowest power operation of any memory solution available, making them ideal for a variety of data collection applications including water and gas meters.

http://www.ramtron.com/products/nonvolatile-memory/serial-product.aspx?id=11