Ferroelectric random accessmemory (FRAM) is a non-volatilememory. FRAM has significanttechnical advantages that enablesolutions not possible with othermemory technology. The underlyingmolecular structure of anFRAM memory cell is shown inFigure 1. When an electric fieldis applied across the ferroelctriccrystal, the central atom moves inthe direction of the applied field.The polarity of this atom remainswhen the electric field is removed,preserving the data withinthe memory without the need forperiodic refresh. Understandingthe three principle benefits ofFRAM enables an electronics engineerto achieve a more efficientand superior design:No delay write—FRAM writesso quickly that there is no needto wait for the write to complete.Typical write speed for FRAM isaround 55 nanoseconds as comparedto the much slower 5 millisecondswrite speed for EEPROM.Virtually unlimited endurance—FRAM can withstand 1E14(100-trillion) read/write cycles,making it virtually impossible towear out.Low power—FRAM requiresmuch less power to performwrites. For example, erasing andwriting 64kbits of data in an FRAMconsumes 1/60th the power ofthat used by an EEPROM and1/400th that used by a serial flash.Now that we’ve covered thebasics, let’s see how we can applyFRAM technology to benefit yourproduct features and time-tomarket.Using FRAM is simple. SerialFRAMs are compatible with serialEEPROMs and parallel FRAMs arecompatible with parallel SRAMs.Existing software will work withFRAMs but most engineers choseto re-work the software. Thereare two significant softwaremodules that may be employedwith EEPROM or flash that are notneeded for FRAM. Removing thisredundant code makes softwarefaster to run, easier to debug, andconsumes less code space.The first of these modules isthe function necessary to wait forEEPROM or flash to complete thewrite operation. There is no pointin polling the FRAM to see if thewrite has completed (the writewill have finished before you cancheck), but this feature is supportedin case you don’t want changeyour EEPROM software.The second module that isredundant with FRAM is softwarethat performs wear levelling. Wearlevelling is a technique often usedwith flash or EEPROM to distributememory writes to numerous locationsso that the write cycle limitof any location is not exceeded.With FRAM’s virtually unlimitedendurance this function is notnecessary.Now let us look at some exampleapplications to see how thetechnology advantages of FRAMhave been used. Automotive infotainmentis becoming increasinglymore sophisticated leading to ademand for more information tobe stored. The stored data is currentvolume, sound source, filtersettings (treble, bass, etc.), balance,user favourites, etc. These settingschange with each different soundsource (CD, DVD, navigation, radio,etc.).Why use FRAM and notEEPROM for this data? All of thisdata must be stored upon powerfail. The traditional EEPROM solutionrequired a significant amountof capacitance to maintain poweron the EEPROM and MCU afterthe main power supply fails. FRAMeliminates the need for this capacitance,saving cost and space.Figure 2 compares the amounts ofdata that can be stored by FRAMand EEPROM on power fail.

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