K20P121M100SF2 Datasheet, PDF (33/68 Pages) Freescale Semiconductor, Inc – Up to 100 MHz ARM Cortex-M4 core with DSP instructions delivering 1.25 Dhrystone MIPS per MHz

Peripheral operating requirements and behaviors
6.4.1.5 Write endurance to FlexRAM for EEPROM
When the FlexNVM partition code is not set to full data flash, the EEPROM data set size
can be set to any of several non-zero values.
The bytes not assigned to data flash via the FlexNVM partition code are used by the
FTFL to obtain an effective endurance increase for the EEPROM data. The built-in
EEPROM record management system raises the number of program/erase cycles that can
be attained prior to device wear-out by cycling the EEPROM data through a larger
EEPROM NVM storage space.
While different partitions of the FlexNVM are available, the intention is that a single
choice for the FlexNVM partition code and EEPROM data set size is used throughout the
entire lifetime of a given application. The EEPROM endurance equation and graph
shown below assume that only one configuration is ever used.
Writes_subsystem =
EEPROM – 2 × EEESPLIT × EEESIZE
EEESPLIT × EEESIZE
× Write_efficiency × n_nvmcycd
where
• Writes_subsystem — minimum number of writes to each FlexRAM location for
subsystem (each subsystem can have different endurance)
• EEPROM — allocated FlexNVM for each EEPROM subsystem based on DEPART;
entered with Program Partition command
• EEESPLIT — FlexRAM split factor for subsystem; entered with the Program
Partition command
• EEESIZE — allocated FlexRAM based on DEPART; entered with Program Partition
command
• Write_efficiency —
• 0.25 for 8-bit writes to FlexRAM
• 0.50 for 16-bit or 32-bit writes to FlexRAM
• n_nvmcycd — data flash cycling endurance
K20 Sub-Family Data Sheet Data Sheet, Rev. 4, 3/2011.
Freescale Semiconductor, Inc.
Preliminary
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