K61P256M120SF3_1210 Datasheet, PDF (40/94 Pages) Freescale Semiconductor, Inc – K61 Sub-Family

Peripheral operating requirements and behaviors
Table 23. NVM reliability specifications (continued)
Symbol Description
Min.
n_nvmcycd Cycling endurance
10 K
FlexRAM as EEPROM
t_nvmretee100 Data retention up to 100% of write endurance
t_nvmretee10 Data retention up to 10% of write endurance
n_nvmcycee Cycling endurance for EEPROM backup
Write endurance
5
20
20 K
n_nvmwree16
n_nvmwree128
n_nvmwree512
n_nvmwree2k
n_nvmwree4k
• EEPROM backup to FlexRAM ratio = 16
• EEPROM backup to FlexRAM ratio = 128
• EEPROM backup to FlexRAM ratio = 512
• EEPROM backup to FlexRAM ratio = 2,048
• EEPROM backup to FlexRAM ratio = 4,096
70 K
630 K
2.5 M
10 M
20 M
Typ.¹
50 K
50
100
50 K
175 K
1.6 M
6.4 M
25 M
50 M
Max.
—
—
—
—
—
—
—
—
—
Unit
cycles
years
years
cycles
writes
writes
writes
writes
writes
Notes
2
2
3
1. Typical data retention values are based on measured response accelerated at high temperature and derated to a constant
25°C use profile. Engineering Bulletin EB618 does not apply to this technology. Typical endurance defined in Engineering
Bulletin EB619.
2. Cycling endurance represents number of program/erase cycles at -40°C ≤ T_j ≤ 125°C.
3. Write endurance represents the number of writes to each FlexRAM location at -40°C ≤Tj ≤ 125°C influenced by the cycling
endurance of the FlexNVM (same value as data flash) and the allocated EEPROM backup per subsystem. Minimum and
typical values assume all byte-writes to FlexRAM.
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
FTFE 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_nvmcycee
where
• Writes_subsystem — minimum number of writes to each FlexRAM location for
subsystem (each subsystem can have different endurance)
K61 Sub-Family Data Sheet, Rev. 4, 10/2012.
40
Freescale Semiconductor, Inc.