MC9S12D64 Datasheet, PDF (101/128 Pages) Freescale Semiconductor, Inc – Device User Guide V01.20

A.3 NVM, Flash and EEPROM
MC9S12DJ64 Device User Guide — V01.20
NOTE: Unless otherwise noted the abbreviation NVM (Non Volatile Memory) is used for
both Flash and EEPROM.
A.3.1 NVM timing
The time base for all NVM program or erase operations is derived from the oscillator. A minimum
oscillator frequency f_NVMOSC is required for performing program or erase operations. The NVM modules
do not have any means to monitor the frequency and will not prevent program or erase operation at
frequencies above or below the specified minimum. Attempting to program or erase the NVM modules at
a lower frequency a full program or erase transition is not assured.
The Flash and EEPROM program and erase operations are timed using a clock derived from the oscillator
using the FCLKDIV and ECLKDIV registers respectively. The frequency of this clock must be set within
the limits specified as f_NVMOP.
The minimum program and erase times shown in Table A-11 are calculated for maximum f_NVMOP and
maximum f_bus. The maximum times are calculated for minimum f_NVMOP and a f_bus of 2MHz.
A.3.1.1 Single Word Programming
The programming time for single word programming is dependant on the bus frequency as a well as on
the frequency f_NVMOP and can be calculated according to the following formula.
t_swpgm = 9 ⋅ _f--N----_V----1_M-----_O----_P-- + 25 ⋅ -f-_b--1--_u---_s-
A.3.1.2 Row Programming
This applies only to the Flash where up to 32 words in a row can be programmed consecutively by keeping
the command pipeline filled. The time to program a consecutive word can be calculated as:
t_bwpgm = 4 ⋅ _f--N----_V----1_M-----_O----_P-- + 9 ⋅ _f--b--1--_u---_s-
The time to program a whole row is:
t_brpgm = t_swpgm + 31 ⋅ t_bwpgm
Row programming is more than 2 times faster than single word programming.
A.3.1.3 Sector Erase
Erasing a 512 byte Flash sector or a 4 byte EEPROM sector takes:
101