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Appendix A Electrical Characteristics
MC9S12XDP512 Data Sheet, Rev. 2.17
Freescale Semiconductor
1259
A.3
NVM, Flash, and EEPROM
NOTE
UnlessotherwisenotedtheabbreviationNVM(nonvolatilememory)isused
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-17
are calculated for maximum f
NVMOP
and
maximum f
bus
. The maximum times are calculated for minimum f
NVMOP
and a f
bus
of 2 MHz.
A.3.1.1
Single Word Programming
Theprogrammingtimeforsinglewordprogrammingisdependantonthebusfrequencyasawellasonthe
frequency f
NVMOP
and can be calculated according to the following formula.
A.3.1.2
Burst Programming
ThisappliesonlytotheFlashwhereupto64wordsinarowcanbeprogrammedconsecutivelyusingburst
programming by keeping the command pipeline filled. The time to program a consecutive word can be
calculated as:
The time to program a whole row is:
Burst programming is more than 2 times faster than single word programming.
tswpgm
9
fNVMOP
25
fbus
+
=
tbwpgm
4
fNVMOP
-----------1
9
fbus
---1
+
=
tbrpgm
tswpgm
63 tbwpgm
+
=