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Appendix A Electrical Characteristics
MC9S12XDP512 Data Sheet, Rev. 2.11
938 Freescale Semiconductor
A.3 NVM, Flash, and EEPROM
NOTE
Unless otherwise noted the abbreviation NVM (nonvolatile 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-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
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.
A.3.1.2 Burst Programming
This applies only to the Flash where up to 64 words in a row can be programmed consecutively using burst
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.
t
swpgm
9
1
f
NVMOP
-------------------------
⋅ 25
1
f
bus
------------
⋅+=
t
bwpgm
4
1
f
NVMOP
-------------------------
⋅ 9
1
f
bus
------------
⋅+=
t
brpgm
t
swpgm
63 t
bwpgm
⋅+=