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Appendix A Electrical Characteristics
MC9S12XE-Family Reference Manual , Rev. 1.07
940
Freescale Semiconductor
A.3
NVM, Flash and Emulated EEPROM
A.3.1
Timing Parameters
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. When attempting to program or erase the NVM
modules at a lower frequency, a full program or erase transition is not assured.
The program and erase operations are timed using a clock derived from the oscillator using the FCLKDIV
register. 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-18
are calculated for maximum f
NVMOP
and
maximum f
bus
unless otherwise shown. The maximum times are calculated for minimum f
NVMOP
.
A.3.1.1
Program Flash Phrase Programming
The programming time for a single phrase of four program flash words + associated eight ECC bits is
dependant on the bus frequency as a well as on the frequency f
NVMOP
and can be calculated according to
the following formulas, whereby N
DLOAD
is the number of extra blocks being programmed by DLOAD,
i.e. programming 2,3,4 blocks using DLOAD, N
DLOAD
=1,2,3 respectively.
The typical phrase programming time can be calculated using the following equation
The maximum phrase programming time can be calculated using the following equation
A.3.1.2
Program Flash Sector Erase
The typical time to erase a1024-byte Program flash sector can be calculated using:
The maximum time to erase a1024-byte Program flash sector can be calculated using:
3
These values include the quantization error which is inherently 1/2 count for any A/D converter.
t
bwpgm
132
1
f
NVMOP
------------------
1515
1150 N
DLOAD
(
)
+
(
)
1
f
NVMBUS
---------------------
+
=
t
bwpgm
132
1
f
NVMOP
------------------
1915
1550 N
DLOAD
(
)
+
(
)
1
f
NVMBUS
---------------------
+
=
t
era
20000
1
f
NVMOP
------------------
700
1
f
NVMBUS
---------------------
+
=
t
era
20000
1
f
NVMOP
------------------
1100
1
f
NVMBUS
---------------------
+
=