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MC68F375
CDR MoneT FLASH FOR THE IMB3 (CMFI)
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
10-21
WARNING
Never stop or alter the IMB3 clock frequency during program or erase
operation. Changing the clock frequency during program or erase will
result in inaccurate pulse widths and variations in the charge trans-
ferred to the array bits.
The value of SCLKR is forced to the user defined value in the corresponding shadow
information words on master reset. When SCLKR[2:0] = 000, the pulse width timer
control will not terminate the program or erase pulse therefore the user must clear EHV
via a software write.
The value of CLKPE[1:0] is forced to the user defined value in the corresponding
shadow information words on master reset, as is the value of CLKPM[6:0].
10.4.9 A Technique to Determine SCLKR, CLKPE, and CLKPM
The following example determines the values of the SCLKR, CLKPE, and CLKPM
fields for a 51.4
S pulse program pulse, PE=0, in a system with a 33.0 MHz system
clock.
In this example system clock frequency = 33.0 MHz; the system clock period is there-
fore 30.3 nS.
1. Determine SCLKR:
From Table 10-11 a 33.0 MHz system clock uses SCLKR[0:2]=100, R=3.
2. Determine CLKPE:
From Table 10-12 a 51.4 S program pulse, PE=0, can be generated by expo-
Table 10-12 Clock Period Exponent and Pulse Width Range
PE
CLKPE[0:1
]
Exponent
(N)
Pulse Width Range for all System Clock
Frequencies from 8.0 MHz to 33.0 MHz.
Minimum Pulse Width
Maximum Pulse Width
8 MHz1
2N1.25E-7
NOTES:
1. CMF clock frequency after SCKLR scaling. Example: A 32 MHz system clock scaled by 3 (SCLKR[0:2] = 0b100)
results in an equivalent CMF clock of 10 MHz.
10 MHz1
2N1E-7
12 MHz1
2N0.833E-7
8 MHz1
2N1.25E-07
10 MHz1
2N1E-7
12 MHz1
2N0.833E-7
0
00
5
4 s
3.2 s
2.7 s
512 s
409.6 s
341.3 s
01
6
8 s
6.4 s
5.3 s
1.024 ms
819.2 s
682.7 s
10
7
16 s
12.8 s
10.7 s
2.048 ms
1.6384 ms
1.365 ms
11
8
32 s
25.6 s
21.3 s
4.096 ms
3.2768 ms
2.731 ms
1
00
15
4.096 ms
3.28 ms
2.73 ms
524.29 ms
419.43 ms
349.5 ms
01
16
8.192 ms
6.55 ms
5.46 ms
1.05 s
838.86 ms
699.1 ms
10
17
16.384 ms
13.11 ms
10.92 ms
2.10 s
1.68 s
1.398 s
11
18
32.768 ms
26.21 ms
21.85 ms
4.19 s
3.35 s
2.796 s
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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