mc9s08ac16 Freescale Semiconductor, Inc, mc9s08ac16 Datasheet - Page 150

• Manufacturer Part Number: mc9s08ac16
• Description: Hcs08 Microcontrollers 8-bit Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 8 Internal Clock Generator (S08ICGV4)
The following sections contain initialization examples for various configurations.
Important configuration information is repeated here for reference.
1
150
1
SCM — self-clocked mode (FLL bypassed
internal)
FBE — FLL bypassed external
FEI — FLL engaged internal
FEE — FLL engaged external
Ensure that
MFD Value
The IRG typically consumes 100 μA. The FLL and DCO typically consumes 0.5 to 2.5 mA, depending upon output frequency.
For minimum power consumption and minimum jitter, choose N and R to be as small as possible.
Bypassed
Engaged
FLL
FLL
000
001
010
011
100
f
ICGDCLK
Clock Scheme
Hexadecimal values designated by a preceding $, binary values designated
by a preceding %, and decimal values have no preceding character.
FEI
4 MHz < f
Medium power (will be less than FEE if oscillator
range = high)
Good clock accuracy (After IRG is trimmed)
Lowest system cost (no external components
required)
IRG is on. DCO is on.
SCM
This mode is mainly provided for quick and reliable
system startup.
3 MHz < f
3 MHz < f
Medium power
Poor accuracy.
IRG is off. DCO is on and open loop.
Multiplication Factor (N)
, which is equal to
Clock Reference Source = Internal
Bus
Bus
Bus
< 20 MHz.
< 5 MHz (default).
< 20 MHz (via filter bits).
Table 8-11. ICGOUT Frequency Calculation Options
10
12
4
6
8
Table 8-10. ICG Configuration Consideration
Table 8-12. MFD and RFD Decode Table
1
MC9S08AC16 Series Data Sheet, Rev. 0
f
ICGOUT
(f
IRG
* R, does not exceed f
f
ext
f
ICGDCLK
/ 7)* 64 * N / R
PRELIMINARY
f
ICGOUT
f
* P * N / R
ext
NOTE
/ R
/ R
1
FEE
4 MHz < f
Medium power (will be less than FEI if oscillator
range = low)
High clock accuracy
Medium/High system cost (crystal, resonator or
external clock source required)
IRG is off. DCO is on.
FBE
f
used.
Lowest power
Highest clock accuracy
Medium/High system cost (Crystal, resonator or
external clock source required)
IRG is off. DCO is off.
RFD
Bus
000
001
010
011
100
Range = 0 ; P = 64
Range = 1; P = 1
ICGDCLKmax
range ≤ 8 MHz when crystal or resonator is
Clock Reference Source = External
Bus
NA
NA
64
P
< 20 MHz
.
Division Factor (R)
Typical f
immediately after reset
Typical f
Freescale Semiconductor
÷16
÷1
÷2
÷4
÷8
ICGOUT
IRG
Note
= 243 kHz
= 8 MHz