mc68hc908sr12 Freescale Semiconductor, Inc, mc68hc908sr12 Datasheet - Page 122

• Manufacturer Part Number: mc68hc908sr12
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Clock Generator Module (CGM)
Data Sheet
122
NOTE:
Exceeding the recommended maximum bus frequency or VCO
frequency can crash the MCU.
5. Select the VCO’s power-of-two range multiplier E, according to
6. Select a VCO linear range multiplier, L, where f
7. Calculate and verify the adequacy of the VCO programmed
8. Verify the choice of P, R, N, E, and L by comparing f
this table:
center-of-range frequency, f
the midpoint between the minimum and maximum frequencies
attainable by the PLL.
For proper operation,
and f
application’s tolerance of f
possible to f
NOTE: Do not program E to a value of 3.
Clock Generator Module (CGM)
VCLKDES
19,660,800 ≤ f
9,830,400 ≤ f
VCLK.
. For proper operation, f
0 < f
Frequency Range
VCLK
f
VRS
L
f
VCLK
VCLK
VRS
=
< 9,830,400
–
round
f
MC68HC908SR12•MC68HC08SR12 — Rev. 5.0
< 19,660,800
=
VCLK
< 39,321,600
VCLKDES
(
VRS
L
⎛
⎜
⎝
×
--------------------------
2
≤
E
2
. The center-of-range frequency is
f
f
--------------------------
E
VCLK
×
NOM
)f
f
, and f
NOM
NOM
2
×
VCLK
⎞
⎟
⎠
2
E
VRS
must be within the
Freescale Semiconductor
must be as close as
NOM
E
0
1
2
= 38.4kHz
VCLK
to f
VRS