MC68HC708XL36 FREESCALE [Freescale Semiconductor, Inc], MC68HC708XL36 Datasheet - Page 92

• Manufacturer Part Number: MC68HC708XL36
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

CGM
Programming the
PLL
MC68HC708XL36
92
NOTE:
Use the following procedure to program the PLL.
The round function means that the result is rounded to the nearest
integer.
1. Choose the desired bus frequency, f
2. Calculate the desired VCO frequency, f
3. Using a reference frequency, f
4. Calculate the VCO frequency, f
5. Calculate the bus frequency, f
Freescale Semiconductor, Inc.
For More Information On This Product,
calculate the VCO frequency multiplier, N.
If the calculated f
application, select another f
Go to: www.freescale.com
Example: f
Example: f
Example:
Example:
CGM
Example: f
bus
N
f
vclkdes
vclkdes
is not within the tolerance limits of your
vclk
f
=
f
vclk
bus
f
round
bus
= 8
N
=
=
= 4
= 4
busdes
busdes
=
32 MHz
------------------- -
=
N f
bus
rclk
32 MHz
------------------- -
4 MHz
vclk
4 MHz = 32 MHz
f
-------- -
4
vclk
f
----------------
4
8 MHz = 32 MHz
f
vclkdes
, and compare f
, equal to the crystal frequency,
busdes
f
= 8 MHz
or another f
rclk
.
rclk
busdes
=
vclkdes
=
8 MHz
8
.
.
rclk
.
bus
with f
MOTOROLA
10-cgm1m_a
busdes
.