MPC555
/
MPC556
CLOCKS AND POWER CONTROL
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
8-2
Figure 8-1 Clock Unit Block Diagram
2:1
SPLL
Clock
GCLK1 / GCLK2
GCLK1C / GCLK2C
VCOOUT
CLKOUT
3:1 MUX
S
y
s
tem
L
o
w
-P
ow
e
r C
o
nt
ro
l
XFC
TMBclk
TMBCLK
Lock
VDDSYN
Drivers
Driver
Main Clock
XTAL
EXTAL
3:1
MUX
RTC / PIT Clock
and DRIVER
Oscillator
MUX
TBCLK
(/4 or /16)
MO
DCK[1:3
]
PITRTCLK
EXTCLK
2:1 MUX
Low
Power
Dividers
(1/2N)
/4 or /256
GCLK2
Back_Up Clock
Detector
Oscillator Loss
ENGCLK
VSSSYN
Drivers
SYSTEM CLOCK
SYSTEM CLOCK
TO RCPU AND BBC
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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