MPC555 / MPC556
CLOCK AND BOARD GUIDELINES
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
E-2
E.2 MPC555 / MPC556 Family Power Distribution
Figure E-1 MPC555 / MPC556 Family Power Distribution Diagram — 3 V
BOARD
VDDL (external 3 V)
VSS (external gnd -
VDDI (internal 3 V)
VSS (internal gnd)
VDDSYN
XFC
VSSSYN
EXTAL
XTAL
KAPWR
VDDSRAM
Keyed
Vcc 3.3 V
KAP 3 V
Cx(pf)
Cy(pf)
>10
Ω
100 nF
Cxfc
100 nF
100 nF
100 nF
<50
Ω
1
µ
F
1 nF
1 nF
1
µ
F
100 nF
R1
3
NOTE 3: All 100 nF capacitors should be
placed close to the pin.
MPC555
/
MPC556
(1 for each pad,
8 total)
(1 for each pad
4 total)
shorted to vss)
(Main Supply)
NOTE 1: The main power supply may
optionally supply operating current to reduce
the keep alive current requirements.
See the circuit in
8.12.1 System Clock Control Register (SCCR)
NOTE 2:
Resistor R
1
is currently not required.
Space should be left on the board to add it
in the future if necessary.
VDDF
NOTE 4: C
L
is a function of specific crystal, C
L
= C
X
+ C
Y.
Q1
100 nF
F
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sc
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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