Clock and Board Guidelines
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
C-5
•
EXTAL pad capacitance is C
PAD
= ~7 pF
C
SOCKET
is socket and board trace capacitance
•
Socket capacitance C <=1pF
•
Board trace capacitance C <=1pF. This should be low since the crystal must be located very close
to the chip.
C.2.1
KAPWR Filtering
The KAPWR signal is the MPC561/MPC563 keep-alive power. KAPWR is used for the crystal oscillator
circuit, and should be isolated from the noisy supplies. It is recommended that an RC filter be used on
KAPWR, or bypass capacitors that are located as close as possible to the part.
Figure C-4. RC Filter Example
Figure C-5. Bypass Capacitors Example (Alternative)
C.2.2
PLL External Components
VDDSYN and VSSSYN are the PLL dedicated power supplies. These supplies must be used only for the
PLL and isolated from all other noisy signals in the board. VDDSYN could be isolated with RC filter (see
), or LC filter. The maximum noise allowed on VDDSYN, and VSSSYN is 50 mV with typical
cut-off frequency of 500 Hz.
KAPWR
VSSSYN
KAP 2.6 V
100 nF
<10
Ω
Board
MPC56x Device
Note: A filter cut off frequency of 500Hz is recommended, however this will result in a
capacitor size of 33uF using a 10 Ohm resistor. This may be too expensive or large
for the system. In this case the filter shown with cut- off frequency of 160kHz will suffice.
KAPWR
VSSSYN
KAP 2.6 V
100 nF
1 µF
Board
MPC56x Device
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...
