mpc8641 Freescale Semiconductor, Inc, mpc8641 Datasheet - Page 118

• Manufacturer Part Number: mpc8641
• Description: Integrated Host Processor Hardware Specifications
• Manufacturer: Freescale Semiconductor, Inc

System Design Information
The AV
of the internal clock, the power supplied to the PLL is filtered using a circuit similar to the one shown in
following figure. For maximum effectiveness, the filter circuit is placed as closely as possible to the
AV
near the AV
capacitors, and finally the 1 Ω resistor to the board supply plane. The capacitors are connected from
AV
frequency. All traces should be kept short, wide and direct.
Note the following:
20.2.2
For details on power sequencing for the AV
Sequence.”
20.3
Due to large address and data buses, and high operating frequencies, the device can generate transient
power surges and high frequency noise in its power supply, especially while driving large capacitive loads.
This noise must be prevented from reaching other components in the MPC8641 system, and the device
itself requires a clean, tightly regulated source of power. Therefore, it is recommended that the system
118
DD
DD
V
•
•
DD
_SRDSn balls to ensure it filters out as much noise as possible. The ground connection should be
_SRDSn to the ground plane. Use ceramic chip capacitors with the highest possible self-resonant
_Core0/1
AV
Signals on the SerDes interface are fed from the SV
DD
Decoupling Recommendations
_SRDSn signals provide power for the analog portions of the SerDes PLL. To ensure stability
DD
DD
PLL Power Supply Sequencing
_SRDSn should be a filtered version of SV
_SRDSn balls. The 0.003-µF capacitor is closest to the balls, followed by the two 2.2-µF
MPC8641 and MPC8641D Integrated Host Processor Hardware Specifications, Rev. 2
Filter Circuit (should not be used for Single core device)
SV
Note: For single core device the filter circuit (in the dashed box) should
be removed and AV
(2-10 kΩ) pull-down resistor.
1. An 0805 sized capacitor is recommended for system initial bring-up.
DD
Figure 64. MPC8641 PLL Power Supply Filter Circuit (for cores)
10 Ω
1.0 Ω
Figure 65. SerDes PLL Power Supply Filter
2.2 µF
DD
_Core1 should be tied to ground with a weak
2.2 µF
GND
DD
1
Low ESL Surface Mount Capacitors
type and supplies refer to
2.2 µF
GND
2.2 µF
DD
1
DD
AV
.
DD
power plan.
_Core0/1
0.003 µF
Section 2.2, “Power Up/Down
AV
DD
_SRDS n
Freescale Semiconductor