mpc8313e Freescale Semiconductor, Inc, mpc8313e Datasheet - Page 81

• Manufacturer Part Number: mpc8313e
• Description: Mpc8313e Powerquicc Ii Pro Processor
• Manufacturer: Freescale Semiconductor, Inc

20.3.1
When heat sink is used, the junction temperature is determined from a thermocouple inserted at the
interface between the case of the package and the interface material. A clearance slot or hole is normally
required in the heat sink. Minimizing the size of the clearance is important to minimize the change in
thermal performance caused by removing part of the thermal interface to the heat sink. Because of the
experimental difficulties with this technique, many engineers measure the heat sink temperature and then
back calculate the case temperature using a separate measurement of the thermal resistance of the
interface. From this case temperature, the junction temperature is determined from the junction to case
thermal resistance.
21 System Design Information
This section provides electrical and thermal design recommendations for successful application of the
MPC8313E SYS_CLK_IN
21.1
The MPC8313E includes two PLLs.
21.2
Each of the PLLs listed above is provided with power through independent power supply pins (AV
AV
will be derived directly from V
There are a number of ways to reliably provide power to the PLLs, but the recommended solution is to
provide five independent filter circuits as illustrated in
providing independent filters to each PLL the opportunity to cause noise injection from one PLL to the
other is reduced.
Freescale Semiconductor
DD2
1. The platform PLL (AV
2. The e300 Core PLL (AV
SYS_CLK_IN input in PCI host mode or SYS_CLK_IN/PCI_SYNC_IN in PCI agent mode. The
frequency ratio between the platform and SYS_CLK_IN is selected using the platform PLL ratio
configuration bits as described in
frequency ratio between the e300 core clock and the platform clock is selected using the e300
PLL ratio configuration bits as described in
respectively). The AV
System Clocking
PLL Power Supply Filtering
Experimental Determination of the Junction Temperature with a
Heat Sink
Where:
MPC8313E PowerQUICC
T
T
T
R
P
J
J
C
θ
D
JC
= junction temperature (°C)
= T
= case temperature of the package
= power dissipation
= junction-to-case thermal resistance
DD
DD2
C
DD
DD1
+ (R
level should always be equivalent to V
)
through a low frequency filter scheme such as the following.
generates the platform clock from the externally supplied
)
θ
generates the core clock as a slave to the platform clock. The
JC
™
x P
Section 19.1, “System PLL
II Pro Processor Hardware Specifications, Rev. 0
D
)
Section 19.2, “Core PLL Configuration.”
Figure
40, one to each of the five AV
Configuration.”
DD
, and preferably these voltages
System Design Information
DD
pins. By
DD1
,
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