MPC875 Freescale Semiconductor, Inc, MPC875 Datasheet - Page 14

• Manufacturer Part Number: MPC875
• Description: Mpc875 Powerquicc Integrated Communications Processor
• Manufacturer: Freescale Semiconductor, Inc

Power Supply and Power Sequencing
7.5
To determine the junction temperature of the device in the application after prototypes are available, the
thermal characterization parameter (Ψ
measurement of the temperature at the top center of the package case using the following equation:
where:
The thermal characterization parameter is measured per the JESD51-2 specification published by JEDEC
using a 40 gauge type T thermocouple epoxied to the top center of the package case. The thermocouple
should be positioned so that the thermocouple junction rests on the package. A small amount of epoxy is
placed over the thermocouple junction and over about 1 mm of wire extending from the junction. The
thermocouple wire is placed flat against the package case to avoid measurement errors caused by the
cooling effects of the thermocouple wire.
7.6
8
This section provides design considerations for the MPC875/MPC870 power supply. The
MPC875/MPC870 has a core voltage (V
voltage than the I/O voltage (V
across V
The signals PA[0:3], PA[8:11], PB15, PB[24:25], PB[28:31], PC[4:7], PC[12:13], PC15, PD[3:15], TDI,
TDO, TCK, TRST, TMS, MII_TXEN, and MII_MDIO are 5 V tolerant. No input can be more than 2.5 V
greater than V
exceed 3.465 V. This restriction applies to power up, power down, and normal operation.
14
1. C.E. Triplett and B. Joiner, “An Experimental Characterization of a 272 PBGA Within an
2. 2. B. Joiner and V. Adams, “Measurement and Simulation of Junction to Board Thermal
Ψ
T
P
Semiconductor Equipment and Materials International
805 East Middlefield Rd
Mountain View, CA 94043
MIL-SPEC and EIA/JESD (JEDEC) specifications
(Available from Global Engineering Documents)
JEDEC Specifications
Automotive Engine Controller Module,” Proceedings of SemiTherm, San Diego, 1998, pp. 47–54.
Resistance and Its Application in Thermal Modeling,” Proceedings of SemiTherm, San Diego,
1999, pp. 212–220.
Power Supply and Power Sequencing
DDH
D
T
JT
Experimental Determination
References
= thermocouple temperature on top of package
= power dissipation in package
= thermal characterization parameter
and V
T
DDH
J
= T
. In addition, 5-V tolerant pins cannot exceed 5.5 V, and remaining input pins cannot
SS
T
+ (Ψ
(GND).
MPC875/MPC870 PowerQUICC™ Hardware Specifications, Rev. 4
JT
× P
DDH
D
)
). The I/O section of the MPC875/MPC870 is supplied with 3.3 V
JT
) can be used to determine the junction temperature with a
DDL
) and PLL voltage (V
DDSYN
[phone]
800-854-7179 or
303-397-7956
http://www.jedec.org
), which both operate at a lower
Freescale Semiconductor