MPC875CVR133 datasheet(14/84 Pages) FREESCALE

14 / 84 page

MPC875/MPC870 PowerQUICC™ Hardware Specifications, Rev. 4

Freescale Semiconductor

Power Supply and Power Sequencing

7.5

Experimental Determination

To determine the junction temperature of the device in the application after prototypes are available, the

thermal characterization parameter (

ΨJT) can be used to determine the junction temperature with a

measurement of the temperature at the top center of the package case using the following equation:

TJ = TT + (ΨJT × PD)

where:

ΨJT = thermal characterization parameter

TT = thermocouple temperature on top of package

PD = power dissipation in package

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

References

Semiconductor Equipment and Materials International

(415) 964-5111

805 East Middlefield Rd

Mountain View, CA 94043

MIL-SPEC and EIA/JESD (JEDEC) specifications

800-854-7179 or

(Available from Global Engineering Documents)

303-397-7956

JEDEC Specifications

http://www.jedec.org

1. C.E. Triplett and B. Joiner, “An Experimental Characterization of a 272 PBGA Within an

Automotive Engine Controller Module,” Proceedings of SemiTherm, San Diego, 1998, pp. 47–54.

2. 2. B. Joiner and V. Adams, “Measurement and Simulation of Junction to Board Thermal

Resistance and Its Application in Thermal Modeling,” Proceedings of SemiTherm, San Diego,

1999, pp. 212–220.

Power Supply and Power Sequencing

This section provides design considerations for the MPC875/MPC870 power supply. The

MPC875/MPC870 has a core voltage (VDDL) and PLL voltage (VDDSYN), which both operate at a lower

voltage than the I/O voltage (VDDH). The I/O section of the MPC875/MPC870 is supplied with 3.3 V

across VDDH and VSS (GND).

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 VDDH. In addition, 5-V tolerant pins cannot exceed 5.5 V, and remaining input pins cannot

exceed 3.465 V. This restriction applies to power up, power down, and normal operation.

MPC875CVR133 Datasheet(PDF) 14 Page - Freescale Semiconductor, Inc

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