MPC855 datasheet(13/76 Pages) MOTOROLA

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MOTOROLA

MPC860 Family Hardware Speciﬁcations

References

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. 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.

Part VIII Layout Practices

Each V

DD pin on the MPC860 should be provided with a low-impedance path to the board’s

supply. Each GND pin should likewise be provided with a low-impedance path to ground.

The power supply pins drive distinct groups of logic on chip. The V

DD power supply should

be bypassed to ground using at least four 0.1 µF-bypass capacitors located as close as

possible to the four sides of the package. The capacitor leads and associated printed circuit

traces connecting to chip V

DD and GND should be kept to less than half an inch per

capacitor lead. A four-layer board is recommended, employing two inner layers as V

CC and

GND planes.

All output pins on the MPC860 have fast rise and fall times. Printed circuit (PC) trace

interconnection length should be minimized in order to minimize undershoot and

reﬂections caused by these fast output switching times. This recommendation particularly

applies to the address and data busses. Maximum PC trace lengths of 6 inches are

recommended. Capacitance calculations should consider all device loads as well as

parasitic capacitances due to the PC traces. Attention to proper PCB layout and bypassing

becomes especially critical in systems with higher capacitive loads because these loads

create higher transient currents in the V

CC and GND circuits. Pull up all unused inputs or

signals that will be inputs during reset. Special care should be taken to minimize the noise

levels on the PLL supply pins.

Part IX Bus Signal Timing

Table 9-6 provides the bus operation timing for the MPC860 at 33, 40, 50, and 66 MHz.

The maximum bus speed supported by the MPC860 is 66 MHz. Higher-speed parts must

be operated in half-speed bus mode (for example, an MPC860 used at 80 MHz must be

conﬁgured for a 40 MHz bus).

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