PPC8567EVTAUGGA datasheet(132/139 Pages) FREESCALE

132 / 139 page

MPC8568E/MPC8567E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 1

132

Freescale Semiconductor

System Design Information

These capacitors should have a value of 0.01 or 0.1 µF. Only ceramic SMT (surface mount technology)

capacitors should be used to minimize lead inductance, preferably 0402 or 0603 sizes.

In addition, it is recommended that there be several bulk storage capacitors distributed around the PCB,

feeding the VDD, TVDD, BVDD, OVDD, GVDD, and LVDD planes, to enable quick recharging of the

smaller chip capacitors. These bulk capacitors should have a low ESR (equivalent series resistance) rating

to ensure the quick response time necessary. They should also be connected to the power and ground

planes through two vias to minimize inductance. Suggested bulk capacitors—100–330 µF (AVX TPS

tantalum or Sanyo OSCON).

25.4

SerDes Block Power Supply Decoupling Recommendations

The SerDes block requires a clean, tightly regulated source of power (SCOREVDD and XVDD) to ensure

low jitter on transmit and reliable recovery of data in the receiver. An appropriate decoupling scheme is

outlined below.

Only surface mount technology (SMT) capacitors should be used to minimize inductance. Connections

from all capacitors to power and ground should be done with multiple vias to further reduce inductance.

•

First, the board should have at least 10 x 10-nF SMT ceramic chip capacitors as close as possible

to the supply balls of the device. Where the board has blind vias, these capacitors should be placed

directly below the chip supply and ground connections. Where the board does not have blind vias,

these capacitors should be placed in a ring around the device as close to the supply and ground

connections as possible.

•

Second, there should be a 1-µF ceramic chip capacitor on each side of the device. This should be

done for all SerDes supplies.

•

Third, between the device and any SerDes voltage regulator there should be a 10-µF, low

equivalent series resistance (ESR) SMT tantalum chip capacitor and a 100-µF, low ESR SMT

tantalum chip capacitor. This should be done for all SerDes supplies.

25.5

Connection Recommendations

To ensure reliable operation, it is highly recommended to connect unused inputs to an appropriate signal

level. All unused active low inputs should be tied to VDD, TVDD, BVDD, OVDD, GVDD and LVDD as

required. All unused active high inputs should be connected to GND. All NC (no-connect) signals must

remain unconnected. Power and ground connections must be made to all external VDD, LVDD, TVDD,

BVDD, OVDD, GVDD and GND pins of the device.

25.6

Pull-Up and Pull-Down Resistor Requirements

The MPC8568E requires weak pull-up resistors (2–10 k

Ω is recommended) on open drain type pins

including I2C pins and MPIC interrupt pins.

Correct operation of the JTAG interface requires configuration of a group of system control pins as

demonstrated in Figure 75. Care must be taken to ensure that these pins are maintained at a valid deasserted

state under normal operating conditions as most have asynchronous behavior and spurious assertion will

give unpredictable results.

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