MPC8535ECVTATH datasheet(115/126 Pages) FREESCALE

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SerDes Block Power Supply Decoupling Recommendations

MPC8535E PowerQUICC™ III Integrated Processor Hardware Specifications, Rev. 2

Freescale Semiconductor

115

These capacitors should have a value of 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). However, customers should work directly with their power regulator vendor for best values types

and quantity of bulk capacitors.

3.5

SerDes Block Power Supply Decoupling Recommendations

he SerDes1 and SerDes2 blocks require a clean, tightly regulated source of power (SnVDD and XnVDD) 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 from each SerDes supply (SnVDD and XnVDD) to the board

ground plane 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.

3.6

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

3.7

Pull-Up and Pull-Down Resistor Requirements

The MPC8535E 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 78.

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.

The following pins must NOT be pulled down during power-on reset: TSEC1_TXD[3], HRESET_REQ,

TRIG_OUT/READY/QUIESCE, MSRCID[2:4], ASLEEP. The UART_SOUT[0:1] and TEST_SEL pins must be set to a

proper state during POR configuration. Please refer to the pinlist table (see Table 62) of the individual device for more details.

See the PCI 2.2 specification for all pull-ups required for PCI.

3.8

Output Buffer DC Impedance

The MPC8535E drivers are characterized over process, voltage, and temperature. For all buses, the driver is a push-pull

single-ended driver type (open drain for I

2C).

MPC8535ECVTATH Datasheet(PDF) 115 Page - Freescale Semiconductor, Inc

MPC8535ECVTATH Datasheet(HTML) 115 Page - Freescale Semiconductor, Inc

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