Mobile Intel Pentium 4 Processor - M and Intel 845MP/MZ Chipset Platform Design Guide

Mobile Intel

Pentium

4 Processor-M and Intel

845MP/845MZ Chipset Platform

Design Guide 43

Figure 15. Filter Recommendation

0 dB

-28 dB

-34 dB

0.2 dB

forbidden

zone

-0.5 dB

forbidden

zone

1 MHz 66 MHz

core

peak1 HzDC

passband

high frequency

band

NOTES:

1. Diagram not to scale.

2. No specification for frequencies beyond fcore (core frequency).

3. fpeak, if existent, should be less than 0.05 MHz.

Other recommendations:

• Capacitors for the filter can be any value between 22 µF and 100 µF as long components with ESL

≤ 5 nH and ESR < 0.3 Ω are used.

• Values of either 4.7 µH or 10 µH may be used for the inductor.

• Use shielded type inductors to minimize magnetic pickup

• Filter should support DC current > 60 mA

• DC voltage drop from VCC_CPU to VCCA should be < 60 mV

• In order to maintain a DC drop of less than 60 mV, the total DC resistance of the filter from

VCC_VID to the processor socket should be a maximum of 1 µ.

Other routing requirements:

• C should be within 600 mils of the VCCA and VSSA pins. An example of the component placement

is shown in Figure 16

• VCCA route should be parallel and next to VSSA route (minimize loop area)

• A minimum of a 12-mil trace should be used to route from the filter to the processor pins.

• L should be close to C