Intel® 820E Chipset

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2.24.ICH2 Design Checklist

This checklist highlights design considerations that should be reviewed before manufacturing an Intel 820E chipset-based motherboard that implements an ICH2. The entries in this checklist should provide the important connections to these devices and any critical supporting circuitry. This is not a complete list and it doesn’t guarantee that a design will function properly.

This list is only a reference. For correct operation, all design guidelines within this document must be followed.

Table 26. PCI Interface

Checklist Items

Recommendations

Reason/Effect

 

 

 

FYI

Inputs to the ICH2 must not be left

Many GPIO signals are fixed inputs that

 

floating.

must be pulled up to different sources.

 

 

See the GPIO section for

 

 

recommendations

 

 

 

PERR#, SERR#, PLOCK#,

These signals require a pull-up

See the PCI 2.2 Component

STOP#, DEVSEL#, TRDY#,

resistor. An 8.2 kpull-up resistor

Specification.

IRDY#, FRAME#, REQ#[4:0],

to VCC 3.3 V or a 2.7 kpull-up

Pull-up recommendations for VCC 3.3 V

GPIO[1:0], THRM#

resistor to VCC 5 V is

and VCC 5 V

 

recommended.

 

 

 

 

 

PCIRST#

The PCIRST#signal should be

Improves signal integrity

 

buffered to for the IDERST# signal.

 

 

33 series resistor to IDE

 

 

connectors

 

 

 

 

PCIGNT#

No external pull-ups are required

These signals are actively driven by the

 

on PCI GNT signals. However, if

ICH2.

 

external pull-ups are implemented,

 

 

they must be pulled up to VCC

 

 

3.3 V.

 

 

 

 

PME#

No extra pull-up resistors

This signal has an integrated pull-up of 9

 

 

k± 3 k.

 

 

 

SERIRQ

External weak (8.2 k) pull-up

Open-drain signal

 

resistor to VCC 3.3 V is

 

 

recommended.

 

 

 

 

GNT[A]# / GPIO[16], GNT[B] /

No extra pull-up is needed.

These signals have integrated pull-ups

GNT[5]# / GPIO[17]

 

of 24 k.

 

 

GNT[A] has an added strap function of

 

 

“top block swap.” The signal is sampled

 

 

on the rising edge of PWROK. The

 

 

default value is high or disabled due to

 

 

the pull-up. A jumper to a pull-down

 

 

resistor can be added to manually

 

 

enable the function.

 

 

 

Design Guide

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Intel 820E manual ICH2 Design Checklist, PCI Interface, Checklist Items Recommendations Reason/Effect