Design Checklist

Design Checklist

3

3.1Overview

The following checklist is intended to be used for schematic reviews of Intel® 440GX AGPset desktop designs. It does not represent the only way to design the system, but provides recommendations based on the Intel® 440GX AGPset reference platform.

3.2Pull-up and Pull-down Resistor Values

Pull-up and pull-down values are system dependent. The appropriate value for your system can be determined from an AC/DC analysis of the pull-up voltage used, the current drive capability of the output driver, input leakage currents of all devices on the signal net, the pull-up voltage tolerance, the pull-up/pull-down resistor tolerance, the input high/low voltage specifications, the input timing specifications (RC rise time), etc. Analysis should be done to determine the minimum/maximum values that may be used on an individual signal. Engineering judgment should be used to determine the optimal value. This determination can include cost concerns, commonality considerations, manufacturing issues, specifications and other considerations.

A simplistic DC calculation for a pull-up value is:

RMAX = (VccPU MIN - VIH MIN) / ILeakage MAX

RMIN = (VccPU MAX - VIL MAX) / IOL MAX

Since ILeakage MAX is normally very small, RMAX may not be meaningful. RMAX is also determined by the maximum allowable rise time. The following calculation allows for t, the

maximum allowable rise time, and C, the total load capacitance in the circuit, including input capacitance of the devices to be driven, output capacitance of the driver, and line capacitance. This calculation yields the largest pull-up resistor allowable to meet the rise time t.

A simplistic AC calculation for a pull-up value is:=

RMAX = -t / ( C * ln( 1 - (VIH MIN / VccPU MIN) ) )

Intel®440GX AGPset Design Guide

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Intel 440GX manual Overview, Pull-up and Pull-down Resistor Values
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440GX specifications

The Intel 440GX chipset was launched in 1997 as part of Intel's series of chipsets known as the 440 family, and it served as a critical component for various Pentium II and Pentium III-based motherboard architectures. Specifically designed for the second generation of Intel’s processors, the 440GX delivered enhanced performance and supported a range of important technologies that defined PC architectures of its time.

One of the main features of the Intel 440GX was its support for a 100 MHz front-side bus (FSB), which significantly improved data transfer rates between the CPU and the memory subsystem. This advancement allowed the 440GX to accommodate both the original Pentium II processors as well as the later Pentium III chips, providing compatibility and flexibility for system builders and consumers alike.

The 440GX chipset included an integrated AGP (Accelerated Graphics Port) controller, which supported AGP 2x speeds. This enabled high-performance graphics cards to be utilized effectively, delivering many enhanced graphics capabilities for gaming and multimedia applications. The AGP interface was crucial at the time as it offered a dedicated pathway for graphics data, increasing bandwidth compared to traditional PCI slots.

In terms of memory support, the 440GX could address up to 512 MB of SDRAM, allowing systems built with this chipset to run comfortably with sufficient memory for the era’s demanding applications. The memory controller was capable of supporting both single and double-sided DIMMs, which provided versatility in memory configuration for system builders.

Another notable feature of the Intel 440GX was its support for multi-processor configurations through its Dual Processors support feature. This allowed enterprise and workstation computers to leverage the performance advantages of multiple CPUs, making the chipset suitable for business and professional environments where multitasking and high-performance computing were essential.

On the connectivity front, the chipset supported up to six PCI slots, enhancing peripheral device integration and expansion capabilities. It also included integrated IDE controllers, facilitating connections for hard drives and CD-ROM devices.

Overall, the Intel 440GX chipset represented a balanced combination of performance, flexibility, and technology advancements for its time. Its introduction helped establish a foundation for subsequent advancements in PC technology and set the stage for more powerful computing systems in the years to come.
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