Design Checklist

standby voltage is not provided by the power supply, then tie PWROK signal on the PIIX4E to the RSMRST# signal.

•If an 8.2K ohm resistor divider is used to divide the RSMRST# signal down to a 3V level for input to the PIIX4E, the rise time of this signal will be approximately 170ns (based on the input capacitance of the PIIX4E), which is within the maximum 250ns requirement of the PIIX4E. It is important that if any other components are connected to RSMRST#, the resistor divider values may need to be adjusted to meet a faster rise time required by the other devices and increased loading. 3V driving devices, such as an 74LVC14 could also be used as a replacement for the voltage divider.

•It is important to prevent glitches on the PWROK signal while the core well is being powered up or down. To accommodate this, the reference schematics shows a pull-up resistor to 3VSB in the last stage of this circuitry to keep PWROK from glitching when the core supply goes out of regulation.

•All logic and pull-ups in the path of PWRGOOD to the CPU, and PWROK to the PIIX4E (with the above exception) can be powered from the core supply.

•The PWROK signal to the chipset is a 3V signal.

•The core well power valid to PWROK asserted at the chipset is a minimum of 1msec.

•PWROK to the chipset must be deasserted a minimum of 0ns after RSMRST#.

•PWRGOOD signal to CPU is driven with an open collector buffer pulled up to 2.5V using a 330 ohm resistor.

•Below is a simplified diagram of the PWRGOOD and PWROK logic which is connected to the CPU slots and PIIX4E respectively in a DP system. The circuitry checks for both slots occupied, both CPU VRMs powered up, and the PS_POK signal from the ATX power supply connector before asserting PWRGOOD and PWROK to the CPU and PIIX4E. A reset button override pull-down is also included, causing the PWRGOOD and PWROK signals to get deasserted when pressed.

Figure 3-8. PWRGOOD & PWROK Logic

Simplified

P W R G O O D a n d P W R O K

generation logic

VCC3

A _ S L O T O C C

B _ S L O T O C C4.7K V R M 1 _ P W R G D

V R M 2 _ P W R G D

I T P _ R E S E T

A T X _ P S _ P O K

Note: The polarities have been altered to simplify drawing.

PWRGOOD to CPU

(2.5V)

PWROK to PIIX4E (3.3V)

v 0 1 1

•The following should be considered when implementing a RESET BUTTON for desktop based systems:

Intel®440GX AGPset Design Guide

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Intel 440GX manual VCC3
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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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