W83628AG

Specialized Overview

The W83628AG is a PCI-to-ISA bus conversion integrated circuit manufactured by Nuvoton Technology Corporation. It operates with 5V ISA and 3.3V PCI interfaces, supporting PCI bus frequencies of 25MHz, 33MHz, and up to 40MHz. The device provides full ISA bus support including ISA Masters and PC/PCI DMA protocol for software-transparent transfers. It supports three fully ISA compatible slots without buffering and features programmable ISA bus divide ratios (3 or 4) to generate SYSCLK from the PCI clock. The component is housed in a 128-pin QFP package.

Specialized Feature Summary

• Provides complete PCI to ISA bridge functionality with subtractive decoding capabilities
• Supports PC/PCI DMA protocol for transparent data transfer between ISA and PCI buses
• Includes serialized IRQ interface to convert legacy parallel ISA interrupts to serial format
• Features programmable configuration registers for performance optimization and decoder control

Specialized Applications

• Bridge solution for Intel chipsets featuring LPC bus but lacking native ISA support
• Enabling legacy ISA expansion slots on modern motherboard designs
• System integration requiring compatibility with older ISA peripherals and controllers

Specialized Procurement Notes

Verify component authenticity through official manufacturer channels or authorized distributors. Confirm the specific revision level matches design requirements, as DC characteristics may vary between revisions. Ensure the 128-QFP package dimensions align with PCB layout specifications. Check for lead-free compliance if required by environmental regulations.

Specialized Selection Notes

Select the W83628AG when a dedicated PCI-to-ISA bridge is required for systems using LPC-based chipsets. This component must be paired with the W83629AG to form a complete bridge solution handling IRQ serialization and DMA control. Evaluate board space constraints as the 128-pin QFP package requires specific footprint allocation compared to single-chip solutions.

Specialized Part Context

The W83628AG functions as the primary bridge controller within the W83628AG/W83629AG pair. It handles address/data translation between PCI and ISA domains. The companion W83629AG manages interrupt serialization and DMA channel passing. Together they provide a cost-effective alternative to larger bridge chips for maintaining ISA compatibility in newer platform architectures.

Specialized Replacement Considerations

Public confirmed substitute part numbers: W83629AG (Companion IC). The W83627 family serves as an alternative LPC I/O solution that can integrate these functions into a single chip, though pinouts and configuration methods differ significantly.