AM79C940BKI

Overview

The AM79C940BKI is a Media Access Controller for Ethernet (MACE) manufactured by Rochester Electronics, LLC. It integrates a Manchester encoder/decoder and supports IEEE 802.3 standards. The component features an 80-pin Thin Quad Flat Pack (TQFP) package designed for space-critical applications such as PCMCIA. It includes a high-speed 16-bit synchronous host interface with transfer cycles of two or three. Internal FIFOs provide 136 bytes for transmit and 128 bytes for receive operations to manage system latency.

Feature Summary

• Integrated controller with Manchester encoder/decoder and AUI port support
• Modular architecture allowing tuning to specific embedded applications
• Direct slave access to configuration registers and FIFOs for DMA compatibility
• Supports JTAG Boundary Scan test access port for board-level production testing

Applications

• Embedded microcontroller Ethernet solutions
• PCMCIA cards requiring space-constrained designs
• Bridge and router applications utilizing external address filtering

Procurement Notes

Verify the manufacturer designation on the component marking against the specified part number. Confirm the package type matches the 80-pin TQFP requirement. Ensure the device meets the necessary environmental specifications for the intended operating temperature range. Check for any specific revision codes that may affect pinout or electrical characteristics compared to original AMD datasheets.

Selection Notes

Select this component when a dedicated MACE controller is required for 10BASE-T Ethernet integration. The 80-pin TQFP package is suitable for applications with strict board space limitations. Consider the integrated FIFO sizes for buffer requirements in systems lacking direct DMA controllers. Verify compatibility with the host system's 16-bit synchronous interface timing constraints.

Part Context

This part belongs to the Am79C940 family of Ethernet media access controllers originally developed by Advanced Micro Devices. Rochester Electronics provides lifecycle support for these legacy components. The B suffix typically denotes a specific speed grade or manufacturing lot within the series. The KI suffix indicates the specific package and temperature rating combination.

Replacement Considerations

The AM79C940JC is a functionally equivalent part from the same family. DP83815 offers similar MAC functionality but integrates physical layer capabilities. Verify pin compatibility before substituting with National Semiconductor or Texas Instruments alternatives.