AM79C940VCW 데이터 시트보기 (PDF) - Advanced Micro Devices

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AM79C940VCW

Media Access Controller for Ethernet (MACE™)

Advanced Micro Devices 

The MACE device provides a complete Ethernet node

solution with an integrated 10BASE-T transceiver, and

supports up to 25-MHz system clocks. The MACE

device embodies the Media Access Control (MAC)

and Physical Signaling (PLS) sub-layers of the IEEE

802.3 standard, and provides an IEEE defined Attach-

ment Unit Interface (AUI) for coupling to an external

Medium Attachment Unit (MAU). The MACE device is

compliant with 10BASE2, 10BASE5, 10BASE-T, and

10BASE-F transceivers.

Additional features also enhance over-all system

design. The individual transmit and receive FIFOs

optimize system overhead, providing substantial

latency during packet transmission and reception, and

minimizing intervention during normal network error

recovery. The integrated Manchester encoder/decoder

eliminates the need for an external Serial Interface

Adapter (SIA) in the node system. If support for an

external encoding/decoding scheme is desired, the

General Purpose Serial Interface (GPSI) allows direct

access to/from the MAC. In addition, the Digital Attach-

ment Interface (DAI), which is a simplified electrical

attachment specification, allows implementation of

MAUs that do not require DC isolation between the

MAU and DTE. The DAI port can also be used to

indicate transmit, receive, or collision status by

connecting LEDs to the port. The MACE device also

provides an External Address Detection Interface

(EADI) to allow external hardware address filtering in

internet working applications.

The Am79C940 MACE chip is offered in a Plastic

Leadless Chip Carrier (84-pin PLCC), a Plastic Quad

Flat Package (100-pin PQFP), and a Thin Quad Flat

Package (TQFP 80-pin). There are several small func-

tional and physical differences between the 80-pin

TQFP and the 84-pin PLCC and 100-pin PQFP config-

urations. Because of the smaller number of pins in the

TQFP configuration versus the PLCC configuration,

four pins are not bonded out. Though the die is identical

in all three package configurations, the removal of

these four pins does cause some functionality differ-

ences between the TQFP and the PLCC and PQFP

configurations. Depending on the application, the

removal of these pins will or will not have an effect.

(See section: “Pins Removed for TQFP Package and

Their Effects.)

With the rise of embedded networking applications op-

erating in harsh environments where temperatures

may exceed the normal commercial temperature (0°C

to +70°C) window, an industrial temperature (-40°C to

+85°C) version is available in all three packages; 84-

pin PLCC, 100-pin PQFP and 80-pin TQFP. The indus-

trial temperature version of the MACE Ethernet control-

ler is characterized across the industrial temperature

range (-40°C to +85°C) within the published power

supply specification (4.75 V to 5.25 V; i.e., ±5% VCC).

Thus, conformance of MACE performance over this

temperature range is guaranteed by the design and

characterization monitor.

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Am79C940

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