AM79C940JCW Advanced Micro Devices, AM79C940JCW Datasheet - Page 2

• Manufacturer Part Number: AM79C940JCW
• Description: Media Access Controller for Ethernet (MACE)
• Manufacturer: Advanced Micro Devices

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
BLOCK DIAGRAM
DBUS 15-0
2
Notes:
1. Only one of the network ports AUI, 10BASE-T, DAI port or GPSI can be active at any time. Some shared signals are active
2. The EADI port is active at all times.
RDTREQ
TDTREQ
ADD 4-0
BE 1–0
EDSEL
RESET
regardless of which network port is active, and some are reconfigured.
SLEEP
AMD
SCLK
INTR
EOF
FDS
DTV
R/W
CS
TC
TCK
PORT CNTRL
Interface
TDI
Unit
JTAG
Bus
TMS
TDO
RCV FIFO
XMT FIFO
Command
Registers
& Status
Control
FIFO
Am79C940
802.3
MAC
Core
hardware
applications.
The Am79C940 MACE chip is offered in a Plastic Lead-
less Chip Carrier (84-pin PLCC), a Plastic Quad Flat
Package (100-pin PQFP), and a Thin Quad Flat Pack-
age (TQFP 80-pin). There are several small functional
and physical differences between the 80-pin TQFP and
the 84-pin PLCC and 100-pin PQFP configurations.
Because of the smaller number of pins in the TQFP con-
figuration 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 differences between the
TQFP and the PLCC and PQFP configurations. De-
pending on the application, the removal of these pins will
or will not have an effect.
XTAL1
ENCODER/
DECODER
10BASE-T
address
Control
(PLS)
EADI
GPSI
MAU
Port
Port
Port
Port
AUI
DAI
XTAL2
filtering
DXCVR
CLSN
SRDCLK
SRD
SF/BD
EAM/R
DO
DI
CI
TXD
TXP
RXD
LNKST
RXPOL
TXDAT
TXEN
RXDAT
RXCRS
STDCLK
TXDAT+
TXEN
SRDCLK
RXDAT
RXCRS
CLSN
in
internetworking
16235C-1
EADI Port
AUI
10BASE-T
DAI Port
GPSI