LAN91C100FD datasheet(9/79 Pages) SMSC

9 / 79 page

FEAST Fast Ethernet Controller with Full Duplex Capability

SMSC DS – LAN91C100FD Rev. D

Page 9

Rev. 10/14/2002

PRELIMINARY

PQFP/TQFP

PIN NO.

NAME

SYMBOL

BUFFER

TYPE

DESCRIPTION

42, 40-38,

36-33

RAM Data

Bus

RD0-RD7

I/O4 with

pullups

Bidirectional. Carries the local buffer memory

read and write data. Reads are always 32 bits

wide. Writes are controlled individually at the

byte level. Floated if FLTST=1 during RECEIVE

FRAME STATUS WORD writes for packet

forwarding information (RA2-RA16=0,

RCVDMA=1, nRWE0-nRWE3=0).

59, 56,

49-47,

45-43,

69-67, 65,

64, 62-60,

81-76, 71,

RAM Data

Bus

RD8-

RD31

I/O4 with

pullups

Bidirectional. Carries the local buffer memory

read and write data. Reads are always 32 bits

wide. Writes are controlled individually at the

byte level.

84, 87, 88,

90, 91, 96,

99, 101,

100, 98, 89,

92, 103,

102, 104

RAM

Address

Bus

RA2-RA16

Outputs. This bus specifies the buffer RAM

doubleword being accessed by the

LAN91C100FD.

nROE

Output. Active low signal used to read a

doubleword from buffer RAM.

31, 57, 73,

nRWE0-

RWE3

Outputs. Active low signals used to write any

byte, word or dword in RAM.

Receive

DMA

RCVDMA

Output. This pin is active during LAN91C100FD

write memory cycles of receive packets.

Crystal 1

Crystal 2

XTAL1

XTAL2

Iclk

An external 25 MHz crystal is connected across

these pins. If a TTL clock is supplied instead, it

should be connected to XTAL1 and XTAL2

should be left open.

5, 10, 23,

27, 41, 63,

74, 83, 85,

107, 119,

125, 132,

143, 165,

179, 186,

191

Power

VDD

+5V power supply pins.

205

Analog

Power

AVDD

+5V analog power supply pins.

14, 32, 46,

50, 66, 75,

82, 94, 111,

116, 120,

122, 128,

134, 138,

169, 174,

180, 185,

200

Ground

GND

Ground pins.

203

Analog

Ground

AGND

Analog ground pin.

Transmit

Enable

TXEN

Output. Used for 10 Mbps ENDEC. This pin

stays low when MIISEL is high.

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