DESCRIPTION OF PIN FUNCTIONS
PQFP/TQFP
PIN NO.
84, 87, 88,
90, 91, 96,
99, 101, 100,
98, 89, 92,
103, 102,
104
97
31, 57, 73,
86
93
3
4
NAME
RAM
Address
Bus
SYMBOL
RA2-RA16
BUFFER
TYPE
O4
DESCRIPTION
Outputs. This bus specifies the buffer RAM
doubleword
being
accessed
by
the
LAN91C100FD.
nROE
nRWE0-
RWE3
RCVDMA
XTAL1
XTAL2
O4
O4
O4
Iclk
Receive
DMA
Crystal 1
Crystal 2
5, 10, 23, 27,
41, 63, 74,
83, 85, 107,
119, 125,
132, 143,
165, 179,
186, 191
205
14, 32, 46,
50, 66, 75,
82, 94, 111,
116, 120,
122, 128,
134, 138,
169, 174,
180, 185,
200
203
2
201
208
207
Power
VDD
Output. Active low signal used to read a
doubleword from buffer RAM.
Outputs. Active low signals used to write any byte,
word or dword in RAM.
Output. This pin is active during LAN91C100FD
write memory cycles of receive packets.
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.
+5V power supply pins.
Analog
Power
Ground
AVDD
GND
+5V analog power supply pins.
Ground pins.
Analog
Ground
Transmit
Enable
Transmit
Data
Carrier
Sense
Collision
Detect
Receive
Data
Transmit
Clock
Receive
Clock
AGND
TXEN
TXD
CRS
COL
O4
O4
I with
pulldown
I with
pulldown
I with
pullup
I with
pullup
I with
pullup
Analog ground pin.
Output. Used for 10 Mbps ENDEC. This pin stays
low when MIISEL is high.
Output. NRZ Transmit Data for 10 Mbps ENDEC
interface.
Input. Carrier sense from 10 Mbps ENDEC
interface. This pin is ignored when MIISEL is high.
Input. Collision detection indication from 10 Mbps
ENDEC interface. This pin is ignored when
MIISEL is high.
Input. NRZ Receive Data from 10 Mbps ENDEC
interface. This pin is ignored when MIISEL is high.
Input. 10 MHz transmit clock used in 10 Mbps
operation. This pin is ignored when MIISEL is
high.
Input. 10 MHz receive clock recovered by the 10
Mbps ENDEC. This pin is ignored when MIISEL is
high.
206
197
RXD
TXC
199
RXC
SMSC DS – LAN91C100FD REV. B
Page 7
Rev. 05/31/2000
SMSC [ SMSC CORPORATION ]
