
LXT9785 and LXT9785E Advanced 8-Port 10/100 Mbps PHY Transceivers
110
Datasheet 
Document Number: 249241
Revision Number: 007
Revision Date: August 28, 2003
N3,
M2,
K2,
H3,
F2,
E3,
B4,
C5
RxData0_S
RxData1_S
RxData2_S
RxData3_S
RxData4_S
RxData5_S
RxData6_S
RxData7_S
O, TS
Receive Data - Ports 0-7
.
These serial output streams provide data received from the 
network. The LXT9785/9785E drives the data out 
synchronously to REFCLK.
SS-SMII Specific Signal Descriptions
K1
TxSYNC
I, ID
SS-SMII Transmit Synchronization.
The MAC must generate a TxSYNC pulse every 10 TxCLK 
cycles to mark the start of TxData segments.
E1
RxSYNC
O, TS,
ID
SS-SMII Receive Synchronization.
The LXT9785/9785E generates these pulses every 10 
RxCLK cycles to mark the start of RxData segments for the 
MAC.
J3
TxCLK
I, ID
SS-SMII Transmit Clock.
The MAC sources this 125 MHz clock as the timing 
reference for TxData and TxSYNC. 
See “Clock/SYNC 
Requirements” on page 125
for detailed clock requirements.
G1
RxCLK
O, TS,
ID
SS-SMII Receive Clock.
The LXT9785/9785E generates these clocks, based on 
REFCLK, to provide a timing reference for RxData and 
RxSYNC to the MAC. 
See “Clock/SYNC Requirements” on 
page 125 
for detailed clock requirements
.
 These outputs are 
only enabled when SS-SMII mode is enabled. 
M3,
M1,
J2,
H2,
F3,
C2,
A4,
C6 
RxData0_SS
RxData1_SS
RxData2_SS
RxData3_SS
RxData4_SS
RxData5_SS
RxData6_SS
RxData7_SS
O, TS,
ID
Receive Data - Ports 0-7.
These serial output streams provide data received from the 
network. The LXT9785/9785E drives the data out 
synchronously to REFCLK.
MDIO Control Interface Signal Descriptions
N5
MDIO
I/O, TS, 
SL, IP
Management Data Input/Output.
Bidirectional serial data channel for communication 
between the PHY and MAC or switch ASIC. Refer to 
Figure 21 on page 140
.
P5
MDINT
OD, TS, 
SL,
IP
Management Data Interrupt.
When Register bit 18.1 = 1, an active Low output on this 
Pin indicates status change. Refer to 
Figure 21 on page 140
.
Table 39. Intel
 LXT9785 BGA15 Signal Descriptions  (Sheet 2 of 7)
BGA15 Ball 
Designation
Symbol
Type
Signal Description
1. Type Column Coding: I = Input, O = Output, OD = Open Drain output, ST = Schmitt Triggered input, TS = 
Three-State-able output, SL = Slew-rate Limited output, IP = weak Internal Pull-up, ID = weak Internal pull-
Down.