
LXT9785 and LXT9785E Advanced 8-Port 10/100 Mbps PHY Transceivers
Datasheet 
Document Number: 249241
Revision Number: 007
Revision Date: August 28, 2003
109
3.6
BGA15 Signal Descriptions
3.6.1
Signal Name Conventions
Signal names may contain either a port designation or a serial designation, or a combination of the 
two designations.   Signal naming conventions are as follows:
 Port Number Only.
 Individual signals that apply to a particular port are designated by the 
Signal Mnemonic, immediately followed by the Port Designation. For example, Transmit 
Enable signals would be identified as TxEN0, TxEN1, and TxEN2.
 Serial Number Only.
 A set of signals which are not tied to any specific port are designated by 
the Signal Mnemonic, followed by an underscore and a serial designation. For example, a set 
of three Global Configuration signals would be identified as CFG_1, CFG_2, and CFG_3.
 Port and Serial Number.
 In cases where each port is assigned a set of multiple signals, each 
signal is designated in the following order: Signal Mnemonic, Port Designation, an 
underscore, and the serial designation. For example, a set of three Port Configuration signals 
would be identified as RxData0_0 and RxData0_1, RxData1_0 and RxData1_1, and 
RxData2_0 and RxData2_1.
3.6.2
Signal Descriptions – SMII and SS-SMII Configurations
Table 39
 provides the BGA15 signal descriptions.
Table 39. Intel
 LXT9785 BGA15 Signal Descriptions  (Sheet 1 of 7)
BGA15 Ball 
Designation
Symbol
Type
Signal Description
SMII/SS-SMII Common Signal Descriptions
N4,
N2,
K3,
J1,
G3,
E2,
D3,
A5
TxData0
TxData1
TxData2
TxData3
TxData4
TxData5
TxData6
TxData7
I, ID
Transmit Data - Ports 0-7.
These serial input streams provide data to be transmitted to 
the network. The LXT9785/9785E clocks the data in 
synchronously to REFCLK.
C3
L4
REFCLK1
REFCLK0
I
Reference Clock.
The LXT9785/9785E always requires a 125 MHz reference 
clock input. Refer to 
Section 4.4.2, “Clock/SYNC 
Requirements” on page 125
 for detailed clock 
requirements.
SMII Specific Signal Descriptions
K1
SYNC
I, ID
SMII Synchronization.
The MAC must generate a SYNC pulse every 10 REFCLK 
cycles to synchronize the SMII.
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.