
LXT9785 and LXT9785E Advanced 8-Port 10/100 Mbps PHY Transceivers
82
Datasheet 
Document Number: 249241
Revision Number: 007
Revision Date: August 28, 2003
3.4
BGA23 Signal Descriptions
3.4.1
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.
3.4.2
Signal Descriptions – RMII, SMII, and SS-SMII Configurations
Table 24. Intel
 LXT9785/LXT9785E RMII Signal Descriptions – BGA23 (Sheet 1 of 3)
Ball/Pin 
Designation
Symbol
Type
1
Signal Description
2,3
BGA23
PQFP
E6,
E12
44
6
REFCLK0
REFCLK1
I
Reference Clock. 
50 MHz RMII reference clock is always required. RMII 
inputs are sampled on the rising edge of REFCLK, 
RMII outputs are sourced on the falling edge. 
See 
“Clock/SYNC Requirements” on page 125.
 for detailed 
CLK requirements.
E2,
F4
61
62
TxData0_0
TxData0_1
I, ID
Transmit Data - Port 0. 
Inputs containing 2-bit parallel di-bits to be transmitted 
from port 0 are clocked in synchronously to REFCLK.
C3,
D4
52
53
TxData1_0
TxData1_1
I, ID
Transmit Data - Port 1.
Inputs containing 2-bit parallel di-bits to be transmitted 
from port 1 are clocked in synchronously to REFCLK
B5
A4
42
43
TxData2_0
TxData2_1
I, ID
Transmit Data - Port 2. 
Inputs containing 2-bit parallel di-bits to be transmitted 
from port 2 are clocked in synchronously to REFCLK.
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.
2. The IP/ID resistors are disabled during H/W Power-Down mode.   If a Pin is an output or an I/O, the IP/ID 
resistors are also disabled when the output is enabled.
3. RxData[0:7]_0, RxData[0:7]_1, CRS_DV[0:7] and RxER[0:7] outputs are three-stated in Isolation and H/W 
Power-Down modes and during H/W reset.