Intel
LXT901A/907A Universal 3.3 V Ethernet Transceiver
10
Datasheet
Document Number: 249098
Revision Number: 003
Revision Date: 27-Nov-2005
21
37
LEDC/
FDE
OD
Collision LED (LEDC)/Full-Duplex Enable (FDE). Open drain driver for the
collision indicator pulls Low during collision.
LED “On” (i.e., Low output) time is extended by approximately 100 ms.
If externally tied Low, enables full-duplex operation by disabling the internal TP
loopback and collision detection circuits in anticipation of external twisted-pair
loopback or full-duplex operation.
If this pin is not used, tie High or directly to Vcc.
22
38
LBK
I
Loopback. Enables internal loopback mode. Refer to Functional Description for
details.
23
33
39
55
GND1
GND2
–
Ground Returns 1 and 2. Grounds
–
40
GNDA
–
Analog Ground.
24
42
RBIAS
I
Bias Control. A 12.4 k
Ω 1% resistor to ground at this pin controls operating
circuit bias.
26
45
RXD
O
Receive Data. Output signal. Connect directly to the receive data input of the
controller.
27
46
CD
O
Carrier Detect. An output to notify the controller of activity on the network.
28
47
RCLK
O
Receive Clock. A recovered 10 MHz clock that is synchronous to the received
data. Connect to the controller receive clock input.
30
52
PLR
O
Polarity Reverse. Output goes High to indicate reversed polarity at the twisted-
pair input.
31
36
32
35
53
58
54
57
TPOPB
TPONB
TPOPA
TPONA
O
Twisted-Pair Transmit Pairs A & B. Two differential driver pair outputs (A and B)
to the twisted-pair cable. The outputs are pre-equalized.
Each pair must be shorted together and tied to the transformer through a
24.9
Ω 1% series resistor to match impedance of 100Ω.
Ω
configurations.
37
59
STP
I
STP Select (LXT901A Transceiver only).
When STP is Low, 150
Ω termination for shielded twisted-pair is selected.
When STP is High, 100
Ω termination for unshielded twisted-pair is selected.
LXT907A Transceiver is designed for 100
Ω unshielded twisted-pair termination
(not selectable).
DSQE
I
Disable SQE (LXT907A Transceiver only).
When DSQE is High, the SQE function is disabled.
When DSQE is Low, the SQE function is enabled.
SQE must be disabled for normal operation in Hub/Switch applications.
The LXT901A Transceiver operates with SQE enabled (not selectable).
38
39
61
62
TPIP
TPIN
I
Twisted-Pair Receive Pair. A differential input pair from the twisted-pair cable.
Receive filter is integrated on-chip. No external filters are required.
40
3
PAUI
I
Port/AUI Select. In Manual Port Select mode (AUTOSEL Low), PAUI selects the
active port.
When PAUI is High, the AUI port is selected.
When PAUI is Low, the TP port is selected.
In Auto Port Select mode, PAUI must be tied to ground.
Table 1.
Signal Descriptions (Continued)
Pin #
Symbol
I/O1
Description
PLCC
LQFP
1. I/O Column Coding: I = Input, O = Output, OD = Open Drain