ELLXT971ABE.A4 Intel, ELLXT971ABE.A4 Datasheet - Page 54

• Manufacturer Part Number: ELLXT971ABE.A4
• Description: IC TRANS 3.3V ETHERNET 64-BGA
• Manufacturer: Intel
• Type: PHY Transceiverr

Specifications of ELLXT971ABE.A4

• Number Of Drivers/receivers: 1/1
• Protocol: IEEE 802
• Voltage - Supply: 3.14 V ~ 3.45 V
• Mounting Type: Surface Mount
• Package / Case: 64-BGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 870479

Intel
5.7.3.3
5.7.3.4
54
®
LXT971A Single-Port 10/100 Mbps PHY Transceiver
Note:
Twisted-Pair Physical Medium Dependent Sublayer
The twisted-pair Physical Medium Dependent (PMD) layer provides signal scrambling and de-
scrambling functions, line coding and decoding functions (MLT-3 for 100BASE-TX, Manchester
for 10BASE-T), as well as receiving, polarity correction, and baseline wander correction functions.
5.7.3.3.1
The purpose of the scrambler/descrambler is to spread the signal power spectrum and further
reduce EMI using an 11-bit, data-independent polynomial. The receiver automatically decodes the
polynomial whenever IDLE symbols are received.
Scrambler Seeding. Once the transmit data (or Idle symbols) are properly encoded, they are
scrambled to further reduce EMI and to spread the power spectrum using an 11-bit scrambler seed.
Five seed bits are determined by the PHY address, and the remaining bits are hard coded in the
design.
Scrambler Bypass. The scrambler/de-scrambler can be bypassed by setting Register bit 16.12 = 1.
The scrambler is automatically bypassed when the fiber port is enabled. Scrambler bypass is
provided for diagnostic and test support.
5.7.3.3.2
The 100 Mbps twisted pair signaling is not polarity sensitive. As a result, the polarity status is not a
valid status indicator.
5.7.3.3.3
The LXT971A Transceiver provides a baseline wander correction function for when the LXT971A
Transceiver is under network operating conditions. The MLT3 coding scheme used in 100BASE-
TX is by definition “unbalanced”. As a result, the average value of the signal voltage can “wander”
significantly over short time intervals (tenths of seconds). This wander can cause receiver errors at
long-line lengths (100 meters) in less robust designs. Exact characteristics of the wander are
completely data dependent.
The LXT971A Transceiver baseline wander correction characteristics allow the device to recover
error-free data while receiving worst-case packets over all cable lengths.
5.7.3.3.4
The LXT971A Transceiver device supports a programmable slew-rate mechanism whereby one of
four pre-selected slew rates can be used. (For details, see
Address 30, Hex 1E” on page
output waveform to match the characteristics of the magnetics.
For hardware control of the slew rate, use the TxSLEW pins.
Fiber PMD Sublayer
The LXT971A Transceiver provides an LVPECL interface for connection to an external 3.3 V or 5
V fiber-optic transceiver. (The external transceiver provides the PMD function for the optical
medium.) The LXT971A Transceiver uses a 125 Mbaud NRZI format for the fiber interface and
does not support 10BASE-FL applications.
Scrambler/Descrambler
Polarity Correction
Baseline Wander Correction
Programmable Slew Rate Control
104.) The slew-rate mechanism allows the designer to optimize the
Table 62, “Transmit Control Register -
Document Number: 249414-003
Revision Date: June 18, 2004
Datasheet