
Preliminary Data Sheet
August 2000
LU5X31F
Gigabit Ethernet Transceiver
Overview
The LU5X31F is a low-cost, low-power gigabit Ether-
net transceiver. It is used for data transmission over
fiber or coaxial media in conformance with IEEE*
802.3z Gigabit Ethernet specification and Fibre
Channel ANSI
X3T11 at 1.0 Gbit/s and
1.25 Gbits/s.
The transmitter section accepts parallel 10-bit, 8b/
10b encoded data that is latched on the rising edge
of REFCLK. It also uses this clock to synthesize the
internal high-speed serial bit clock. The serialized
data is then available at the differential PECL out-
puts, terminated in 50
or 75
to drive either an
optical transmitter or coaxial media.
The receive section receives high-speed serial data
at its differential PECL input port. This data is fed to
the digital clock recovery section, which generates a
recovered clock and retimes the data. The retimed
data is deserialized and presented as 10-bit parallel
data on the output port. A divided-down version of
the recovered clock, synchronous with parallel data
bytes, is also available as a TTL compatible output.
The receive section recognizes the comma character
and aligns the comma containing byte on the word
boundary, when ENCDET = 1.
* IEEE s a registered trademark of The Institute of Electrical and
Electronics Engineers, Inc.
ANSI is a registered trademark of American National Standards
Institute.
FireWireis a registered trademark of Apple Computer, Inc.
Features
I
Designed to operate in Ethernet, fibre channel,
FireWire
or backplane applications.
I
Operationally compliant to IEEE 802.3z Gigabit
Ethernet specification.
I
Operationally compliant to Fibre Channel ANSI
X3T11. Provides FC-0 services at 1.0 Gbit/s—
1.25 Gbits/s (10-bit encoded data rate).
I
100 MHz—125 MHz differential or single-ended
reference clock.
I
10-bit parallel interface.
I
8b/10b encoded data.
I
High-speed comma character recognition (K28.1,
K28.5, K28.7) for latency-sensitive applications
and alignment to word boundary.
I
Two 62.5 MHz receive-byte clocks.
I
Single-analog PLL design requires no external
components for the frequency synthesizer.
I
Novel digital data lock in receiver avoids the need
for multiple analog PLLs.
I
Expandable beyond single-channel SERDES.
I
PECL high-speed interface I/O for use with optical
transceiver or coaxial copper media.
I
Requires one external resistor for PECL output ref-
erence level definition.
I
Available in both 64-pin MQFP (14 mm) and 64-pin
TQFP (10 mm) packages.
I
Low-power digital 0.25 μm CMOS technology.
I
3.3 V ± 5% power supply.
I
0 °C—70 °C ambient temperature.