LXT980/980A Dual-Speed, 5-Port Fast
Ethernet Repeater
Datasheet
General Description
The LXT980 is a 5-port 10/100 Class II Repeater that is fully compliant with IEEE 802.3
standards. Four ports directly support either 100BASE-TX/10BASE-T copper media or
100BASE-FX fiber media via pseudo-ECL (PECL) interfaces. The fifth port, a 10 or 100 Mbps
Media Independent Interface (MII), connects to Media Access Controllers (MACs) for bridge/
switch applications. At 100 Mbps, the MII can also be configured to interface to another PHY
device, such as the LXT970. This data sheet applies to all LXT980 products (LXT980,
LXT980A, and any subsequent variants), except as specifically noted.
The LXT980 provides auto-negotiation with parallel detection for the four PHY ports. These
ports can also be manually configured, either by hardware or software. The LXT980 provides
two internal repeater state machines—one operating at 10 Mbps and one at 100 Mbps. Once
configured, the LXT980 automatically connects each port to the appropriate repeater.
The LXT980 also provides two Inter-Repeater Backplanes (IRBs) for expansion — one
operating at 10 Mbps and one at 100 Mbps. Up to 240 ports can logically be combined into one
repeater using these buses. The LXT980 supports SNMP and RMON management via on-chip
32- and 64-bit counters. The counters and control information are accessible via a high-speed
Serial Management Interface (SMI). The device supports two Source Address Tracking registers
per port and a Source Address Matching Function.
Product Features
■ Four 10/100 ports with complete twisted-
pair PHYs including integrated filters and
100BASE-FX PECL interfaces.
■ High-speed Serial Management Interface
(SMI).
■ Two address-tracking registers per port.
■ Source Address matching function.
■ 10/100 MII port connection to either MAC
or PHY.
■ Integrated LED drivers with user-selectable
■ Independent segments for 10 and 100 Mbps
modes.
operation.
■ Available in 208-pin QFP package.
■ Case temperature range: 0-115°C.
■ Cascadable Inter-Repeater Backplanes
(IRBs).
■ Hardware assist for RMON and the
Repeater MIB.
As of January 15, 2001, this document replaces the Level One document
LXT980/980A Dual-Speed, 5-Port Fast Ethernet Repeater.
Order Number: 249111-001
January 2001