LXT9880 datasheet(48/118 Pages) INTEL

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LXT9860/9880 — Advanced 10/100 Repeater with Integrated Management

Datasheet

Document #: 248987

Revision#: 003

Rev Date: 08/07/01

3.8.1

IRB Signal Types

IRB signals can be characterized by the following connection types (For Stacking and Cascading

connections, see Table 19 on page 50):

• Local—connected between devices on the same board

• Stack—connected between boards

• Full—connected between devices in the same board and between boards.

3.8.2

IRB Isolation

The ISOLATE outputs (IR10ISO and IR100ISO) are provided to control the enable pins of external

bidirectional transceivers. In stacking applications, they can be used to isolate one board from the

rest of the stack. Only one device can control these signals. The output states of these pins are

controlled by the Isolate bits in the Repeater Configuration Register.

3.8.3

10 Mbps-Only Operation

3.8.3.1

MAC IRB Access

The MACACTIVE pin allows an external MAC or other digital ASIC to interface directly to the

10 Mbps IRB. When the MACACTIVE pin is asserted, the LXT98x0 drives the IR10CFS and

IR10CFSBP signals on behalf of the external device, allowing it to participate in collision detection

functions.

3.8.3.2

Management Master Chain Arbitration

This daisy chain is provided for correct statistics gathering in 10 Mbps cascaded configurations. In

stacked applications, this daisy chain must be maintained through cascades. In stand-alone

applications, or for the first device in a chain, the MMSTRIN input must be pulled Low for the

management counters to work correctly.

3.8.4

LXT98x/91x/98x0 Compatibility

The LXT98x0 devices feature low-power 3.3V design. The LXT98x and LXT91x devices operate

at 5V and are incompatible with the LXT98x0 devices in cascades. The LXT98x0 devices,

however, are backwards stackable with LXT98x and LXT91x repeaters.

Note:

Refer to “Inter-Repeater Backplane Compatibility” on page 71.

LXT9880 Datasheet(PDF) 48 Page - Intel Corporation