ICS1893AFILFT datasheet(26/137 Pages) RENESAS

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ICS1893AF, Rev D 10/26/04

October, 2004

Chapter 6

Interface Overviews

ICS1893AF Data Sheet - Release

6.2

Serial Management Interface

The ICS1893AF provides an ISO/IEC compliant, two-wire Serial Management Interface as part of its

MAC/Repeater Interface. This Serial Management Interface is used to exchange control, status, and

configuration information between a Station Management entity (STA) and the physical layer device (PHY),

that is, the ICS1893AF.

The ISO/IEC standard also specifies a frame structure and protocol for this interface as well as a set of

Management Registers that provide the STA with access to a PHY such as the ICS1893AF. A Serial

Management Interface is comprised of two signals: a bi-directional data pin (MDIO) along with an

associated input pin for a clock (MDC). The clock is used to synchronize all data transfers between the

ICS1893AF and the STA.

In addition to the ISO/IEC defined registers, the ICS1893AF provides several extended status and control

registers to provide more refined control of the MII and MDI interfaces. For example, the QuickPoll Detailed

Status Register provides the ability to acquire the most-important status functions with a single MDIO read.

Note:

In the ICS1893AF, the MDIO and MDC pins remain active for all the MAC/Repeater Interface

modes (that is, 10M MII, 100M MII, 100M Symbol, and 10M Serial).

6.3

Twisted-Pair Interface

For the twisted-pair interface, the ICS1893AF uses 1:1 ratio transformers for both transmit and receive.

Better operation results from using a split ground plane through the transformer. In this case:

• The RJ-45 transformer windings must be on the chassis ground plane along with the Bob Smith

termination.

• The ICS1893AF system ground plane must include the ICS1893AF-side transformer windings along with

the 61.9

Ω resistors and the 120-nH inductor.

• The transformer provides the isolation with one set of windings on one ground plane and another set of

windings on the second ground plane.

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