LAN8742AI-CZ datasheet(49/124 Pages) MICROCHIP

Part #	LAN8742Ai-CZ

Description	Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX and flexPWR짰 Technology

PDF	124 Pages

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Manufacturer	MICROCHIP [Microchip Technology]

Direct Link	http://www.microchip.com

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 2013-2015 Microchip Technology Inc.

DS00001989A-page 49

LAN8742A/LAN8742Ai

3.8.9.2

Matched Cable Diagnostics

Matched cable diagnostics enable cable length estimation on 100 Mbps-linked cables of up to 120 meters. If there is an

active 100 Mb link, the approximate distance to the link partner can be estimated using the Cable Length Register. If

the cable is properly terminated, but there is no active 100 Mb link (the link partner is disabled, nonfunctional, the link is

at 10 Mb, etc.), the cable length cannot be estimated and the Cable Length Register should be ignored. The estimated

distance to the link partner can be determined via the Cable Length (CBLN) lookup table provided in Table 3-11. The

typical cable length measurement margin of error for a matched cable case is +/- 20 m. The matched cable length mar-

gin of error is consistent for all cable types from 0 to 120 m.

TABLE 3-11:

MATCH CASE ESTIMATED CABLE LENGTH (CBLN) LOOKUP TABLE

CBLN Field Value

Estimated Cable Length

0 - 3

517

627

738

849

959

102

113

123

Note:

For a properly terminated cable (Match case), there is no reflected signal. In this case, the TDR Channel

Length field is invalid and should be ignored.

LAN8742Ai-CZ Datasheet(PDF) 49 Page - Microchip Technology