LXT970A datasheet(41/74 Pages) INTEL

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Dual-Speed Fast Ethernet Transceiver — LXT970A

Datasheet

3.0

Application Information

3.1

Magnetics Information

The LXT970A requires a 1:1 ratio for both the receive and the transmit transformers. Refer to

Table 18 for magnetics requirements.

A cross-reference list of magnetic manufacturers and part numbers is available in Application Note

73, Magnetic Manufacturers, which can be found on the Intel web site (developer.intel.com/design/

network/). Designers must test and evaluate all components for suitability in their applications.

3.2

Crystal Information

The LXT970A requires a parallel-resonant fundamental-mode crystal that meet specifications as

shown in Table 19. XI and XO input capacitance and voltage requirements are provided in Table 25

on page 48.

Crystals are available from various manufacturers. Designers should test and validate all crystals

before committing to a specific component. Based on limited evaluation, Table 20 provides

suitable crystal component manufacturers.

Table 18. Magnetics Requirements

Parameter

Min

Nom

Max

Units

Test Condition

Rx and Tx Turns Ratio

–

1:1

––

Insertion Loss

0.0

–

1.1

Primary Inductance

350

––

µH

Transformer Isolation

–

Differential to common mode rejection

––

-40

.1 to 60 MHz

––

-35

60 to 100 MHz

Return Loss

––

-17

.1 to 60 MHz

––

-15

60 to 100 MHz

Rise Time

2.0

–

3.5

10% to 90%

Table 19. Crystal Requirements

Parameter

Min

Nom

Max

Units

Test Condition

Frequency

–

25.0

–

MHz

Frequency Stability

––

±100

ppm

-40 - 85oC

1. See Table 25 (Clock Characteristics) for additional device specifications.

Table 20. Crystal Component Manufacturers

Component

Manufacturer

Part Number

Crystal

Epson America

MA-505-25.000M

Caliber Electronics

AA18C1-25.000MHz

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