DP83848JSQSLASHNOPB datasheet(67/84 Pages) TI1

67 / 84 page

0.1µF

10 µF

Pin 19 (PFBOUT)

0.1 µF

Pin 16 (PFBIN1)

Pin 30 (PFBIN2)

DP83848H, DP83848J, DP83848K, DP83848M, DP83848T

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SNLS250E – MAY 2008 – REVISED APRIL 2015

Figure 7-4. Power Feedback Connection

7.2.1.4

Magnetics

The magnetics have a large impact on the PHY performance as well. While several components are listed

below, others may be compatible following the requirements listed in Table 6-4. It is recommended that

the magnetics include both an isolation transformer and an integrated common mode choke to reduce

EMI. When doing the layout, do not run signals under the magnetics. This could cause unwanted noise

crosstalk. Likewise void the planes under discrete magnetics, this will help prevent common mode noise

coupling. To save board space and reduce component count, an RJ-45 with integrated magnetics may be

used.

Table 7-4. Magnetics Requirements

PARAMETER

TYP

UNITS

CONDITION

Turn Ratio

1:1

—

±2%

Insertion Loss

-1

1-100 MHz

-16

1-30 MHz

Return Loss

-12

30-60 MHz

60-80 MHz

-30

1-50MHz

Differential to Common Rejection Ratio

-20

50-150 MHz

-35

30 MHz

Crosstalk

-30

60 MHz

Isolation

1,500

HPOT

7.2.2

Detailed Design Procedure

7.2.2.1

MAC Interface (MII/RMII)

The Media Independent Interface (MII) connects the PHYTER component to the Media Access Controller

(MAC). The MAC may in fact be a discrete device, integrated into a microprocessor, CPU or FPGA. On

the MII signals, the IEEE specification states the bus should be 68-

Ω impedance. For space critical

designs, the PHYTER family of products also support Reduced MII (RMII). For additional information on

this mode of operation, refer to the AN-1405 DP83848 Single 10/100 Mb/s Ethernet Transceiver Reduced

Media Independent Interface (RMII) Mode Application Report (SNLA076).

7.2.2.1.1 Termination Requirement

To reduce digital signal energy, 50-

Ω series termination resistors are recommended for all MII output

signals (including RXCLK, TXCLK, and RX Data signals.)

Application, Implementation, and Layout

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