KSZ9031RNX(2012) Ver la hoja de datos (PDF) - Micrel

Número de pieza

componentes Descripción

Fabricante

KSZ9031RNX
(Rev.:2012)

Gigabit Ethernet Transceiver with RGMII Support

Micrel 

Micrel, Inc.

KSZ9031RNX

Magnetic – Connection and Selection

A 1:1 isolation transformer is required at the line interface. Use one with integrated common-mode chokes for designs

exceeding FCC requirements. An optional auto-transformer stage following the chokes provides additional common-mode

noise and signal attenuation.

The KSZ9031RNX design incorporates voltage-mode transmit drivers and on-chip terminations.

With the voltage-mode implementation, the transmit drivers supply the common-mode voltages to the four differential

pairs. Therefore, the four transformer center tap pins on the KSZ9031RNX side should not be connected to any power

supply source on the board; rather, the center tap pins should be separated from one another and connected through

separate 0.1µF common-mode capacitors to ground. Separation is required because the common-mode voltage could be

different between the four differential pairs, depending on the connected speed mode.

Figure 20 shows the typical gigabit magnetic interface circuit for the KSZ9031RNX.

Figure 20. Typical Gigabit Magnetic Interface Circuit

October 2012

72

M9999-103112-1.0

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