MSC8154 datasheet(31/68 Pages) FREESCALE

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Electrical Characteristics

MSC8154 Quad-Core Digital Signal Processor Data Sheet, Rev. 2

Freescale Semiconductor

2.5.2.3

SerDes Transmitter and Receiver Reference Circuits

Figure 6 shows the reference circuits for SerDes data lane transmitter and receiver.

2.5.3

DC-Level Requirements for SerDes Interfaces

The following subsections define the DC-level requirements for the SerDes reference clocks, the PCI Express data lines, the

Serial RapidIO data lines, and the SGMII data lines.

2.5.3.1

DC-Level Requirements for SerDes Reference Clocks

The DC-level requirement for the SerDes reference clock inputs is different depending on the signaling mode used to connect

the clock driver chip and SerDes reference clock inputs, as described below:

•

Differential Mode

— The input amplitude of the differential clock must be between 400 mV and 1600 mV differential peak-peak (or

between 200 mV and 800 mV differential peak). In other words, each signal wire of the differential pair must have

a single-ended swing of less than 800 mV and greater than 200 mV. This requirement is the same for both external

DC-coupled or AC-coupled connection.

— For an external DC-coupled connection, the maximum average current requirements sets the requirement for

average voltage (common mode voltage) as between 100 mV and 400 mV. Figure 7 shows the SerDes reference

clock input requirement for DC-coupled connection scheme.

Figure 6. SerDes Transmitter and Receiver Reference Circuits

Figure 7. Differential Reference Clock Input DC Requirements (External DC-Coupled)

Transmitter

Receiver

SR[1–2]_TXm

SR[1–2]_RXm

SR[1–2]_TXm

SR[1–2]_RXm

Note: The [1–2] indicates the specific SerDes Interface (1 or 2) and the m indicates the

specific channel within that interface (0,1,2,3). Actual signals are assigned by the

HRCW assignments at reset (see Chapter 5, Reset in the reference manual for details)

SR[1–2]_REF_CLK

Vmax < 800 mV

Vmin > 0V

100 mV < Vcm < 400 mV

200 mV < Input Amplitude or Differential Peak < 800 mV

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