MPC8548E datasheet(65/144 Pages) FREESCALE

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MPC8548E PowerQUICC™ III Integrated Processor Hardware Specifications, Rev. 6

Freescale Semiconductor

High-Speed Serial Interfaces (HSSI)

Figure 42. Single-Ended Reference Clock Input DC Requirements

15.2.3

Interfacing With Other Differential Signaling Levels

•

With on-chip termination to SGND_SRDSn (xcorevss), the differential reference clocks inputs are

HCSL (high-speed current steering logic) compatible DC-coupled.

•

Many other low voltage differential type outputs like LVDS (low voltage differential signaling) can

be used but may need to be AC-coupled due to the limited common mode input range allowed (100

to 400 mV) for DC-coupled connection.

•

LVPECL outputs can produce signal with too large amplitude and may need to be DC-biased at

clock driver output first, then followed with series attenuation resistor to reduce the amplitude, in

addition to AC-coupling.

NOTE

Figure 43 through Figure 46 below are for conceptual reference only. Due

to the fact that clock driver chip's internal structure, output impedance and

termination requirements are different between various clock driver chip

manufacturers, it’s very possible that the clock circuit reference designs

provided by clock driver chip vendor are different from what is shown

below. They might also vary from one vendor to the other. Therefore,

Freescale Semiconductor can neither provide the optimal clock driver

reference circuits, nor guarantee the correctness of the following clock

driver connection reference circuits. The system designer is recommended

to contact the selected clock driver chip vendor for the optimal reference

circuits with the MPC8548E SerDes reference clock receiver requirement

provided in this document.

SD_REF_CLK

400 mV < SD_REF_CLK Input Amplitude < 800 mV

0 V

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