MPC8535E datasheet(94/126 Pages) FREESCALE

94 / 126 page

MPC8535E PowerQUICC™ III Integrated Processor Hardware Specifications, Rev. 2

High-Speed Serial Interfaces

Freescale Semiconductor

Figure 60. Differential Reference Clock Input DC Requirements (External AC-Coupled)

Figure 61. Single-Ended Reference Clock Input DC Requirements

2.20.2.3

Interfacing With Other Differential Signaling Levels

With on-chip termination to SnGND (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 (Low Voltage Positive Emitter-Coupled Logic) 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 62 to Figure 65 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 is 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 MPC8535E SerDes reference clock receiver

requirement provided in this document.

n_REF_CLK

Vcm

200mV < Input Amplitude or Differential Peak < 800 mV

Vmax < Vcm + 400 mV

Vmin > Vcm – 400 mV

n_REF_CLK

400 mV < SD

n_REF_CLK Input Amplitude < 800 mV

MPC8535E Datasheet(PDF) 94 Page - Freescale Semiconductor, Inc