MPC8378E datasheet(83/128 Pages) FREESCALE

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MPC8378E PowerQUICC II Pro Processor Hardware Specifications, Rev. 8

Freescale Semiconductor

•

Single-ended Mode

— The reference clock can also be single-ended. The SD _REF_CLK input amplitude

(single-ended swing) must be between 400 mV and 800 mVp-p (from Vmin to Vmax) with

SDn_REF_CLK either left unconnected or tied to ground.

—The SDn_REF_CLK input average voltage must be between 200 mV and 400 mV. Figure 58

shows the SerDes reference clock input requirement for single-ended signaling mode.

— To meet the input amplitude requirement, the reference clock inputs might need to be DC or

AC-coupled externally. For the best noise performance, the reference of the clock could be DC

or AC-coupled into the unused phase (SDn_REF_CLK) through the same source impedance as

the clock input (SDn_REF_CLK) in use.

Figure 56. Differential Reference Clock Input DC Requirements (External DC-Coupled)

Figure 57. Differential Reference Clock Input DC Requirements (External AC-Coupled)

Figure 58. Single-Ended Reference Clock Input DC Requirements

n_REF_CLK

Vmax < 800 mV

Vmin > 0 V

100 mV < Vcm < 400 mV

200 mV < Input Amplitude or Differential Peak < 800 mV

n_REF_CLK

Vcm

200 mV < Input Amplitude or Differential Peak < 800 mV

150

Vmin > Vcm – 400m V

fdafdVmax < Vcm + 400 mV

Vmax < Vcm + 400 mV

n_REF_CLK

400 mV < SD

n_REF_CLK Input Amplitude < 800 mV

MPC8378E Datasheet(PDF) 83 Page - Freescale Semiconductor, Inc