MPC8544E datasheet(70/117 Pages) FREESCALE

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MPC8544E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 5

Freescale Semiconductor

High-Speed Serial Interfaces (HSSI)

assumes that the LVPECL clock driver’s output impedance is 50

Ω. R1 is used to DC-bias the LVPECL

outputs prior to AC-coupling. Its value could be ranged from 140 to 240

Ω depending on clock driver

vendor’s requirement. R2 is used together with the SerDes reference clock receiver’s 50-

Ω termination

resistor to attenuate the LVPECL output’s differential peak level such that it meets the MPC8544E SerDes

reference clock’s differential input amplitude requirement (between 200 and 800 mV differential peak).

For example, if the LVPECL output’s differential peak is 900 mV and the desired SerDes reference clock

input amplitude is selected as 600 mV, the attenuation factor is 0.67, which requires R2 = 25

Ω. Please

consult clock driver chip manufacturer to verify whether this connection scheme is compatible with a

particular clock driver chip.

Figure 51. AC-Coupled Differential Connection with LVPECL Clock Driver (Reference Only)

Figure 52 shows the SerDes reference clock connection reference circuits for a single-ended clock driver.

It assumes the DC levels of the clock driver are compatible with MPC8544E SerDes reference clock

input’s DC requirement.

Figure 52. Single-Ended Connection (Reference Only)

SDn_REF_CLK

Clock Driver

100

Ω differential PWB trace

SerDes Refer.

CLK Receiver

Clock Driver

CLK_Out

LVPECL CLK

Driver Chip

10nF

MPC8544E

SDn_REF_CLK

100

Ω differential PWB trace

SerDes Refer.

CLK Receiver

Clock Driver

CLK_Out

Single-Ended

CLK Driver Chip

Total 50

Ω. Assume clock driver’s

output impedance is about 16

Ω.

MPC8544E

MPC8544E Datasheet(PDF) 70 Page - Freescale Semiconductor, Inc

MPC8544E Datasheet(HTML) 70 Page - Freescale Semiconductor, Inc

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