PPC440SPE datasheet(70/80 Pages) AMCC

70 / 80 page

PowerPC 440SPe Embedded Processor

AMCC Proprietary

Revision 1.23 - Sept 21, 2006

Preliminary Data Sheet

DDR SDRAM I/O Specifications

The DDR SDRAM controller times its operation with internal PLB clock signals and generates MemClkOut0 from

the PLB clock. The PLB clock is an internal signal that cannot be directly observed. However MemClkOut0 is the

same frequency as the PLB clock signal and is in phase with the PLB clock signal.

Note: MemClkOut0 can be advanced with respect to the PLB clock by means of the SDRAM0_CLKTR

programming register. In a typical system, users advance MemClkOut by 90

°. This depends on the specific

application and requires a thorough understanding of the memory system in general (refer to the DDR

SDRAM controller chapter in the PPC440SPe Embedded Processor User’s Manual).

In the following sections, the label MemClkOut0(0) refers to MemClkOut0 when it has not been phase-shifted, and

MemClkOut0(90) refers to MemClkOut0 when it has been phase-advanced 90

°. Advancing MemClkOut0 by 90°

creates a 3/4 cycle setup time and 1/4 cycle hold time for the address and control signals in relation to

MemClkOut0(90). The rising edge of MemClkOut0(90) aligns with the first rising edge of the DQS signal.

The following DDR data is generated by means of simulation and includes logic, driver, package RLC, and lengths.

It is not to be used as a circuit design recommendation. Values are calculated over best case and worst case

processes with speed, temperature, and voltage as follows:

Best Case = Fast process, 0°C, +1.6V

Worst Case = Slow process, +95°C, +1.4V

Note: In all the following DDR tables and timing diagrams, minimum values are measured under best case

conditions and maximum values are measured under worst case conditions.

The signals are terminated as indicated in the figure below for the DDR timing data in the following sections.

Figure 7. DDR SDRAM Signal Termination

10pF

MemClkOut0

120

30pF

Addr/Ctrl/Data/DQS

VTT = SVDD/2

PPC440SPe

Note: This diagram illustrates the model of the DDR SDRAM interface used when generating simulation timing data.

It is not a recommended physical circuit design for this interface. An actual interface design will depend on many

factors, including the type of memory used and the board layout.

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