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July 17, 2002
76
SDR Memory Design
5.3.7 Recommended Design Procedure
1.
Determine the required memory configuration, soldered-down vs. SODIMM.
2.
Generate schematics. If soldered-down memory is used, the second resistor for termination of data lines
must be added. If an advanced CAD package is used, apply delay rules to memory lines per Table 14.
Also, add delay rules to match line lengths within signal groups. Apply structures to soldered-down
memory per the JEDEC SODIMM specification.
3.
Determine the board stack-up to yield the desired characteristic impedance. Recalculate termination
resistor values as needed.
4.
Place SDR SDRAM close to the processor (no further than 4” from processor), preferably orthogonal
with the processor, center-lines aligned. Place termination resistors as close to their source as possible.
5.
Route clock lines, as direct and short as possible, splitting off in equal-length branches at the farthest
point (starburst pattern).
6.
Route CKEs, selects, data, address and control lines. If delay rules were not added in step 2, match line
length within signal groups and add skew-correction values from Table 14.
7.
From line length data, calculate the time needed for the CLKIN delay.
Содержание Crusoe TM5500
Страница 1: ...TM5500 TM5800 System Design Guide July 17 2002...
Страница 6: ...July 17 2002 6 List of Tables...
Страница 8: ...July 17 2002 8 List of Figures...
Страница 50: ...July 17 2002 50 Processor Power Supplies and Power Management...
Страница 110: ...July 17 2002 110 System Design Considerations...
Страница 122: ...July 17 2002 122 System Design Checklists...
Страница 128: ...July 17 2002 128 Serial Write protection PLD Data...
Страница 130: ...July 17 2002 130 Index...