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CY2305 and CY2309 as PCI and SDRAM Buffers
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The Self Adjusting Solution:
• This solution will automatically compensate for different
SDRAM input loads (only on Module 1 and Module 2).
• CLKOUT must drive CK0 on the SDRAM module 1 and
module 2 so that CLKOUT is always fully loaded (pin 42
on the SDRAM module).
• SDRAM modules must be installed in order (module 1 first
and module 3 last).
• Module 2 and 3 clocks are three-stated when those
SDRAM modules are not present, but CLKOUT will contin-
ue to run.
• Module 1 clocks can only be three-stated by three-stating
CPUCLK which will also three-state modules 2 and 3.
CY2309
SDRAM Module 2
Zero Delay
Buffer
CLKA4
CLKA3
CLKA2
CLKA1
CLKOUT
REF
SDRAM Module 3
CLKB4
CLKB3
CLKB2
CLKB1
S1
S2
Module Sense
Module Sense
CY2305
SDRAM Module 1
Zero Delay
Buffer
CPUCLK
CLK4
CLK3
CLK2
CLK1
CLKOUT
REF
Decoding
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