CY2305 Cypress Semiconductor, CY2305 Datasheet - Page 5

• Manufacturer Part Number: CY2305
• Description: CY2305 and CY2309 as PCI and SDRAM Buffers
• Manufacturer: Cypress Semiconductor

PCICLK
Applications
5 and 9 PCI Device/Slot Zero Delay Buffer Solution
The CY2305 and CY2309 are an excellent clocking solution
for a system that requires more PCI clocks than the currently
popular clock chips provide. The CY2305 comes in a tiny
150-mil 8-pin SOIC package and the CY2309 comes in a
small 150-mil 16-pin SOIC package. The CY2305 and
CY2309 are priced very aggressively for the high volume PC
market. There are two solutions for implementing a PCI zero
delay buffer with the Cypress zero delay buffers: a 5 de-
vice/slot and a 9 device/slot buffer.
The 5 Device/Slot Solution:
The 9 Device/Slot Solution:
PCICLK
• PCI/Slot 1 (CLKOUT) must always be loaded.
• If PCI Slots represent different loads, they will have earlier
• PCI/Slot 1 (CLKOUT) must always be loaded.
• Select lines can be used to shut down output banks, see
or later clocks (See Lead or Lag Adjustments section of
“Special Features of Cypress Zero Delay Buffers”.
CY2309 data sheet.
V
dd
REF
CY2305
Zero Delay
Buffer
REF
S1
S2
CY2309
Zero Delay
Buffer
CLKOUT
CLKOUT
CLKA1
CLKA2
CLKA3
CLKA4
CLKB1
CLKB2
CLKB3
CLKB4
CLK1
CLK2
CLK3
CLK4
4 PCI Devices/Slots
4 PCI Devices/Slots
4 PCI Devices/Slots
PCI Device 1
PCI Device 1
5
CY2305 and CY2309 as PCI and SDRAM Buffers
CPUCLK
CPUCLK
1 SDRAM DIMM Zero Delay Buffer Solution
The CY2305 is an excellent clocking solution for a system
using 1 SDRAM DIMM. The CY2305 comes in a very small
150-mil 8-pin SOIC package and is priced very aggressively
for the high volume PC market. There are two solutions for
implementing 1 SDRAM DIMM support with the CY2305: the
first is the adjustable delay solution, and the second is the self
adjusting delay solution.
The Adjustable Delay Solution:
The Self Adjusting Solution:
• C
• To make the SDRAM inputs lead or lag the reference input
• This solution will automatically compensate for different
• CLKOUT must drive CK0 on the SDRAM module so that
delay.
see the Lead or Lag Adjustments section of “Special Fea-
tures of the Cypress Zero Delay Buffers”.
SDRAM input loads.
CLKOUT is always fully loaded (pin 42 on the SDRAM
module).
load
must be equal to SDRAM module loading for zero
REF
REF
CY2305
Zero Delay
Buffer
CY2305
Zero Delay
Buffer
CLKOUT
CLKOUT
CLK1
CLK2
CLK3
CLK4
CLK1
CLK2
CLK3
CLK4
C
SDRAM Module
load
SDRAM Module