W256 Cypress Semiconductor Corp., W256 Datasheet - Page 2

• Manufacturer Part Number: W256
• Description: 12 Output Buffer For 2 DDR And 3 Sdram Dimms
• Manufacturer: Cypress Semiconductor Corp.

Pin Summary
SEL_DDR
SCLK
SDATA
BUF_IN
FBOUT
PWR_DWN#
DDR[0:5]T_SDRAM
[0,2,4,6,8,10]
DDR[0:5]C_SDRAM
[1,3,5,7,9, 11]
VDD3.3_2.5
GND
Name
Pins
28
16
15
10
1
2
3, 7, 12, 19, 23, 27
4, 8, 13, 18, 22, 26
5, 9, 14, 21, 25
6, 11, 17, 20, 24
Preliminary
Input to configure for DDR-ONLY mode or STANDARD SDRAM mode.
1 = DDR-ONLY mode.
0 = STANDARD SDRAM mode.
When SEL_DDR is pulled high or configured for DDR-ONLY mode, all
the buffers will be configured as DDR outputs.
Connect VDD3.3_2.5 to a 2.5V power supply in DDR-ONLY mode.
When SEL_DDR is pulled LOW or configured for STANDARD SDRAM
output, all the buffers will be configured as STANDARD SDRAM outputs.
Connect VDD3.3_2.5 to a 3.3V power supply in STANDARD SDRAM
mode.
SMBus clock input
SMBus data input
Reference input from chipset. 2.5V input for DDR-ONLY mode; 3.3V
input for STANDARD SDRAM mode.
Feedback clock for chipset. Output voltage depends on VDD3.3_2.5V.
Active LOW input to enable Power Down mode; all outputs will be pulled
LOW.
Clock outputs. These outputs provide copies of BUF_IN. Voltage swing
depends on VDD3.3_2.5 power supply.
Clock outputs. These outputs provide complementary copies of BUF_IN
when SEL_DDR is active. These outputs provide copies of BUF_IN
when SEL_DDR is inactive. Voltage swing depends on VDD3.3_2.5 pow-
er supply.
Connect to 2.5V power supply when W256 is configured for DDR-ONLY
mode. Connect to 3.3V power supply, when W256 is configured for stan-
dard SDRAM mode.
Ground
Description
2
W256