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參數資料
| 型號： | W255 |
| 英文描述： | Clocks and Buffers |
| 中文描述： | 時鐘和緩沖器 |
| 文件頁數： | 1/10頁 |
| 文件大小： | 129K |
| 代理商： | W255 |
200-MHz 24-Output Buffer for 4 DDR
or 3 SDRAM DIMMS
W255
Cypress Semiconductor Corporation
Document #: 38-07255 Rev. *C
3901 North First Street
San Jose
CA 95134
Revised December 14, 2002
408-943-2600
Features
One input to 24-output buffer/driver
Supports up to 4 DDR DIMMs or 3 SDRAM DIMMS
One additional output for feedback
SMBus interface for individual output control
Low skew outputs (< 100 ps)
Supports 266-, 333-, and 400-MHz DDR SDRAM
Dedicated pin for power management support
Space-saving 48-pin SSOP package
Functional Description
The W255 is a 3.3V/2.5V buffer designed to distribute
high-speed clocks in PC applications. The part has 24 outputs.
Designers can configure these outputs to support four unbuf-
fered DDR DIMMS or to support three unbuffered standard
SDRAM DIMMs and two DDR DIMMS. The W255 can be used
in conjunction with the W250 or similar clock synthesizer for
the VIA Pro 266 chipset.
The W255 also includes an SMBus interface which can enable
or disable each output clock. On power-up, all output clocks
are enabled (internal pull up).
Block Diagram
SMBus
Decoding
BUF_IN
SDATA
SCLOCK
DDR0T_SDRAM10
DDR0C_SDRAM11
DDR1T_SDRAM0
DDR1C_SDRAM1
DDR2T_SDRAM2
DDR2C_SDRAM3
DDR3T_SDRAM4
DDR3C_SDRAM5
DDR4T_SDRAM6
DDR4C_SDRAM7
DDR5T_SDRAM8
DDR5C_SDRAM9
DDR6T
DDR6C
DDR7T
DDR7C
DDR8T
DDR8C
DDR9T
DDR9C
1
2
3
4
5
6
7
SEL_DDR*
VDD2.5
GND
DDR11T
DDR11C
DDR10T
DDR10C
VDD2.5
GND
DDR9T
DDR9C
VDD2.5
PWR_DWN#*
GND
DDR8T
DDR8C
VDD2.5
GND
DDR7T
DDR7C
DDR6T
DDR6C
GND
SCLK
SSOP
Top View
Pin Configuration
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
FBOUT
VDD3.3_2.5
GND
DDR0T_SDRAM10
DDR0C_SDRAM11
DRR1T_SDRAM0
DDR1C_SDRAM1
VDD3.3_2.5
DDR2T_SDRAM2
DDR2C_SDRAM3
VDD3.3_2.5
BUF_IN
GND
DDR3T_SDRAM4
DDR3C_SDRAM5
VDD3.3_2.5
GND
DDR4T_SDRAM6
DDR4C_SDRAM7
DDR5T_SDRAM8
DDR5C_SDRAM9
VDD3.3_2.5
SDATA
GND
R_DWN#
DDR10T
DDR10C
DDR11T
DDR11C
FBOUT
Power Down Control
SEL_DDR
Note:
1.
Internal 100K pull-up resistors present on inputs marked
with *. Design should not rely solely on internal pull-up resistor
to set I/O pins HIGH.
相關PDF資料 |
PDF描述 |
|---|---|
| W255H | 200-MPz 24-Output Buffer for 4DDR or 3 SDRAM DIMMS |
| W255HT | 200-MPz 24-Output Buffer for 4DDR or 3 SDRAM DIMMS |
| W25P010AD-8 | x32 Fast Synchronous SRAM |
| W25P010AF-6 | x32 Fast Synchronous SRAM |
| W25P010AF-7 | x32 Fast Synchronous SRAM |
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