CY28359
273 MHz 6 Output Buffer for DDR400 DIMMS
Features
• Dual 1- to 3-output buffer/driver
• Supports up to 2 DDR DIMMs
• Outputs are individually enabled/disabled
• Low-skew outputs (< 100 ps)
• Supports 266 MHz, 333 MHz and 400 MHz DDR SDRAM
• SMBus Read and Write support
• Space-saving 28-pin SSOP package
Functional Description
The CY28359 is a 2.5V buffer designed to distribute
high-speed clocks in PC applications. The part has 6 differ-
ential outputs. Designers can configure these outputs to
support up to two DDR DIMMs. The CY28359 can be used in
conjunction with the CY28326 or similar clock synthesizer for
the VIA P4X600 chipset.
The CY28359 also includes an SMBus interface which can
enable or disable each output clock. On power-up, all output
clocks are enabled.
Block Diagram
BUF_INA
FB_OUTA
DDRAT0
DDRAC0
DDRAT1
DDRAC1
DDRAT2
DDRAC2
DDRBT0
DDRBC0
DDRBT1
DDRBC1
DDRBT2
DDRBC2
FB_OUTB
Pin Configuration
FB_OUTB
BUF_INB
DDRBT0
DDRBC0
DDRBT1
DDRBC1
VDD
VSS
FB_OUTA
BUF_INA
VSS
DDRAT0
DDRAC0
DDRAT1
SDATA
SEL_ADDR
SCLK
SMBus
Decoding
BUFF_INB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VDD
VSS
SEL_ADDR
DDRBT2
DDRBC2
VSS
VDD
DDRAT2
DDRAC2
SDATA
SCLK
VSS
VDD
DDRAC1
28 PIN SSOP
CY28359
Rev 1.0, November 24, 2006
2200 Laurelwood Road, Santa Clara, CA 95054
Tel:(408) 855-0555
Fax:(408) 855-0550
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