June 2005 ASM2I2318ANZ

rev 0.3


Alliance Semiconductor
2575, Augustine Drive • Santa Clara, CA • Tel: 408.855.4900 • Fax: 408.855.4999 • www.alsc.com
Notice: The information in this document is subject to change without notice.
18 Output, 3.3V SDRAM Buffer for Desktop PCs with 3 DIMMs

Features
ƒ One input to 18 output Buffer/Driver
ƒ Supports up to four SDRAM DIMMs
ƒ Two additional outputs for feedback
ƒ Serial interface for individual output control
ƒ Low skew outputs (< 250 pS)
ƒ Up to 133 MHz operation
ƒ Dedicated OE pin for testing
ƒ Space-saving 48 Pin SSOP package
ƒ 3.3V operation

Functional Description
The ASM2I2318ANZ is a 3.3V buffer designed to distribute
high-speed clocks in PC applications. The part has 18
outputs, 16 of which can be used to drive up to four
SDRAM DIMMs, and the remaining can be used for
external feedback to a PLL. The device operates at 3.3V
and outputs can run up to 133MHz, thus making it
compatible with Pentium II
®*
processors. The
ASM2I2318ANZ can be used in conjunction with the clock
synthesizer for a complete Pentium II motherboard
solution. The ASM2I2318ANZ also includes a serial
interface which can enable or disable each output clock.
On power-up, all output clocks are enabled (internal pull
up). A separate Output Enable pin facilitates testing on
ATE.

*Pentium is a registered trademark of Intel Corporation.

Block Diagram


Serial Interface
Decoding
SDATA
SCLOCK
OE
BUF_IN
SDRAM0
SDRAM1
SDRAM2
SDRAM3
SDRAM4
SDRAM5
SDRAM6
SDRAM7
SDRAM8
SDRAM9
SDRAM10
SDRAM11
SDRAM12
SDRAM13
SDRAM14
SDRAM15
SDRAM16
SDRAM17