July 2005 ASM5I961C

rev 0.2


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.
Low Voltage Zero Delay Buffer

Features
ƒ Fully Integrated PLL
ƒ Up to 200MHz I/O Frequency
ƒ LVCMOS Outputs
ƒ Outputs Disable in High Impedance
ƒ LVCMOS Reference Clock Options
ƒ LQFP and TQFP Packaging
ƒ ±50pS Cycle–Cycle Jitter
ƒ 150pS Output Skews
Functional Description
The ASM5I961C is a 2.5V or 3.3V compatible, 1:18 PLL
based zero delay buffer. With output frequencies of up to
200MHz, output skews of 150pS the device meets the
needs of the most demanding clock tree applications.
The ASM5I961 is offered with two different input
configurations. The ASM5I961C offers an LVCMOS
reference clock while the ASM5I961P offers an LVPECL
reference clock.
When pulled high the OE pin will force all of the outputs
(except QFB) into a high impedance state. Because the OE
pin does not affect the QFB output, down stream clocks
can be disabled without the internal PLL losing lock.
The ASM5I961C is fully 2.5V or 3.3V compatible and
requires no external loop filter components. All control
inputs accept LVCMOS compatible levels and the outputs
provide low impedance LVCMOS outputs capable of
driving terminated 50Ω transmission lines. For series
terminated lines the ASM5I961C can drive two lines per
output giving the device an effective fanout of 1:36. The
device is packaged in a 32 lead LQFP and TQFP
Packages.

Block Diagram




Figure 1. ASM5I961C Logic Diagram

Q0
Q1
Q2
Q3
Q14
Q15
Q16
QFB
0
1
100-200 MHz
50-100 MHz
Ref
FB
PLL
50K
50K
50K
50K
CCLK
FB_IN
F_RANGE
OE