1

SY89823L

Micrel, Inc.

M9999-091908

hbwhelp@micrel.com or (408) 955-1690

FEATURES

voltage

power

The SY89823L is a high-performance bus clock driver with 22

differential High-Speed Transceiver Logic (HSTL), 1.5V compatible

output pairs. The device is designed for use in low-voltage (3.3V/

1.8V) applications that require a large number of outputs to drive

precisely aligned, ultra-low skew signals to their destination. The

input is multiplexed from either HSTL or Low-Voltage Positive-

Emitter-Coupled Logic (LVPECL) by the CLK_SEL pin.

The Output Enable (OE) is synchronous and triple-buffered so

that the outputs will only be enabled/disabled when they are already

in the LOW state. This avoids any potential of generating a runt clock

pulse when the device is enabled/disabled, as can occur with an

asynchronous control. The triple-buffering feature provides a three-

clock delay from the time the OE input is asserted/de-asserted to

when the clock appears at the outputs.

The SY89823L features low pin-to-pin skew (50ps max.) and low

part-to-part skew (200ps max.), performance previously unachievable

in a standard product having such a high number of outputs. The

SY89823L is available in a single, space-saving package, enabling

a lower overall cost solution.

All support documentation can be found on Micrel’s web site at:

www.micrel.com.

3.3V, 500MHz 1:22

DIFFERENTIAL HSTL (1.5V)

FANOUT BUFFER/TRANSLATOR

DESCRIPTION

SY89823L

LOGIC SYMBOL

CLK_SEL

HSTL_CLK

/HSTL_CLK

LVPECL_CLK

/LVPECL_CLK

OE

0

1

22

22

Q0 - Q21

/Q0 - /Q21

EN

ENABLE

LOGIC

Rev.: D

Amendment: /0

Issue Date:

September 2008

Precision Edge is a registered trademark of Micrel, Inc.

CLK_SEL

0

0

LOW

HIGH

0

1

LOW

HIGH

1

0

HSTL_CLK

/HSTL_CLK

1

1

LVPECL_CLK

/LVPECL_CLK

Note:

1. The output enable (OE) signal is synchronized with the low level of the

HSTL_CLK and LVPECL_CLK signal.

TRUTH TABLE

APPLICATIONS

TYPICAL PERFORMANCE

0

100

200

300

400

500

600

700

800

900

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

OUTPUT FREQUENCY (GHz)

Output Amplitude

vs. Frequency