Precision Edge®
3.3V, 2.0GHz ANY DIFF. IN-TO-LVDS
PROGRAMMABLE CLOCK DIVIDER
FANOUT BUFFER W/ INTERNAL TERMINATION
SY89873L
®
Micrel, Inc.
Precision Edge
SY89873L
FEATURES
Guaranteed AC performance
®
Precision Edge
• > 2.0GHz f
• > 3.0GHz f
output toggle
input
MAX
MAX
DESCRIPTION
• < 800ps t (matched-delay between banks)
PD
• < 15ps within-device skew
• < 190ps rise/fall time
This 3.3V low-skew, low-jitter, precision LVDS output clock
divider accepts any high-speed differential clock input (AC- or
DC-coupled) CML, LVPECL, HSTL or LVDS and divides down
the frequency using a programmable divider ratio to create a
frequency-locked, lower speed version of the input clock. The
SY89873L includes two output banks. Bank A is an exact
copy of the input clock (pass through) with matched
propagation delay to Bank B, the divided output bank. Available
divider ratios are 2, 4, 8 and 16. In a typical 622MHz clock
system this would provide availability of 311MHz, 155MHz,
77MHz or 38MHz auxiliary clock components.
Low jitter design
• < 1ps
cycle-to-cycle jitter
RMS
Unique input termination and V pin for DC-coupled
and AC-coupled inputs: any differential inputs
(LVPECL, LVDS, CML, HSTL)
T
Precision differential LVDS outputs
Matched delay: all outputs have matched delay,
independent of divider setting
The differential input buffer has a unique internal termination
design that allows access to the termination network through
a VT pin. This feature allows the device to easily interface to
TTL/CMOS inputs for select and reset/disable
Two LVDS output banks (matched delay)
• Bank A: Buffered copy of input clock (undivided)
all AC- or DC-coupled differential logic standards. A V
REF-AC
• Bank B: Divided output (÷2, ÷4, ÷8, ÷16),
reference is included for AC-coupled applications.
two copies
The SY89873L is part of Micrel’s high-speed Precision
®
3.3V power supply
Edge timing and distribution family. For 2.5V applications,
consider the SY89872U. For applications that require an
LVPECL output, consider the SY89871U.
Wide operating temperature range: –40°C to +85°C
Available in 16-pin (3mm × 3mm) QFN package
The /RESET input asynchronously resets the divider outputs
(Bank B). In the pass-through function (Bank A) the /RESET
synchronously enables or disables the outputs on the next
falling edge of IN (rising edge of /N). Refer to the Timing
Diagram.
APPLICATIONS
SONET/SDH line cards
Transponders
All support documentation can be found on Micrel’s web
site at: www.micrel.com.
High-end, multiprocessor servers
FUNCTIONAL BLOCK DIAGRAM
TYPICAL APPLICATION
Enable
FF
/RESET
622MHz/155.5MHz
SONET Clock Generator
Enable
MUX
QA
VREF-AC
QA
/QA
622MHz LVDS
Clock Out
/QA
OC-12 or
OC-3
Clock Gen
622MHz LVPECL
Clock In
IN
/IN
IN
50Ω
50Ω
QB0
QB 155.5MHz LVDS
/QB
Clock Out
VT
Divided
by
2, 4, 8
or 16
/QB0
/IN
QB1
Bank B: 155.5MHz: For OC-3 line card
Set to divide-by-4
/QB1
Bank A: 622MHz: For OC-12 line card
Set to pass-through
S0
S1
Decoder
Precision Edge is a registered trademark of Micrel, Inc.
Rev.: F
Amendment: /0
M9999-082407
hbwhelp@micrel.com or (408) 955-1690
1
Issue Date: February 2007