LMK04000_14 Datasheet, PDF (1/66 Pages) Texas Instruments – Family Low-Noise Clock Jitter Cleaner with Cascaded PLLs

www.ti.com
LMK04000, LMK04001, LMK04002, LMK04010
LMK04011, LMK04031, LMK04033
SNOSAZ8J – SEPTEMBER 2008 – REVISED SEPTEMBER 2011
LMK04000 Family Low-Noise Clock Jitter Cleaner with Cascaded PLLs
Check for Samples: LMK04000, LMK04001, LMK04002, LMK04010, LMK04011, LMK04031, LMK04033
FEATURES
1
•23 Cascaded PLLatinum™ PLL Architecture
– PLL1
– Phase Detector Rate of up to 40 MHz
– Integrated Low-Noise Crystal Oscillator
Circuit
– Dual Redundant Input Reference Clock
with LOS
– PLL2
– Normalized [1 Hz] PLL Noise Floor of -
224 dBc/Hz
– Phase Detector Rate up to 100 MHz
– Input Frequency-Doubler
– Integrated Low-Noise VCO
• Ultra-Low RMS Jitter Performance
– 150 fs RMS Jitter (12 kHz – 20 MHz)
– 200 fs RMS Jitter (100 Hz – 20 MHz)
• LVPECL/2VPECL, LVDS, and LVCMOS outputs
• Support Clock Rates up to 1080 MHz
• Default Clock Output (CLKout2) at power up
• Five Dedicated Channel Divider and Delay
Blocks
• Pin Compatible Family of Clocking Devices
• Industrial Temperature Range: -40 to 85 °C
• 3.15 V to 3.45 V Operation
• Package: 48 Pin WQFN (7.0 x 7.0 x 0.8 mm)
APPLICATIONS
• Data Converter Clocking
• Wireless Infrastructure
• Networking, SONET/SDH, DSLAM
• Medical
• Military / Aerospace
• Test and Measurement
• Video
DESCRIPTION
The LMK04000 family of precision clock conditioners provides low-noise jitter cleaning, clock multiplication and
distribution without the need for high-performance voltage controlled crystal oscillators (VCXO) module. Using a
cascaded PLLatinum™ architecture combined with an external crystal and varactor diode, the LMK04000 family
provides sub-200 femtosecond (fs) root mean square (RMS) jitter performance.
The cascaded architecture consists of two high-performance phase-locked loops (PLL), a low-noise crystal
oscillator circuit, and a high-performance voltage controlled oscillator (VCO). The first PLL (PLL1) provides a low-
noise jitter cleaner function while the second PLL (PLL2) performs the clock generation. PLL1 can be configured
to either work with an external VCXO module or use the integrated crystal oscillator with an external crystal and
a varactor diode. When used with a very narrow loop bandwidth, PLL1 uses the superior close-in phase noise
(offsets below 50 kHz) of the VCXO module or the crystal to clean the input clock. The output of PLL1 is used as
the clean input reference to PLL2 where it locks the integrated VCO. The loop bandwidth of PLL2 can be
optimized to clean the far-out phase noise (offsets above 50 kHz) where the integrated VCO outperforms the
VCXO module or crystal used in PLL1.
The LMK04000 family features dual redundant inputs, five differential outputs, and an optional default-clock upon
power up. The input block is equipped with loss of signal detection and automatic or manual selection of the
reference clock. Each clock output consists of a programmable divider, a phase synchronization circuit, a
programmable delay, and an LVDS, LVPECL, or LVCMOS output buffer. The default startup clock is available on
CLKout2 and it can be used to provide an initial clock for the field-programmable gate array (FPGA) or
microcontroller that programs the jitter cleaner during the system power up sequence.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PLLatinum is a trademark of Texas Instruments.
2
All other trademarks are the property of their respective owners.
3
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008–2011, Texas Instruments Incorporated