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813N252I-04 - Block Diagram
813N252I-04 - Pinout


VCXO Jitter Attenuator & Femtoclock® NG Multiplier

The 813N252I-04 is a PLL based synchronous multiplier that is optimized for PDH or SONET to Ethernet clock jitter attenuation and frequency translation. The device contains two internal frequency multiplication stages that are cascaded in series. The first stage is a VCXO PLL that is optimized to provide reference clock jitter attenuation. The second stage is a FemtoClock® NG frequency multiplier that provides the low jitter, high frequency Ethernet output clock that easily meets Gigabit and 10 Gigabit Ethernet jitter requirements. Pre-divider and output divider multiplication ratios are selected using device selection control pins. The multiplication ratios are optimized to support most common clock rates used in PDH, SONET and Ethernet applications. The VCXO requires the use of an external, inexpensive pullable crystal. The VCXO uses external passive loop filter components which allows configuration of the PLL loop bandwidth and damping characteristics. The device is packaged in a space-saving 32-VFQFN package and supports industrial temperature range.


  • Fourth generation FemtoClock® Next Generation (NG) technology
  • One LVPECL output pair and one LVDS output pair Each output supports independent frequency selection at 25MHz, 125MHz, 156.25MHz and 312.5MHz
  • Two differential inputs support the following input types: LVPECL, LVDS, LVHSTL, SSTLHCSL
  • Accepts input frequencies from 8kHz to 155.52MHz including 8kHz, 1.544MHz, 2.048MHz, 19.44MHz, 25MHz, 77.76MHz, 125MHz and 155.52MHz
  • Attenuates the phase jitter of the input clock by using a low-cost pullable fundamental mode VCXO crystal
  • VCXO PLL bandwidth can be optimized for jitter attenuation and reference tracking using external loop filter connection
  • FemtoClock NG frequency multiplier provides low jitter, high frequency output
  • Absolute pull range: 100ppm
  • FemtoClock NG VCO frequency: 625MHz
  • RMS phase jitter @ 125MHz, using a 25MHz crystal (12kHz ‘- 20MHz): 0.3ps (typical)
  • 3.3V supply voltage
  • -40°C to 85°C ambient operating temperature
  • Available in lead-free (RoHS 6) package

Product Specification

Outputs (#)Output TypeOutput Freq Range (MHz)Input Freq (MHz)Inputs (#)Input TypeOutput Banks (#)Core Voltage (V)Output Voltage (V)Output Skew (ps)Phase Jitter Typ RMS (ps)Phase Jitter Max RMS (ps)
2LVDS, LVPECL25.000000 - 312.5000000.008000 - 155.5200002LVDS, HSTL, SSTL, HCSL, LVPECL23.33.3750.3000.700

Product Options

Orderable Part IDPart StatusPkg. CodePkg. TypeLead Count (#)Temp. GradePb (Lead) FreeCarrier TypeSample & Buy
813N252BKI-04LFActiveNLG32P3VFQFPN32IYesTrayCheck Availability
813N252BKI-04LFTActiveNLG32P3VFQFPN32IYesReelCheck Availability


Technical Documentation

Title Other Languages Type Format File Size Datesort icon
Datasheets & Errata
813N252I-04 Data Sheet Datasheet PDF 521 KB Dec 14, 2015
Apps Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 229 KB Jul 5, 2016
AN-841 Pullable Crystal Selection and VCXO Tuning Application Note PDF 248 KB Sep 23, 2014
AN-831 The Crystal Load curve Application Note PDF 308 KB Sep 22, 2014
show all (19)
AN-848 VCXO - Crystal Selection Application Note PDF 138 KB May 14, 2014
AN-849 Loop Filter Component Selection for VCXO Based PLLs Application Note PDF 132 KB May 14, 2014
AN-847 VCXO - Absolute Pull Range Application Note PDF 70 KB May 13, 2014
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 12, 2014
AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 8, 2014
AN-838 Peak-to-Peak Jitter Calculations Application Note PDF 32 KB May 7, 2014
AN-839 RMS Phase Jitter Application Note PDF 149 KB May 7, 2014
AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 37 KB May 6, 2014
AN-835 Differential Input with VCMR being VIH Referenced Application Note PDF 77 KB May 6, 2014
AN-830 Quartz Crystal Drive Level Application Note PDF 59 KB May 5, 2014
AN-815 Understanding Jitter Units Application Note PDF 476 KB Apr 24, 2014
AN-827 Application Relevance of Clock Jitter Application Note PDF 1.06 MB Apr 24, 2014
AN-802 Crystal-Measuring Oscillator Negative Resistance Application Note PDF 52 KB Mar 12, 2014
AN-806 Power Supply Noise Rejection Application Note PDF 353 KB Jan 15, 2014
AN-805 Recommended Ferrite Beads Application Note PDF 38 KB Jan 15, 2014
AN-801 Crystal-High Drive Level Application Note PDF 109 KB Jan 15, 2014
PCN# : A1511-01(R1) Add SPEL India as Alternate Assembly Location Product Change Notice PDF 596 KB Jan 28, 2016
PCN# : A1511-01 Add SPEL India as Alternate Assembly Location Product Change Notice PDF 544 KB Nov 13, 2015
PCN# : W1308-01 Change of Passivation Thickness Product Change Notice PDF 941 KB Sep 11, 2013
show all (4)
PCN# : N1210-01 Die Revision Change 813N252AKI-04LF & 813N252AKI-09LF Product Change Notice PDF 54 KB Oct 18, 2012
IDT Clock Generation Overview 日本語 Overview PDF 1.83 MB Apr 28, 2016
IDT Clock Distribution Overview 日本語 Overview PDF 3.79 MB Apr 25, 2016