NOTICE - The following device(s) are recommended alternatives:

The 5T940 generates a high precision FEC (Forward Error Correction)or non-FEC source clock for SONET/SDH systems as well as asource clock for Gigabit Ethernet systems. This device also has clockregeneration capability: it creates a "clean" version of the clock input byusing the internal oscillator to square the input clock's rising and fallingedges and remove jitter. In the event that the main clock input fails, thedevice automatically locks to a backup reference clock using a hitlessswitchover mechanism.This device detects loss of valid CLKIN and leaves the VCO of the PLL atthe last valid frequency while an alternate input REFIN is selected. If CLKINand REFIN are different frequencies, the multiplication factor will be adjusted toretain the same output frequency.The 5T940 can act as a translator from a differential LVPECL, LVDS, orsingle-ended LVTTL input to LVPECL or LVDS outputs. The 5T940-10has LVDS outputs and the 5T940-30 has LVPECL outputs.The three modes of output frequency range are controlled by the SELmode,which is a 3-level pin. When SELmode is high or low, the QOUT is a multipliedversion of the input clock while QREG is a regenerated version of the input clock.When SELmode is mid, the QOUT is a multiplied version of the input clock whileQREG is QOUT/4.The 5T940 features a selectable loop bandwidth.The 5T940 features a selectable loop bandwidth.


  • Input frequency:- For SONET non-FEC: 19.44MHz, 38.88MHz, 77.76MHz, 155.52MHz,311.04MHz, or 622.08MHz- For SONET FEC: 20.83MHz, 41.66MHz, 83.31MHz, 166.63MHz,333.26MHz, or 666.52MHz
  • - For 10GE copper: 19.53MHz, 39.06MHz, 78.125MHz, 156.25MHz,312.5MHz, or 625MHz
  • - For 10GE optical: 20.14MHz, 40.28MHz, 80.56MHz, 161.13MHz,322.26MHz, or 644.53MHz
  • 3-level inputs for feedback divide ratio and output frequency rangeselection
  • 1x, 2x, 4x, 8x, 16x, and 32x outputs on QOUT
  • Regenerated input clock or QOUT/4 on QREG
  • Lock indicator
  • Power-down modeLVPECL or LVDS outputs
  • Three modes of output frequency range- Mode 0: QOUT range 155.5 - 166.6MHz. QREG is a regenerated versionof the input clock.- Mode 1: QOUT range 622 - 666.5MHz. QREG output 155.5-166.6MHz.- Mode 2: QOUT range 622 - 666.5MHz. QREG is a regenerated version- Mode 2: QOUT range 622 - 666.5MHz. QREG is a regenerated versionof the input clock frequency.
  • Selectable loop bandwidths
  • Hitless switchover
  • Differential LVPECL, LVDS, or single-ended LVTTL input interface

Product Options

Orderable Part ID Part Status Pkg. Code Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
5T940-10NLGI Obsolete NLG28 VFQFPN 28 I Yes Tray
5T940-30NLGI Obsolete NLG28 VFQFPN 28 I Yes Tray
5T940-30NLGI8 Obsolete NLG28 VFQFPN 28 I Yes Reel

Technical Documentation

Title Other Languages Type Format File Size Date
Application Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 229 KB Jul 5, 2016
AN-831 The Crystal Load curve Application Note PDF 308 KB Sep 22, 2014
AN-846 Termination - LVDS Application Note PDF 50 KB May 12, 2014
AN-844 Termination - AC Coupling Clock Receivers Application Note PDF 82 KB May 12, 2014
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 11, 2014
AN-835 Differential Input with VCMR being VIH Referenced Application Note PDF 77 KB May 10, 2014
AN-803 Crystal Timing Budget and Accuracy for IDT Timing Clock Products Application Note PDF 44 KB May 7, 2014
AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 7, 2014
AN-839 RMS Phase Jitter Application Note PDF 149 KB May 6, 2014
AN-838 Peak-to-Peak Jitter Calculations Application Note PDF 32 KB May 6, 2014
AN-834 Hot-Swap Recommendations Application Note PDF 67 KB May 5, 2014
AN-833 Differential Input Self Oscillation Prevention Application Note PDF 94 KB May 5, 2014
AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 37 KB May 5, 2014
AN-832 Timing Budget and Accuracy Application Note PDF 48 KB May 5, 2014
AN-830 Quartz Crystal Drive Level Application Note PDF 59 KB May 4, 2014
AN-827 Application Relevance of Clock Jitter Application Note PDF 1.06 MB Apr 23, 2014
AN-815 Understanding Jitter Units Application Note PDF 476 KB Apr 23, 2014
AN-802 Crystal-Measuring Oscillator Negative Resistance Application Note PDF 52 KB Mar 11, 2014
AN-805 Recommended Ferrite Beads Application Note PDF 38 KB Jan 14, 2014
AN-801 Crystal-High Drive Level Application Note PDF 109 KB Jan 14, 2014
AN-806 Power Supply Noise Rejection Application Note PDF 353 KB Jan 14, 2014
PCN# : TB1311-01 New Carrier Tape on VFQFPN-28, VFQFPN-40, VFQFPN-48 Product Change Notice PDF 790 KB Apr 7, 2014
PDN# : CQ-13-02 (R1) PRODUCT DISCONTINUANCE NOTICE Product Discontinuation Notice PDF 601 KB Dec 21, 2013
PDN# : CQ-13-02 Q2FY14 Quarter PDN for Manufacturing Discontinuance Product Discontinuation Notice PDF 327 KB Oct 26, 2013
PCN#: A-0410-02, Change IDT marking logo with new IDT gridless w Product Change Notice PDF 24 KB Nov 13, 2012
PCN#: A-0412-04 - To comply with Pb-free labels - Green Products Product Change Notice PDF 80 KB Dec 13, 2004
PCN#: L-0405-04 To comply with current EIA Std Product Change Notice PDF 143 KB May 17, 2004
PCN#: A-0310-01, Green Products Product Change Notice PDF 26 KB Oct 9, 2003