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 Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
Obsolete 28 I Yes Tray
Obsolete 28 I Yes Tray
Obsolete 28 I Yes Reel

Documentation & Downloads

Title Other Languages Type Format File Size Date
Application Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 322 KB
AN-831 The Crystal Load curve Application Note PDF 395 KB
AN-846 Termination - LVDS Application Note PDF 133 KB
AN-844 Termination - AC Coupling Clock Receivers Application Note PDF 170 KB
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 495 KB
AN-803 Crystal Timing Budget and Accuracy for IDT Timing Clock Products Application Note PDF 128 KB
AN-840 Jitter Specifications for Timing Signals Application Note PDF 442 KB
AN-838 Peak-to-Peak Jitter Calculations Application Note PDF 115 KB
AN-839 RMS Phase Jitter Application Note PDF 233 KB
AN-834 Hot-Swap Recommendations Application Note PDF 153 KB
AN-832 Timing Budget and Accuracy Application Note PDF 131 KB
AN-833 Differential Input Self Oscillation Prevention Application Note PDF 180 KB
AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 120 KB
AN-835 Differential Input with VCMR being VIH Referenced Application Note PDF 160 KB
AN-830 Quartz Crystal Drive Level Application Note PDF 143 KB
AN-827 Application Relevance of Clock Jitter Application Note PDF 1.15 MB
AN-815 Understanding Jitter Units Application Note PDF 565 KB
AN-802 Crystal-Measuring Oscillator Negative Resistance Application Note PDF 136 KB
AN-801 Crystal-High Drive Level Application Note PDF 202 KB
AN-806 Power Supply Noise Rejection Application Note PDF 438 KB
AN-805 Recommended Ferrite Beads Application Note PDF 121 KB
PCN# : TB1311-01 New Carrier Tape on VFQFPN-28, VFQFPN-40, VFQFPN-48 Product Change Notice PDF 790 KB
PDN# : CQ-13-02 (R1) PRODUCT DISCONTINUANCE NOTICE Product Discontinuation Notice PDF 601 KB
PDN# : CQ-13-02 Q2FY14 Quarter PDN for Manufacturing Discontinuance Product Discontinuation Notice PDF 327 KB
PCN#: A-0410-02, Change IDT marking logo with new IDT gridless w Product Change Notice PDF 24 KB
PCN#: A-0412-04 - To comply with Pb-free labels - Green Products Product Change Notice PDF 80 KB
PCN#: L-0405-04 To comply with current EIA Std Product Change Notice PDF 143 KB
PCN#: A-0310-01, Green Products Product Change Notice PDF 26 KB