Skip to main content
8T49N524I - Pinout


Programmable FemtoClock® NG LVPECL/LVDS Dual 4-Output Fractional Clock Generator


The IDT8T49N524I is an eight output programmable any-rate dual clock generator with selectable LVDS or LVPECL outputs. Both clock generators use Fractional Output Dividers to be able to generate output frequencies that are independent of each other and independent of the input frequency. Output frequencies for both clock generators are generated from a single crystal or reference clock. Clock Generator A supports three different factory-programmed default frequencies that can be selected from using only the FSEL control pins. Alternatively any desired output frequency can be programmed over the I2C serial port. The chosen output frequency is then driven out the QA0 to QA3 outputs.
Clock Generator B supports a single factory-programmed default frequency. It can also be programmed for any output frequency via the serial port. The output frequency is driven out the QB0 to QB3 outputs. Please consult IDT for programming software that can be used to determine the required settings for any desired configuration.
Excellent phase noise performance is achieved with IDT’s fourth Generation FemtoClock® NG PLL technology, which delivers sub-0.5ps RMS phase jitter in the integer divide mode.


  • Fourth Generation FemtoClock® NG PLL technology
  • Eight outputs selectable as LVPECL or LVDS
  • Input selectable: fundamental mode crystal or clock reference
  • Supports fundamental mode crystals from 10MHz - 40MHz
  • CLK, nCLK input pair can accept the following differential input levels: LVPECL, LVDS, HCSL
  • Input frequencies from 5MHz up to 800MHz
  • Two independent output frequencies can be generated
  • Output frequencies independent of each other and of input
  • Output frequencies from 15.5MHz - 650MHz, and 975MHz - 1300MHz
  • RMS phase jitter at 125MHz (12kHz - 20MHz): 0.282ps (typical)
  • RMS phase jitter at 156.25MHz (12kHz - 20MHz): 0.278ps (typical)
  • Full 2.5V or 3.3V power supply
  • I2C programming interface
  • -40°C to 85°C ambient operating temperature
  • Lead-free (RoHS 6) packaging
    3.3V / 3.3V / 3.3V
    3.3V / 3.3V / 2.5V (LVPECL only)
    2.5V / 2.5V / 2.5V
  • 4-output (8T49N004I) 6-output (8T49N006I) and 8-output (8T49N008I) with Integer Output Divider also available

Product Specification

Phase Jitter Typ RMS (ps)Inputs (#)Input TypeInput Freq (MHz)Outputs (#)Output TypeOutput Freq Range (MHz)
0.3231LVDS, LVPECL, HCSL5.000000 - 800.0000008LVDS, LVPECL975.000000 - 1300.000000, 15.500000 - 650.000000

Product Options

Orderable Part IDPart StatusPkg. CodePkg. TypeLead Count (#)Temp. GradePb (Lead) FreeCarrier TypeSample & Buy
8T49N524-001NLGIActiveNLG40P2VFQFPN40IYesTrayCheck Availability
8T49N524-001NLGI8ActiveNLG40P2VFQFPN40IYesReelCheck Availability
8T49N524-002NLGINot Recommended
NLG40P2VFQFPN40IYesTrayCheck Availability
8T49N524-002NLGI8Not Recommended
NLG40P2VFQFPN40IYesReelCheck Availability
8T49N524-003NLGIActiveNLG40P2VFQFPN40IYesTrayCheck Availability
8T49N524-003NLGI8ActiveNLG40P2VFQFPN40IYesReelCheck Availability
8T49N524-004NLGIActiveNLG40P2VFQFPN40IYesTrayCheck Availability
8T49N524-004NLGI8ActiveNLG40P2VFQFPN40IYesReelCheck Availability


Technical Documentation

Title Type Format File Size Datesort icon
Datasheets & Errata
IDT8T49N524I Datasheet Datasheet PDF 502 KB Jan 23, 2014
Errata#: NEN-13-01 Errata Notification Datasheet PDF 90 KB Jun 21, 2013
User Guides & Manuals
Programmable FemtoClock Ordering Product Information Manual PDF 140 KB Oct 10, 2014
Apps 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-844 Termination - AC Coupling Clock Receivers Application Note PDF 82 KB May 13, 2014
show all (21)
AN-846 Termination - LVDS Application Note PDF 50 KB May 13, 2014
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 12, 2014
AN-803 Crystal Timing Budget and Accuracy for IDT Timing Clock Products Application Note PDF 44 KB May 8, 2014
AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 8, 2014
AN-839 RMS Phase Jitter Application Note PDF 149 KB May 7, 2014
AN-838 Peak-to-Peak Jitter Calculations Application Note PDF 32 KB May 7, 2014
AN-832 Timing Budget and Accuracy Application Note PDF 48 KB May 6, 2014
AN-833 Differential Input Self Oscillation Prevention Application Note PDF 94 KB May 6, 2014
AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 37 KB May 6, 2014
AN-834 Hot-Swap Recommendations Application Note PDF 67 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-827 Application Relevance of Clock Jitter Application Note PDF 1.06 MB Apr 24, 2014
AN-815 Understanding Jitter Units Application Note PDF 476 KB 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# : TB1311-01 New Carrier Tape on VFQFPN-28, VFQFPN-40, VFQFPN-48 Product Change Notice PDF 790 KB Apr 8, 2014
PCN# : W1308-01 Change of Passivation Thickness Product Change Notice PDF 941 KB Sep 11, 2013