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

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 Options

Orderable Part ID Part Status Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
Obsolete VFQFPN 40 I Yes Tray
Obsolete VFQFPN 40 I Yes Reel
Obsolete VFQFPN 40 I Yes Tray
Obsolete VFQFPN 40 I Yes Reel
Obsolete VFQFPN 40 I Yes Tray
Obsolete VFQFPN 40 I Yes Reel
Obsolete VFQFPN 40 I Yes Tray
Obsolete VFQFPN 40 I Yes Reel

Documentation & Downloads

Title Other Languages Type Format File Size Date
Datasheets & Errata
IDT8T49N524I Datasheet Datasheet PDF 1.11 MB
Errata#: NEN-13-01 Errata Notification Datasheet Errata PDF 90 KB
User Guides & Manuals
Programmable FemtoClock Ordering Product Information Manual PDF 140 KB
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-833 Differential Input Self Oscillation Prevention Application Note PDF 180 KB
AN-834 Hot-Swap Recommendations Application Note PDF 153 KB
AN-832 Timing Budget and Accuracy Application Note PDF 131 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# : A1904-01 Add Greatek, Taiwan as an Alternate Assembly Facility Product Change Notice PDF 983 KB
PDN# : CQ-19-01(R1) Quarterly Market Declined PDN Product Discontinuation Notice PDF 1014 KB
PDN# : CQ-19-01 Quarterly Market Declined PDN Product Discontinuation Notice PDF 537 KB
PDN# : CQ-17-01 Quarter PDN for Declined Market Product Discontinuation Notice PDF 580 KB
PCN# : A1611-02 Add JCET China as Alternate Assembly and Change of Material Set at Alternate Assembly Location Product Change Notice PDF 583 KB
PCN# : TB1311-01 New Carrier Tape on VFQFPN-28, VFQFPN-40, VFQFPN-48 Product Change Notice PDF 790 KB
PCN# : W1308-01 Change of Passivation Thickness Product Change Notice PDF 941 KB
Timing Solutions Products Overview Overview PDF 4.11 MB
IDT Products for Radio Applications 日本語 Product Brief PDF 2.34 MB
IDT Clock Generation Overview 日本語 Overview PDF 1.83 MB