Ethernet & USB Clock Generator for Freescale B4/ T4-based Systems

The IDT840NT4-01I is clock generator designed to provide ethernet and USB clocks for Freescale B4/ T4-based systems. The IDT840NT4-01I utilizes IDT’s FemtoClock NG® PLL technology to synthesize eight low phase-jitter Ethernet reference clocks. The clock generator also provides a 24MHz USB reference clock and a 25MHz reference output.


  • Ten LVCMOS clock outputs:
    Five LVCMOS 125MHz Ethernet outputs
    Three LVCMOS 25MHz /125MHz Ethernet outputs
    One LVCMOS 24MHz USB output
    One LVCMOS 25MHz REF output
  • QREF output; can be used to drive X1 of other devices, saving a crystal
  • Selectable crystal input, or differential LVPECL input; test mode
  • RMS Phase Jitter, 125MHz, integration range 12kHz - 20MHz: 0.75ps (typical)
  • Cycle-to-Cycle jitter: 75ps (typical)
  • Flexible voltage supply modes; supports legacy and future system requirements, minimizes power consumption
    Core voltage: (VDD, VDD_XTAL, VDDA)/
    Output voltage: (VDDO_A, VDDO_B, VDDO_C, VDDO_REF)
    Core / Output
    3.3V / 3.3V
    3.3V / 2.5V
    3.3V / 1.8V
    2.5V / 2.5V
    2.5V / 1.8V
  • -40°C to 85°C ambient operating temperature
  • Space-saving Pb-free, 48-pin 7x7mm QFN; minimal board space
  • Lead-free (RoHS 6) packaging

Product Options

Orderable Part ID Part Status Pkg. Code Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
840NT4-01NLGI Active NLG48P1 VFQFPN 48 I Yes Tray Availability
840NT4-01NLGI8 Active NLG48P1 VFQFPN 48 I Yes Reel Availability

Technical Documentation

Title Other Languages Type Format File Size Date
Datasheets & Errata
840NT4-01 Datasheet Datasheet PDF 663 KB Jun 10, 2015
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-845 Termination - LVCMOS Application Note PDF 62 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-837 Overdriving the Crystal Interface Application Note PDF 50 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# : W1308-01 Change of Passivation Thickness Product Change Notice PDF 941 KB Sep 10, 2013
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 24, 2016