Crystal-to-3.3V, 2.5V Multiple Frequency Clock Generator w/Fanout Buffer

The 8T49N028 is a low RMS phase jitter Clock Synthesizer with selectable internal crystal oscillator or external clock references and eight outputs, configurable as either LVDS, LVPECL or High Impedance.
 
After power up, two frequency select pins determine one of up to four different sets of factory preprogrammed crystal or input frequency and output frequency configurations. From a single input reference, as many as three different output frequencies may be selected for the output banks: two of these frequencies can be generated by the internal crystal oscillator, and/or external clock pre-divider, and/or A output divider, and/or B output divider. The third output frequency is from the B output divider. Device pre-programming can be overwritten through the provided I2C interface.
 
Examples of valid frequency configuration setups illustrate this device's flexibility, and are shown in Table 3A. The specific internal register settings for each of the four frequency sets are specified by an IDT order code. Custom codes can be provided by contacting IDT.

Features

  • Fourth Generation FemtoClock NG PLL technology
  • Eight selectable LVPECL or LVDS outputs (bank selectable, two output channels per bank)
  • CLK, nCLK input pair can accept the following differential input levels: LVPECL, LVDS, HCSL
  • FemtoClock NG VCO Range: 1.92GHz - 2.5GHz
  • Bank A and B output frequencies are mux selectable from internal crystal oscillator, reference clock input, output divider A or output divider B
  • Clock from OUTPUT DIVIDER A, RMS phase jitter at 156.25MHz
    (12KHz - 20MHz): 225fs (typical)
  • Clock from OUTPUT DIVIDER B, RMS phase jitter at 156.25MHz
    (12KHz - 20MHz): 219fs (typical)
  • Clock from OUTPUT DIVIDER B, RMS phase jitter at 156.25MHz
    (10kHz - 1MHz): 165fs (typical) Full 2.5V or 3.3V power supply
  • Full 2.5V or 3.3V power supply
  • I2C programming interface
  • PCI Express (2.5 Gb/S), Gen 2 (5 Gb/s) and Gen 3 (8 Gb/s) jitter compliant
  • -40°C to 85°C ambient operating temperature
  • 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
8T49N028-001NLGI Active NLG48P1 VFQFPN 48 I Yes Tray Availability
8T49N028-001NLGI8 Active NLG48P1 VFQFPN 48 I Yes Reel Availability

Technical Documentation

Title Other Languages Type Format File Size Date
Datasheets & Errata
8T49N028 Datasheet Datasheet PDF 986 KB Nov 5, 2014
User Guides & Manuals
Programmable FemtoClock Ordering Product Information Manual PDF 140 KB Oct 9, 2014
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-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
PCNs & PDNs
PCN# : A1611-02 Add JCET China as Alternate Assembly and Change of Material Set at Alternate Assembly Location Product Change Notice PDF 583 KB Dec 19, 2016
PCN# : W1308-01 Change of Passivation Thickness Product Change Notice PDF 941 KB Sep 10, 2013
Other
The IDT Communications Products Advantage Overview PDF 4.00 MB Mar 21, 2018
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