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8T49N028I

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, LVDSHCSL
  • 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 Specification

Phase Jitter Typ RMS (ps)Inputs (#)Input TypeInput Freq (MHz)Outputs (#)Output TypeOutput Voltage (V)Output Freq Range (MHz)
0.2122LVPECL, LVDS, HCSL, Crystal10.000000 - 312.5000008LVDS, LVPECL2.5, 3.315.160000 - 1250.000000

Product Options

Orderable Part IDPart StatusPkg. CodePkg. TypeLead Count (#)Temp. GradePb (Lead) FreeCarrier TypeSample & Buy
8T49N028-001NLGIActiveNLG48VFQFPN48IYesTrayCheck Availability
8T49N028-001NLGI8ActiveNLG48VFQFPN48IYesReelCheck Availability

Documents

Technical Documentation

Title Type Format File Size Datesort icon
Datasheets & Errata
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8T49N028 Datasheet Datasheet PDF 986 KB Nov 6, 2014
User Guides & Manuals
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Programmable FemtoClock Ordering Product Information Manual PDF 140 KB Oct 10, 2014
Apps Notes & White Papers
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AN-828 Termination - LVPECL Application Note PDF 229 KB Jul 5, 2016
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AN-831 The Crystal Load curve Application Note PDF 308 KB Sep 22, 2014
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AN-844 Termination - AC Coupling Clock Receivers Application Note PDF 82 KB May 13, 2014
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AN-846 Termination - LVDS Application Note PDF 50 KB May 13, 2014
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AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 12, 2014
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AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 8, 2014
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AN-803 Crystal Timing Budget and Accuracy for IDT Timing Clock Products Application Note PDF 44 KB May 8, 2014
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AN-838 Peak-to-Peak Jitter Calculations Application Note PDF 32 KB May 7, 2014
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AN-839 RMS Phase Jitter Application Note PDF 149 KB May 7, 2014
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AN-832 Timing Budget and Accuracy Application Note PDF 48 KB May 6, 2014
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AN-833 Differential Input Self Oscillation Prevention Application Note PDF 94 KB May 6, 2014
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AN-837 Overdriving the Crystal Interface Application Note PDF 50 KB May 6, 2014
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AN-835 Differential Input with VCMR being VIH Referenced Application Note PDF 77 KB May 6, 2014
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AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 37 KB May 6, 2014
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AN-834 Hot-Swap Recommendations Application Note PDF 67 KB May 6, 2014
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AN-830 Quartz Crystal Drive Level Application Note PDF 59 KB May 5, 2014
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AN-815 Understanding Jitter Units Application Note PDF 476 KB Apr 24, 2014
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AN-827 Application Relevance of Clock Jitter Application Note PDF 1.06 MB Apr 24, 2014
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AN-802 Crystal-Measuring Oscillator Negative Resistance Application Note PDF 52 KB Mar 12, 2014
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AN-806 Power Supply Noise Rejection Application Note PDF 353 KB Jan 15, 2014
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AN-801 Crystal-High Drive Level Application Note PDF 109 KB Jan 15, 2014
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AN-805 Recommended Ferrite Beads Application Note PDF 38 KB Jan 15, 2014
PCNs & PDNs
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PCN# : W1308-01 Change of Passivation Thickness Product Change Notice PDF 941 KB Sep 11, 2013