Skip to main content
49FCT3805 - Block Diagram


3.3V CMOS Buffer/Clock Driver

The FCT3805 is a 3.3 volt, non-inverting clock driver built using advanced dual metal CMOS technology. The device consists of two banks of drivers, each with a 1:5 fanout and its own output enable control. The device has a "heartbeat" monitor for diagnostics and PLL driving. The MON output is identical to all other outputs and complies with the output specifications in this document. The FCT3805 offers low capacitance inputs with hysteresis. The FCT3805 is designed for high speed clock distribution where signal quality and skew are critical. The FCT3805 also allows single point-topoint transmission line driving in applications such as address distribution, where one signal must be distributed to multiple recievers with low skew and high signal quality. For more information on using the FCT3805 with two different input frequencies on bank A and B, please see AN-236.


  • 0.5 MICRON CMOS Technology
  • Guaranteed low skew < 500ps (max.)
  • Very low duty cycle distortion < 1.0ns (max.)
  • Very low CMOS power levels
  • TTL compatible inputs and outputs
  • Inputs can be driven from 3.3V or 5V components
  • Two independent output banks with 3-state control
  • 1:5 fanout per bank
  • Heartbeat” monitor output
  • VCC = 3.3V ± 0.3V
  • Available in SSOP, SOIC, and QSOP packages

Product Specification

Outputs (#)Output TypeOutput Freq Range (MHz)Input Freq (MHz)Inputs (#)Input TypeOutput Banks (#)Core Voltage (V)Output Voltage (V)Divider ValueOutput Skew (ps)Additive Phase Jitter Typ RMS (ps)

Product Options

Orderable Part IDPart StatusPkg. CodePkg. TypeLead Count (#)Temp. GradePb (Lead) FreeCarrier TypeSample & Buy
49FCT3805APYGActivePYG20SSOP20CYesTubeCheck Availability
49FCT3805APYGIActivePYG20SSOP20IYesTubeCheck Availability
49FCT3805AQGActivePCG20QSOP20CYesTubeCheck Availability
49FCT3805AQGIActivePCG20QSOP20IYesTubeCheck Availability
49FCT3805ASOGActivePSG20SOIC20CYesTubeCheck Availability
49FCT3805ASOGIActivePSG20SOIC20IYesTubeCheck Availability


Technical Documentation

Title Other Languages Type Format File Size Datesort icon
Datasheets & Errata
49FCT3805 Datasheet Datasheet PDF 70 KB May 17, 2010
Apps Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 229 KB Jul 5, 2016
AN-845 Termination - LVCMOS Application Note PDF 62 KB May 13, 2014
AN-844 Termination - AC Coupling Clock Receivers Application Note PDF 82 KB May 13, 2014
show all (9)
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 12, 2014
AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 8, 2014
AN-834 Hot-Swap Recommendations Application Note PDF 67 KB May 6, 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-805 Recommended Ferrite Beads Application Note PDF 38 KB Jan 15, 2014
PCN# : A1602-01(R1) Add Greatek Taiwan as Alternate Assembly Product Change Notice PDF 611 KB Apr 14, 2016
PCN# : A1602-01 Add Greatek Taiwan as Alternate Assembly Product Change Notice PDF 611 KB Feb 15, 2016
PCN# : A1208-01R1 Gold to Copper Wire Product Change Notice PDF 254 KB Dec 21, 2012
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 25, 2016