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

The 873991 is a low voltage, low skew, 3.3V LVPECL or ECL Clock Generator. The 873991 has two selectable clock inputs. The PCLK, nPCLK pair can accept an LVPECL input and the TEST_CLK pin can accept a LVCMOS or LVTTL input. This device has a fully integrated PLL along with frequency configurable outputs. An external feedback input and output regenerates clocks with "zero delay". The four independent banks of outputs each have their own output dividers, which allow the device to generate a multitude of different bank frequency ratios and output-toinput frequency ratios. The output frequency range is 25MHz to 400MHz and the input frequency range is 6.25MHz to 125MHz. The PLL_SEL input can be used to bypass the PLL for test and system debug purposes. In bypass mode, the input clock is routed around the PLL and into the internal output dividers. The 873991 also has a SYNC output which can be used for system synchronization purposes. It monitors Bank A and Bank C outputs for coincident rising edges and signals a pulse per the timing diagrams in this data sheet. This feature is used primarily in applications where Bank A and Bank C are running at different frequencies, and is particularly useful when they are running at non-integer multiples of each other.


  • 14 differential LVPECL outputs
  • Selectable differential LVPECL or TEST_CLK inputs
  • PCLK, nPCLK can accept the following input levels: LVPECL, CML, SSTL
  • TEST_CLK accepts the following input levels: LVCMOS, LVTTL
  • Input frequency range: 6.25MHz to 125MHz
  • Output frequency: 400MHz (maximum)
  • VCO range: 200MHz to 800MHz
  • Output skew: 250ps (maximum)
  • Cycle-to-cyle jitter: ±50ps (typical)
  • LVPECL mode operating voltage supply range: VCC = 3.135V to 3.465V, VEE = 0V
  • ECL mode operating voltage supply range: VCC = 0V, VEE = -3.465V to -3.135V
  • 0°C to 70°C ambient operating temperature
  • Industrial temperature available upon request
  • Lead-Free package fully RoHS compliant

Product Options

Orderable Part ID Part Status Pkg. Code Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
873991AYLF Obsolete PPG52 TQFP 52 C Yes Tray
873991AYLFT Obsolete PPG52 TQFP 52 C Yes Reel

Technical Documentation

Title Other Languages Type Format File Size Date
Datasheets & Errata
873991 Datasheet Datasheet PDF 264 KB Jan 24, 2017
Application Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 229 KB Jul 5, 2016
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-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 7, 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-836 Differential Input to Accept Single-ended Levels Application Note PDF 37 KB May 5, 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-805 Recommended Ferrite Beads Application Note PDF 38 KB Jan 14, 2014
PDN# : CQ-15-04 Quarterly Market Declined PDN Product Discontinuation Notice PDF 545 KB Aug 12, 2015
PCN# : A1401-02 Alternate Copper Wire Assembly Site Product Change Notice PDF 36 KB Feb 15, 2014
PCN#: A1309-03 Additional Assembly Sources Product Change Notice PDF 398 KB Oct 20, 2013
PDN# : N-12-22R2 PRODUCT DISCONTINUANCE NOTICE Product Discontinuation Notice PDF 363 KB Jun 13, 2013
Timing Solutions Products Overview Overview PDF 4.11 MB Oct 31, 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

Software & Tools

Title Other Languages Type Format File Size Date
873991 IBIS Model Model - IBIS ZIP 30 KB Dec 23, 2008