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

The 87951I is a low voltage, low skew 1-to-9 Differential-to-LVCMOS/LVTTL Cock Generator. The CS87951I has two selectable clock inputs. The single ended clock input accepts LVCMOS or LVTTL input levels. The CLK1, nCLK1 pair can accept most standard differential input levels. With output frequencies up to 180MHz, the 87951I is targeted for high performance clock applications. Along with a fully integrated PLL, the 87951I contains frequency configurable outputs and an external feedback input for regenerating clocks with "zero delay".


  • Fully integrated PLL
  • Nine single ended 3.3V LVCMOS/LVTTL outputs
  • Selectable single ended CLK0 or differential CLK1, nCLK1 inputs
  • The single ended CLK0 input can accept the following input levels: LVCMOS or LVTTL input levels
  • CLK1, nCLK1 supports the following input types: LVDS, LVPECL, LVHSTL, SSTL, HCSL
  • Output frequency range: 25MHz to 180MHz
  • VCO range: 200MHz to 480MHz
  • External feedback for "zero delay" clock regeneration
  • Cycle-to-cycle jitter: ±100ps (typical)
  • Output skew: 375ps (maximum)
  • PLL reference zero delay: 350ps window (maximum)
  • 3.3V operating supply
  • -40°C to 85°C ambient operating temperature
  • Available in lead-free RoHS-compliant package

Product Options

Orderable Part ID Part Status Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
Obsolete 32 I Yes Tray
Obsolete 32 I Yes Reel

Documentation & Downloads

Title Other Languages Type Format File Size Date
Application Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 322 KB
AN-845 Termination - LVCMOS Application Note PDF 146 KB
AN-844 Termination - AC Coupling Clock Receivers Application Note PDF 170 KB
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 495 KB
AN-840 Jitter Specifications for Timing Signals Application Note PDF 442 KB
AN-834 Hot-Swap Recommendations Application Note PDF 153 KB
AN-833 Differential Input Self Oscillation Prevention Application Note PDF 180 KB
AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 120 KB
AN-835 Differential Input with VCMR being VIH Referenced Application Note PDF 160 KB
AN-827 Application Relevance of Clock Jitter Application Note PDF 1.15 MB
AN-815 Understanding Jitter Units Application Note PDF 565 KB
AN-805 Recommended Ferrite Beads Application Note PDF 121 KB
PDN# : CQ-15-01 (R1) Quarter PDN for Declined Market Product Discontinuation Notice PDF 550 KB
PDN# : CQ-15-01 Quarter PDN for Declined Market Product Discontinuation Notice PDF 547 KB
PCN# : A1401-02 Alternate Copper Wire Assembly Site Product Change Notice PDF 36 KB
PCN# : TB1303-01 Change of Carrier Tape for TQFP-32, TQFP-48 Product Change Notice PDF 472 KB
87951I IBIS Model Model - IBIS ZIP 20 KB
Clock Distribution Overview 日本語 Overview PDF 217 KB
Timing Solutions Products Overview Overview PDF 4.11 MB
IDT Clock Generation Overview 日本語 Overview PDF 1.83 MB