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8521 - Block Diagram
8521 - Pinout


Low Skew,1-to-9 Differential-to-HSTL Fanout Buffer

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

The 8521 is a low skew, 1-to-9 Differential-to-HSTL Fanout Buffer. The 8521 has two selectable clock inputs. The CLK, nCLK pair can accept most standard differential input levels. The PCLK, nPCLK pair can accept LVPECL, CML, or SSTL input levels. The clock enable is internally synchronized to eliminate runt pulses on the outputs during asynchronous assertion/deassertion of the clock enable pin. Guaranteed output skew, part-to-part skew and crossover voltage characteristics make the 8521 ideal for today's most advanced applications, such as IA64 and static RAMs.


  • 9 HSTL outputs
  • Selectable differential CLK, nCLK or LVPECL clock inputs
  • CLK, nCLK pair can accept the following differential input levels: LVPECL, LVDS, HSTL, SSTLHCSL
  • PCLK, nPCLK supports the following input types: LVPECL, CMLSSTL
  • Maximum output frequency: 500MHz
  • Output skew: 50ps (maximum)
  • Part-to-part skew: 250ps (maximum)
  • Propagation delay: 1.8ns (maximum)
  • VOH = 1.4V (maximum)
  • 3.3V core, 1.8V output operating supply voltages
  • 0°C to 70°C ambient operating temperature
  • Industrial temperature information available upon request

Product Specification

Outputs (#)Output TypeOutput Freq Range (MHz)Input Freq (MHz)Inputs (#)Input TypeOutput Banks (#)Core Voltage (V)Output Skew (ps)Additive Phase Jitter Typ RMS (ps)
9HSTL0.000000 - 500.0000000.000000 - 500.0000002SSTL, LVPECL, LVDS, HSTL, CML, HCSL13.350

Product Options

Orderable Part IDPart StatusPkg. CodePkg. TypeLead Count (#)Temp. GradePb (Lead) FreeCarrier TypeSample & Buy
8521BYLFLast Time BuyPRG32TQFP32CYesTrayCheck Availability
8521BYLFTLast Time BuyPRG32TQFP32CYesReelCheck Availability
8521BYLNLast Time BuyPRG32TQFP32CYesTrayCheck Availability
8521BYLNTLast Time BuyPRG32TQFP32CYesReelCheck Availability


Technical Documentation

Title Other Languages Type Format File Size Datesort icon
Datasheets & Errata
8521 Datasheet Datasheet PDF 237 KB Jun 21, 2016
Apps 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 13, 2014
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 12, 2014
show all (11)
AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 8, 2014
AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 37 KB May 6, 2014
AN-833 Differential Input Self Oscillation Prevention Application Note PDF 94 KB May 6, 2014
AN-835 Differential Input with VCMR being VIH Referenced Application Note PDF 77 KB May 6, 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
PDN# : CQ-16-01 PRODUCT DISCONTINUANCE NOTICE Product Discontinuation Notice PDF 552 KB May 4, 2016
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
show all (8)
PCN# : TB1504-01R1 Qty per Reel Standardization for Selective Packages Product Change Notice PDF 95 KB Oct 22, 2015
PCN# : TB1504-01 Qty per Reel Standardization for Selective Packages Product Change Notice PDF 50 KB Jul 21, 2015
PCN# : A1401-02 Alternate Copper Wire Assembly Site Product Change Notice PDF 36 KB Feb 16, 2014
PCN# : A1309-01 Changed of Traceability Mark Format Product Change Notice PDF 439 KB Oct 11, 2013
PCN# : TB1303-01 Change of Carrier Tape for TQFP-32, TQFP-48 Product Change Notice PDF 472 KB Mar 31, 2013
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
IDT Fanout Buffers Product Overview Product Brief PDF 739 KB Feb 17, 2015
show all (4)
High-Performance, Low-Phase Noise Clocks Buffers product brief Product Brief PDF 378 KB Aug 14, 2012

Software & Tools

Title Type Format File Size Datesort icon
8521 IBIS Model Model - IBIS ZIP 39 KB Sep 21, 2010
8521 IBIS Model Model - IBIS ZIP 7 KB Nov 11, 2009