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

The 843442I is a low jitter, high performance clock generator and a member of the FemtoClock® family of silicon timing products. The 843442I is designed for use in applications using the SAS and SATA interconnect. The 843442I uses an external, 25MHz, parallel resonant crystal to generate two selectable output frequencies: 75MHz and 150MHz. This silicon based approach provides excellent frequency stability and reliability. The 843442I features down and center spread spectrum (SSC) clocking techniques.


  • Designed for use in SAS, SAS-2, and SATA systems
  • Center (±0.25%) Spread Spectrum Clocking (SSC)
  • Down (-0.23% or -0.5%) SSC
  • Two differential 3.3V LVPECL output pairs
  • Crystal oscillator interface designed for 25MHz (CL = 18pF) frequency
  • External fundamental crystal frequency ensures high reliability and low aging
  • Selectable output frequencies: 75MHz, 150MHz
  • Output frequency is tunable with external capacitors
  • RMS phase jitter at 150MHz (integrated from 12kHz to 20MHz): 1.07ps (typical)
  • 3.3V operating supply
  • -40°C to 85°C ambient operating temperature
  • Available in lead-free (RoHS 6) package

Product Options

Orderable Part ID Part Status Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
Obsolete TSSOP 16 I Yes Tube
Obsolete TSSOP 16 I Yes Reel

Documentation & Downloads

Title Other Languages Type Format File Size Date
Datasheets & Errata
843442I Datasheet Datasheet PDF 286 KB
Application Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 322 KB
AN-831 The Crystal Load curve Application Note PDF 395 KB
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 495 KB
AN-803 Crystal Timing Budget and Accuracy for IDT Timing Clock Products Application Note PDF 128 KB
AN-840 Jitter Specifications for Timing Signals Application Note PDF 442 KB
AN-838 Peak-to-Peak Jitter Calculations Application Note PDF 115 KB
AN-839 RMS Phase Jitter Application Note PDF 233 KB
AN-837 Overdriving the Crystal Interface Application Note PDF 133 KB
AN-832 Timing Budget and Accuracy Application Note PDF 131 KB
AN-834 Hot-Swap Recommendations Application Note PDF 153 KB
AN-830 Quartz Crystal Drive Level Application Note PDF 143 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-802 Crystal-Measuring Oscillator Negative Resistance Application Note PDF 136 KB
AN-801 Crystal-High Drive Level Application Note PDF 202 KB
AN-806 Power Supply Noise Rejection Application Note PDF 438 KB
AN-805 Recommended Ferrite Beads Application Note PDF 121 KB
PDN# : CQ-15-04 Quarterly Market Declined PDN Product Discontinuation Notice PDF 545 KB
PCN# : TB1403-01 Changed in Carrier Tape, Plastic Reel and Quantity per Reel on TSSOP-14, TSSOP-16 Product Change Notice PDF 663 KB
PCN# : TB1303-02 Change of Tape & Reel Packing Method for Selective Products Product Change Notice PDF 361 KB
IDT Products for Radio Applications 日本語 Product Brief PDF 2.34 MB
IDT Clock Generation Overview 日本語 Overview PDF 1.83 MB