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

840304I is an optimized PCI-X and PCI-e clock generator and a member of the family of high performance clock solutions from IDT. The 840304I uses a 25MHz parallel crystal to generate 33.33MHz to 133.33MHz clock signals, replacing solutions requiring multiple oscillator and fanout buffer solutions. The device supports 1% downspread spread spectrum clocking. The 840304I has excellent phase jitter (<1ps rms) over integration range of 1.5MHz - 22MHz. Designed for Backplane, networking and industrial applications, the 840304I can also drive the high-speed PCI-X and PCI-e SerDes clock inputs of communication processors, DSPs, switches and bridges.


  • Four LVCMOS/LVTTL outputs, 20Ω typical output impedance One REF_OUT LVCMOS/LVTTL clock output
  • Selectable crystal oscillator interface, 25MHz, 18pF parallel resonant crystal or LVCMOS/LVTTL single-ended clock input
  • Support the following output frequencies: 33.33MHz, 66.67MHz, 100MHz or 133.33MHz
  • VCO: 400MHz
  • PLL and N divider bypass and output enable
  • RMS phase jitter @100MHz, using a 25MHz crystal, (1.5MHz - 22MHz): 0.46ps (typical) @ 3.3V
  • Supports SSC, 1% downspread
  • Full 3.3V and 2.5V supply modes
  • -40°C to 85°C ambient operating temperature
  • Available in and lead-free (RoHS 6) package

Product Options

Orderable Part ID Part Status Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
Obsolete 24 I Yes Tube
Obsolete 24 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-831 The Crystal Load curve Application Note PDF 395 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-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-832 Timing Budget and Accuracy Application Note PDF 131 KB
AN-834 Hot-Swap Recommendations Application Note PDF 153 KB
AN-837 Overdriving the Crystal Interface Application Note PDF 133 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-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
PCN# : TB1303-02 Change of Tape & Reel Packing Method for Selective Products Product Change Notice PDF 361 KB