The ICS650-21 is a low cost, low-jitter, high-performance clock synthesizer for system peripheral applications. Using analog/digital Phase Locked Loop (PLL) techniques, the device accepts a parallel resonant 25 MHz crystal input to produce up to eight output clocks. The device provides clocks for PCI, SCSI, Fast Ethernet, Ethernet, USB, and AC97. The user can select one of three USB frequencies and also one of two AC97 audio frequencies. The OE pin puts all outputs into a high-impedance state for board level
testing. All frequencies are generated with less than one ppm error, meeting the demands of SCSI and Ethernet clocking.


  • Packaged in 20-pin SSOP (QSOP)
  • Pb (lead) free package, RoHS compliant 
  • Lower jitter version of ICS650-01
  • Operating voltage of 3.3 V or 5 V
  • Zero ppm synthesis error in all clocks
  • Inexpensive 25 MHz crystal or clock input
  • Provides Ethernet and Fast Ethernet clocks
  • Provides SCSI clocks
  • Provides PCI clocks
  • Selectable AC97 audio clock
  • Selectable USB clock
  • OE pin tri-states the outputs for testing
  • Selectable frequencies on three clocks
  • Duty cycle of 45/55 for Processor clock and Audio clock
  • Advanced, low-power CMOS process
  • Industrial temperature range available

Product Options

Part Number Part Status Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
Active QSOP 20 C Yes Tube
Active QSOP 20 C Yes Reel


Title language Type Format File Size Date
Datasheets & Errata
650-21 Datasheet Datasheet PDF 249 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-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-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-830 Quartz Crystal Drive Level Application Note PDF 143 KB
AN-815 Understanding Jitter Units Application Note PDF 565 KB
AN-827 Application Relevance of Clock Jitter Application Note PDF 1.15 MB
AN-802 Crystal-Measuring Oscillator Negative Resistance Application Note PDF 136 KB
AN-801 Crystal-High Drive Level Application Note PDF 202 KB
AN-805 Recommended Ferrite Beads Application Note PDF 121 KB
AN-806 Power Supply Noise Rejection Application Note PDF 438 KB
AN-803 Crystal Timing Budget and Accuracy for Renesas Timing Clock Products Application Note PDF 108 KB
PCN# : A1808-01 Transfer Assembly Location from Amkor Philippines for select pacakges Product Change Notice PDF 39 KB
PCN# : TB1504-01R1 Qty per Reel Standardization for Selective Packages Product Change Notice PDF 95 KB
PCN# : TB1504-01 Qty per Reel Standardization for Selective Packages Product Change Notice PDF 50 KB
PCN# : TB1303-02 Change of Tape & Reel Packing Method for Selective Products Product Change Notice PDF 361 KB
PCN# : A1208-01R1 Gold to Copper Wire Product Change Notice PDF 254 KB
PDN# : CQ-18-03 Product Discontinuance Notice Product Discontinuation Notice PDF 218 KB
IDT Clock Generation Overview 日本語 Overview PDF 1.83 MB