CYIFS781BSXC

The Cypress FS781 is Spread Spectrum clock generator ICs (SSCG) designed for the purpose of reducing electromagnetic interference (EMI) found in today’s high-speed digital systems. The FS781 SSCG clocks use a Cypress-proprietary technology to modulate the input clock frequency, XIN, by modulating the frequency of the digital clock. By modulating the reference clock the measured EMI at the fundamental and harmonic frequencies of FSOUT is greatly reduced. This reduction in radiated energy can significantly reduce the cost of complying with regulatory requirements without degrading digital waveforms. The Cypress FS781 is clocks are very simple and versatile devices to use. By programming the two range select lines, S0 and S1, any frequency from 6- to 82-MHz operating range can be selected. The FS781 is designed to operate over a very wide range of input frequencies and provides 1×, 2×, and 4× modulated clock outputs. The FS781 devices have a simple frequency selection table that allows operation from 6 MHz to 82 MHz in four separate ranges. The bandwidth of the frequency spread at FSOUT is determined by the values of the loop filter components. The modulation rate is determined internally by the input frequency and the selected input frequency range.

• Spread Spectrum clock generator (SSCG) with 1×, 2×, and 4× outputs
• 6- to 82-MHz operating frequency range
• Modulates external clocks including crystals, crystal oscillators, or ceramic resonators
• Programmable modulation with simple R-C external loop filter (LF)
• Center spread modulation
• 3V-5V power supply
• TTL-/CMOS-compatible outputs
• Low short-term jitter
• Low-power Dissipation
  • 3.3 VDC = 37 mW - typical
  • 5.0 VDC = 115 mW - typical
• Available in 8-pin SOIC and TSSOP packages