CY25566

• 25- to 200-MHz operating frequency range
• Wide range of spread selections (9)
• Accepts clock or crystal inputs
• Provides four clocks
    -SSCLK1a
    -SSCLK1b
    -SSCLK2
    -REFOUT
• Low-power dissipation
    -3.3V = 70 mW (typical @ 40 MHz, no load)
• Center spread modulation
• Low cycle-to cycle jitter
• 16-pin SOIC package

The Cypress CY25566 is a Spread Spectrum Clock Generator (SSCG) IC used for the purpose of reducing electromagnetic interference (EMI) found in today's high-speed digital electronic systems.

The CY25566 uses a Cypress-proprietary phase-locked loop (PLL) and Spread Spectrum Clock (SSC) technology to synthesize and frequency modulate the input frequency of the digital clock. By frequency modulating the clock, (SSCLK1a/b and SSCLK2), the measured EMI at the fundamental and harmonic frequencies is greatly reduced. The modulated output frequency is centered on the input frequency.

This reduction in radiated energy can significantly reduce the cost of complying with regulatory agency requirements and improve time to market without degrading system performance.

The CY25566 provides four output clocks: SSCLK1a, SSCLK1b, SSCLK2, and REFOUT. SSCLK1a/b and SSCLK2 are modulated clocks and REFOUT is a buffered copy of the reference clock or oscillator. The CY25566 frequency and spread % ranges are selected by programming S0, S1, S2, and S3 digital inputs. S0 and S1 use three (3) logic states including High (H), Low (L), and Middle (M) to select one of nine available frequency and spread % ranges. Refer to Figure 2 for details on programming three level inputs S0 and S1. See Table 1, Table 2, and Table 3 for programming details for S2 and S3.

The CY25566 will operate over a wide range of frequencies from 25 to 200 MHz. Operation to 200 MHz is possible with the use of dual drivers at pins 8 and 9. With a wide range of selectable bandwidths, the CY25566 is a very flexible low-EMI clock. Modulation can be disabled to provide a four-output conventional clock.

The CY25566 is available in a 16-pin SOIC (150-mil.) package with a commercial operating temperature range of 0°C to 70°C.