ASM3P5821A

October 2003 www.DataSheet4U.com ASM3P5821A rev 1.0 Features FCC approved method of EMI attenuation. Generates a 1X low EMI spread spectrum clock of the input frequency. Input frequency range: 20MHz –34MHz. Internal loop filter minimizes external components and board space. Frequency deviation: -1.5% Low inherent cycle-to-cycle jitter. 3.3V operating voltage. TTL or CMOS compatible inputs and outputs. Ultra-low power CMOS design. o o Pinout range. Available in 8-pin SOIC and TSSOP. TBD mA @ 3.3V, 25MHz TBD mA @ 3.3V, 31MHz compatible with Cypress CY25811. The ASM3P5821A reduces electromagnetic interference (EMI) at the clock source, allowing system wide reduction of EMI of down stream clock and data dependent signals. The ASM3P5821A allows significant system cost savings by reducing the number of circuit board layers ferrite beads, shielding and other passive components that are traditionally required to pass EMI regulations. The ASM3P5821A uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all digital method. The ASM3P5821A modulates the output of a single PLL in order to “spread” the bandwidth of a synthesized clock, and more importantly, decreases the peak amplitudes of its harmonics. This results in significantly lower system EMI compared to the typical narrow band signal produced by oscillators and most frequency generators. Lowering EMI by increasing a signal’s bandwidth is called ‘spread spectrum clock g...