P2781

July 2005 rev 1.5 General Purpose EMI Reduction IC Features ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ Provides up to 15dB of EMI suppression FCC approved method of EMI attenuation Generates a 1X, 2X, and 4X low EMI spread spectrum clock of the input frequency Input frequency range from 3 to 78MHz External loop filter for spread % adjustment Spreading ranges from ±0.25% to ±5.0% Ultra low cycle-to-cycle jitter Zero-cycle slip 3.3V operating voltage range 10 mA output drives TTL or CMOS compatible outputs Ultra-low power CMOS design P278XA is available in 8 pin SOIC and TSSOP Packages Available for industrial and automotive temperature ranges. P2781/82/84 other digital video and imaging applications. The P278xA reduces electromagnetic interference (EMI) at the clock source, which provides system wide reduction of EMI of all clock dependent signals. The P278xA allows significant system cost savings by reducing the number of circuit board layers and shielding that are traditionally required to pass EMI regulations. The P278xA uses the most efficient and optimized modulation profile approved by the FCC. The P278xA 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 ...