ASM3P2185B Datasheet | Alliance Semiconductor Corporation

September 2003 .. rev 1.0 EMI Reduction IC Features FCC approved method of EMI attenuation. Provides up to 15d B EMI reduction. Generates a 1X low EMI spread spectrum clock of the input frequency. Input frequency range: 25MHz to 50 MHz. Internal loop filter minimizes external ponents and board space. Down Spread and Center Spread. 2 spread frequency deviation selections: -1.25% and ± 0.8%. Low inherent cycle-to-cycle jitter. 3.3V operating voltage range. TTL or CMOS patible inputs and outputs. Low power CMOS design. Supports notebook VGA and other LCD timing controller applications. Products are available for industrial temperature range. Available in 8-pin SOIC and TSSOP. The ASM3P2185B reduces electromagnetic interference (EMI) at the clock source, allowing system wide EMI reduction for all the down stream clocks and data dependent signals. The ASM3P2185B allows significant system cost savings by reducing the number of circuit board layers, ferrite beads, shielding, and other passive ponents that are traditionally required to pass EMI regulations. The ASM3P2185B uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all digital method. The ASM3P2185B 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 pared 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 generation’. Product Description The ASM3P2185B is a versatile spread spectrum frequency modulator designed specifically for a wide range of input clock frequencies from 25MHz to 50MHz. The ASM3P2185B can generate an EMI reduced clock from an OSC or a system generated clock. Applications The ASM3P2185B is targeted towards EMI...