The ASM3P28XX devices are versatile spread spectrum frequency modulators designed specifically for a wide range of input clock frequencies from 10MHz to 40MHz. Refer to Input/Output Frequency Range Selection Table. The ASM3P28XX can generate an EMI reduced clock from crystal, ceramic resonator, or system clock. The ASM3P28XX-A and the ASM3P28XX-B offer various combinations of spread options and percentage deviations. Refer to Frequency Deviation and Spread Selection Table. These combinations include Down and Center Spread, and percentage deviation range from ±0.625% to -3.5%. The ASM3P28XX reduces electromagnetic interference (EMI) at the clock source, allowing system wide reduction of EMI of downstream clock and data dependent signals. The ASM3P28XX 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 ASM3P28XX 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 generation’. The ASM3P28XX uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all-digital method.