ASM3P5821A

The ASM3P5821A is a versatile spread spectrum frequency modulator designed specifically for input clock frequencies in the range of 20MHz 34MHz. The
ASM3P5821A can generate an EMI reduced clock from crystal, ceramic resonator, or system clock. That offers a percentage deviation of 1.5%.

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 ASM3P2969A 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'.