ASM3P2821B

The ASM3P2821B is targeted towards EMI management for high speed digital applications such as PC peripheral devices, consumer electronics and embedded controller systems.

The ASM3P2821B is a versatile spread spectrum frequency modulator designed specifically for input clock frequencies in the range of 15MHz - 27MHz. The ASM3P2821B can generate an EMI reduced clock from a ceramic resonator or system clock. The ASM3P2821B offers a percentage deviation of 2.5%.

The ASM3P2821B reduces electromagnetic interference (EMI) at the clock source, allowing system wide reduction of EMI of down stream clock and data dependent signals. The ASM3P2821B 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 ASM3P2821B uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all digital method.

The ASM3P2821B 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'.