The P1819 is a Versatile Spread Spectrum Frequency Modulator designed specifically for input clock frequencies from 20 to 40MHz. (Refer Input Frequency and Modulation Rate Table). The P1819 reduces electromagnetic interference (EMI) at the clock source, allowing system wide reduction of EMI of down stream clock and data dependent signals. The P1819 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 P1819 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 P1819 is available in different spread deviation, refer to “Spread Deviation Selection” Table. The P1819 uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all digital method.
• FCC approved method of EMI attenuation.
• Provides up to 15dB EMI reduction.
• Generates a low EMI Spread Spectrum clock and a non-spread reference clock of the input frequency.
• Optimized for Frequency range from 20 to 40MHz.
• Internal loop filter minimizes external components and board space.
• Selectable spread options: Down and Center.
• Low Inherent Cycle-to-Cycle jitter.
• Eight spread % selections: ±0.625% to –3.5%.
• ModRate is compliant with ATI M7x VGA spec.
• 3.3V ± 0.3V Operating Voltage range.
• Low power CMOS design.
• Supports notebook VGA and other LCD timing controller applications.
• Power Down function for mobile application.
• Available in Commercial temperature range.
• Available in 8-pin SOIC and TSSOP Packages.
The P1819 is targeted towards EMI management for memory and LVDS interfaces in mobile graphic chipsets and high-speed digital applications such as PC peripheral devices, consumer electronics, and embedded controller systems.