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MAX7490：Dual Universal Switched-Capacitor Filters

The MAX7490/MAX7491 consist of two identical low-power, low-voltage, wide dynamic range, rail-to-rail, 2nd-order switched-capacitor building blocks. Each of the two filter sections, together with two to four external resistors, can generate all standard 2nd-order functions: bandpass, lowpass, highpass, and notch (band reject). Three of these functions are simultaneously available. Fourth-order filters can be obtained by cascading the two 2nd-order filter sections. Similarly, higher order filters can easily be created by cascading multiple MAX7490/MAX7491s. Two clocking options are available: self-clocking (through the use of an external capacitor) or external clocking for tighter cutoff frequency control. The clock-to-center frequency ratio is 100:1. Sampling is done at twice the clock frequency, further separating the cutoff frequency and Nyquist frequency. The MAX7490/MAX7491 have an internal rail splitter that establishes a precise common voltage needed for single-supply operation. The MAX7490 operates from a single +5V supply and the MAX7491 operates from a single +3V supply. Both devices feature a low-power shutdown mode and come in a 16-pin QSOP package.

Key Features Dual 2nd-Order Filter in a 16-Pin QSOP Package High Accuracy Q Accuracy: ±0.2% Clock-to-Center Frequency Error: ±0.2% Rail-to-Rail Input and Output Operation Single-Supply Operation: +5V (MAX7490) or +3V (MAX7491) Internal or External Clock Highpass, Lowpass, Bandpass, and Notch Filters Clock-to-Center Frequency Ratio of 100:1 Internal Sampling-to-Center Frequency Ratio of 200:1 Center Frequency up to 40kHz Easily Cascaded for Multipole Filters Low-Power Shutdown: < 1µA Supply Current

MAX7490, MAX7491: Typical Application Circuit Applications/Uses Adaptive Filters ADC Anti-Aliasing Multipole Filters Phase-Locked Loops (PLLs) Post-DAC Filtering Set-Top Boxes Tunable Active Filters

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