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
Applications/Uses
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
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