The MAX293/MAX294/MAX297 are easy-to-use, 8th-order, lowpass, elliptic, switched-capacitor filters that can be set up with corner frequencies from 0.1Hz to 25kHz (MAX293/MAX294) or from 0.1Hz to 50Hz (MAX297).
The MAX293/MAX297's 1.5 transition ratio provides sharp rolloff and -80dB of stopband rejection. The MAX294's 1.2 transition ratio provides the steepest rolloff and -58dB of stopband rejection. All three filters have fixed responses, so the design task is limited to selecting the clock frequency that controls the filter's corner frequency.
An external capacitor is used to generate a clock using the internal oscillator, or an external clock signal can be used. An uncommitted op amp (noninverting input grounded) is provided for building a continuous-time lowpass filter for post-filtering or anti-aliasing. Steep rolloff and high order make these filters ideal for anti-aliasing applications that require maximum bandwidth, and for communication applications that require filtering signals in close proximity within the frequency domain.
The MAX293/MAX294/MAX297 are available in 8-pin DIP and 16-pin wide SO packages, delivering aggressive performance from a tiny area.
Key Features
Applications/Uses
8th-Order Lowpass Elliptic Filters
Clock-Tunable Corner-Frequency Range:
0.1Hz to 25Hz (MAX293/MAX294)
0.1Hz to 50Hz (MAX297)
No External Resistors or Capacitors Required
Internal or External Clock
Clock to Corner Frequency Ratio
100:1 (MAX293/MAX294)
50:1 (MAX297)
Operate with a Single +5V Supply or Dual ±5V Supplies
Uncommitted Op Amp for Anti-Aliasing or Clock-Noise Filtering
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