MAXIM MAX293EWE+T

The MAX293/MAX294/MAX297 8th-order (eight-pole), elliptic, switched-capacitor, lowpass filters provide the steepest possible rolloff with frequency of the four common filter types (Butterworth, Bessel, Chebyshev, elliptic). The high Q value of the poles near the passband edge combined with stopband zeros allows for the sharp attenuation characteristic of elliptic filters. The MAX293/MAX297 have a 1.5 transition ratio and typically -78dB and -79dB of stopband rejection, respectively; the MAX294 has a 1.2 transition ratio (providing the steepest rolloff) and typically -58dB of stopband rejection. The MAX293/MAX294 operate with a 100:1 clock to corner frequency ratio and a 25kHz maximum corner frequency, with corner frequency defined as the point where the filter output attenuation falls just below the passband ripple. The passband ripple is typically 0.15dB (MAX293) and 0.27dB (MAX294). The MAX297 operates with a 50:1 clock to corner frequency ratio and a 50kHz maximum corner frequency. Its passband ripple is typically 0.23dB.

• The MAX293/MAX294/MAX297 are easy-to-use, 8th order, lowpass, elliptic, switched-capacitor filters that can be setup with corner frequencies from 0.1Hz to 25kHz (MAX293/MAX294) or from 0.1Hz to 50kHz (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 opamp (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.

• Data-Acquisition Systems
• Anti-liasing
• DAC Post-Filtering
• Voice/Data Signal Filtering