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8th-Order, Lowpass, Elliptic, Switched-Capacitor Filters

Also See MAX7400/3/4/7 for Lowest-Power Applications

Product Details

Key Features

Applications/Uses

Parametric specs for Active Filters
Filter Type Lowpass
Filter Sections 1
Order Per Filter Section 8
Highest Cutoff (kHz) (min) 50
Lowest Cutoff (Hz) (max) 0.1
Filter Class Switched Cap
Filter Characteristic Elliptic
Program Method Clock
Oper. Temp. (°C) -55 to +125
-40 to +85
0 to +70
Package/Pins CDIP/8
PDIP/8
SOIC (N)/8
SOIC (W)/16
Budgetary
Price (See Notes)
4.91
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Simplified Block Diagram

Technical Docs

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Parameters

Parametric specs for Active Filters
Filter Type Lowpass
Filter Sections 1
Order Per Filter Section 8
Highest Cutoff (kHz) (min) 50
Lowest Cutoff (Hz) (max) 0.1
Filter Class Switched Cap
Filter Characteristic Elliptic
Program Method Clock
Oper. Temp. (°C) -55 to +125
-40 to +85
0 to +70
Package/Pins CDIP/8
PDIP/8
SOIC (N)/8
SOIC (W)/16
Budgetary
Price (See Notes)
4.91

Key Features

  • 8th-Order Lowpass Elliptic Filters
  • Clock-Tunable Corner-Frequency Range:
    • 0.1Hz to 25kHz (MAX293/MAX294)
    • 0.1Hz to 50kHz (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
  • 8-Pin DIP and 16-Pin Wide SO Packages

Applications/Uses

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

Description

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 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 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.

Simplified Block Diagram

MAX293, MAX294, MAX297: Typical Operating Circuit MAX293, MAX294, MAX297: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .