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LMF90 Datasheet 4th-Order Elliptic Notch Filter

Manufacturer: National Semiconductor (now Texas Instruments)

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General Description

The LMF90 is a fourth-order elliptic notch (band-reject) filter based on switched-capacitor techniques No external components are needed to define the response function The depth of the notch is set using a two-level logic input and the width is programmed using a three-level logic input Two different notch depths and three different ratios of notch width to center frequency may be programmed by connecta b ing these pins to V ground or V Another three-level logic pin sets the ratio of clock frequency to notch frequency An internal crystal oscillator is provided Used in conjunction with a low-cost color TV crystal and the internal clock frequency divider a notch filter can be built with center frequency at 50 Hz 60 Hz 100 Hz 120 Hz 150 Hz or 180 Hz for rejection of power line interference Several LMF90s can be operated from a single crystal An additional input is provided for an externally-generated clock signal Y Y Y No external components needed to set response characteristics Notch width attenuation and clock-to-center-frequency ratio independently programmable 14 pin 0 3 wide package Key Specifications Y Y Y Y Y Y Y Y f0 Range 0 1 Hz to 30 kHz f0 accuracy over full temperature range (max) 1 5% g 2V to g 7 5V or 4V to 15V Supply voltage range Passband Ripple (typ) 0 25 dB Attenuation at f0 (typ) 39 dB or 48 dB (selectable) fCLK f0 100 1 50 1 or 33 3 1 Notch Bandwidth (typ) 0 127 f0 0 26 f0 or 0 55 f0 Output offset voltage (max) 120 mV Applications Y Y Y

Overview

LMF90 4th-Order Elliptic Notch Filter December 1994 LMF90 4th-Order Elliptic Notch.

Key Features

  • Y Center frequency set by external clock or on-board clock oscillator Automatic test equipment Communications Power line interference rejection Typical Connection 60 Hz Notch Filter Connection Diagram Dual-In-Line and Small Outline Packages TL H 10354.
  • 2 Top View Order Number LMF90CCN LMF90CIWM LMF90CCWM LMF90CIJ LMF90CCJ LMF90CIN LMF90CMJ or LMF90CMJ 883 See NS Package Number J14A M14B or N14A TL H 10354.
  • 1 C1995 National Semiconductor Corporation TL H 10354 RRD-B30M.

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