LTC1062

LTC1062 5th Order Lowpass Filter U U FEATURES ■ Lowpass Filter with No DC Error ■ Low Passband Noise ■ Operates DC to 20kHz ■ Operates On a Single 5V Supply or Up to ±8V ■ 5th Order Filter ■ Maximally Flat Response ■ Internal or External Clock ■ Cascadable for Faster Rolloff ■ Buffer Available U APPLICATIO S ■ 60Hz Lowpass Filters ■ Antialiasing Filter ■ Low Level Filtering ■ Rolling Off AC Signals from High DC Voltages ■ Digital Voltmeters ■ Scales ■ Strain Gauges TYPICAL APPLICATIO 10Hz 5th Order Butterworth Lowpass Filter 25.8k VIN V– = –5V 1µF 1 FB 2 AGND 8 BOUT 7 OUT DC ACCURATE OUTPUT BUFFERED OUTPUT LTC1062 3 V– V+ 6 45 DIVIDER COSC RATIO COSC= 3900pF V+ = 5V 1062 TA01 NOTE: TO ADJUST OSCILLATOR FREQUENCY, USE A 6800pF CAPACITOR IN SERIES WITH A 50k POT FROM PIN 5 TO GROUND DESCRIPTIO The LTC®1062 is a 5th order all pole maximally flat lowpass filter with no DC error. Its unusual architecture puts the filter outside the DC path so DC offset and low frequency noise problems are eliminated. This makes the LTC1062 very useful for lowpass filters where DC accuracy is important. The filter input and output are simultaneously taken across an external resistor. The LTC1062 is coupled to the signal through an external capacitor. This RC reacts with the internal switched capacitor network to form a 5th order rolloff at the output. The filter cutoff frequency is set by an internal clock that can be externally driven. The clock-to-cutoff frequency ratio is typicall...