MF4

MF4 4th Order Switched Capacitor Butterworth Lowpass Filter July 1999 MF4 4th Order Switched Capacitor Butterworth Lowpass Filter General Description The MF4 is a versatile, easy to use, precision 4th order Butterworth low-pass filter. Switched-capacitor techniques eliminate external component requirements and allow a clock-tunable cutoff frequency. The ratio of the clock frequency to the low-pass cutoff frequency is internally set to 50 to 1. A Schmitt trigger clock input stage allows two clocking options, either self-clocking (via an external resistor and capacitor) for stand-alone applications, or for tighter cutoff frequency control an external TTL or CMOS logic compatible clock can be applied. The maximally flat passband frequency response together with a DC gain of 1 V/V allows cascading MF4 sections together for higher order filtering. Features n n n n n n n n n Low Cost Easy to use 8-pin mini-DIP or 14-pin wide-body S.O. No external components 5V to 14V supply voltage Cutoff frequency range of 0.1 Hz to 20 kHz Cutoff frequency accuracy of ± 0.3% typical Cutoff frequency set by external clock Separate TTL and CMOS/Schmitt-trigger clock inputs Connection Diagram Dual-In-Line Package DS005064-2 Order Number MF4CN-50 See NS Package Number N08E Block Diagram DS005064-1 TRI-STATE ® is a registered trademark of National Semiconductor Corp. © 1999 National Semiconductor Corporation DS005064 www.national.com Block Diagram Pin Pin Name CLK IN (Continued) Pin Pin...