Features: ·Three bandpass filters with one-third octave center frequency spacing
·Choice of internal or external clock
·No external components other than clock or crystal and two capacitors
Application·Real-Time Audio Analyzers (ANSI Type E, Class II)
·Acoustical Instrumentation
·Noise Testing
Pinout
SpecificationsTotal Supply Voltage ............................................................-0.3V to +16V
Voltage at Any Pin ...................................................V- - 0.3V to V+ + 0.3V
Input Current per Pin (Note 3) .......................................................±5 mA
Total Input Current (Note 3) ......................................................±g20 mA
Lead Temperature (Soldering 10 sec.)
Dual-In-Line Package (Plastic) .........................................................300
Surface Mount Package (Note 4)
Vapor Phase (60 seconds) ...............................................................215
Infrared (15 seconds) ......................................................................220
Power Dissipation (Note 5) ..........................................................500 mW
Maximum Junction Temperature .......................................................150
Storage Temperature Range ............................................-65 to +150
ESD Susceptibility (Note 6) .............................................................2000VDescriptionThe LMF380 is a triple, one-third octave filter set designed for use in audio, audiological, and acoustical test and measurement applications. Built using advanced switched-capacitor techniques, the LMF380 contains three filters, each having a bandwidth equal to one-third of an octave in frequency. By combining several LMF380s, each covering frequency range of one octave, a filter set can be implemented that encompasses the entire audio frequency range while using only a small fraction of the number of components and circuit board area that would be required if a conventional active filter approach were used.
The center frequency range is not limited to the audio band, however. Center frequencies as low as 0.125 Hz or as high as 25 kHz are attainable with the LMF380.
The center frequency of each filter is determined by the clock frequency.
The clock signal can be supplied by external source, or it can be generated by the internal oscillator, using an external crystal and two capacitors. Since the LMF380 has an internal clock frequency divider (÷2) and an output pin for the half-frequency clock signal, a single clock oscillator for the top-octave LMF380 becomes the master clock for the entire array of filters in a multiple LMF380 application. Accuracy is enhanced by close matching of the internal components: the ratio of the clock frequency to the center frequency is typically accurate to ±0.5%, and passband gain and stopband attenuation are guaranteed over the full temperature range.
LMF380 Data Sheet
