AF121 Datasheet | National Semiconductor

.~,.. ~National <t .,.. Semiconductor .C,.I. <t Active Filters AF121, AF122 DTMF Bandpass Filters General Description The AF121 and AF122 are 6th order elliptic bandpass filters designed for use with digital DTMF detectors. These filters are patible with tone detector circuits such as the Rockwell CRC8030 and the Mostek MK5102 DTMF digital receivers. The filters provide 40 dB separation between the high and low frequency signaling groups and the dial tone frequencies. The bandpass feature eliminates the need for a separate 'dial tone reject filter_ Features - patible with Rockwell CRC8030 and Mostek MK5102 - Gain o±0.5 dB - Ripple 2 dB peak to peak - Input...