BA1442A

Audio ICs AM radio / FM IF stereo system IC BA1442A The BA1442A is an AM radio and FM IF stereo system IC developed for radio cassette players. The FM circuit is comprised of a differential IF amplifier, a double-balance type quadrature detector, and a PLL-type stereo MPX circuit. The AM circuit is comprised of a local oscillator, a double-balanced mixer, an IF amplifier, a detector, and an AGC circuit. FApplications Radio cassette players FFeatures 1) The “S” curve characteristic of the FM detector can be used for upper heterodyne (“N” curve) operation. 2) Audio high cut and low cut can be used to improve the AM fidelity. 3) A reference voltage supply is provided to ensure good frequency stability in the shortwave bands. 4) Good FM stability. 5) Built-in damping resistor (3.3kΩ) for the quadrature coil. 6) The FM MPX uses a Laser Locked Loop, making adjustment of the VCO and addition of external components unnecessary. 7) Built-in forced monaural function for the MPX (VCO stops, LED off). 8) VCO of the MPX is switched off during AM operation. 9) The stereo indicator pin has a constant drive current, and a current limiting resistor is not required. 10) Few external components required. FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 337 Audio ICs FBlock diagram BA1442A FPin descriptions 338 Audio ICs BA1442A 339 Audio ICs BA1442A 340 Audio ICs BA1442A FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 5V...