BA7781K

Video ICs Stereo microphone amplifier for camcorders BA7781K The BA7781K allows construction of a stereo-microphone amplifier for camcorder use with a minimum number of external components. The IC has a built-in wind-noise detection circuit, and wind-noise rejection filter. The filter circuit is controlled automatically. The IC can operate off a 3.0V power supply. Applications Camcorders Features 1) Operates off a 3.0V to 5.25V power supply. 2) Automatic wind-noise rejection circuit. 3) Matrix circuit for stereo emphasis. 4) Automatic switching circuit for external microphones, built-in external monaural decision circuit, and input switch mode decision circuit. Block diagram MTX OUT L PRE OUT L INV OUT L MTX IN L MODE 24 HPF IN L 18 WND 15dB DET NOR INV IN L 24 EXT IN L 25 EXT BG 26 INT IN L 27 GND REG GND 28 VREG 29 INT 23 22 21 20 19 17 16 DET OUT 15 DET IN 14 BIAS BIAS VCC 13 VCC 12 LPF INV OUT – + 13dB + – MIX 10dB EXT + – BIAS INT IN R 30 RIPL 31 INT OUT L 11 LPF INV IN 10 MIX OUT 09 MIC MONO 08 OUT R EXT 13dB NOR WND 06 MTX OUT R EXT IN R 32 EXT 01 MODE 1 02 PRE OUT R 03 INV IN R 04 INV OUT R + – 05 MTX IN R 15dB 07 HPF IN R 1 Video ICs BA7781K Absolute maximum ratings (Ta = 25°C) Parameter Power supply voltage Power dissipation Operating temperature Storage temperature Symbol VCC Pd Topr Tstg Limits 7.0 400∗ – 10 ~ +70 – 55 ~ +125 Unit V mW °C °C Recommended operating conditions (Ta = 25°C) Parameter Power supply voltage Symbol VCCS Mi...