The BH7775K is an audio signal processing system IC that includes a peak-noise reduction (PNR) processor, an FM modulator / demodulator circuit, an input / output switcher, an automatic FM detector circuit, an FM band-pass filter, a normal-audio circuit, a regulator circuit, and automatic adjusting circuits (VCO and BPF).

Features

1) Operates off dual ± power supply which allows a large reduction in the number of coupling capacitors required. A built-in regulator makes it easy to construct a power supply system.

2) A built-in 2-wire serial control decoder circuit allows serial control of the internal mode settings.

3) Automatic adjusting VCO and BPF circuits that use the color signal subcarrier frequency (NTSC: 3.579545MHz and PAL: 4.433619MHz) ensure stable adjustment that is not effected by stress when the chip is mounted, or variations over time.

4) 4-input switcher (turner, BS, and line 1 and 2). Output switch with built-in STEREO / LEFT / RIGHT switching, Hi-Fi / MIX / NORMAL switching, and BS monitor functions.

5) The PNR processor and FM modulation / demodulation circuit provide reverse characteristics at recording and playback. Also, carrier frequency adjustment and FM de-emphasis / playback level adjustment have been combined.

6) Built-in FM band-pass filter connects directly to the playback amplifier and excels at attenuation of the other channel. The FM recording output circuit has a high-performance high-frequency cutoff filter that produces a sine wave output.

7) Switching noise is reduced by a slope-control type differential compensation circuit.

8) Built-in envelope detector circuit and noise-detecting automatic FM detector circuit.

9) Built-in normal-audio signal processing circuit that allows SP / LP / EP equalizer switching. Control terminal provided for use with the BA7755AF high-voltage head switcher.

Applications

VHS Video cassette recorders