The BH7800K incorporates the functions for a VHS audio signal processing system on a single chip. The circuits on the chip are a peak-noise reduction processor (PNR), an FM modulator / demodulator circuit, an I / O switcher, an automatic FM detector circuit, an FM bandpass filter, and a regulator circuit.

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 two-line SSB (Synchronized Serial Bus) control decoder circuit is provided, allowing the various IC modes to be set using serial control.

3) A four line input switcher is included (tuner, BS, and line 1 / 2). The output switcher can switch between STEREO, LEFT, and RIGHT, and Hi-Fi, MIX, and NORMAL, and a BS MONITOR function is also provided.

4) The PNR processor and FM modulator / demodulator circuit have reversed characteristics at recording and playback. In addition, the adjustment for carrier frequency and FM deviation / playback level are common.

5) The built-in bandpass filter excels at attenuation of other channels, and can be directly coupled to the playback amplifier. The FM recording output block has a high-performance low-pass filter to produce sine wave output.

6) Slope-control-type FM-switching-noise compensation circuit.

7) Envelope detector circuit and noise-detector-type automatic FM detector circuit.

8) VCO that uses the color signal sub-carrier frequency fSC (NTSC: 3.59545MHz, PAL: 4.433619MHz) and auto-adjusting BPF circuit ensure stable adjustment with no fluctuation due to mounting stress or time.

Applications

VCRs