VCR Hi-Fi audio signal REC / PB amplifier with flying-erase oscillator

The BA7745FS has the recording and playback amplifiers required for Hi-Fi VCR signal processing, and also contains a flying-erase oscillator. The recording system uses a constant-current amplifeir with AGC to eliminate the need to adjust the recording current, and ensure stable operation as the head wears. The IC also features REC MUTE and OVER REC functions .

The playback system has a high-gain preamplifier, a low-offset head switch, a VCA and an EP-gain amplifier. The flying-erase oscillator has low 2nd and 3rd harmonic distortion, and when connected to an external driver large output current can be obtained.

Features

1) The low-noise playback amplifier has a total gain of 83dB (Typ.). Designed for VHS-bandoperation with low external parts count. It has two built-in circuits for Hi-Fi VCR operation.

2) The circuit has been designed to suppress headswitching noise.

3) Built-in EP / SP gain switching function that boosts the playback gain by 5dB.

4) Built-in VCA for easy playback output adjustment.

5) High-output recording amplifier for audio FM recording.

6) Constant-current drive provides stable recording characteristics when the load (head impedance) is fluctuating.

7) Built-in recording level AGC eliminates the need to adjust recording current.

8) Built-in low-pass filter limits the input bandwidth of the recording amplifier.

9) Built-in OVER REC recording current amplifier function and REC MUTE function that stops recording output.

10) Built-in high-frequency oscillator for use with flying erase function.

11) Record / playback switching can be done directly via the system controller, and consumes litlle power.

12) Possible to construct a high-performance audio system by pairing this chip with a Hi-Fi-audio signal processing IC.

Applications

VCRs