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Video ICs

VCR Hi-Fi audio signal REC / PB

amplifier with flying-erase oscillator

BA7745FS

The BA7745FS has the recording and playback amplifiers required for Hi-Fi VCR signal processing, and also con-

tains 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 out-

put current can be obtained.

A H / L control system eliminates the need for special power supplies for the recording and playback systems. The

IC has low power consumption, and comes in a compact 32-pin SSOP-P package that requires little area on the

PCB. It will improve the reliability and performance of your designs while reducing external component requirements.

VCRs

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 head-

switching 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 record-

ing.

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 record-

ing 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.