BA7745FS Datasheet, PDF (1/8 Pages) Rohm – VCR Hi-Fi audio signal REC / PB amplifier with flying-erase oscillator

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.
•^Applications
VCRs
•Features
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.
1