BA7746S Datasheet, PDF (1/12 Pages) Rohm – VCR Hi-Fi audio signal REC / PB amplifier

Video ICs
VCR Hi-Fi audio signal REC / PB
amplifier
BA7746S / BA7746FS
The BA7746S and BA7746FS contains the recording and playback amplifiers required for Hi-Fi VCR signal process-
ing. The recording system uses a constant-current amplifier 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, VCA, and an EP-gain amplifier.
In addition, all functions operate off a single 5V supply, and a H / L control system eliminates the need for special
power supplies for the recording and playback systems. The IC has low power consumpution, and comes in a com-
pact 32-pin SSOP-A 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
1) The low-noise playback amplifier has a total gain of
79dB (Typ.). Designed for VHS-band operation 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 povides 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) Low power consumption. Operates off a single 5V
power supply.
11) Record / playback switching can be done directly
via the system controller, and consumes littele
power.
12) Possible to construct a high-performance audio
system by pairing this chip with a Hi-Fi-audio signal
processing IC.
•^{Absolute maximum ratings (Ta = 25°C)}
Parameter
Symbol
Limits
Unit
Power supply voltage
VCC
Power
dissipation
BA7746S
BA7746FS
Pd
7.0
V
1050^∗1
mW
800^∗2
mW
Operating temperature
Topr
– 10 ~ + 70
°C
Storage temperature
Tstg
– 55 ~ + 125
°C
∗1 When mounted on a 90mm × 50mm × 1.6mm glass epoxy board, reduced by 10.5mW for each increase in Ta of 1°C over 25°C.
∗2 When mounted on a 90mm × 50mm × 1.6mm glass epoxy board, reduced by 8mW for each increase in Ta of 1°C over 25°C.
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