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.
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.
2) The circuit has been designed to suppress head-
switching noise.
9) Built-in OVER REC recording current amplifier
function and REC MUTE function that stops record-
ing output.
3) Built-in EP / SP gain switching function that boosts
the playback gain by 5dB.
10) Low power consumption. Operates off a single 5V
power supply.
4) Built-in VCA for easy playback output adjustment.
5) High-output recording amplifier for audio FM record-
ing.
11) Record / playback switching can be done directly
via the system controller, and consumes littele
power.
6) Constant-current drive povides stable recording
characteristics when the load (head impedance) is
fluctuating.
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
VCC
Limits
7.0
Unit
V
Power supply voltage
1
BA7746S
BA7746FS
1050
800
mW
mW
°C
Power
dissipation
Pd
2
Topr
Tstg
– 10 ~ + 70
Operating temperature
Storage temperature
– 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.
1