ROHM BA7797F Datasheet
1
Video ICs
VCR standard audio signal processor
BA7797F
The BA7797F is standard audio signal processor designed for use in VCRs and tape decks. The circuit is comprised
of a playback preamplifier, a line amplifier, a recording amplifier, an ALC circuit and high-voltage head switch.
The IC has a built-in coil equivalent circuit for recording equalization, which eliminates the need for an external component.
•
Applications
Video cassette recorders and tape decks
•
Features
1) Two input switching systems built-in (LINE and TUNER).
2) Built-in coil equivalent circuit for recording equalization.
3) High-performance low-noise playback amplifier.
4) ALC level can be adjusted by connection of an
external resistor.
5) Compatible with single-mode EQ making it ideally
suited to widely-used decks.
•
Block diagram
LINE
ALC
PB
REC
REC
0dB
EQ
REC AMP
BUFF
MUTE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
GND
+ 28dB
V
CC
PB IN
REC HEAD SW
REC OUT
REC L
RIPPLE FILTER
REC / EE CTRL
LINE OUT
ALC LEVEL ADJ
PB NFB
PB OUT
PB LINE IN
ALC FILTER
TUNER IN
PB / TU / LINE CTRL
LINE IN
MUTE CTRL
ATT
– 8dB
ATT
– 8dB
2
Video ICs BA7797F
•
Absolute maximum ratings (Ta = 25°C)
Parameter Symbol Limits Unit
V
CC 13 V
550
∗
mW
Topr °C
Tstg °C
Pd
– 10 ~ + 65
– 55 ~ + 125
Power supply voltage
Power dissipation
Operating temperature
Storage temperature
∗
When mounted on a 50mm × 50mm × 1.6mm glass epoxy board. Reduced by 5.5mW for
each increase in Ta of 1°C over 25°C.
•
Recommended operating conditions (Ta = 25°C)
Parameter
Symbol
Min. Typ. Max. Unit
V
CC
7.5 — 12.5 V
Power supply voltage
•
Pin descriptions (VCC = 10V)
1 PB IN 2.0V
REC: 120kΩ
REC: 11Ω
2 REC HEAD SW 0.0V
REC: OPEN
3 REC OUT 4.7V EF (P-P)
4 REC L 4.7V B (NPN)
5
V
CC
10.0V —
6 RIPPLE FILTER 10.0V 10kΩ (V
CC)
7 REC / EE CTRL —
8 LINE OUT 4.7V EF (P-P)
9 ALC LEVEL ADJ 4.1V
10 MUTE CTRL —
11 LINE IN 4.7V 120kΩ
12 PB / TU / LINE CTRL —
13 TUNER IN 4.7V 120kΩ
14 ALC FILTER
PB: 0.0V
15 PB LINE IN 4.7V 120kΩ
16 PB OUT 2.0V EF (P-P)
17 PB NFB 2.0V B (NPN)
18 GND 0.0V —
Pin No. Pin name Function Pin voltage I / O circuit
REC: 17Ω (ON)
EF (NPN) ~ 100Ω
PB: Not fixed
See input / output circuit
See Fig. 4
See input / output circuit
See input / output circuit
Playback amplifier input / playback head switch
High-withstanding voltage recording head switch
Recording amplifier output
Recording EQ switch
V
CC
Ripple filter
REC / EE control
Line amplifier output
ALC level adjustment
Mute control
Line input
PB / TU / LINE control
Tuner input
For setting the time constant for the ALC filter
(attack and recovery times)
Line input for playback
Playback amplifier output
Playback amplifier feedback
GND
∗
EF: emitter follower, P-P: push pull, B: base, and C: collector.
All measurements made using the measurement circuit (Fig.1) with V
CC = 10V and quiescent circuit conditions.
All numerical values are standardized values.
3
Video ICs BA7797F
•
Input / output circuits
H
L
CTRL
56kΩ
REC
AMP
PB
HEAD SW
7
REC / EE
REC / EE CTRL 7
M
56kΩ
MUTE
CTRL
10
MUTE CTRL 10
H
L
56kΩ
CTRL
12
PB / TU / LINE CTRL 12
PB / TU / LINE
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