ROHM BA7796FS Datasheet

1

Video ICs

VCR standard audio signal processor

BA7796FS

The BA7796FS is a 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, an EQ switch, and high-volt­age head switch.
The IC has three input switching systems, and 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) Three input switching systems built-in (LINE1,
LINE2, and TUNER).

2) Built-in coil equivalent circuit for recording equaliza­tion.

3) Two-mode EQ switch.

4) High-performance low-noise playback amplifier.

5) Fixed ALC level ( – 7.2dB when V

CC = 12V).

6) Phase-inverting recording amplifier.

•

Absolute maximum ratings (Ta = 25°C)

•

Recommended operating conditions (Ta = 25°C)

Parameter Symbol Limits Unit

V

CC

13 V

Pd 800

∗

mW
Topr °C
Tstg °C

– 10 ~ + 65
– 55 ~ + 125

Power supply voltage
Power dissipation
Operating temperature
Storage temperature

∗

When mounted on a 90mm × 50mm × 1.6mm glass epoxy board.

Reduced by 8.0mW for each increase in Ta of 1°C over 25°C.

Parameter Symbol Min. Typ. Max. Unit

V

CC

7.5 — 12.5 VPower supply voltage

2

Video ICs BA7796FS

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Block diagram

LINE

ALC

PB

PB

REC

REC

SP

0dB

EQ

REC AMP

BUFF

MUTE

+ 28dB

12

11

10

9

8

7

6

5

4

3

2

1

24

23

22

21

20

19

18

17

16

15

14

13

HEAD EQ SW

PB IN

REC HEAD SW

REC OUT

REC L2

REC L1

EQ CTRL

V

CC

RIPPLE FILTER

REC / EE CTRL

LINE OUT

GND

HEAD GND

PB NFB

PB EQ SW

PB OUT

PB LINE IN

ALC FILTER

TUNER IN

INPUT SW CTRL

LINE IN1

PB / EE CTRL

LINE IN2

MUTE CTRL

LP + EP

ATT

–

8dB

ATT

–

8dB

ATT

–

8dB

C [F]

Units: R [Ω]

3

Video ICs BA7796FS

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Pin descriptions

I / O circuit

1 2.0V

REC: 120kΩ

REC: 11

Ω

2 0.0V
3 0.0V

REC: OPEN
4 5.7V EF (P - P)
5 5.7V
6 5.7V
7 —
8V

CC

12.0V —

9 12.0V 10k

Ω (V

CC)

10 —
11 5.7V
12 GND 0.0V —
13 —
14 5.6V 120k

Ω

15 —
16 5.6V 120k

Ω

17 —
18 5.6V 120k

Ω

19

PB: 0.0V

PB: not fixed

20 5.6V 120k

Ω

21 2.0V
22 2.0V
23 2.0V
24 0.0V —

Pin No.

HEAD EQ SW

PB IN

REC HEAD SW

REC OUT

REC L2
REC L1

EQ CTRL

RIPPLE FILTER
REC / EE CTRL

LINE OUT

MUTE CTRL

LINE IN2

PB / EE CTRL

LINE IN1

INPUT SW CTRL

TUNER IN

ALC FILTER

PB LINE IN

PB EQ SW

PB OUT

PB NFB

HEAD GND

EF (P - P)

EF (P - P)

B (NPN)

B (NPN)

REC: 11

Ω (ON)

220kΩ

/ 20

Ω (ON)

EF (NPN) ~ 100Ω

35

Ω (ON) / OPEN

19Ω (ON) / OPEN

Pin voltagePin name Function

See input / output circuit

See input / output circuit

See input / output circuit

See input / output circuit

See input / output circuit

Playback amplifier input / playback head switch
Head resonance capacitor switch

High-withstanding voltage recording head switch
Recording amplifier output

Recording EQ switch
Recording EQ pin
EQ control
V

CC

Ripple filter
REC / EE control
Line amplifier output
GND
Mute control
Line input 2
PB / EE control
Line input 1
Input switch control
Tuner input
For setting the time constant for the ALC filter

(attack and recovery times)
Line input for playback
Playback amplifier output
Playback equalizer switch
Playback amplifier feedback
GND for playback amplifier and head switch

∗

EF: emitter follower, P-P: push pull, B: base, and C: collector.

All measurements made using the measurement circuit (Fig. 1) with V

CC = 12V and quiescent circuit conditions.

All numerical values are standardized values.