Datasheet BA7796FS Datasheet (ROHM)

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

•

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

•

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.

4

Video ICs BA7796FS

•

Input / output circuits

L
H

7

10kΩ

HL

CTRL

10

56kΩ

REC
AMP

PB

M

13

56kΩ

MUTE

CTRL

M

15

56kΩ

CTRL

H

L

56kΩ

17

EQ CTRL 7

PB / EE CTRL 15

INPUT SW CTRL 17

PB / EE

INPUT SW
CTRL

HEAD SW

L, M, and H in the above diagrams are 1.7V, 2.5V, and 3.3V respectively.

REC / EE

MUTE CTRL 13

REC / EE CTRL 10

EQ CTRL

5

Video ICs BA7796FS

Parameter

Symbol

Min. Typ. Max. Unit Conditions

Measurement

circuit

IqEE 7.4 9.8 13.0 mA

Fig.1

IqPB 7.4 9.8 13.0 mA

Fig.1

IqREC 6.4 8.4 11.2 mA

Fig.1

GVCLP 27.0 28.0 29.0 dB
G

VCLT 19.0 20.0 21.0 dB

THD

LT — 0.1 0.3 %

7.3 10.5 — dBV
—

– 81.5

– 75 dBV

V

OA – 8.2 – 7.2 – 6.2 dBV

THD

A — 0.1 0.5 %

MT —

– 82.0

– 72 dB

G

VCR 19.0 20.0 21.0 dB

THD

R — 0.13 0.4 %

V

OmR 7.0 10.0 — dBV

G

VOR 60 71 — dB

G

VOP 61 68 — dB

V

NINP —

– 122.5

– 114

dBV

G

VCP 35.0 36.0 37.0 dB

R

PH — 11 20 Ω

R

RH — 11 20 Ω

BVRHDC — 010µA
BVRHAC 80 100 —

Fig.2

E3 = ± 55V

Fig.1

Fig.1

Fig.1

VOmLT

VNOLT

VP-P

VO = – 8dBV
V

O = – 8dBV

R

g = 4.7kΩ, DIN AUDIO

V

IN = – 25dBV

V

O = 0dBV, DIN AUDIO

LINE1, LINE2, TUNER→REC OUT
VO = – 8dBV

R

g = 680Ω, DIN AUDIO

PB IN→PB OUT

f = 70kHz, V

3 ⬉ ± 1.5V

V

O = – 8dBV, RL = 4.7kΩ

∗

THD = 1%, RL = 4.7kΩ

∗

VIN = – 25dBV, RL = 4.7kΩ

∗

VO = – 8dBV, RL = 4.7kΩ

∗

THD = 1% , RL = 4.7kΩ

∗

∗

Measured at BW = 0.4 to 30kHz.

Fig.1
Fig.1
Fig.1
Fig.1
Fig.1
Fig.1
Fig.1
Fig.1

Fig.1
Fig.1
Fig.1

Fig.1
Fig.1

Fig.1
Fig.1

Quiescent current EE
Quiescent current PB
Quiescent current REC
〈Line amplifier〉
Voltage gain (PB input)
Voltage gain (LINE1, LINE2, TU inputs)
Distortion
Maximum output level
Output residual noise
ALC level
ALC distortion
Mute attenuation ratio
〈Recording amplifier〉
Voltage gain
Distortion
Maximum output level
Openloop gain
〈Playback preamplifier〉
Openloop gain
Input conversion noise
Voltage gain (stand alone, SP mode)
〈Head switch〉
PB head switch impedance
REC head switch impedance

REC head switch DC withstanding voltage
REC head switch AC withstanding voltage

No signal input
No signal input
No signal input

—

—

—

•

Electrical characteristics (unless otherwise noted, Ta = 25°C, VCC = 12V, and f = 1kHz)

6

Video ICs BA7796FS

8.2k

12k

330k

330

LINE

ALC

PB

PB

REC

REC

SP

LP + EP

0dB

EQ

REC AMP

BUFF

MUTE

4.7k

2.2M

4.7k

4.7k

4.7k

1.5k
12k 15k

4.7k

680

68k

PB IN

3.3µ

HEAD EQ SW

REC HEAD SW

REC OUT

4.7µ

EQ CT RL

33µ

22µ

VCC

REC / EE

CTRL

4.7µ

LINE OUT

1

2

3

4

5

6

7

8

9

10

11

12

+ 28dB

13

14

15

16

17

18

19

20

21

22

23

24

MUTE CTRL

0.1µ
LINE IN2

PB / EE CTRL

LINE IN1

0.1µ

TUNER IN

0.1µ

22µ

0.1µ

4.7k

ON : ALC OFF

LINE PB IN

PB OUT

4.7µ

0.01µ 22µ

ON : GvoPB

4.7k

INPUT SW CTRL

ATT

– 8dB

ATT

– 8dB

ATT

– 8dB

6000p1800p

C [F]

Units: R [Ω]

Fig. 1

+

+

+

+ +

+

+

+

•

Measurement circuits

7

Video ICs BA7796FS

V

~

BVRHAC

100k

100k

V3

V

0.1µ

0.1µ

~

1k

e

3

SW3

1

2

3

4

PB IN

REC OUT

REC

LP + EP

Fig. 2 REC head switch AC withstanding voltage measurement circuit

•

Control mode table

(1) REC / EE CTRL, PB / EE CTRL, INPUT SW CTRL

REC / EE PB HSW LINE SW REC AMP

L L L TUNER OFF ON TUNER OFF
L L M LINE2 OFF ON LINE2 OFF
L L H LINE1 OFF ON LINE1 OFF
LH— PB OFF ON PB OFF
H L L TU REC ON OFF TUNER ON
H L M L2 REC ON OFF LINE2 ON
H L H L1 REC ON OFF LINE1 ON
HH— inhibit ————

REC HSWINPUT SWPB / EE

If REC / EE CTRL is set to“M”, the REC pause state is possible (REC head switch: open, REC amplifier: off).

Control pins

ModeMode

Function

(2) MUTE CTRL

MUTE LINE SW

H MUTE OPEN
L MUTE CLOSE

FunctionControl pins

Mode

(3) EQ CTRL

E Q 2 MODE 3 MODE HEAD EQ PB EQ REC EQ

L SP SP OFF CLOSE CLOSE
M — LP ON OPEN CLOSE
H EP EP ON OPEN OPEN

Mode FunctionControl pins

8

Video ICs BA7796FS

•

Application example

8.2k

12k

330k

330

LINE

ALC

PB

PB

REC

REC

SP

0dB
BIAS
OSC

EQ

REC AMP

BUFF

MUTE

3.3µ

VCC

22µ

REC / EE

CTRL

REC + B

EQ CTRL

LINE OUT

+ 28dB

22µ

0.01µ

0.1µ

0.1µ
TUNER IN

0.1µ
LINE IN1

PB / EE CTRL

0.1µ
LINE IN2

MUTE CTRL12

11

10

9

8

7

6

5

4

3

2

1

24

23

22

21

20

19

18

17

16

15

14

13

LP + EP

INPUT SW CTRL

33µ

ATT

– 8dB

ATT

– 8dB

ATT

– 8dB

RL

C [F]

Units: R [Ω]

Fig. 3

+

+

+

+ +

+

+

•

Operation notes
(1) Mute signal
Apply the mute signal shown below at power on and
off.
If the muting time is short, a “pop” sound will be audi­ble, particularly when the power is switched on.

The mute signal must also be applied when switching
PB, LINE1,LINE2 and TUNER.

(2) Recording control
Do not switch the PB and REC modes on together.
This will cause erroneous operation.
(3) Line output
The line output can drive a load resistance of up to
2kΩ.
Some types of load can result in local oscillation (eg.
large capacitive loads that draw large current), so cau­tion is required. In particular, when there is a possibility
that the line output will be connected to a shielded
cable, or line cable, connect a resistor of about 1kΩ in
series with the output so that the capacitive load is not
directly coupled to the IC output terminal.

(H)

(H)

Vcc
MUTE CTRL

LINE OUT

2 sec. Min.

9

Video ICs BA7796FS

•

Electrical characteristic curves

21

PB

SP; ON.
2223

8.2k
12k

0.01

µ

22

µ

330

OUT

330k

60

50

40

30

20

10

100 1k 10k 100k 1M 10M

FREQUENCY: f (Hz)

GAIN: GV (dB)

EP

SP

VCC = 12V
V

IN = – 65dBV

Fig. 4 Gain vs. frequency (PB amplifier)

+

MAXIMUM OUTPUT VOLTAGE: Vom (dBV)

0

100

LINE

10µ

+

Vcc = 12V
THD = 1%

ALC OFF

200 500 1k 2k 5k 10k

2

4

6

8

10

VOUT

RL

LOAD RESISTANCE: RL (Ω)

(BW = 0.4 ~ 30k [Hz])

Fig. 5 Line amplifier load drive

characteristics

INPUT LEVEL: VIN (dBV)

OUTPUT LEVEL: VOUT (dBV)

VCC = 12V

f = 1kHz

– 40

– 30

– 30 – 20 – 10

– 20

– 10

00

10

0

Fig. 6 ALC input / output characteristics

Input: LINE1 IN
Output: LINE OUT

564

OUT

12k

6000p

1800p

1.5k

15k

SP

EP

100 1k 10k 100k

50

40

30

20

10

FREQUENCY: f (Hz)

GAIN: GVR (dB)

VCC = 12V

ALC OFF

Input: LINE1 IN

Output: REC OUT

Fig. 7 Gain vs. frequency (REC amplifier)

10

Video ICs BA7796FS

SSOP - A24

0.15

0.3Min.

7.8 ± 0.3

5.4 ± 0.2

1.8 ± 0.1

0.11

1

24

0.36 ± 0.1

10.0 ± 0.2

12

13

0.8

0.15 ± 0.1

•

External dimensions (Units: mm)