Datasheet BA7797F Datasheet (ROHM)

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

4

Video ICs BA7797F

•

Electrical characteristics (unless otherwise noted, Ta = 25°C, VCC = 10V, and f = 1kHz)

Parameter Symbol Min. Typ. Max. Unit Conditions

I

qEE 6.4 8.5 11.3 mA

I

qPB 6.4 8.5 11.3 mA

I

qREC 5.2 6.9 9.2 mA

G

VCLP 27.0 28.0 29.0 dB

G

VCLT 19.0 20.0 21.0 dB

THD

LT — 0.1 0.3 %

V

OMLT 5.9 8.4 — dBV

V

NOLT —

– 81.5

– 75 dBV

V

OA – 9.0 – 8.0 – 7.0 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 5.7 8.2 — 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 —1120Ω

R

RH —1725Ω

BV

RHDC —010µAE2 = ± 55V

BV

RHAC 80 100 — V

P-P

Measurement

circuit

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

Fig.1
Fig.1
Fig.1

Fig.1
Fig.1
Fig.1

V

O = – 8dBV

V

O = – 8dBV

V

O = – 8dBV, RL = 4.7kΩ

∗

THD = 1%, RL = 4.7kΩ

∗

VO = 0dBV, DIN AUDIO

LINE IN, TUNER IN→REC OUT
VO = – 8dBV

V

IN = – 25dBV, RL = 4.7kΩ

∗

VO = – 8dBV, RL = 4.7kΩ

∗

THD = 1%, RL = 4.7kΩ

∗

Rg = 680Ω, DIN AUDIO
PB IN→PB OUT

f = 70kHz, V

2 ⬉ ± 1.5V

Rg = 4.7kΩ, DIN AUDIO
V

IN = – 25dBV, 9pin: OPEN

Fig.2

∗

Measured at BW = 400Hz to 30kHz.

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)
〈Head switch〉
PB head switch impedance
REC head switch impedance
REC head switch DC withstanding voltage
REC head switch AC withstanding voltage

No signal
No signal
No signal

5

Video ICs BA7797F

•

Measurement circuits

1

2

3

4

5

6

7

8

9

18

17

16

15

14

13

12

11

10

4.7µ

4.7k

1.5k

12k

6000p

22µ

CTRL

4.7k

4.7k

0.1µ
47k

4.7k

0.1µ

47k

2.2M

22µ

4.7k

0.1µ
47k

TUNER IN

22µ

330

0.01µ

4.7k

12k

330k

4.7µ

4.7µ

REC AMP

EQ

0dB

ALC

LINE

3.3µ

68k

680

PB IN

REC HEAD SW

REC OUT

VCC

33µ

REC / EE

LINE OUT

BUFF

MUTE

PB

REC

ON: Gvo PB

PB OUT

PB LINE IN

ON: ALC OFF

PB / TU / LINE CTRL

LINE IN

MUTE CTRL

REC

ATT

– 8dB

ATT

– 8dB

+ 28dB

1800p

Units: R [Ω]

C [F]

Fig.1

+

+

+

+

+

+

+

+

REC head switch AC withstanding voltage measurement circuit

Fig. 2

1

REC

V

V

2

3

0.1µ

0.1µ

BVRHAC

V2

e2

100k

100k 1k

SW

2

REC OUT

PB IN

~

6

Video ICs BA7797F

Control pins

(1) REC / EE control, PB / TU / LINE control

Function

L L LINE OFF ON LINE OFF
L M TUNER OFF ON TUNER OFF
L H PB OFF ON PB OFF
H L ON OFF LINE ON
H M ON OFF TUNER ON
H H inhibit————

REC / EE PB / TU / LINE PB HSW REC HSW LINE SW REC AMP

LINE REC

TU REC

Mode

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

•

Control mode table

MUTE

H MUTE OPEN

L MUTE CLOSE

LINE SW

Mode

Control pins Function

(2) Mute control

•

Application example

12k

330k

330

REC + B

LINE

ALC

PB

REC

REC

0dB

BIAS
OSC

EQ

REC AMP

0.1µ

RL

CTRL

BUFF

MUTE

8.2k

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

3.3µ

22µ0.01µ

REC / EE

+ 28dB

VCC

ATT

– 8dB

ATT

– 8dB

EQ CTRL

TUNER IN

PB / TU / LINE CTRL

LINE IN

MUTE CTRL

ALC LEVEL ADJ

LINE OUT

EQ CTRL

22µ

33µ

0.1µ 0.1µ

Units: R [Ω]

C [F]

Fig.3

+

+

+

+

+

+

+

7

Video ICs BA7797F

•

Operation notes
(1) ALC level
Set the ALC level in the range – 8dBV to 0dBV by con­necting a resistor between pin 9 and GND.

The formula for approximating the value of this resistor
is as follows:
When pin 9 is open, V

OA is preset to – 8dBV (for VCC =

10V).
Note that the supply voltage V

CC has an effect.

(2) 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.

9

ALC LEVEL

R

4k

32k

V

BIAS

ALC DET

ADJ

Fig.4

(H)

(H)

V

CC

MUTE CTRL

LINE OUT

Fig.5

2 sec. Min.

Also, be certain to apply the mute signal when switch­ing between PB / LINE / TU. In the case of LINE / TU
switching, it is possible to suppress switching noise by
applying a time constant to the signal, in which case it
is not necessary to apply the mute signal.

(3) Recording control
Do not switch the PB and REC modes on together.
This will cause faulty operation.

(4) Line output
The line output can drive a load resistance of up to 2kΩ.
Depending on the type of load, it can cause 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.

2

VCC – 0.7

• V

BIAS

VOA = •

2

•

1

4k

4k + 32k × R / (32k + R)

2

1

•

4k

4k + 32k × R / (32k + R)

=

2

VCC – 0.7

• V

BIAS

VBIAS =

32k × R / (32k + R)

4k + 32k × R / (32k + R)

9pin Voltage =

8

Video ICs BA7797F

•

Electrical characteristic curves

10 100 1k 10k 100k 1M

20

40

50

60

30

VCC = 10V
V

IN = – 60dBV

0.01µ

22µ

330k 12k

1617

+

+

–

PB

330

GAIN: GV (dB)

FREQUENCY: f (Hz)

10M

Fig. 6 Gain vs. frequency (PB amplifier)

MAXIMUM OUTPUT LEVEL: Vom (dBV)

LOAD RESISTANCE: RL (Ω)

100 200 500 1k 2k 5k 10k

0

2

4

6

8

10

10µ

+

LINE

VOUT

RL

VCC = 10V
THD = 1%

ALC OFF

(BW = 0.4 ~ 30kHz)

Fig. 7 Line amplifier load drive

characteristics

OUTPUT LEVEL: VOUT (dBV)

INPUT LEVEL: VIN (dBV)

–40

–20

–10

00

10

–30

–30 –20 –10 00

VCC = 10V

VCC = 8.58V

f = 1kHz
Input: LINE IN

Output: LINE OUT

Fig. 8 ALC input / output characteristics

GAIN GVR: (dB)

FREQUENCY: f (Hz)

100

10

20

30

40

50

1k 10k 100k

V

CC = 10V

REC
&EQ

12k

+

1.5k

1800p 6000p

4

3

OUT

10µ

4.7k

Input: LINE IN

Output: REC OUT

Fig. 9 Gain vs. frequency (REC amplifier)

•

External dimensions (Units: mm)

SOP18

0.4 ± 0.11.27

0.3Min.

0.11

1.8 ± 0.1

5.4 ± 0.2

7.8 ± 0.3

0.15 ± 0.1

18

1

11.2 ± 0.2

10

9

0.15