ROHM BA7795FS Datasheet

1

Video ICs

VCR standard audio signal processor

BA7795LS / BA7795FS

The BA7795LS and BA7795FS are standard audio signal processor ICs. They contain a playback preamplifier, line
amplifier, recoeding amplifier, ALC circuit, EQ switch circuit and high-voltage head switch, and provide all of the functions
required for normal-audio signal processing on a single IC with a minimum number of external components required.

•

Applications

Video cassette recorders and tape decks

•

Features

1) Available in compact SZIP and SSOP-A24-pin pack­ages.

2) High-with standing-voltage head switch (AC with
standing voltage: Min. 80V

P-P (f = 70kHz) ).

3) Simple, three-mode EQ switch built-in (BA7795LS).

4) Built-in LINE / TUNER selector switch.

5) High-performance low-noise playback amplifier.

Input conversion noise figure – 122dBV

(Typ. Rg = 680, DIN AUDIO).

6) ALC level can be varied.

7) ALC loop external mute eliminates audible noise at
power on, and ALC attack noise.

8) Signal processing circuit can be constructed with the
addition of just a few external components.

•

Block diagram

1

3

5

7

9

11

13

15

17

19

21

23

24

22

20

18

16

14

12

10

8

6

4

2 PB IN

GND

PB NFB

PB EQ

PB OUT

PB LINE IN

ALC FILTER

LINE IN

TUNER IN

GND

LINE OUT

REC / EE CTRL

HEAD EQ

REC HSW

RIPPLE FILTER

V

CC

EQ CTRL

PB / TU / EE CTRL

BIAS

MUTE CTRL

REC NFB

ALC LEVEL

REC OUT

REC EQ

ALC

– 20dB

PB

MUTE

BF

REC

– 8dB

TUNER

– 8dB

LINE

LINE

+ 20dB

BIAS

SP

PB

REC

EP

LP +

REC

EP

BA7795LS

∗

The BA7795FS has a different pin

layout to the BA7795LS.

2

Video ICs BA7795LS / BA7795FS

•

Pin descriptions

BA7795LS Pin No. BA7795FS Pin No. Pin name Function

17

HEAD EQ

28

PB IN

39

REC HSW

410

GND

511

RIPPLE FILTER

612

PB NFB

713

V

CC

814

PB EQ

915

EQ CTRL

10 16

PB OUT

11 17

PB / TU / EE CTRL

12 18

PB LINE IN

13 19

ALC LEVEL

14 20

ALC FILTER

15 21

BIAS

16 22

LINE IN

17 23

MUTE CTRL

18 24

TUNER IN

19 1

REC NFB

20 2

GND

21 3

REC OUT

22 4

BF OUT

23 5

REC EQ

24 6

REC / EE CTRL

Head resonance capacitor switch
Playback amplifier input / playback head switch
High-withstanding voltage recording head switch
GND (playback amplifier)
Ripple filter
Playback amplifier feedback
Power supply
Playback EQ switch
EQ control
Playback amplifier output
PB / TU / EE control (PB / EE control)
Playback line amplifier
ALC level setting
ALC filter time constant
Bias
Line input
MUTE control
Tuner input (REC / EE control)
Recording amplifier feedback
GND
Recording amplifier output
Line amplifier output
Recording EQ switch (recording EQ switch 2)
REC / EE control (recording EQ switch 1)

•

Absolute maximum ratings (Ta = 25°C)

•

Recommended operating conditions (Ta = 25°C)

Parameter Symbol Limits Unit

V

CC

13 V

BA7795LS

Pd mW

BA7795FS

Topr °C
Tstg °C

400

∗

1

800

∗

2

– 10 ~ + 65
– 55 ~ + 125

∗

1 Reduced by 4.0mW for each increase in Ta of 1°C over 25°C.

∗

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

Applied voltage
Power

dissipation
Operating temperature

Storage temperature

Parameter Symbol Limits Unit

7.5 ~ 12.5 VV

CC

Power supply voltage

3

Video ICs BA7795LS / BA7795FS

•

Electrical characteristics (unless otherwise noted, Ta = 25°C, VCC = 9V, and f = 1kHz)

Parameter Symbol Min. Typ. Max. Unit Conditions

I

qEE 6.3 8.3 10.8 mA

I

qPB 6.3 8.3 10.8 mA

I

qREC 4.9 6.4 8.4 mA

G

VCP 27.0 28.0 29.0 dB V

O

= – 8dBV

G

VCL 19.0 20.0 21.0 dB V

O

= – 8dBV

THD

L — 0.1 0.3 % V

O

= – 8dBV, RL = 4.7kΩ

∗

1

V

OmL 5.0 7.2 — dBV THD = 1%, RL = 4.7kΩ

∗

1

V

NOL — – 81.5 – 75 dBV Rg = 4.7kΩ, DIN AUDIO

V

OA – 7.0 – 6.0 – 5.0 dBV

R

1 / R2 = 8.2 / 39kΩ

V

IN = – 23dBV

THD

A — 0.18 0.5 % VIN = – 23dBV, RL = 4.7kΩ

∗

1

MT — – 82.5 – 72 dB Vo = 0dBV, DIN AUDIO

G

VCR 19.0 20.0 21.0 dB

THD

R — 0.03 0.3 % VO = – 8dBV

V

OmR 5.5 7.4 — dBV VO = – 8dBV, RL = 4.7kΩ

∗

1

G

VOR 65 77 — dB THD = 1%, RL = 4.7kΩ

∗

1

G

VOP 62 68 — dB

V

NINP — – 122.5 – 114 dBV Rg = 680Ω, DIN AUDIO

G

VCP-L 56 57.5 59 dB PB IN →BF OUT

R

PH — 11 20 Ω

R

RH — 11 20 Ω

BV

RHAC 80 100 — V

P-P

f = 70kHz

LINE, TUNER input→REC OUT

∗

1 Measured at BW = 400Hz to 30kHz.

When no signal
When no signal
When no signal

Quiescent current EE
Quiescent current PB
Quiescent current REC
〈Line amplifier〉
Power supply gain (PB input)
Power supply 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
Open loop gain
〈Playback preamplifier〉
Open loop gain
Input conversion noise
Total gain
〈Head switch〉
PB head switch impedance
REC head switch impedance
REC head switch AC withstanding voltage

4

Video ICs BA7795LS / BA7795FS

•

Input / output circuits

10kΩ

EQ
CTRL

56kΩ

PB / TU / EE
CTRL

MUTE

CTRL

56kΩ

REC / EE

CTRL

56kΩ

REC PB

HSW

Fig. 1