ROHM BA7357S Datasheet

1

Video ICs

VIF / SIF signal processor

BA7357S

The BA7357S is a multi-format (M, B / G, D / K, and I) VIF / SIF signal processor for television and VCR applications.
It features a built-in sound-trap and band-pass filters, and employs a pulse-count audio detector that does not require
adjustment. This IC reduces external component requirements, and allows space savings.

•

Applications

TVs and VCRs

•

Features

1) Separate-carrier PLL with full synchronous detec­tion. Excellent DG / DP, CS beat (920kHz) and
cross color. In addition, by pulling down the SIF
input (pin 9) it can be used as an intercarrier.

2) The IF AGC time constant is dual-layered to allow
faster speeds.

3) The variable-gain amplifier has excellent linearity to
ensure low distortion, and AGC variance and tem­perature drift have been minimized.

4) Significant improvement in image quality through
use of a filter that reduces CS beat.

5) Built-in SOUND filter (4.5MHz SOUND Trap and

4.5MHz SOUND BPF).

The MODE switch can be used to switch the
SOUND filter frequency band to match the transmis­sion format (M: 4.5, B / G: 5.5, I: 6.0, D / K:

6.5MHz).

6) The audio detector uses a pulse-counter detector
that does not require adjustment, eliminating the
need for a detector coil. Broad S-curve for multiplex
broadcast compatibility.

7) Use of pulse-counter detection and the built-in
SOUND filter means fewer pins, external compo­nents and adjustment locations are required. The IC
is available in a 22-pin SDIP package and will
enable cost and space savings.

•

Absolute maximum ratings (Ta = 25°C)

•

Recommended operating conditions (Ta = 25°C)

Parameter Symbol Limits Unit

V

CCMax. V

Pd

Max.

10.5

∗

1

1250

∗

2

mW

Topr – 15 ~ + 70 °C

Tstg – 40 ~ + 150 °C

V

P2Max. 10.5 V

Applied voltage
Power dissipation
Operating temperature
Storage temperature
Pin 2 applied voltage

∗

1 24Ω resistor connected between VCC and Vreg.

∗

2 Reduced by 10mW for each increase in Ta 1°C over 25°C.

Parameter Symbol Limits Unit

8.8 ~ 9.2

∗

1

V

11.7 ~ 12.3

∗

2

V

8.5 ~ 9.5

∗

1

VCC9V

VCC12V

VCC V

Power supply voltage (9V)
Power supply voltage (12V)
Guaranteed operating power

supply voltage

∗

1 24Ω resistor connected between VCC and Vreg.

∗

2 56Ω resistor connected between VCC and Vreg.

2

Video ICs BA7357S

•

Block diagram

1

2

3

4

5

6

7

8

9

10

11

22

21

20

19

18

17

16

15

14

13

12

AFTOUT

RFAGC

AGCADJ

RF

AGC

SIF

TRAP

VIDEO

AMP

AFT

PLL

DET

– 45

SHIFT

VCOVregMODE

REF

OSC

AF

AMP

FM

DEMOD

LIM

LIM

500k

BPF

BIAS

SIF

BPF

SIF

SW

VIF

AMP

VIF

AMP

VIF

AMP

SIF

AMP

+ 45

SHIFT

B/W

INV

EQ

AMP

IF

AGC

AGCFLT

GND1

VIFB

VIFA

GND2

SIF

AFC

VO4.5M

EQFLT

VEQO

PLLFLT

AFTCOIL

Vreg

PLLCOILA

PLLCOILB

MODE

X5

AFOUT

IR

3

Video ICs BA7357S

•

Pin descriptions

FunctionPin namePin No.

IF AGC FILTER

RF AGC OUT

VIF, BIAS GND
VIF B IN
VIF A IN
SIF, PLL GND

2nd SIF OUT

AUDIO OUT

MODE SW

Vreg
AFT COIL

EQ Filter

AFT OUT

RF AGC delay point adjustment

SIF IN / intercarrier SW
AUDIO detector Filter and A / V mute SW

FIilter BIAS resistor ( ± 1%)

Filter system reference frequency oscillator

PLL oscillator COIL
PLL oscillator COIL

PLL phase detect filter
VIDEO OUT after EQ amplifier

3
4

2

1

AGCADJ

AGCFLT
5 GND1
6 VIFB
7 VIFA
8 GND2
9 SIF

10 AFC
11 VO4.5M
12 IR
13 AFOUT
14 X5
15 MODE
16 PLL COIL B
17 PLL COIL A
18 Vreg
19 AFT COIL
20 PLL FLT
21 VEQO
22 EQFLT

RFAGC

AFTOUT

4

Video ICs BA7357S

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Equivalent circuits

∗

VCC and VCC2 in the equivalent circuit diagrams are connected to the Vreg terminal (pin 18).

AFT output.
Vreg / GND push-pull output.

RFAGC output.
Open-collector output. Gain can be
set using an external resistor
(minimum value of the maximum sink
current of pin 2 is 0.7mA) . Keep the
pin 2 voltage at 10.5V or less.

RFAGC delay point adjustment.
Connect to GND via a variable
resistor (approx. 100kΩ).

For filter time constant for VIFAGC.

2.7V

(when 100kΩ

resistor

connected)

1 AFTOUT OUT

—

OUT

—

—

—

5.0V

——

0V

2 RFAGC

3 AGCADJ

4 AGCFLT

5 GND1

Pin namePin No.

IN / OUT

Standard voltage FunctionEquivalent circuit

GND terminal for VIF, AGC and AFT.

VCC

GND

500

1k

1

500

2

V

CC

GND

4k

3

V

CC

GND

4.5k

4k

25.2k

1k

4

400

V

CC

GND

5

Video ICs BA7357S

7 VIFA

6 VIFB

IN

4.2V

8 GND2 — —

0V

IN

6.6V

—

2.7V

—

5.2V

9 SIF

10 AFC

11 VO4.5M

Standard voltage

IN / OUT

Video IF input.
Use with balanced input.

SIF and PLL GND.

Audio IF input.
Can set to intercarrier mode by
pulling down via a 2kΩ resistor.

Terminal for holding the audio
output DC level fixed.
Connect to GND via a 4.7µF
capacitor and to Vreg via a 10µF
capacitor to reduce BUZZ.
Set this pin to 0.3V or lower to
apply Audio / Video Mute.

2nd SIF output.
Connect a Trap to this pin to vary
the Sound Filter characteristics.
The internal impedance is a high
(Approximately) 1kΩ, so connect a
Buffer to output.

Pin name

Pin No.

FunctionEquivalent circuit

5

7

V

CC

GND

1k

1k

1k

5.3k5.3k

9

20k

15k

15k

17pF

V

CC

GND

10

3.5V

40k

V

CC

GND

11

V

CC

GND

Sound
Filter

8k