ROHM BH7634AS Datasheet

1

Multimedia ICs

Audio / video switch for CANAL - Plus
decoder

BH7634AS

The BH7634AS is one-chip IC that contains audio and video switches that support 21-pin SECAM and PAL connec­tors.
The I

2

C BUS for switch control simplifies applications, while the two expansion ports allow up to two external inputs.

•

Applications

VCRs

•

Features

1) I

2

C BUS control.

2) Video input is sync tip clamped, and includes a
small-capacity (0.022µF) input capacitor.

3) Three FSCOUT values.

4) Two expansion ports.

5) Audio mute function.

6) 75Ω driver output (pins 20 and 23) requires no
attached capacitor.

•

Absolute maximum ratings (Ta = 25°C)

Power supply voltage
Power dissipation
Operating temperature
Storage temperature

∗

Reduce by 12mW for each increase in Ta of 1°C over 25°C.

Parameter Symbol Limits Unit

V

CC 13.5 V

Pd

1200

mW
Topr – 25 ~ + 60 °C
Tstg – 55 ~ + 125 °C

•

Recommended operating conditions (Ta = 25°C)

Parameter

V

CC 8.5 13 V12

Symbol Min. Typ. Max. Unit

Operating power supply voltage

2

Multimedia ICs BH7634AS

•

Block diagram

VEDC IN

1

DRVGND

2

VTUNIN

3

DRVV

CC

4

VEXTIN

5

GND

6

ADECIN

7

FSCOUT

8

AEXTIN

9

AUXCTL1

10

ATUNIN

11

AUXCTRL2

AUXCTL2

AUXCTL2

FOR SW

I

2

C BUS

CONTROL

AUXCTL1

AUXCTL1

CURRENT

LIMITER

6.0V
REG

V

CC

VCC

12

VVTRIN

24

VEXTOUT

DRIVER

DRIVER

BUFFER

BUFFER

BUFFER

BUFFER

BUFFER

23

VVTROUT

22

VVPSOUT

21

VDECOUT

20

V

CC

19

AVTRIN

18

AEXTOUT

17

AVTROUT

16

ADECOUT

15

SCL

14

SDA

13

A

B

VSW1

A

B

C

VSW2

A
B

C

VSW3

A

B

ASW1

A
B

C

ASW2

A
B

C

ASW3

MUTE

6dB

6dB

CLAMP

CLAMP

CLAMP CLAMP

3

Multimedia ICs BH7634AS

•

Pin descriptions

Pin No.

3
4

2

1

VTUNIN
DRVV

CC

5 VEXTIN
6 GND
7 ADECIN
8 FSCOUT

9 AEXTIN
10 AUXCTL1
11 ATUNIN
12 AUXCTL2
13 SDA
14 SCL
15 ADECOUT
16 AVTROUT
17 AEXTOUT
18 AVTRIN
19 V

CC

20 VDECOUT
21 VVPSOUT
22 VVTROUT
23 VEXTOUT
24 VVTRIN

DRVGND

VDECIN

Composite video signal input (sink chip clamp).
The driver power supply. Not internally connected to V

CC (pin 19).

The driver ground. Not internally connected to the ground (pin 6).

Pin name

Composite video signal input (sink chip clamp).
Ground
Audio signal input.
Outputs one of three values (11.8V, 5.9V or 0.2V) as controlled by the I

2

C BUS.
Audio signal input.
Open collector. Normally pulled up to roughly 10k.
Audio signal output.
Open collector. Normally pulled up to roughly 10k.
I

2

C BUS Serial Data input.

I

2

C BUS Serial Clock input.
Audio output.
Audio output.
Audio output.
Audio input.
Power supply.
Composite video signal output.
Composite video signal output.
Composite video signal output.
Composite video signal output.
Composite video signal input (sink chip clamp).

Composite video signal input (sink chip clamp).

Function

4

Multimedia ICs BH7634AS

•

Pin descriptions and input output equivalent circuits

50µA

1k

50µA

1k

50k

DRVGND

GND

DRVVCC

VCC

50k

6V

12V

FS control

Three voltages are output
via I

2

C BUS control: 11.8V,

5.9V, 0.2V.

8 FSCOUT

—

™ —

Pin No.

1

3

5

24

VDECIN

VTUNIN

VEXTIN

VVTRIN

26DRVGND

GND

419DRVV

CC

VCC

7

9

11

18

ADECIN

AEXTIN

ATUNIN

AVTRIN

™ — 1.6V

—— 0V

— — 12V

™ — 5.3V

IN OUT

Pin name

Typ.

voltage

I / O equivalent circuits Pin description

Video signal input

For composite video signal
input (sink chip clamp input).

Ground

DRVGND is the driver
ground. GND is the ground
for the circuit itself. GND and
DRVGND are not connected
internally.

Power supply

DRVV

CC is the driver

power supply. V

CC is the

power supply for the circuit
itself. V

CC and DRVVCC

are not connected internally.

Audio signal input

For audio signal input.
Input impedance is 50k.