ST TEA6425 User Manual
■ 6 Video Inputs - 8 Video Outputs
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
IN 1
SDA
IN 2
SCL
IN 3
IN 4
SUB
IN 5
IN 6
V
CC
OUT 1
OUT 2
OUT 3
OUT 4
OUT 5
OUT 6
OUT 7
OUT 8
GND
V
CCP
■ 2 Internal Selectable YC Adders
■ 15MHz Bandwidth @ -3dB
■ Selectable 0.5/6.5dB Gain FOR EACH Output
■ High Impedance Switch for each Output (3-
state operation)
■ Programmable Clamp Mode on each Input
(sync bottom or average value)
■ -60dB Crosstalk @ 5MHz
■ 4 Sub-address Capability
2
■ I
C Bus Control
DESCRIPTION
This device is intended for switching between video and chroma signals such as CVBS, SVHS,
baseband CVBS, MAC . Each input clamp mode,
each output gain, all switching are controlled
through the I
2
C bus. The 8 outputs can be set separately in high impedance state, to enable parallel
DC connection of several devices (up to 4).
TEA6425
VIDEO CELLULAR MATRIX
DIP20
(Plastic Package)
ORDER CODE: TEA6425
SO20L
(Plastic Micropackage)
ORDER CODE: TEA6425D
Figure 1. Pin Connections
September 2003 1/10
6425-01.eps
1
TEA6425
Figure 2. Block Diagram
SUB-ADDRESS
INPUTS
SCL
SDA
V
CC1
V
CC2
1
3
5
6
8
10
4
2
7
9
20
TEA6425
PROG.
CLAMP
PROG.
CLAMP
PROG.
CLAMP
PROG.
CLAMP
PROG.
CLAMP
PROG.
CLAMP
I2C
DECODER
6 x 8
MATRIX
0/6dB0/6dB0/6dB0/6dB0/6dB0/6dB0/6dB0/6
3 STATE OUTPUTS
11
GND
1312
OUTPUTS
dB
191817161514
6425-02.eps
Figure 3. Cellular Matrix Connections
1st/4 addresses
CVBS
or C
6 INPUTS
PROG.
CLAMP
2
I C
DECODER
Full MATRIX
ADDER
0dB
6dB
3 STATE
OUT
6 X 8
IC1
8 OUTPUTS LINES
2nd/4 addresses
2
I C
DECODER
6 X 8
Full
MATRIX
IC2
6 INPUTS
IC3
IC4
6425-03.eps
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1
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
Supply Voltage 12 V
Voltage at Pin i to GND 0, V
CC
Operating Ambient Temperature 0, + 70
Storage Temperature -20, + 150
T
V
T
CC
V
oper
stg
I
THERMA L D ATA
Symbol Parameter Value Unit
R
(j-a) Junction-ambient Thermal Resistance Min. 80
th
TEA6425
V
o
C
o
C
o
C/W
ELECTRICAL CHARACTERISTICS (V
= 4.7kΩ ; Gain condition, clamp and 3-state are controlled by I
CC
= 8V, T
amb
= 25oC, V
= 1V, Gain = 6.5dB, C
IN
2C
bus, unless otherwise specified)
load
= 20pF, R
Symbol Parameter Test Conditions Min. Typ. Max. Unit
SUPPLY
V
I
Supply Voltage 7.2 8 8.8 V
CC
Supply Current 45 60 mA
CC
RR Supply Voltage Rejection f = 1kHz 40 46 dB
VIDEO INPUTS (clamping at bottom sync level)
V
V
clamp
V
I
clamp
I
Max. Signal Amplitude Clamp Active 2 V
IN
Clamp Level Clamp Active 1.7 2 2.3 V
Input DC Level Clamp Inactive 2.7 3 3.3 V
DC
Leakage Current 1 input connected to 1 output 2 5 µA
IN
Clamp Current V
- 200mV 0.9 3 mA
clamp
VIDEO OUTPUTS
R
OUT
Z
C
Output Resistance 15 50 W
Output "off" Impedance no load 50 k
HI
C
HI
in 3-state no load 3 pF
OUT
G1 Voltage Gain f = 100kHz 0 0.5 1 dB
G2 Voltage Gain f = 100kHz 6 6.5 7 dB
V
V
sync
Top Level Sync (Y or CVBS) G = 6.5dB, Clamp Active 1 1.25 2 V
2
Output Mean Level (chroma)
bias
G = 0.5dB, Clamp Inactive
G = 6.5dB, Clamp Inactive
2.4
3
3.4
3
4
Isolation "off" State f = 5MHz 60 dB
Crosstalk Attenuation between
Channels
B Bandwidth
f = 5MHz 50 60 dB
= 20pF, G = 6.5dB
C
load
at ± 0.5dB
at ± 1dB
at - 3dB
5
10
21
load
PP
Ω
V
V
MHz
FUNCTIONAL DESCRIPTION
2
This device is controlled via the I
C bus. 4 addresses can be se lected by a 4-l ev el d ete ctor o n Pin 7,
thus enabling parallel connection of 4 devices.
Via the I
2
C bus :
– The input sign als c an be clam ped at t heir ne ga-
tive peak (top sync).
– The gain factor of the outputs can be selected
between 0.5 and 6.5dB.
– Each of the 6 inputs can be connec ted to the 8
outputs.
– Each out put can i ndividu ally be set in a high im-
pedance state.
Two internal SVHS m ixers will a dd t he selected Y
and C inputs. Two dedicated outputs will have the
option to select this added signal also.
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