Functional description, Non-i2c bus control, Switch for ctv receivers tda8440 – Philips TDA8440 User Manual
Page 4
November 1985
4
Philips Semiconductors
Product specification
Switch for CTV receivers
TDA8440
FUNCTIONAL DESCRIPTION
The TDA8440 is a monolithic system of switches and can be used in CTV receivers equipped with an AUXILIARY
VIDEO/AUDIO plug.
The IC incorporates 3-state switches; they comprise:
a) An electronic video switch with selectable gain (times 1 or times 2) for switching between an internal video signal
(from the IF amplifier) and an AUXILIARY input signal.
b) Two electronic audio switches, for two sound channels (stereo or dual language), for switching between internal
audio sources and signals from the AUXILIARY VIDEO/AUDIO plug.
A selection can be made between two input signals and an OFF-state. The OFF-state is necessary if more than one
TDA8440 device is used.
The SDA and SCL pins can be connected to the I
2
C bus or to d.c. switching voltages. Inputs S
0
(pin 11), S
1
(pin 13), and
S
2
(pin 6) are used for selection of sub-addresses or switching to the non-I
2
C mode. Inputs S
0
, S
1
and S
2
can be
connected to the supply voltage (H) or to ground (L). In this way no peripheral components are required for selection.
Table 1
Sub-addressing
NON-I
2
C BUS CONTROL
If the TDA8440 switching device has to be operated via the AUXILIARY VIDEO/AUDIO plug, inputs S
2
, S
1
and S
0
must
be connected to the supply line (12 V).
The sources (internal and external) and the gain of the video amplifier can be selected via the SDA and SCL pins with
the switching voltage from the AUXILIARY VIDEO/AUDIO plug:
•
Sources I are selected if SDA = 12 V (external source)
•
Sources II are selected if SDA = 0 V (TV mode)
•
Video amplifier gain is 2
×
if SCL = 12 V (external source)
•
Video amplifier gain is 1
×
if SCL = 0 V (TV mode)
If more than one TDA8440 device is used in the non-I
2
C bus system, the OFF pin can be used to switch off the desired
devices. This can be done via the 12 V switching voltage on the AUXILIARY VIDEO/AUDIO plug.
•
All switches are in the OFF position if OFF = H (12 V)
•
All switches are in the selected position via SDA and SCL pins if OFF = L (0 V)
S
2
S
1
S
0
SUB-ADDRESS
A
2
A
1
A
0
L
L
L
0
0
0
L
L
H
0
0
1
L
H
L
0
1
0
L
H
H
0
1
1
H
L
L
1
0
0
H
L
H
1
0
1
H
H
L
1
1
0
H
H
H
non I
2
C addressable