1995 Feb 06 5
Philips Semiconductors Product specification
4 × 4 video switch matrix TDA8540
FUNCTIONAL DESCRIPTION
The TDA8540 is controlled via a bidirectional I2C-bus.
3 bits of the I2C address can be selected via the address
pin, thus providing a facility for parallel connection of
7 devices.
Control options via the I2C-bus:
• The input signals can be clamped at their negative peak
(top sync).
• The gain factor of the outputs can be selected between
1× or 2×.
• Each of the four outputs can individually be connected
to one of the four inputs.
• Each output can individually be set in a high impedance
state.
• Two binary output data lines can be controlled for
switching accompanying sound signals.
The SDA and SCL pins (pins 19 and 18) can be connected
to the I
2
C-bus or to DC switching voltage sources. Address
inputs S0 to S2 (pins 11, 7 and 5) are used to select
sub-addresses or switching to the non-I2C mode. Inputs
S0 to S2 can be connected to the supply voltage (HIGH) or
the ground (LOW). In this way no peripheral components
are required for selection.
Table 1 I
2
C-bus sub-addressing
I
2
C-bus control
After power-up the outputs are initialized in the high
impedance state, and D0 and D1 are at a LOW level.
Detailed description of the I2C-bus specification, with
applications, is given in brochure
“The I2C-bus and how to
use it”
. This brochure may be ordered using the code
9398 393 40011.
The TDA8540 is aslave receiver and the protocol is given
in Table 2.
S2 S1 S0
SUB-ADDRESS
A2 A1 A0
LLL000
LLH001
LHL010
LHH011
HLL100
HLH101
HHL110
H H H non I
2
C addressable
Table 2 The TDA8540 protocol
Notes
1. S = START condition.
2. Data transmission to the TDA8540 starts with the slave address (SLV).
3. A = acknowledge bit, generated by TDA8540.
4. P = STOP condition.
Table 3 Data transmission to the TDA8540 begins with SLV
Notes
1. A2 to A0: pin programmable slave address bits.
2. R/
W = 0; write only.
After the SLV, a second byte, SUB, is required for selecting the functions, as shown in Table 4.
SEQUENCE
S
(1)
SLV
(2)
A
(3)
SUB A
(3)
DATA A
(3)
DATA A
(3)
P
(4)
A6
MSB
A5 A4 A3 A2 A1 A0
R/W
LSB
1001A2
(1)
A1
(1)
A0
(1)
0
(2)