Philips TDA8443A

1995 Mar 07 5

Philips Semiconductors Product speciﬁcation

I2C-bus controlled YUV/RGB switch TDA8443A

FUNCTIONAL DESCRIPTION

The circuit contains two sets of inputs (see Fig.1). Both

channels can receive RGB or YUV signals. Each set of

inputs has its own synchronization input, which internally

generates a pulse to clamp the inputs. The internal

clamping pulse can also be controlled by a signal (e.g. a

sandcastle pulse) applied to pin 24. The pulse will occur

during the time that the signal at pin 24 is between

5.5 and6.5 V. If both a sync signal and a pin 24 signal are

used the signal should be applied to pin 24 via a 1kΩ

resistor.

RGB signals of Channel 2 can be matrixed to YUV signals.

The outputs can be set in a high impedance OFF state,

which allows the use of seven devices in parallel

(I2C-bus mode).

The circuit can be controlled by an I2C-bus compatible

microcontroller or directly by DC voltages. The fast

switching input can be operated via pin 16 of the

peritelevision connector.

I2C-bus mode

The protocol for the devices in I2C-bus mode is shown

in Fig.3.

Table 1 Protocol bit description

BIT DESCRIPTION

STA start condition

MA2 toMA0 address selection bits; see Table2

ACK acknowledge bit

D7 channel selection bit; see Table3

D6 matrix selection bit; see Table3

D5 toD3 gain control bits; see Table 4

D2 fast switching priority bit; see Table5

D1 andD0 output state control bits; see Table 6

STO stop condition

Fig.3 I2C-bus protocol.

handbook, full pagewidth

STA 1 1 0 1 MA2 MA1 MA0 0 ACK D7 D6 D5 D4 D3 D2 D1 D0 ACK STO

MSA003

SeeTable 1.