GENERAL DESCRIPTION

The TDA3561A is a decoder for the PAL colour television standard. It combines all functions required for the identification and demodulation of PAL signals. Furthermore it contains a luminance amplifier, an RGB-matrix and amplifier. These amplifiers supply output signals up to 5 V peak-to-peak (picture information) enabling direct drive of the discrete output stages. The circuit also contains separate inputs for data insertion, analogue as well as digital, which can be used for

text display systems (e.g. (Teletext/broadcast antiope), channel number display, etc. Additional to the TDA3560, the circuit includes the following features:

• The peak white limiter is only active during the time that the 9,3 V level at the output is exceeded. The start of the limiting function is delayed by one line period. This avoids peak white limiting by test patterns which have abrupt transitions from colour to white signals.

• The brightness control is obtained by inserting a variable pulse in the luminance channel. Therefore the ratio of brightness variation and signal amplitude at the three outputs will be identical and independent of the difference in gain

of the three channels. Thus discolouring due to adjustment of contrast and brightness is avoided.

• Improved suppression of the internal RGB signals when the device is switched to external signals, and vice versa.

• Non-synchronized external RGB signals do not disturb the black level of the internal signals.

• Improved suppression of the residual 4,4 MHz signal in the RGB output stages.

• Cascoded stages in the demodulators and burst phase detector minimize the radiation of the colour demodulator inputs.

• High current capability of the RGB outputs and the chrominance output.