GENERAL DESCRIPTION

The TDA3505 and TDA3506 are monolithic integrated circuits which perform video control functions in a PAL/SECAM decoder. The TDA3505 is for negative colour difference signals−(R-Y),−(B-Y) and the TDA3506 is for positive colour difference signals+(R-Y),+(B-Y).

The required input signals are: luminance and colour difference (negative or positive) and a 3-level sandcastle pulse for control purposes. Linear RGB signals can be inserted from an external source. RGB output signals are available for driving the video output stages. The circuits provide automatic cut-off control of the picture tube.

Features

• Capacitive coupling of the colour difference and luminance input signals with black level clamping in the input stages

• Linear saturation control acting on the colour difference signals

• (G-Y) and RGB matrix

• Linear transmission of inserted signals

• Equal black levels for inserted and matrixed signals

• 3 identical channels for the RGB signals

• Linear contrast and brightness controls, operating on both the inserted and matrixed RGB signals

• Peak beam current limiting input

• Clamping, horizontal and vertical blanking of the three input signals controlled by a 3-level sandcastle pulse

• 3 DC gain controls for the RGB output signals (white point adjustment)

• Emitter-follower outputs for driving the RGB output stages

• Input for automatic cut-off control with compensation for leakage current of the picture tube