The TDA4685 is a monolithic integrated circuit with a luminance and a colour difference interface for video processing in TV receivers. Its primary function is to process the luminance and colour difference signals from a colour decoder which is equipped e.g. with the multistandard decoder TDA4655 or TDA9160 plus delay line TDA4661 and the Picture Signal Improvement (PSI) IC, TDA467X, or from a feature module.
• Operates from an 8 V DC supply
• Black level clamping of the colour difference, luminance and RGB input signals with coupling-capacitor DC level storage
• Two analog RGB inputs, selected either by fast switch signals or via I2C-bus; brightness and contrast control of both RGB inputs
• Saturation, contrast, brightness and white adjustment via I2C-bus
• Same RGB output black levels for Y/CD and RGB input signals
• Timing pulse generation from either a 2 or 3-level sandcastle pulse for clamping, vertical synchronization and cut-off timing pulses
• Automatic cut-off control or clamped output selectable via I2C-bus
• Automatic cut-off control with picture tube leakage current compensation
• Cut-off measurement pulses after end of the vertical blanking pulse or end of an extra vertical flyback pulse
• Two switch-on delays to prevent discolouration before steady-state operation
• Average beam current and peak drive limiting
• PAL/SECAM or NTSC matrix selection via I2C-bus
• Emitter-follower RGB output stages to drive the video output stages
• I2C-bus controlled DC output e.g. for hue-adjust of NTSC (multistandard) decoders.