GENERAL DESCRIPTION
The TDA4681 is a monolithic integrated circuit with a colour difference interface for video processing in TV receivers. Its primary function is to process the luminance and colour difference signals from multistandard colour decoders, TDA4555, TDA4650/T, TDA4655/T or TDA4657, Colour Transient Improvement (CTI) IC, TDA4565, Picture Signal Improvement (PSI) IC, TDA4670 or from a feature module.

FEATURES
• 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 fully-controlled, analog RGB inputs, selected either by fast switch signals or via I2C-bus
• Saturation, contrast and brightness 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, horizontal and vertical synchronization, cut-off and white level timing pulses
• Automatic cut-off control with picture tube leakage current compensation
• Software-based automatic white level control or fixed white levels via I2C-bus
• Cut-off and white level measurement pulses in the last 4 lines of the vertical blanking interval (I2C-bus selection for PAL, SECAM, or NTSC, PAL-M)
• Increased RGB signal bandwidths for progressive scan and 100 Hz operation (selected via I2C-bus)
• 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
• Three adjustable reference voltage levels (via I2C-bus) for automatic cut-off and white level control
• Emitter-follower RGB output stages to drive the video output stages
• Hue control output for the TDA4555, TDA4650/T, TDA4655/T or TDA4657.