TDA4780 datasheet(2/44 Pages) PHILIPS

2 / 44 page

1997 Feb 06

Philips Semiconductors

Preliminary speciﬁcation

RGB video processor with automatic

cut-off control and gamma adjust

TDA4780

FEATURES

• Gamma adjust

• Dynamic black control (adaptive black)

• All input signals clamped on black-levels

• Automatic cut-off control, alternative: output clamping

on fixed levels

• Three adjustable reference voltage levels via I2C-bus for

automatic cut-off control

• Luminance/colour difference interface

• Two luminance input levels allowed

• Two RGB interfaces controlled by either fast switches or

by I2C-bus

• Two peak drive limiters, selection via I2C-bus

• Blue stretch, selection via I2C-bus

• Luminance output for scan velocity modulation

(SCAVEM)

• Extra luminance output; same pin can be used as hue

control output e.g. for the TDA4650 and TDA4655

• Non standard operations like 50 Hz/32 kHz are also

possible

• Either 2 or 3 level sandcastle pulse applicable

• High bandwidth for 32 kHz application

• White point adjusts via I2C-bus

• Average beam current and improved peak drive limiting

• Two switch-on delays to prevent discoloration during

start-up

• All functions and features programmable via I2C-bus

• PAL/SECAM or NTSC matrix selection.

GENERAL DESCRIPTION

The TDA4780 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 or TDA4665 and the Picture Signal

Improvement (PSI) IC TDA467X or from a feature module.

The required input signals are:

• Luminance and negative colour difference signals

• 2 or 3-level sandcastle pulse for internal timing pulse

generation

• I2C-bus data and clock signals.

Two sets of analog RGB colour signals can also be

inserted, e.g. one from a peritelevision connector

(SCART plug) and the other one from an On-Screen

Display (OSD) generator. The TDA4780 has I2C-bus

control of all parameters and functions with automatic

cut-off control of the picture tube cathode currents.

It provides RGB output signals for the video output stages.

In clamped output mode it can also be used as an RGB

source.

The main differences with the sister type TDA4680 are:

• Additional features, namely gamma adjust, adaptive

black, blue stretch and two different peak drive limiters

• The measurement lines are triggered by the trailing

edge of the vertical component of the sandcastle pulse

• I2C-bus receiver only. Automatic white level control is

not provided; the white levels are determined directly by

the I2C-bus data.

• The TDA4780 is pin compatible (except pin 18) with the

TDA4680. The I2C-bus slave address can be used for

both ICs. When a function of the TDA4780 is not

included in the TDA4680, the I2C-bus command is not

executed. Special commands (except control bit FSWL)

for the TDA4680 will be ignored by the TDA4780.

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