1997 Feb 06
2
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 I
2
C-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 I
2
C-bus
Two peak drive limiters, selection via I
2
C-bus
Blue stretch, selection via I
2
C-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 I
2
C-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 I
2
C-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
I
2
C-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 I
2
C-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
I
2
C-bus receiver only. Automatic white level control is
not provided; the white levels are determined directly by
the I
2
C-bus data.
The TDA4780 is pin compatible (except pin 18) with the
TDA4680. The I
2
C-bus slave address can be used for
both ICs. When a function of the TDA4780 is not
included in the TDA4680, the I
2
C-bus command is not
executed. Special commands (except control bit FSWL)
for the TDA4680 will be ignored by the TDA4780.
1997 Feb 06
3
Philips Semiconductors
Preliminary specification
RGB video processor with automatic
cut-off control and gamma adjust
TDA4780
QUICK REFERENCE DATA
ORDERING INFORMATION
SYMBOL
PARAMETER
MIN.
TYP.
MAX.
UNIT
V
P
supply voltage (pin 5)
7.2
8.0
8.8
V
I
P
supply current (pin 5)
80
100
120
mA
V
8(p-p)
luminance input (peak-to-peak value) (C)VBS
-
0.45/1.43
-
V
V
6(p-p)
-
(B
-
Y) input (peak-to-peak value)
-
1.33
-
V
V
7(p-p)
-
(R
-
Y) input (peak-to-peak value)
-
1.05
-
V
V
14
three-level sandcastle pulse
H + V
-
2.5
-
V
H
-
4.5
-
V
BK
-
8.0
-
V
two-level sandcastle pulse
H + V
-
2.5
-
V
BK
-
4.5
-
V
V
i
RGB input signals at pins 2, 3, 4, 10, 11 and 12 (black-to-white value)
-
0.7
-
V
V
o(p-p)
RGB output at pins 24, 22 and 20 (black-to-white value)
-
2.0
-
V
T
amb
operating ambient temperature
-
20
-
+70
C
TYPE
NUMBER
PACKAGE
NAME
DESCRIPTION
VERSION
TDA4780
DIP28
plastic dual in-line package; 28 leads (600 mil)
SOT117-1
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