TDA9330 Philips Semiconductors, TDA9330 Datasheet - Page 48

• Manufacturer Part Number: TDA9330
• Description: I2C-bus controlled TV display processors
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Adjustment of geometry control parameters
The deflection processor of the TDA933xH offers
15 control parameters for picture alignment, as follows:
For the vertical picture alignment;
For the horizontal picture alignment;
It is important to notice that the ICs are designed for use
with a DC-coupled vertical deflection stage. This is why
a vertical linearity alignment is not necessary (and
therefore not available).
For a particular combination of picture tube type, vertical
output stage and E-W output stage, the required values for
the settings of S-correction and E-W corner/parabola ratio
must be determined. These parameters can be preset via
the I
The rest of the parameters are preset with the mid-value of
their control range, i.e. 1FH, or with the values obtained by
previously-adjusted TV sets on the production line.
The vertical shift control is intended to compensate offsets
in the external vertical output stage or in the picture tube.
It can be shown that, without compensation, these offsets
will result in a certain linearity error, especially with picture
tubes that need large S-correction. In 1st-order
approximation, the total linearity error is proportional to the
value of the offset and to the square of the S-correction
that is needed. The necessity to use the vertical shift
alignment depends on the expected offsets in the vertical
output stage and picture tube, on the required value of the
S-correction and on the demands upon vertical linearity.
2000 May 08
S-correction
Vertical amplitude
Vertical slope
Vertical shift
Vertical zoom
Vertical scroll
Vertical wait.
Horizontal shift
Horizontal parallelogram
Horizontal bow
E-W width with extended range for the zoom function
E-W parabola/width ratio
E-W upper corner/parabola ratio
E-W lower corner/parabola ratio
E-W trapezium correction.
I
2
2
C-bus controlled TV display processors
C-bus and do not need any additional adjustment.
48
To adjust the vertical shift and vertical slope independently
of each other, a special service blanking mode can be
entered by setting bit SBL HIGH. In this mode, the RGB
outputs are blanked during the second half of the picture.
There are two different methods for alignment of the
picture in the vertical direction. Both methods use the
service blanking mode.
The first method is recommended for picture tubes that
have a marking for the middle of the screen. With the
vertical shift control, the last line of the visible picture is
positioned exactly in the middle of the screen. After this
adjustment, the vertical shift should not be changed any
more. The top of the picture is positioned by adjusting the
vertical amplitude, and the bottom by adjusting the vertical
slope.
The second method is recommended for picture tubes that
have no marking for the middle of the screen. For this
method, a video signal is required in which the middle of
the picture is indicated (e.g. the white line in the circle test
pattern). The beginning of the blanking is positioned
exactly on the middle of the picture using the vertical slope
control. The top and bottom of the picture are then
positioned symmetrically with respect to the middle of the
screen by adjusting the vertical amplitude and vertical
shift. After this adjustment, the vertical shift has the correct
setting and should not be changed any more.
If the vertical shift alignment is not required, VSH should
be set to its mid-value, i.e. VSH = 1FH (31 DEC). The top
of the picture is then positioned by adjusting the vertical
amplitude and the bottom of the picture by adjusting the
vertical slope.
After the vertical picture alignment, the picture is
positioned in the horizontal direction by adjusting the E-W
width, E-W parabola/width ratio and horizontal shift. Finally
(if necessary), the left and right-hand sides of the picture
are aligned in parallel by adjusting the E-W trapezium
control.
Additional horizontal corrections are possible using the
parallelogram and bow controls.
To obtain the correct range of the vertical zoom function,
the vertical geometry should be adjusted at a nominal
setting of the zoom DAC at position 19H (25 DEC) and the
vertical scroll DAC at 1FH (31 DEC).
TDA933xH series
Preliminary specification