TDA8366H datasheet(40/48 Pages) PHILIPS

40 / 48 page

January 1995

Philips Semiconductors

Objective speciﬁcation

I2C-bus controlled PAL/NTSC TV

processor

TDA8366

Adjustment of geometry control parameters

The deflection processor of the TDA8366 offers nine

control parameters for picture alignment:

• Vertical picture alignment

– S-correction

– vertical amplitude

– vertical slope

– vertical shift

• Horizontal picture alignment

– horizontal shift

– EW width

– EW parabola/width

– EW corner/parabola

– EW trapezium correction.

It is important to notice that the TDA8366 is designed for

use with a DC-coupled vertical deflection stage. This is the

reason why a vertical linearity alignment is not necessary

(and therefore not available).

For a particular combination of picture tube type, vertical

output stage and EW output stage it is determined which

are the required values for the settings of S-correction, EW

parabola/width ratio and EW corner/parabola ratio. These

parameters can be preset via the I2C-bus, and do not need

any additional adjustment. The rest of the parameters are

preset with the mid-value of their control range (i.e. 1FH),

or with the values obtained by previous TV-set

adjustments.

The vertical shift control is meant for compensation of

off-sets in the external vertical output stage or in the

picture tube. It can be shown that without compensation

these off-sets will result in a certain linearity error,

especially with picture tubes that need large S-correction.

The total linearity error is in first order approximation

proportional to the value of the off-set, and to the square of

the S-correction needed. The necessity to use the vertical

shift alignment depends on the expected off-sets in vertical

output stage and picture tube, on the required value of the

S-correction, and on the demands upon vertical linearity.

For adjustment of the vertical shift and vertical slope

independent of each other, a special service blanking

mode can be entered by setting the SBL bit HIGH. In this

mode the RGB-outputs are blanked during the second half

of the picture. There are 2 different methods for alignment

of the picture in vertical direction. Both methods make use

of 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. The

top of the picture is placed by adjustment of the vertical

amplitude, and the bottom by adjustment of 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). With the vertical slope control the beginning of the

blanking is positioned exactly on the middle of the picture.

Then the top and bottom of the picture are placed

symmetrical with respect to the middle of the screen by

adjustment of the vertical amplitude and vertical shift.

After this adjustment the vertical shift has the right setting

and should not be changed.

If the vertical shift alignment is not required VSH should be

set to its mid-value (i.e. VSH = 1F). Then the top of the

picture is placed by adjustment of the vertical amplitude

and the bottom by adjustment of the vertical slope. After

the vertical picture alignment the picture is positioned in

the horizontal direction by adjustment of the EW width and

the horizontal shift. Finally (if necessary) the left- and

right-hand sides of the picture are aligned in parallel by

adjusting the EW trapezium control.

After adjustment of the picture for normal vertical

deflection as described, no additional adjustment is

necessary for the compress and expand mode. If required

a small correction of the picture height can be made by

adjusting the vertical slope. This will not effect the linearity.

TDA8366H датащи(PDF) 40 Page - NXP Semiconductors

TDA8366H датащи(HTML) 40 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

датащи скачать

ссылки URL