TDA9110 datasheet(21/29 Pages) STMICROELECTRONICS

21 / 29 page

EW Output

EW amp

Keystone

Sidepin amp

Parallelogram

Internal Vertical

Dynamic Focus

added to

Horizontal one

Sidepin Balance

Output Current

To Horizontal

Phase

VDCOUT

VDCIN

VDCOUT

Vertical Ramp V

OUT

AMP

Figure 20 : Geometric Corrections Principle

III - VERTICAL PART

III.1 - Geometric Corrections

The principle is represented on Figure 20.

Starting from the vertical ramp, a parabola shaped

current is generated for E/W correction, dynamic

horizontal phase control correction, and vertical

dynamic Focus correction.

The parabola generator is made by an analog

multiplier, the output current of which is equal to :

∆I= k ⋅ (VOUT -VDCOUT)2

where Vout is the vertical output ramp (typically

between 2 and 5V) and Vdcout is the vertical DC

output adjustable in the range 3.2V to 3.8V which

generate a dissymetric parabola if needed (key-

stone adjustment).

In order to keep a good screen geometry for any

end user preferencesadjustment,we implemented

the ”geometry tracking”.

Due to large output stages voltage range (E/W,

FOCUS), the combination of tracking function with

maximum vertical amplitude max or min vertical

position and maximum gain on the DAC control

may lead to the output stages saturation. This must

be avoided by limiting the output voltage with ap-

ropriate I

2C registers values.

For the E/Wpart and the Dynamic Horizontalphase

control part, a sawtooth shaped differential current

in the following form is generated :

∆I’ = k’ ⋅ (VOUT -VDCOUT)

Then

∆I and ∆I’ are addedand converted into volt-

age for the E/W part.

Each of the two E/W components or the two Dy-

namic Horizontal phase control ones may be inhib-

ited by their own I

2C select bit.

The E/W parabola is available on Pin 24 via an

emitter follower which has to be biased by an

external resistor (10k

Ω). It can be DC coupled with

external circuitry.

The Vertical Dynamic Focus is combined with the

Horizontal one on Pin 15.

The dynamic Horizontal phasecontrol current drives

internally the H-position, moving the Hfly position on

the Horizontal sawtooth in the range of

± 1.4% TH

both on SidePin Balance and Parallelogram.

OPERATING DESCRIPTION (continued)

TDA9110

21/29

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