TDA9105 datasheet(20/32 Pages) STMICROELECTRONICS

20 / 32 page

OPERATING DESCRIPTION (continued)

Geometric Corrections (continued)

SIDE PIN BAL. OUT

EW OUT

VERT. DYN. FOCUS OUT

VDCIN

KEYSTONE

EW AMP

VDCIN

KEY BALANCE

SIDEPIN AMP

VDCIN

ANALOG MULTIPLIER

VERTICAL RAMP

Figure 20 : Geometric Corrections Principle

For E/Wpart and Dynamic Horizontal phase control

part, a sawtooth shaped differential current in the

following form is generated:

∆I’ = k’ (VRAMP -VDCIN).

Then

∆Iand ∆I’ are added together and converted

into voltage.

These two parabola are respectively available on

Pin 37 and Pin 40 by the way of an emitter follower

which has to be biased by an external resistor

(10k

Ω). They can be DC coupled with external

circuitry.

VOUT = 2.5V + K1’(VRAMP -VDCIN)

+K1 (VRAMP -VDCIN)

K1 is adjustable by EW amp control (Pin 39)

K1’ is adjustable by KEYST control (Pin 38)

Dyn. Hor.

Phase Control

VOUT =4V+ K2’(VRAMP -VDCIN)

+K2 (VRAMP -VDCIN)

K2 is adjustable by SPB amp control (Pin 42)

K2’ is adjustable by KEYBAL control (Pin 41)

For vertical dynamic focus part, only a constant

amplitude parabola is generated in the form :

VOUT = 6V - 0.75 x (VAMP -VDCIN)

The output connection is the same as the two other

corrections (Pins 37-40).

It is important to note that the parasitic parabola

during the discharge of the vertical oscillator ca-

pacitor is suppressed.

TDA9105

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