TDA9115 datasheet(31/45 Pages) STMICROELECTRONICS

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TDA9115

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Figure 13. EWOut output waveforms

9.6 DYNAMIC CORRECTION OUTPUT

SECTION

9.6.1 Vertical Dynamic Correction output

VDyCor

A parabola at vertical deflection frequency is avail-

able on pin VDyCor. Its amplitude is adjustable via

VDC-AMP I2C bus control. It tracks with real verti-

cal amplitude and position (including breathing

compensation). It is also affected by C- and S-cor-

rections.

The use of this correction waveform is up to the

application (e.g. dynamic focus).

9.7 DC/DC CONTROLLER SECTION

The section is designed to control a switch-mode

DC/DC converter. A switch-mode DC/DC conver-

tor generates a DC voltage from a DC voltage of

different value (higher or lower) with little power

losses. The DC/DC controller is synchronized to

horizontal deflection frequency to minimize poten-

tial interference into the picture.

Its operation is similar to that of standard UC3842.

The schematic diagram of the DC/DC controller is

in Figure 14. The BOut output controls an external

switching circuit (a MOS transistor) delivering

pulses synchronized on horizontal deflection fre-

quency, the phase of which depends on I2C bus

configuration, see the table at the end of this chap-

ter. Their duration depends on feedback provided

to the circuit, generally a copy of DC/DC converter

output voltage and a copy of current passing

through the DC/DC converter circuitry (e.g. current

through external power component). The polarity

of the output can be controlled by BOutPol I2C bus

bit. A NPN transistor open-collector is routed out to

the BOut pin.

During the operation, a sawtooth is to be found on

pin BISense, generated externally by the applica-

tion. According to BOutPh I2C bus bit, the R-S flip-

flop is set either at H-drive signal edge (rising or

falling, depending on BOHEdge I2C bus bit), or a

Keystone

PCC

alone

tVR

V(VCap)

TVR

V(EWOut)

VEW-PCC

VEW-Key

VEW-DC

V(HEHT)

VRefO

VHEHT(min)

HSIZE (I2C)

mini

mum

medium

max

imum

VEW(min)

VEW(max)

Vertical sawtooth

tVR

V(VCap)

TVR

VRefO

VHEHT(min)

Breathing

compensation

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