STV9118 datasheet(34/46 Pages) STMICROELECTRONICS

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STV9118

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Figure 13. EWOut output waveforms

10.6 - DYNAMIC CORRECTION OUTPUT SECTION

10.6.1 - 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 and polarity controlled

via VDyCorPol I2C bus bit. It tracks with real verti-

cal amplitude and position (including breathing

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

rections.

The signal is buffered by an NPN emitter follower,

the emitter of which is routed to VDyCor output,

with an internal resistor to ground

The use of the correction waveform is up to the ap-

plication (e.g. dynamic focus).

10.7 - 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). A NPN tran-

sistor open-collector is routed out to the BOut pin.

Keystone

PCC

Top

Bottom

Corners

Vertical sawtooth

alone

tVR

V(VCap)

TVR

V(EWOut)

alone

VEW-PCC

VEW-TCor

VEW-BCor

VEW-Key

VEW-DC

V(HEHT)

VRefO

VHEHT(min)

HSIZE (I2C)

min

imu

med

ium

max

imu

VEW(min)

VEW(max)

Vertical sawtooth

tVR

V(VCap)

TVR

VRefO

VHEHT(min)

Breathing

compensation

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