TDA9109 datasheet(20/30 Pages) STMICROELECTRONICS

20 / 30 page

BOUT

HORIZONTAL

OUTPUT

INHIBITION

VERTICAL

OUTPUT

INHIBITION

Horizontal Flyback

0.7V

XRAY Protection

CC Checking

CC or VDD off or I

C Reset

XRAY

VSCinh

I2C Drive on/off

I2C Ramp on/off

DD Checking

VSDinh

Figure 14 : Safety Functions Block Diagram

OPERATING DESCRIPTION (continued)

II.4 - Output Section

The H-drive signal is sent to the output through a

shaping stage which also controls the H-drive duty

cycle (I

2C adjustable) (see Figure 11). In order to

secure the scanning power part operation, the

output is inhibited in the following cases :

- when VCC or VDD are too low,

- when the XRAY protection is activated,

- during the Horizontal flyback,

- when the HDrive I

2C bit control is off.

The output stage consists of a NPN bipolar transis-

tor. Only the collector is accessible(see Figure 13).

This output stage is intended for ”reverse” base

control, where setting the output NPN in off-state

will control the power scanning transistor in off-

state (see Application Diagram).

The maximum output current is 30mA, and the

corresponding voltage drop of the output VCEsat is

0.4V Max.

Obviously the power scanning transistor cannot be

directly driven by the integratedcircuit. An interface

has to be added between the circuit and the power

transistor either of bipolar or MOS type.

II.5 - X-RAY Protection

The X-Ray protection is activated by application of

a high level on the X-Ray input (8V on Pin 25).

It inhibits the H-Drive and B+ outputs.

This protection is latched ; it may be reset either by

VCC or VDD switch off or by I

2C (see Figure 14).

20k

Ω

GND 0V

HFLY

400

Ω

Figure 12 : Flyback Input Electrical Diagram

H-DRIVE

VCC

Figure 13

II.6 - Vertical Dynamic Focus

The TDA9109/SN delivers a vertical parabola

waveform on Pin 10.

This vertical dynamic focus is tracked with VPOS

and VAMP. Its amplitude can be adjusted. It is also

affectedby Sand C corrections. This positive signal

once amplified is to be sent to the CRT focusing

grids.

TDA9109/SN

20/30

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