TDA9103 datasheet(16/27 Pages) STMICROELECTRONICS

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REF

H-amp Reg-in

Compensation

Clamp

SENSE

H-FREQ

Buffer

SMPS

OUT

RAP CYC

Basc

Figure 18 : SMPS Block Diagram

H Osc

Sawtooth

SMPS Drive

SMPS Current

1.6V

6.4V

0.75T

0.25T

Error Amplifier

Output (1.2V Max)

Figure 19 : SMPS Timing Diagram

Usys t

TDA9103

Hamp

Adjust

REF

4.8V

S WITCHING

REGULATOR

Flyback P eak

Dete ction a nd Re gulation

Hyoke

HDRIVE

Usys t is

a pproximatively

proportiona l

to Hfreq

S te p-up Conve rte r

H S ca n ning P art

Figure 20 : H Scanning Amplitude Regulation Example

The following functions are implemented in the

TDA9103 :

- A DC controlled variable gain amplifier allowing a

variation of

±14% of the voltage reference.

This is used to set the horizontal image ampli-

tude.

- An error amplifier, the non inverting input of which

is connected to the above mentioned adjustable

voltage reference.

The inverting input and the output of the error

amplifier are externally accessible.

- A comparator which determines the conduction

of the external transistor by comparing the output

voltage of the error amplifier and the voltage

applied on Pin 42 (ISENSE), which is the image of

the current in the power transistor (current mode

principle).

- A flip-flop which memorizes the on or off state of

the power transistor.

- An output buffer stage (open collector).

TDA9103

16/27

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