August 1991

18

Philips Semiconductors

Product specification

Deflection processor for computer

controlled TV receivers

TDA8433

APPLICATION INFORMATION

The formulae from which the typical

vertical drive and typical E-W drive

waveforms are generated are given

in the following sub-paragraphs. For

this purpose a typical application

diagram for the vertical drive stage

is assumed to be as illustrated in

Fig.7. Pin 20 is the vertical drive

output which drives an inverting

power amplifier. The feedback

network, R1 to R4 and C1 and C2,

has two functions;

• To transfer the voltage on the

feedback pin (pin 21) to a voltage

across the feedback resistor R1

• To stabilize the voltage across C1

at a fixed value.

For this typical application the

formula for the vertical scan

waveform refers to the voltage at

pin 21. The formula for the E-W

drive waveform refers to the voltage

at pin 19.

All DAC variables that control the

vertical and E-W drive waveforms

are normalized. Each DAC is

defined as having a control range

between 0 and 1. The 0

corresponds to a register value of

HEX00 and the 1 to a maximum

value of HEX1F (for a 5-bit DAC) or

HEX3F (for a 6-bit DAC).

Table 4

DAC variables

Further definitions

If the Trapezium function (T) compensates for the internal offset voltage then the

actual formula for Z will simplify to:

Z =

Since 0 V

that:

−1 < Z < 1.

a: Picture height

0

< a < 1

64 steps (6 bits)

y: V-linearity

0

< y < 1

64 steps (6 bits)

s: V-S correction

0

< s < 1

64 steps (6 bits)

d: V-shift

0

< d < 1

64 steps (6 bits)

v: V-compensation

0

< v < 1

32 steps (5 bits)

w: Picture width

0

< w < 1

64 steps (6 bits)

p: E-W parabola

0

< p < 1

64 steps (6 bits)

c: E-W corner

0

< c < 1

64 steps (6 bits)

t: Trapezium

0

< t < 1

64 steps (6 bits)

h: H-compensation

0

< h < 1

32 steps (5 bits)

A = 0.80 (a + 2)/3

P = 0.55 p

Y = 0.17 y

C = 0.38 c

S = 0.42 s

T = 0.32 (1 + 2t) volts

D = 2.4

− 0.7 d volts

W = 0.16 w

Z =

−1 + 2 x (V