TDA8433 Datasheet, PDF (20/25 Pages) NXP Semiconductors – Deflection processor for computer controlled TV receivers

Philips Semiconductors
Deflection processor for computer
controlled TV receivers
Product specification
TDA8433
All correction voltages are related to
the supply voltage. The TDA8433 is
designed to accept a supply voltage
of 30 V. Normally higher voltages are
employed therefore a voltage
amplifier, with a gain of V_supply/30, is
used between the TDA8433 and the
diode modulator.
The formula for the E-W drive output
voltage at pin 19 is:
V_E-W = 30 x {1 − (1 − W) (1 − PA² Z² +
CA⁴ Z⁴) (1 − 1.1 x hE)} + 1.8 V
As can be seen from the formula, the
picture width, parabola function and
H-compensation are influenced by
each other. The functions are
discussed separately with the other
compensations set to zero.
Picture width control (P-C-h-O)
It is possible to change the picture
width by adjusting 'W' from 0 to 0.16.
Thus the complete range for the
picture control width is −10 to +10%.
By only changing the picture width
control the output voltage at pin 19
can vary between 1.8 and 6.6 V
typical.
Parabola function
The parabola function is also
dependent on the picture height
function. The values given are valid
for a nominal height setting
(A = 0.67 V). The parabola function
consists of two parts:
• A parabola part - E-W parabola is
created by squaring a linear
sawtooth. The range of this pure
parabola varies from 0 to 25%
typical i.e. the amplitude of the
parabola waveform is
programmable from 0 to 7.5 V
(typical).
• A fourth order part - E-W corner is
created by squaring the parabola.
The range of this corner correction
varies from 0 to 7% (typical) i.e. the
amplitude of the corner correction
waveform is programmable from 0
to −2.2 V (typical). A negative
output voltage is not possible. The
E-W corner correction waveform
has to be subtracted from one of
the other alignment functions.
The split-up into the E-W parabola
and the E-W corner enables each
television set to be aligned with
straight vertical lines. The trapezium
is also related to the parabola
function. The main reason for the
trapezium correction is to
compensate for internal offsets in the
geometry control part. Therefore:
• The amount of trapezium
correction is fully dependent on the
amount of parabola correction and
corner correction that is needed.
With no parabola and corner
correction the trapezium output will
be zero.
• The maximum possible trapezium
output is 1.6 V (typical - see Fig.7).
This is the case where: a = 0.5, c =
0 and p = 1 i.e. no corner correction
and the maximum parabola
correction at nominal picture height
settings.
H-compensation control
The horizontal deflection can be
modulated by the instantaneous
value of the signal applied to the EHT
compensation input. This external
signal should reflect the EHT
variations. The amount of deflection
reduction is in the range 0 to 10% if
the input at pin 7 is at
(V_supply/2) −4.3 V (maximum
modulation is 1.7 V typical). With
maximum modulation this range
corresponds to an output voltage of
0 to 3.3 V. There is no reduction when
the EHT-compensation input is at
V_supply/2 V (typical 6 V).
August 1991
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