2000 May 08 9
Philips Semiconductors Preliminary specification
I2C-bus controlled TV display processors
TDA933xH series
The horizontal drive signal is switched on and off via the
so-called slow-start/slow-stop procedure. This function is
realizedby varying the tonof the horizontal drive pulse. For
EHT generators without a bleeder, the IC can be set to a
‘fixed beam current mode’ via bit FBC. In this case, the
picture tube capacitance is discharged with a current of
approximately 1 mA. The magnitude of the discharge
current is controlled via the black current feedback loop.
If necessary, the discharge current can be enlarged with
the aid of an external currentdivision circuit. With the fixed
beam current option activated, it is still possible to have a
black screen during switch-off. This can be realized by
placing the vertical deflectionin an overscan position. This
mode is activated via bit OSO.
An additional mode of the IC is the ‘low-power start-up’
mode.This mode is activated when asupplyvoltageof 5 V
is supplied to the start-up pin.
The required current for this mode is 3 mA (typ.). In this
condition, the horizontal drive signal has the nominal t
off
and the ton grows gradually from zero to approximately
30% of the nominal value. This results in a line frequency
of approximately 50 kHz (2fH) or 25 kHz (1fH). The output
signal remains unchanged until the main supply voltage is
switched on and the I2C-bus data has been received. The
horizontal drive then gradually changes to the nominal
frequency and duty cycle via the slow-start procedure.
TheICcanonlybeswitched on and to standby mode when
both standby bits (STB0 and STB1) are changed. The
circuit will not react when only one bit changes polarity.
The IC has a general purpose bus controlled DAC output
with a 6-bit resolution and with an output voltage range
between 0.2 to 4 V. In the TDA9331H, the DC voltage on
this output is proportional to the horizontal line frequency
(only in VGA mode). This voltage can be used to control
the supply voltage of the horizontal deflection stage, to
maintain constant picture width for higher line frequencies.
VERTICAL DEFLECTION AND GEOMETRY CONTROL
The drive signals for the vertical and E-W deflection
circuits are generated by a vertical divider, which derives
its clock signal from the line oscillator. The divider is
synchronized by the incoming VDpulse, generated by the
input processor or the feature box. The vertical ramp
generator requires an external resistor and capacitor; the
tolerances for these components must be small. In the
normal mode, the vertical deflection operates in constant
slope and adapts its amplitude, depending on the
frequency of the incoming signal (50 or 60 Hz, or
100 or 120 Hz). When the TDA933xH is switched to the
VGA mode, the amplitude of the vertical scan is stabilized
andindependent of the incomingvertical frequency. In this
mode, the E-W drive amplitude is proportional to the
horizontalfrequency so that the correctiononthe screen is
not affected.
The vertical drive is realized by a differential output
current. The outputs must be DC-coupled to the vertical
output stage (e.g. TDA8354).
The vertical geometry can be adjusted via the I2C-bus.
Controls are possible for the following parameters:
• Vertical amplitude
• S-correction
• Vertical slope
• Vertical shift (only for compensation of offsets in output
stage or picture tube)
• Vertical zoom
• Verticalscroll (shifting the picture inthevertical direction
when the vertical scan is expanded)
• Vertical wait, an adjustable delay for the start of the
vertical scan.
Withregardtothevertical wait, the following conditions are
valid:
• In the 1fHTV mode, the start of the vertical scan is fixed
and cannot be adjusted with the vertical wait
• In the 2fH TV mode, the start of the vertical scan
depends on the value of the Vertical Scan Reference
(VSR) bus bit. If VSR = 0, the start of the vertical scan is
related to the end of the incoming VDpulse. If VSR = 1,
it is related to the start. In both cases, the start of the
scan can be adjusted with the vertical wait setting
• In the multi-sync mode (TDA9331H and TDA9332H
both in 1fHmode and 2fHmode), the start of the vertical
scan is related to the start of the incoming VDpulse and
can be adjusted with the vertical wait setting.
The minimum value for the vertical wait setting is 8 line
periods. If the setting is lower than 8, the wait period will
remain at 8 line periods.
The E-W drive circuit has a single-ended output. The E-W
geometry can be adjusted on the following parameters:
• Horizontal width with increased range because of the
‘zoom’ feature
• E-W parabola/width ratio
• E-W upper corner/parabola ratio
• E-W lower corner/parabola ratio
• E-W trapezium.