STV2246 View Datasheet(PDF) - STMicroelectronics
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STV2246 Datasheet PDF : 86 Pages
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STV224X, STV228X, STV223X - FUNCTIONAL DESCRIPTION
olds, the OSD RGB signals are selected. When
the FBOSD voltage is greater than the second
threshold (4 V blanking threshold), the RGB out-
pulse is maintained until VCC1 is less than 3 V
(VCC1 power supply is switched off). The Safety
function can be disabled via the I²C bus. When
puts are blanked during the whole field, but not register 15hex data D7 is set to “1”, the Safety
during inserted cut-off lines (the cut-off loop is al- function is reset and no longer active.
ways active). The blanking feature, via the FBOSD
input pin, enables Vertical Oversize Blanking
when a 4:3 picture is displayed on a 16:9 screen in
Zoom mode. The picture outside the screen is
blanked by the Oversize Blanking pulse supplied
by the external vertical IC (STV9306).
3.2.7 Vertical Output
3.2.11 Combined Line Flyback / Super-
Sandcastle
Combined Line Flyback input and Super-Sandcas-
tle output: The line blanking level is clamped at
3 V, the burst key pulse voltage is 5 V and vertical
pulse voltage is 2 V. The line pulse is extracted
with a 2.5 V slicing level used for RGB line blank-
The Vertical output pulse is locked on a pulse that ing and PLL2 control.
is twice the horizontal frequency to ensure perfect 3.2.12 Line Blanking
interlacing.
The Vertical output pulse duration is 10.5 lines.
) Horizontal output pulse is a 28 µs line pulse on an
t(s open collector output.
3.2.8 Vertical Control
uc Bus-controlled DC output voltage for adjusting the
vertical amplitude (pin VAMP). This voltage supply
d is used to adjust the slope of the vertical sawtooth
ro generated by the external vertical booster.
P Bus-controlled vertical position (pin VERT). The
high level of the vertical pulse is used to adjust the
te vertical position.
le The bus-controlled vertical output (pin VERT) low
level voltage can be either 0.2 V or 2.0 V.
o 3.2.9 Horizontal Output
bs Start-up circuit: the horizontal output is at high lev-
el (disabled) when VCC1 increases from 0 to 6.0 V
O and when VCCD has not reached 4 V.
- Soft mode circuit: it provides a softer operating
) horizontal output with a 75% duty cycle [tHIGH /
t(s (tHIGH +tLOW)]. This results in a smaller conducting
time (16 µs instead of 28 µs).
c This mode is active at start-up until two frames af-
u ter the VCC2 reaches 75% of the VCC1. It is also
d active at shutdown when the VCC1 floats between
ro 6 V and 5.4 V. And finally, this mode is used if the
VCC2 drops below 75% of the VCC1.
P At shutdown, horizontal pulses are disabled when
te VCC1 is less than 5.4 V or when VCCD is less than
3.5 V.
leThe horizontal output pulse may be disabled via
the bus (force a high level on HOUT).
soThe horizontal position adjustment is controlled via
b the bus.
Line blanking at RGB outputs is logical OR of line
flyback pulse and internal line blanking pulse with
a 12 µs width.
In Wide Line Blanking mode, line blanking at RGB
outputs is logical OR of line flyback pulse and in-
ternal line blanking pulse with a 15.8 µs width.
Wide line blanking is recommended when display-
ing a 4:3 image on a 16:9 screen (horizontal scan-
ning reduction).
3.2.13 Copy Protection Mode
This mode is used to improve the display of copy-
protected video signals.
3.3 FILTERS
3.3.1 Integrated Trap Filter
Q = 1.5 (f-3dB = f0 (1-1/2Q)),
Center frequency:
– 4.43 MHz, 3.58 MHz for PAL and NTSC.
– 4.25 MHz, for SECAM
(-20 dB rejection between 4.1 MHz and
4.4 MHz).
The chroma trap filter is switched off in SVHS
mode, or in color standard search mode (standard
not identified). In external YCrCb mode, the trap
and luma delay can be switched off via the I²C bus.
3.3.2 Integrated Chroma Bandpass
Q = 3.5, Center frequency: 4.43 MHz, 3.58 MHz.
The Bus Control Frequency Shift is used to opti-
mize the chroma response for the video signal
from the IF stage.
3.3.3 Integrated Bell Filter for SECAM
Q = 16, Center frequency: 4.286 MHz.
3.2.10 Horizontal Control
Safety input on BCL Pin. When the BCL Pin is
switched to ground, the horizontal output pulse is
The Bus Control Frequency Shift is used to opti-
mize the chroma response for the video signal
from the IF stage.
disabled and the inhibition of horizontal output
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