STV2247H View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
STV2247H Datasheet PDF : 86 Pages
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STV224XH/228XH/223XH - 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-
puts are blanked during the whole field, but not
during inserted cut-off lines (the cut-off loop is al-
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
The Vertical output pulse is locked on a pulse that
is twice the horizontal frequency to ensure perfect
interlacing.
The Vertical output pulse duration is 10.5 lines.
Horizontal output pulse is a 28 µs line pulse on an
open collector output.
3.2.8 Vertical Control
Bus-controlled DC output voltage for adjusting the
vertical amplitude (pin VAMP). This voltage supply
is used to adjust the slope of the vertical sawtooth
generated by the external vertical booster.
Bus-controlled vertical position (pin VERT). The
high level of the vertical pulse is used to adjust the
vertical position.
The bus-controlled vertical output (pin VERT) low
level voltage can be either 0.2 V or 2.0 V.
3.2.9 Horizontal Output
Start-up circuit: the horizontal output is at high lev-
el (disabled) when VCC1 increases from 0 to 6.0 V
and when VCCD has not reached 4 V.
Soft mode circuit: it provides a softer operating
horizontal output with a 75% duty cycle [tHIGH /
(tHIGH +tLOW)]. This results in a smaller conducting
time (16 µs instead of 28 µs).
This mode is active at start-up until two frames af-
ter the VCC2 reaches 75% of the VCC1. It is also
active at shutdown when the VCC1 floats between
6 V and 5.4 V. And finally, this mode is used if the
VCC2 drops below 75% of the VCC1.
At shutdown, horizontal pulses are disabled when
VCC1 is less than 5.4 V or when VCCD is less than
3.5 V.
The horizontal output pulse may be disabled via
the bus (force a high level on HOUT).
The horizontal position adjustment is controlled via
the bus.
3.2.10 Horizontal Control
Safety input on BCL Pin. When the BCL Pin is
switched to ground, the horizontal output pulse is
disabled and the inhibition of horizontal output
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
register 15hex data D7 is set to “1”, the Safety
function is reset and no longer active.
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-
ing and PLL2 control.
3.2.12 Line Blanking
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.
The Bus Control Frequency Shift is used to opti-
mize the chroma response for the video signal
from the IF stage.
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