STV5730 ST Microelectronics, STV5730 Datasheet - Page 13

• Manufacturer Part Number: STV5730
• Description: MULTISTANDARD ON-SCREEN DISPLAY FOR VCR
• Manufacturer: ST Microelectronics

The MUTE search time constant may be either
8 lines or 32 lines, according to the M3 mode bit.
The signal that is delivered to the MUTE output pin
is synchronized on the vertical sync if M11 is
cleared. It is forced low if the M2 mode bit is low.
This signal may be monitored by the microproces-
sor to switch the STV5730 from mixed mode to full
page mode and vice versa (using the C0 control
bit).
5 - THE LUMA GENERATION
The luma signal is generatedby the STV5730 from
timing information created by the character and
video timing generators and voltage levels created
by the internal bias level generator or entered on
the LESCREEN and LECHAR pins (as selected by
the C10 control bit).
The luma signal is output on the YOUT pin to allow
the user to notch filter it. It is then re-input on the
YIN pin. YOUT and YIN may be connectedtogether
for minimal cost applications.
5.1 - Internal Bias Mode
This mode is intended for minimal cost applica-
tions. C10 must be cleared. The luma levels of the
OSD output signal are as follows :
- LEBLACK : black level
- LESYNC : sync level
- LESCREEN : page background level
- LECHAR : character level
LEBLACK is also used to clamp the VIDEO IN
signal and to create the character border.
5.2 - External Bias Mode
This mode is intended to give more flexibility to the
user. C10 must be set. The LESCREEN and
LECHAR levels may be user defined relatively to
the internal LEBLACK level. The final luma ampli-
tude should not be greater than the peak white
level. These levels may be static or dynamic. Dy-
namic levels can be easily generated by analog
sum of the R/G/B and CO STV5730 outputs (a few
resistors are necessary) to give grey scale charac-
ter shading in the mixed mode. C0 is useful to
control the character foreground luma level.
6 - THE CHROMA GENERATION
The STV5730 encoder is operates in full page
mode only. It may perform PAL or NTSC encoding
according to the C8 control bit.
A 4*fsc chroma quartz crystal is necessary
(fsc = 4.43MHz for PAL, 3.58MHz for NTSC).
The encoder can be turned off by the M6 mode bit
for black & white or for SECAM applications.
nominal value : 1.25V 20mV
nominal value : LEBLACK - 300mV
nominal value : LEBLACK + 150mV
nominal value : LEBLACK + 550mV
The character encoding is controlled by the C9
control bit.
The chroma signal is output on the COUT pin for
external filtering and for attenuationif necessary. It
is then re-entered on the CIN pin and added to the
YIN pin signal to create the final CVBS output
signal.
The chroma saturation is controlled by the
STV5730 :
- burst nominal amplitude : 360mV
- blue or yellow colors nominal amplitude :
- red, magenta, green or cyan colors nominal am-
7 - THE MARKERS
The STV5730 can generate 3 different markers that
can be activated simultaneously (i.e. on the same
page).
The following marker features are performed :
- Blinking character, character background off.
- Not blinking character, character background on
- Blinking character, character background on.
8 - THE TRANSLUCENT MIXED MODE
Figure 4 :
The VIDEO OUT1 and VIDEO OUT2 outputs may
be summed via two external resistors to create a
translucent text (mixed mode). In this case, the
background picture is still visible behind the text.
The background picture visibility (or level of trans-
lucence is controlled by the resistor ratio.
Another benefit from this function is to allow
PAL/SECAM/NTSC multistandard applications to
360mV
plitude : 520mV
The character foreground blinks (BK = 1, BE = 0
or C1 = 1).
(C1 = 0, BE = 1).
The character foreground blinks and the charac-
ter background remains (BK = 1, BE = 1, C1 = 0).
disable
PP
The Translucent Mixed Mode Output
Configuration
VIDEO OUT2
PP
VIDEO OUT1
STV5730
2 8
1
PP
R1
R2
STV5730
S
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