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參數(shù)資料
| 型號(hào)： | STV2246 |
| 元件分類： | 參考電壓二極管 |
| 英文描述： | Low Current Operation at 250 ，Low Reverse Leakage,Low Noise Zener Diode |
| 中文描述： | 250 的低電流運(yùn)算，低反向泄露，低噪聲穩(wěn)壓二極管 |
| 文件頁(yè)數(shù)： | 20/76頁(yè) |
| 文件大小： | 2157K |
| 代理商： | STV2246 |
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STV223XD/224XC - FUNCTIONAL DESCRIPTION
20/76
3.4 VIDEO CIRCUIT
RGB Inputs
The RGB (OSD) input has priority over the exter-
nal RGB input. The RGB (EXT) source is matrixed
into YUV signals for color and contrast adjust-
ments. The brightness is adjusted according to the
internal and external RGB and OSD RGB signals.
The Contrast Control regulates both external and
internal RGB signals and has a maximum attenua-
tion of -24 dB. It also regulates the OSD RGB sig-
nal and its maximum attenuation is limited to
-12 dB. The Contrast Control for RGB (OSD) input
can be disabled via the bus. The brightness of the
RGB (OSD) input varies according to the main
brightness level.
The RGB (EXT) insertion signal can be disabled or
forced via the bus. A fast blanking detector on an
external fast blanking input and OSD fast blanking
input operate during frame retrace. The Fast
Blanking detection status is sent to the I2C bus
read register.
The OSD fast blanking input has several functions:
OSD Insertion Control, RGB Output Blanking or
Half Contrast Control.
Half-contrast Control Pin (TQFP64)
The 6 dB gain reduction will be applied to the inter-
nal YUV signals when the half-contrast function is
turned ON, and the voltage of the half-contrast in-
put exceeds the threshold (0.7 V Typ.).
The Half Contrast function is also available in the
SDIP56 package. The Half Contrast input is com-
bined with the FBOSD input.
Automatic Cut-off Current Loop
The Cut-off Loop range is 2 V (the cut-off level of
the RGB outputs is between 1.5 V and 3.5 V,
2.5 V Typ.). The cut-off current is measured se-
quentially during the three lines after the internal
frame blanking signal (the blue cathode current is
measured first, then the green and red). The Leak-
age cathode current is measured during frame
blanking and is memorized on an internal capaci-
tor. Cut-off pulses can be inserted after the exter-
nal vertical oversize blanking signal. The Cut-off
loop can be frozen via the bus. To prevent cut-off
lines from being visible in 16/9 mode, cut-off puls-
es are not inserted when the cut-off loop is frozen.
Warm-up Detector
At power on, the cut-off loop is not active and high
DC levels are inserted during "cut-off" lines. The
Cut-off loop will be active when the cathode cur-
rent reaches the warm-up detection threshold.
This causes the picture to be displayed from a
dark screen. The RGB outputs are blanked until
cut-off current is close to the reference voltage.
The manual cut-off mode can be selected via the
I2C bus. In this mode, the I
CATH
input pin is inac-
tive and cut-off pulses are not inserted. The RGB
black levels are independently controlled by three
I2C bus registers (8-bit resolution). The black level
of each RGB output can be adjusted within a
range of 2.5V typ.
Beam Current Limiter DC Voltage Input (BCL)
The BCL will first decrease the contrast and then
the brightness when the contrast attenuation
reaches -5 dB. The red, green, blue channel gain
for white point adjustment takes place via the bus.
The red and green DC levels for black point adjust-
ment takes place via the bus.
The PAL/SECAM matrix is provided and a specific
NTSC matrix is used when demodulation angles
are (0°,104°).
Bus-controlled Contrast and Saturation
The Contrast Control regulates internal RGB, ex-
ternal RGB and OSD RGB inputs. The maximum
attenuation on internal and external RGB inputs is
-24 dB and is limited to -12 dB for OSD RGB in-
puts. The bus-controlled saturation range is 50 dB.
Bus-controlled Brightness and Sharpness
The total brightness range is 60% of the black-to-
white amplitude at maximum contrast. The bright-
ness control regulates all RGB sources (internal,
external and OSD). Bus-controlled Sharpness
(peaking) is provided in PAL/SECAM/NTSC
standards.
Bus-controlled Coring function on Sharpness
When the Coring-on-sharpness function is
switched ON, the peaking function is not active on
low amplitude signals (below 10 IRE).
The Black Stretch circuit can be disabled via the
bus. Two modes are provided, one to be used
when the video signal is transmitted with a set-up
(7.5IRE set-up in NTSC), the other to be used
when the video signal is transmitted without a set-
up (PAL/SECAM).
The bus-controlled Blue Screen feature is used to
insert a blue background on the screen when no
video is available. The RGB OSD can be dis-
played when the blue screen is active.
The APR (Automatic RGB Peak Regulation) func-
tion is used to take advantage of the total RGB
output range. APR circuits detect the peak level of
the RGB outputs (before OSD insertion) and regu-
late the RGB gain (contrast) so that signals above
the APR threshold are limited. For example, at
maximum drive and contrast levels with the APR
function switched OFF, the 100 IRE input signal
gives 3 V(B/W) to the RGB outputs. With APR ON
and the APR threshold at 70 IRE, the 70 IRE input
signal gives 3 V (B/W) at RGB outputs. For input
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| STV2246C | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:I2C BUS-CONTROLLED MULTISTANDARD SINGLE CHIP TV PROCESSOR |
| STV2246H | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:IC BUS-CONTROLLED MULTISTANDARD SINGLE CHIP TV PROCESSOR |
| STV2247 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:I2C bus-controlled multistandard single chip TV processor |
| STV2247C | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:I2C BUS-CONTROLLED MULTISTANDARD SINGLE CHIP TV PROCESSOR |
| STV2247H | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:IC BUS-CONTROLLED MULTISTANDARD SINGLE CHIP TV PROCESSOR |
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