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VCT3801A 参数 Datasheet PDF下载

VCT3801A图片预览
型号: VCT3801A
PDF下载: 下载PDF文件 查看货源
内容描述: 视频/控制/图文电视IC系列 [Video/Controller/Teletext IC Family]
分类和应用: 电视
文件页数/大小: 172 页 / 2219 K
品牌: MICRONAS [ MICRONAS ]
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VCT 38xxA  
ADVANCE INFORMATION  
2.10.9.RGB Processing  
a)  
After adding the post-processed luma, the digital RGB  
signals are limited to 10 bits. Three multipliers are  
used to digitally adjust the white drive. Using the same  
multipliers an average beam current limiter is imple-  
mented (see Section 2.11.1. on page 25).  
Cr in  
Cb in  
t
t
t
2.10.10.OSD Color Look-up Table  
b)  
The VCT 38xxA has five input lines for an OSD signal.  
This signal forms a 5-bit address for a color look-up  
table (CLUT). The CLUT is a memory with 32 words  
where each word holds a RGB value.  
Ampl.  
Bits 0 to 3 (bit 4=0) form the addresses for the ROM  
part of the OSD, which generates full RGB signals (bit  
0 to 2) and half-contrast RGB signals (bit 3).  
c)  
Cr out  
Cb out  
Bit 4 addresses the RAM part of the OSD with 16  
freely programmable colors, addressable with bit 0 to  
3. The programming is done via the I2C bus.  
The amplitude of the CLUT output signals can be  
adjusted separately for R, G, and B via the I2C bus.  
The switchover between video RGB and OSD RGB is  
done via the priority decoder.  
a) CrCb input of DTI  
b) CrCb input + correction signal  
c) sharpened and limited CrCb  
Fig. 2–16: Digital color transient improvement  
2.10.11.Picture Frame Generator  
When the picture does not fill the total screen (height  
or width too small) it is surrounded with black areas.  
These areas (and more) can be colored with the pic-  
ture frame generator. This is done by switching over  
the RGB signal from the matrix to the signal from the  
OSD color look-up table.  
2.10.8.Inverse Matrix  
A 6-multiplier matrix transcodes the Cr and Cb signals  
to R-Y, B-Y, and G-Y. The multipliers are also used to  
adjust color saturation in the range of 0 to 2. The coef-  
ficients are signed and have a resolution of 9 bits.  
There are separate matrix coefficients for main and  
side pictures. The matrix computes:  
The width of each area (left, right, upper, lower) can be  
adjusted separately. The generator starts on the right,  
respectively lower side of the screen and stops on the  
left, respectively upper side of the screen. This means,  
it runs during horizontal, respectively vertical flyback.  
The color of the complete border can be stored in the  
programmable OSD color look-up table in a separate  
address. The format is 3 x 4-bit RGB. The contrast can  
be adjusted separately.  
RY= MR1*Cb+MR2*Cr  
GY= MG1*Cb+MR2*Cr  
BY= MB1*Cb+MR2*Cr  
The initialization values for the matrix are computed  
from the standard ITUR (CCIR) matrix:  
The picture frame generator includes a priority master  
circuit. Its priority is programmable and the border is  
generated only if the priority is higher than the priority  
of the other sources (video/OSD). Therefore, the bor-  
der can be underlay or overlay depending on the pic-  
ture source.  
R
G
B
1
1
1
0
1.402  
0.713  
0
Y
Cb  
Cr  
0.345  
1.773  
=
For a contrast setting of CTM+32, the matrix values  
are scaled by a factor of 64 (see Table 2–4 on  
page 34).  
22  
Micronas  
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