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VCT38XXA 参数 Datasheet PDF下载

VCT38XXA图片预览
型号: VCT38XXA
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 / 2222 K
品牌: MICRONAS [ MICRONAS ]
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ADVANCE INFORMATION  
VCT 38xxA  
2.11.Video Back-end  
Cutoff and white-drive current measurement are car-  
ried out during the vertical blanking interval. They  
always use the small bandwidth setting. The current  
range for the cutoff measurement is set by connecting  
a sense resistor to the MADC input. For the white-drive  
measurement, the range is set by using another sense  
resistor and the range select switch 2 output pin  
(RSW2). During the active picture, the minimum and  
maximum beam current is measured. The measure-  
ment range can be set by using the range select  
switch 1 pin (RSW1) as shown in Fig. 2–19 and Fig. 2–  
20. The timing window of this measurement is pro-  
grammable. The intention is, to automatically detect  
letterbox transmission or to measure the actual beam  
current. All control loops are closed via the external  
control microprocessor.  
The digital RGB signals are converted to analog RGBs  
using three video digital-to-analog converters (DAC)  
with 10-bit resolution. An analog brightness value is  
provided by three additional DACs. The adjustment  
range is 40 % of the full RGB range.  
Controlling the white-drive/analog brightness and also  
the external contrast and brightness adjustments is  
done via the Fast Processor, located in the front-end.  
Control of the cutoff DACs is done via I2C bus regis-  
ters.  
Finally cutoff and blanking values are added to the  
RGB signals. Cutoff (dark current) is provided by three  
9-bit DACs. The adjustment range is 60 % of full scale  
RGB range.  
Beam Current  
The analog RGB-outputs are current outputs with cur-  
rent-sink characteristics. The maximum current drawn  
by the output stage is obtained with peak white RGB.  
An external half contrast signal can be used to reduce  
the output current of the RGB outputs to 50 %.  
SENSE  
A
D
MADC  
R2  
RSW1  
2.11.1.CRT Measurement and Control  
R3  
RSW2  
The display processor is equipped with an 8-bit  
PDM-ADC for all measuring purposes. The ADC is  
connected to the SENSE input pin, the input range is 0  
to 1.5V. The bandwidth of the PDM filter can be  
selected; it is 40/80 kHz for small/large bandwidth set-  
ting. The input impedance is more than 1 M.  
R1  
Fig. 2–19: MADC range switches  
CR + IBRM + WDRV WDR  
white  
drive  
R
CR + IBRM  
cutoff  
R
R
black  
ultra black  
CG + IBRM  
cutoff  
G
G
B
CB + IBRM  
cutoff  
B
active measure-  
ment resistor  
R1  
R1||R2||R3  
R1||R3  
R1||R2||R3  
RSW2  
=on  
RSW1=on, RSW2=on  
RSW1=on, RSW2=on  
PICTURE MEAS.  
PMSO  
TUBE MEASUREMENT  
PICTURE MEAS.  
TML  
PMST  
Lines  
Fig. 2–20: MADC measurement timing  
Micronas  
25