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| 型號： | TLV990-21PFBG4 |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 消費家電 |
| 英文描述： | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
| 封裝： | GREEN, PLASTIC, TQFP-48 |
| 文件頁數(shù)： | 11/23頁 |
| 文件大?。?/td> | 408K |
| 代理商： | TLV990-21PFBG4 |
TLV99021
3V, 10BIT, 21MSPS AREA CCD ANALOG FRONT END
SLAS299A AUGUST 2000 REVISED MARCH 2004
19
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
PRINCIPLES OF OPERATION
automatic optical black and offset correction (continued)
A weighted rolling average of the optical black pixels is taken during averaging. The weighting factor can be
programmed in control register2. The weighting factor determines the speed of convergence of the digital
filtering implemented within the CCD signal processor. Weighting factors closer to 1 result in faster
convergence. As the weighting factor decreases towards its minimum value of 1/256, the speed of convergence
of the digital filtering decreases.
The algorithm also takes hot pixels and cold pixels into consideration. A hot optical black pixel is a defective
pixel that generates too much charge, while a cold pixel is the one that generates very little or no charge. A digital
comparator compares the digitized optical black pixels with user-selected hot and cold pixel limits. If the optical
black pixel value is out of range, then that hot or cold pixel is replaced with the value of the previous pixel.
Due to different exposure times, there might be a sudden optical black level shift at the start of each frame. Thus,
a quick optical black level correction is desirable. The user can set an internal control bit (the SOF bit in control
register2) to automatically disable the hot/cold pixel limits and to set the digital filtering weighting factor to 1
(equivalent to one-line averaging). In this way the optical black correction could be performed very quickly for
the first line of each frame.
The number of black pixels in each line is programmable. The number of black pixels per line that can be
averaged is 2N, where N can be any integer from 0 to 6.
The autocalibration feature can be bypassed if the user prefers to directly program the offset DAC registers.
Switching the autocalibration mode to the direct-programming mode requires two register writes. First, the
control bits for the offset DACs in the control register must be changed; then the desired offset value for the
register is loaded to the offset DAC registers for proper error correction. If the total offset, including optical black
level, is less than
±255 ADC LSBs, only the FDAC needs to be programmed. When switching from direct-
programming mode to autocalibration mode, the previous DAC register values, rather than default DAC register
values, are used as starting offsets.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| TLV990-28 | 制造商:Texas Instruments 功能描述:CCD Analogue Front End 28MSPS TLV990-28 |
| TLV99028PFB | 制造商:Texas Instruments 功能描述: |
| TLV990-28PFB | 功能描述:視頻模擬/數(shù)字化轉(zhuǎn)換器集成電路 3-V 10-Bit 28-MSPS Area CCD RoHS:否 制造商:Texas Instruments 輸入信號類型:Differential 轉(zhuǎn)換器數(shù)量:1 ADC 輸入端數(shù)量:4 轉(zhuǎn)換速率:3 Gbps 分辨率:8 bit 結(jié)構(gòu): 輸入電壓:3.3 V 接口類型:SPI 信噪比: 電壓參考: 電源電壓-最大:3.45 V 電源電壓-最小:3.15 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:TCSP-48 封裝:Reel |
| TLV990-28PFBG4 | 功能描述:視頻模擬/數(shù)字化轉(zhuǎn)換器集成電路 3-V 10-Bit 28-MSPS Area CCD RoHS:否 制造商:Texas Instruments 輸入信號類型:Differential 轉(zhuǎn)換器數(shù)量:1 ADC 輸入端數(shù)量:4 轉(zhuǎn)換速率:3 Gbps 分辨率:8 bit 結(jié)構(gòu): 輸入電壓:3.3 V 接口類型:SPI 信噪比: 電壓參考: 電源電壓-最大:3.45 V 電源電壓-最小:3.15 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:TCSP-48 封裝:Reel |
| TLV990-40 | 制造商:Texas Instruments 功能描述:CCD Analogue Front End 40MSPS TLV990-40 |
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