VV6501C001 STMicroelectronics, VV6501C001 Datasheet - Page 18

• Manufacturer Part Number: VV6501C001
• Description: IC SENSOR COLOR VGA CMOS 36CLCC
• Manufacturer: STMicroelectronics
• Type: CMOS Imagingr

Specifications of VV6501C001

• Pixel Size: 5.6µm x 5.6µm
• Active Pixel Array: 640H x 480V
• Frames Per Second: 30
• Voltage - Supply: 3V, 5V
• Package / Case: 36-CLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-3883; VV6501C001

Functional Description
3.1.9
18/60
Dark calibration
In order to produce a high quality output image from the VV6501, it is necessary to accurately
control the black level of the video signal. There are two main sources of error:
The black level is corrected by using dark pixel rows to “learn” the offset so that it can then be
subtracted from the image data. Dark rows have the same exposure setting as the visible lines but
are shielded from incident light.
For 10-b data the ideal “black” code is set to be 64 (when viewing 8-b data the ‘black’ code should
be 16). The aim of the dark calibration algorithm is to “learn” the offset required such that “black”
image lines have code 64.
Dark current
Offsets in the output path.
typ. value: 400 - 1360
Idark
Ilight
Idark
typ. value = 400
+
Image Line
raw image
Dark Line
Normal pixel
Dark pixel
Vpix
Vpix
Dpix
Figure 15: Overview of dark offset cancellation
Dpix
Figure 16: Role of dark offset calibration
dark offset = 336
Dark calibration
ADC element
ADC element
Column
+ offset
Column
+ offset
10-b
10-b
typ. value: 64-1024
typ. value = 64
processed image
Image Line
Dark Line
Digital Logic
Learn offset
cancellation
+ Idark
Offset
VV6501