EVK-5430-001 ST Microelectronics, Inc., EVK-5430-001 Datasheet - Page 19

• Manufacturer Part Number: EVK-5430-001
• Description: Monochrome Analog Output CMOS Image Sensors
• Manufacturer: ST Microelectronics, Inc.

VV5430
7.3
The VV5430 can be configured to operate in two auto-exposure modes, selected by the BKLIT pin (pin28) state, or via the serial
interface (Setup Code_1, bit 0). The default mode (BKLIT = 0) provides exposure control for normally illuminated scenes. For
scenes where a bright background can cause the foreground subject to be severely under exposed, the ‘Backlit’ mode (BKLIT =
1) offers superior performance.
‘Backlit Mode’ (BKLIT=1) operates by using a higher threshold level for the exposure control comparator over the central area of
an image, which is therefore exposed for longer and so enhanced. The area in which the higher comparator threshold is used
when BKLIT=1 is illustrated below:
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Note: The threshold level used for the central area is a preset mutiple of the normal mode reference level, and is not
Backlit Mode
alterable. In some circumstances this may not be sufficient difference to cause a noticable effect on the overall expo-
sure of the image.
Normal operation (BKLIT=0)
80%
Visible
image
Figure 7 : Backlit exposure region
10%
90%
control area
Exposure
CD5430F-A
Higher threshold area (BKLIT=1)
25%
25%
75%
Threshold
Higher
80%
30%
Exposure Control