ICM205B datasheet(7/41 Pages) ETC1

7 / 41 page

ICM205B: VGA CMOS sensor with digital YUV output

Data Sheet V1.3, Oct. 2002

10/16/2002

web site: http://www.ic-media.com/

web site: http://www.ic-media.com.tw/

page 7

Functional Description

Image Array

The image array consists of 640x480 pixels. Each pixel has a light sensitive photo diode and a set of

control and transfer transistors. At the beginning of the cycle, a row of pixels are pre-charged to its

maximum value. Then they are exposed to light for several lines worth of time and sampled by the ADC.

Correlated double sampling (CDS) is performed by subtracting the reset value (sampled right before

sampling the signal) from the signal value. The purpose of CDS is to eliminate the point-wise fixed

pattern noise (FPN). The output of CDS is approximately proportional to the amount of received light,

ranging from 0 to 255.

Color Filter

Each pixel is covered by a color filter. They form the Bayer Pattern as shown in Figure 2. (Row 0, Column

0) is covered by a Red filter, (Row 0, Column 1) and (Row 1, Column 0) by Green filters, and (Row 1,

Column 1) by a Blue filter. Since each pixel only gets part of the frequency band, the data need further

processing (i.e., color interpolation and color correction) in order to approximate the full visible spectrum.

Figure 2. Color filter Bayer pattern

Exposure and Gain Control

The brightness of the scene may change by a great amount that renders the captured image either

over-exposed or under-exposed. To accommodate for different brightness, the user may change the

exposure time by adjusting the AD_EXPOSE_TIMEH, and AD_EXPOSE_TIMEL. The exposure time is

measured in terms of the time to read out one line of data, which is equal to 64

µs (assuming the line

length is 770 @ 24 MHz). If the number of lines per frame is set at 520 (the default), the exposure time can

vary from 1 to 519 lines.

50/60Hz anti-flickering control

To eliminate the flickering caused by the 50Hz or 60Hz light source normally found indoor, an

anti-flickering control circuit is build in. The selection is between off and on. When it is on, then the

selection is between 50 or 60Hz.

ICM205B Datasheet(PDF) 7 Page - List of Unclassifed Manufacturers