TC25SPD Datasheet, PDF (5/19 Pages) Texas Instruments – 680 X 500 PIXEL CCD IMAGE SENSOR

TC253SPD
680ā×ā500 PIXEL CCD IMAGE SENSOR
TERMINAL
NAME
NO.
ADB
9
CMG
6
IAG1
12
IAG2
2
NC
8
ODB
1
VOUT
7
SAG1
11
SAG2
3
SRG1
4
SRG2
5
SUB
10
Terminal Functions
SOCS062B – JANUARY 2001 – REVISED MAY 2002
I/O
DESCRIPTION
I
Supply voltage for amplifiers and clearing drain
I
Charge multiplication gate
I
Image area gate 1
I
Image area gate 2
–
No connection
I
Supply voltage for antiblooming drain
O
Output signal, multiplier channel
I
Storage area gate 1
I
Storage area gate 2
I
Serial register gate 1
I
Serial register gate 2
Chip substrate
detailed description
The TC253SPD sensor consists of four basic functional blocks: the image-sensing area, the image storage
area, the serial register, and the charge multiplier. The location of each of these blocks is identified in the
functional block diagram.
image-sensing and storage areas
Figure 1 and Figure 2 show cross sections with potential-well diagrams and top views of the pixels in the
image-sensing and storage areas. As light enters silicon in the image-sensing area, electrons are generated
and collected in potential wells of the pixels. Applying a suitable dc bias to the antiblooming drain provides
blooming protection. Electrons that exceed a specified level, determined by the ODB bias, are drained away
from the pixels. If it is necessary to remove all previously accumulated charge from the wells, a short positive
pulse must be applied to the drain. This marks the beginning of the new integration period. After the integration
cycle is completed, charge is quickly transferred into the memory where it waits for readout. The lines can be
read out from the memory in a sequential order to implement progressive scan, or two lines can be summed
together to implement the pseudo-interlace scan.
Twenty-two columns at the left edge of the image-sensing area are shielded from incident light. These pixels
provide the dark reference used in subsequent video-processing circuits to restore the video black level. An
additional four dark lines located between the image-sensing area and the image storage area were added for
isolation.
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