TC236P Datasheet, PDF (3/17 Pages) Texas Instruments – 680-×500-PIXEL CCD IMAGE SENSOR

TC236P
680- × 500-PIXEL CCD IMAGE SENSOR
TERMINAL
NAME NO.
ADB
4
IAG1
12
IAG2
2
ODB
1
OUT1
5
OUT2
6
RST
7
SAG
10, 11
SRG
8
SUB
3, 9
Terminal Functions
SOCS055A – JUNE 1996 – REVISED APRIL 1997
I/O
DESCRIPTION
I
Supply voltage for amplifier-drain bias
I
Image-area gate 1
I
Image-area gate 2
I
Supply voltage for overflow-drain antiblooming bias
O Output signal 1
O Output signal 2
I
Reset gate
I
Storage-area gate
I
Serial-register gate
Substrate
detailed description
The TC236P consists of four basic functional blocks: the image-sensing area, the image-storage area, the
serial-register gates, and the low-noise signal-processing amplifier block with charge-detection nodes and
independent resets. 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 top views of the image-sensing and storage-area elements. As light enters the
silicon in the image-sensing area, free electrons are generated in both wells and collected in the virtual wells
of the sensing elements. The color sensitivity is obtained by manufacturing a mosaic color filter directly onto the
photosites of the image-sensing area (see Figure 3 for a mapping of the filter topology). Blooming protection
is provided by applying a dc bias to the overflow-drain bias pin. If it is necessary to clear the image before
beginning a new integration time (for implementation of electronic fixed shutter or electronic auto-iris), it is
possible to do so by applying a pulse that is at least 1 µs in duration to the overflow-drain bias. After integration
is complete, the charge is transferred into the storage area; the transfer timing is dependent on whether the
readout mode is interlace or progressive scan. If the progressive-scan readout mode is selected, the readout
may be performed normally with one register or high speed by using both registers (see Figure 6 through
Figure 8 for the interlace and progressive-scan readout modes).
There are 22 columns at the left edge of the image-sensing area that are shielded from incident light; these
elements provide the dark reference used in subsequent video-processing circuits to restore the video black
level. There are also four dark lines between the image-sensing and the image-storage area that prevent charge
leakage from the image-sensing area into the image-storage area.
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