XRD98L61 Datasheet, PDF (31/37 Pages) Exar Corporation – CCD Image Digitizers with CDS, PGA and 12-Bit A/D

Preliminary
XRD98L61
Active Video
Pixels
CCD
Signal
CAL
(Black Level)
CLAMP
(DC restore)
Vert. Shift Reject
(internal)
End of Line N
Dummy &
OB pixels
Vertical Shift
t_CLAMP
Disconnect CDS from
input pins
Start of Line N+1
OB pixels
t_CAL
Active Video pixels
Figure 21. Line Rate Timing with OneShot=0, VSreject=1 & ClampCal=1
One Shot (CAL Only) Mode
In this mode, the CAL signal is used to activate the DC
restore clamp and to define the optical black pixels for
calibration. The CAL pulse should frame the longest
group of OB pixels at either the end or beginning of
each line. The DC restore Clamp switch is turned ON
during the first four pixels of each CAL pulse. The
remaining pixels under the CAL pulse are used for
black level calibration.
This mode also has an option to disconnect the CDS
from the input pins during the Vertical Shift time. To
enable this option write a “1” to the VSreject bit in the
Clock register. The signal at the CLAMP pin is used to
define the Vertical Shift period (i.e. the time when the
CDS is disconnected from the input pins).
Rev. P4.00
31