AD9923A Analog Devices, AD9923A Datasheet - Page 45

• Manufacturer Part Number: AD9923A
• Description: CCD Signal Processor
• Manufacturer: Analog Devices

SHUTTER TIMING CONTROL
The CCD image exposure time is controlled by the substrate clock
signal (SUBCK) that pulses the CCD substrate to clear out
accumulated charge. The AD9923A supports three types of
electronic shuttering: normal, high precision, and low speed.
Together with the SUBCK pulse placement, the AD9923A can
accommodate different readout configurations to further
suppress the SUBCK pulses during multiple field readouts. The
AD9923A also provides programmable outputs to control an
external mechanical shutter (MSHUT), strobe/flash (STROBE),
and CCD bias select signal (VSUB). Up to four general shutter
pulses (SHUT0 to SHUT3) and two VSUB pulses (VSUB0 and
VSUB1) can be programmed and assigned to any of the three
shutter output pins. The user can also combine the following
XV2, XV4, XV6, XV8
SUBCK
XV9, XV10, XV13
V7B
V2, V4, V6, V8
V9, V10, V13
XSUBCNT
XSUBCK
VSG8
XV7
VMM
VM
VH
VL
VLL
VH
VM
VL
Figure 62. XV2, XV4, XV6, XV8, XV9, XV10, XV13 and V2, V4, V6, V8, V9, V10, V13 Output Polarities
Figure 63. XSUBCNT, XSUBCK, and SUBCK Output Polarities
Figure 61. XV7, VSG8, and V7B Output Polarities
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shutter and VSUB pulses with a logic XOR operation (symbolized
by ^) to generate more complex timing (up to four toggle posi-
tions per line) for MSHUT, STROBE and VSUB: SHUT0 ^ VSUB0,
SHUT0 ^ VSUB1, SHUT0 ^ SHUT1, and SHUT0 ^ SHUT2.
SUBCK: Three-Level Output
The AD9923A supports a three-level output from the SUBCK
buffer: VH, VMM, and VLL. The VH power supply is shared
with the V-driver outputs, but VMM and VLL are dedicated
mid and low supplies for the SUBCK buffer. There are two in-
puts to the SUBCK buffer, XSUBCK and XSUBCNT. XSUBCNT
is created by an internal multiplexer that selects from XV1 to
XV13, VSG1 to VSG8, MSHUT, STROBE, VSUB, SHUT0 to
SHUT3, FG_TRIG, high and low.
AD9923A