AD9923BBCZ Analog Devices Inc, AD9923BBCZ Datasheet - Page 48

• Manufacturer Part Number: AD9923BBCZ
• Manufacturer: Analog Devices Inc

Specifications of AD9923BBCZ

• Analog Front End Type: CCD
• Analog Front End Category: Video
• Interface Type: Serial (3-Wire)
• Sample Rate: 36MSPS
• Input Voltage Range: 0.7V
• Operating Supply Voltage (min): 2.7V
• Operating Supply Voltage (typ): 3V
• Operating Supply Voltage (max): 3.6V
• Resolution: 12b
• Number Of Adc's: 1
• Power Supply Type: Analog/Digital
• Operating Temp Range: -25C to 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 105
• Package Type: CSPBGA
• Number Of Channels: 1
• Lead Free Status / RoHS Status: Compliant

AD9923
SUBCK Suppression
Normally, the SUBCK begins pulsing on the line following the
sensor gate line (VSG). Some CCDs require suppressing the
SUBCK pulse for one or more lines following the VSG line. The
SUBCKSUPPRESS register enables such suppression.
Readout After Exposure
After the exposure, the readout of the CCD data occurs, beginning
with the sensor gate (VSG) operation. By default, the AD9923
generates VSG pulses in every field. When only a single exposure
and readout frame are needed, as is the case in the CCD preview
mode, the VSG and SUBCK pulses can operate in every field.
However, often during readout, the SUBCK output must be
suppressed until the readout is complete. The READOUTNUM
register specifies the number of additional fields after the exposure
to continue the suppression of SUBCK. READOUTNUM can be
programmed for 0 to 7 fields, and should be preprogrammed at
startup, not at the same time as the exposure write. A typical
interlaced CCD frame readout mode generally requires two
fields of SUBCK suppression (READOUTNUM = 2) during
readout. A 3-field, 6-phase CCD requires three fields of SUBCK
suppression after the readout begins (READOUTNUM = 3).
If SUBCK output is required to initiate backup during the last field
of readout, program the READOUTNUM register to one less
than the total number of CCD readout fields. Like the exposure
operation, the readout operation must be triggered using the
TRIGGER register.
SUBCK Additional Masking
The SUBCKMASK register (Address 0x65), allows more complex
SUBCK masking. It enables users to select the internal SHUT3
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signal and create a custom SUBCK masking pattern that spans
several fields.
When generating an exposure by using the TRIGGER register,
as described above, the AD9923 outputs the SUBCK and VSG
signals on every field by default. This works well for continuous,
single field exposure and readout operations, such as those in
the CCD live preview mode. However, if the CCD requires a
longer exposure time, or if multiple readout fields are needed,
the TRIGGER register is needed to initiate specific exposure
and readout sequences.
Typically, the exposure and readout bits in the TRIGGER register
are used together. This initiates a complete exposure-plus-readout
operation. After the exposure, the readout occurs automatically.
The values in the EXPOSURE and READOUTNUM registers
determine the length of each operation.
It is possible to independently trigger the readout operation
without triggering the exposure operation. This causes the readout
to occur at the next VD, and the SUBCK output is suppressed
according to the value set in the READOUTNUM register.
The TRIGGER register also controls the SHUT and VSUB signals.
Each signal is individually controlled, but dependent on the trigger-
ing of the exposure and readout operations. See Figure 70 for a
complete example of triggering the exposure and readout
operations.
Alternatively, it is possible to manually control the exposure and
readout operations by carefully updating the SUBCKSUPPRESS
and VSG masking registers upon every VD field. As described in
the following sections, it is possible to have partial or full manual
control of the shutter signals. This allows greater flexibility in
generating custom exposure/readout/shutter signal timing.