CXD2498R
Control data/shutter data: [Electronic shutter]
The CXD2498R realizes various electronic shutter functions by using control data D13 SMD and D14 HTSG
and shutter data D10 to D19 SVD, D20 to D31 SHD and D32 to D41 SPL. These functions are
described in detail below.
First, the various modes are shown below. These modes are switched using control data D13 SMD.
D13
Description of operation
0 Electronic shutter stopped mode
1 Electronic shutter mode
The electronic shutter data is expressed as shown in the table below using D20 to D31 SHD as an example.
However, MSB (D31) is a reserve bit for the future specification, and it is handled as a dummy on this IC.
MSB
D31 D30 D29 D28
X001
↓
1
D27 D26 D25 D24
1100
↓
C
LSB
D23 D22 D21 D20
0011
↓
3
SHD is expressed as
1C3H .
[Electronic shutter stopped mode]
During this mode, all shutter data items are invalid.
SUB is not output in this mode, so the shutter speed is the accumulation time for one field.
[Electronic shutter mode]
During this mode, the shutter data items have the following meanings.
Symbol
SVD
SHD
SPL
Data
D10 to D19
D20 to D31
D32 to D41
Description
Number of vertical periods specification (000h ≤ SVD ≤ 3FFh)
Number of horizontal periods specification (000h ≤ SHD ≤ 7FFh)
Vertical period specification for high-speed shutter operation (000h ≤ SPL ≤ 3FFh)
Note) The bit data definition area is assured in terms of the CXD2498R functions, and does not assure the
CCD characteristics.
The period during which SVD and SHD are specified together is the shutter speed. An image of the exposure
time calculation formula is shown below. In actual operation, the precise exposure time is calculated from the
operating frequency, VD and HD periods, decoding value during the horizontal period, and other factors.
(Exposure time) = SVD + {(number of HD per 1V) – (SHD + 1)}
Concretely, when specifying high-speed shutter, SVD is set to “000h”. (See the figure.) During low-speed
shutter, or in other words when SVD is set to “001h” or higher, the serial interface data is not loaded until this
period is finished.
The vertical period indicated here corresponds to one field in each drive mode. In addition, the number of
horizontal periods applied to SHD can be considered as (number of SUB pulses – 1).
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