IBIS4-A-6600 Datasheet, PDF (14/40 Pages) Cypress Semiconductor – 6.6 MP CMOS Image Sensor

ADVANCE
INFORMATION
IBIS4-A-6600
CYII4SM6600AB
Setting of the ADC reference voltages
Figure 10. ADC resistor ladder
VDDA_ADC
VHIGH_ADC ~ 1.5V
VLOW_ADC ~ 0.42V
RADC = 577 Ohm
Internal
150 Ohm (ESD)
277 Ohm
High reference voltage
used by ADC
Low reference voltage
used by ADC
150 Ohm (ESD)
GND
The internal resistance has a value of approximately 577 Ω.
Only 277 Ω of this internal resistance is actually used as
reference for the internal ADC. This causes the actual ADC
voltage range to be half of the voltage difference between
VHIGH_ADC and VLOW_ADC. This results in the following
values for the external resistors:
Table 11. ADC resistor values
Resistor
RVHIGH_ADC
RInternal
RVLOWADC
Value (Ω)
560
577
220
Subsample Modes
To increase the frame rate for lower resolution and/or regions
of interest, a number of sub sampling modes have been
implemented. The possible sub sample modes are listed in
Table 12. . The bits can be programmed in the IMAGE_CORE
register (see 2.9.2.8). To preserve the color information, 2
adjacent pixels are read in any mode, while the number of
pixels that is not read, varies from mode to mode. This will be
designed as a repeated block of 24 pixels wide, which is the
lowest common multiple of the modes described above.
Including the dummy pixels and the two additional
rows/columns, the number of starting coordinates for the x and
y shift register is thus 99 in the X and 138 in the Y direction.
The total number of pixels, excluding dummy pixels, is a
multiple of 24, and two additional pixels to have the same
window edges independently of the sub-sampling mode. In the
X direction, two columns are always addressed at the same
moment since the signals from the odd and even columns
must be put simultaneously on the corresponding bus. In the
Y direction, the rows are addressed one by one. This results
in slightly different implementations of the sub-sampling
modes for the two directions (Figure 11. and Figure 12.).
Table 12. Subsample Patterns
Mode
Bits
A
000
B
001
C
010
D
011
E
1xx
Read
2
2
2
2
2
Step
2
4
6
8
12
Default mode
(Skip 2)
(Skip 4)
(Skip 6)
(Skip 10)
Document Number: 001-02366 Rev. *D
Page 14 of 40
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