AR0833 Datasheet, PDF (53/64 Pages) ON Semiconductor – 8 Mp CMOS Digital Image Sensor

AR0833: 1/3.2-Inch 8 Mp CMOS Digital Image Sensor
Gain
Gain
Analog gain
AR0833 supports both analog and digital gain.
Analog gain is provided by colamp and ADC reference scaling (there is no ASC gain due
to column parallel nature of architecture). Only global (not per-color) coarse gain can be
set by analog gain. Global gain register (R0x305E) sets the analog gain. Bits [1:0] set the
colamp gain while bits [4:2] are reserved for ADC gain. While the 2-bit colamp gain
provides up to 4x analog gain, only LSB (bit [2]) of ADC gain bits is utilized to support 2x
ADC gain. Table 16 is the recommended gain setting:
Table 16: Recommended Analog Gain Setting
Colamp Gain Codes
(R0x305E[1:0])
0
0
0
1
1
0
1
1
1
0
1
1
ADC Gain Codes
(R0x305E[4:2])
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
Colamp
Gain ADC Gain
1
1
2
1
3
1
4
1
3
2
4
2
Total
Gain
1
2
3
4
6
8
Digital Gain
Digital gain provides both per-color and fine (sub 1x) gain. The analog and digital gains
are multiplicative to give the total gain. Digital gain is set by setting bits R0x305E[15:5] to
set global gain or by individually setting digital color gain R0x3056-C[15:5] where these
11 bits are designed in 4p7 format i.e. 4 MSB provide gain up to 15x in step of 1x while 7
LSB provide sub-1x gain with a step size of 1/128. This sub-1x gain provides the fine gain
control for the sensor.
Total Gain
Max. total gain required by design spec is 8x (analog) and 16x (digital) with min. step size
of 1/8. The total gain equation can be formulated as:
Total gain
=
1
+
dec  R0x305E[1:0]  


1
+
R0x305E[2]

d_----e_--c_---_---R_---0_---x_---3_---0_---5_---X_----[_--1_---5_---:_--5_---]_---
128
(EQ 17)
Note:
where X is 6, 8, A, C, for Gr, B, R and Gb, respectively
ON Semiconductor recommends using the registers mentioned above for gain set-
tings. Avoid R0x3028 to R0x3038 unless their mapping to above registers is well under-
stood and taken into account.
Temperature Sensor
A standalone PTAT based temperature sensor has been implemented. The block is
controlled independent of sensor timing and all communication happens through the
two-wire serial interface.
AR0833_DS Rev. H Pub. 4/15 EN
53
©Semiconductor Components Industries, LLC, 2015.