MT9P001 Datasheet, PDF (34/48 Pages) ON Semiconductor – CMOS Digital Image Sensor

MT9P001: 1/2.5-Inch 5Mp Digital Image Sensor
Features
signal can be inverted by setting Invert_Strobe (R0x1E[5] = 1. To use strobe as a flash in
snapshot modes or with mechanical shutter, set the Strobe_Enable register bit field
R0x1E[4] = 1.
Signal Chain and Datapath
The signal chain and datapath are shown in Figure 25. Each color is processed inde-
pendently, including separate gain and offset settings. Voltages sampled from the pixel
array are first passed through an analog gain stage, which can produce gain factors
between 1 and 8. An analog offset is then applied, and the signal is sent through a 12-bit
analog-to-digital converter. In the digital space, a digital gain factor of between 1 and 16
is applied, and then a digital offset of between –2048 and 2047 is added. The resulting 12-
bit pixel value is then output on the DOUT[11:0] ports.
The analog offset applied is determined automatically by the black level calibration
algorithm, which attempts to shift the output of the analog signal chain so that black is
at a particular level. The digital offset is a fine-tuning of the analog offset.
Figure 25: Signal Path
Pixel
Voltage
Analog
Gain
X
Analog Signal Chain Digital Datapath
Analog
Offset
Black
Level
Calibration
Digital
Offset
Correction
+
ADC
X
+
Digital
Gain
DOUT[11:0]
Gain
There are two types of gain supported: analog gain and digital gain. Combined, gains of
between 1 and 128 are possible. The recommended gain settings are shown in Table 15.
Table 15: Gain Increment Settings
Gain Range
1– 4
4.25–8
9–128
Note:
Increments
0.125
0.25
1
Digital Gain
0
0
1–120
Analog Multipier
0
1
1
Analog gain should be maximized before applying digital gain.
Analog Gain
8–32
17–32
32
Analog Gain
The combined gain for a color C is given by:
G_C = AG_C x DG_C.
The analog gain is specified independently for each color channel. There are two
components, the gain and the multiplier. The gain is specified by Green1_Analog_Gain,
Red_Analog_Gain, Blue_Analog_Gain, and Green2_Analog_Gain in steps of 0.125. The
MT9P001_DS Rev. L 4/15 EN
34
©Semiconductor Components Industries, LLC,2015.