NOIL1SM0300A-QDC ON Semiconductor, NOIL1SM0300A-QDC Datasheet - Page 7

• Manufacturer Part Number: NOIL1SM0300A-QDC
• Manufacturer: ON Semiconductor

Specifications of NOIL1SM0300A-QDC

• Lead Free Status / Rohs Status: Supplier Unconfirmed

Programmable Gain Amplifiers
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Offset Regulation
the input range of the ADC.
a range from 0.1V (bright) to 1.3V (black). The input range
of the ADC is from 0.75V to 1.75V. The amount of offset
added is controlled by two SPI settings: VBLACK<7:0> and
VOFFSET<7:0>. The formula to add offset is:
causes a spread of about 100 mV on the dark level. To allow
FPN correction during post processing of the image, this
spread on the dark level needs to be covered by the input
range of the ADC. This is why the default settings of the SPI
are programmed to add an offset of 200 mV. This way the
dark level goes from 1.3V to 1.5V and is the FPN
information still converted by the ADC. To match the ADC
range, it is recommended to program an offset of 340 mV. To
program this offset, the Voffset and Vblack registers can be
used. Figure 7 illustrates the operation of the offset
regulation with an example. The blue histogram is the
histogram of the image taken after the column amplifiers.
The programmable gain amplifiers have two functions:
The purpose of offset regulation is to bring the signal in
After the column amplifiers, the signal from the pixels has
Voutput = Vsignal + (Voffset - Vblack)
Note that the FPN (fixed pattern noise) of the sensor
Adding an offset to the signal to fit it into the range of
the ADC. This is controlled by the VBLACK and
VOFFSET SPI settings.
Amplifying the signal after the offset is added.
ADC_OUT
CLK_ADC
ADC_IN
<9:0>
D1
50ns
D2
5.5 clock cycles
DUMMY
D3
Figure 6. ADC Timing
http://onsemi.com
D4
7
Consider as an example that the device has a black level of
1.45V and a swing of 100 mV. With this swing, it fits in the
input range of the ADC, but a large part of the range of the
ADC is not used in this case. For this reason an offset is
added first, to align the black level with the input range of the
ADC. In the first step, an offset of 200 mV is added with the
default settings of VBLACK and VOFFSET. This results in
the red histogram with a average black level of 1.65V. This
means that the spread on the black level falls completely
inside the range of the ADC. In a second step, the signal is
amplified to use the full range of the ADC.
D5
3.7ns
D6
Figure 7. Offset Regulation
D1
D7
D2
1.45V 1.65V
D8
D3
1.75V
VADC_HIGH
D4
Volts