VS6502V015/T2 STMicroelectronics, VS6502V015/T2 Datasheet - Page 34

• Manufacturer Part Number: VS6502V015/T2
• Description: SENSOR COLOR VGA CMOS SMOP
• Manufacturer: STMicroelectronics
• Type: CMOS Imagingr

Specifications of VS6502V015/T2

• Pixel Size: 5.6µm x 5.6µm
• Active Pixel Array: 644H x 484V
• Frames Per Second: 30
• Voltage - Supply: 2.6 V ~ 3.6 V
• Package / Case: SMOP2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-3884-1

Optical Characteristics
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Optical Characteristics
The average sensitivity is a measure of the image sensor response to a given light stimulus. The
optical stimulus is a white light source with a color temperature of 3200K, producing uniform
illumination at the surface of the sensor package. For a color sensor, an IR blocking filter, CM500,
is added to the light source. The analog gain of the sensor is set to x1. The exposure time, ∆t, is set
as 50% of maximum. The illuminance, I, is adjusted so the average sensor output code, Xlight, is
roughly mid-range equivalent to a saturation level of 50%. Once Xlight has been recorded the
experiment is repeated with no illumination to give a value Xdark.
The sensitivity is then calculated as
Dark signal
The dark signal is a measure of the effect of pixel leakage current on the sensor output. The
measurement is performed without illumination. As the dark signal is small the analogue gain, G, of
the sensor is increased to x4. For the same reason the clock divisor is set to16. As the leakage is
highly temperature dependent, measurement is done at a controlled temperature of 25
mean sensor output is then recorded at 2 exposure settings: Xdark at the maximum exposure time;
Xblack at zero exposure.
The dark signal is calculated as
Temporal noise of pixel and readout
A measure of the temporal noise is required to quantify the noise floor. As the signal is small the
gain, G, is set to the maximum of x16. In order to remove fixed pattern noise sources it is calculated
as the standard deviation, σ
images. Random noise is expressed in mV.
Dynamic range
The dynamic range is the measure of the maximum and minimum signal levels at which the sensor
can be used.
The figure for temporal noise is used to find the dynamic range as follows
Sensor SNR
The SNR measurement given here is based on the temporal noise. The SNR is calculated as the
pixel saturation voltage divided by the temporal noise at that saturation level. The optical setup is
the same as for the measurement of average sensitivity. The sensor gain, G, is set to x1.
The SNR figure is then calculated as:
Fixed Pattern Noise (FPN)
The FPN of an image sensor is the average pixel non-temporal noise divided by the average pixel
voltage. The illumination source is the same as for the average sensitivity measurement. The FPN
is calculated at coarse exposure settings of 0,10,150,250 and 302 with a gain set to 1. 10 frames
are grabbed and averaged to produce a temporally independent frame before each calculation.
FPN is expressed in mV.
black
Xdark Xblack
---------------------------------------- -
, of the difference of a pair of zero exposure and zero illumination
Xlight Xdark
-------------------------------------- -
∆t G
–
⋅
20
∆t I ⋅
⋅
–
log
⎛
⎝
G Vsat
--------------------
σsignal
and is expressed in volts per second.
⋅
. The result is expressed in volts per lux-second.
⎞
⎠
.
20
⋅
log
⎛
⎝
G Vsat
--------------------
σblack
⋅
o
C. The
⎞
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.
VS6502