VS6552 Datasheet, PDF (6/26 Pages) STMicroelectronics – VGA Color CMOS Image Sensor Module

VS6552
3 FUNCTIONAL DESCRIPTION
The first sections of this chapter detail the main
blocks in the device:
■ Analog video block
■ Digital video block
The later sections of this chapter describe other
functional aspects of the device. Device level op-
erating modes, including suspend, are detailed
3.1 Analog Video Block
3.1.1 Features
■ ADC: 10-bit A/D converter - SRAM readout
■ Dynamic range 60 dB (typical)
■ SNR 37 dB @ 50 cd.m² (typical)
Figure 2. Analog Video Block
SRAM readout
X-Address
Column ADC
VGA
pixel
array
raw sensor data
Timing signals
Power
management
Digital
logic
Y address
Timing signals
3.1.2 Analogue Block Diagram
The analog video block from Figure 4, consists of
a VGA resolution pixel array, power management
circuitry. The digital block provides all timing sig-
nals to drive the analog block.
Pixel voltage values are read out and digitized us-
ing the address decoders and column ADC
3.2 Digital Video Block
3.2.1 Features
■ Frame rate: 30 frame/s max. (VGA) can be
reduced down to less than 3 frame/s (VGA)
■ Automatic dark calibration to ensure consistent
video level over varying scenes
■ Fixed pattern noise (FPN) data gathering
■ Line and frame statistics gathering
■ On-chip Power-On-Reset cell
■ Single video output format: VGA 640 x 480
■ H - Scaler function to aid software only
viewfinder implementations
3.2.2 Dark Calibration Algorithm
VS6552 runs a dark calibration algorithm on the
raw image data to control the video offsets caused
by dark current. This ensures that a high quality
image is output over a range of operating condi-
tions. First frame dark level is correctly calibrated,
for subsequent frames the adjustment of the dark
level is damped by a leaky integrator function to
avoid possible frame to frame flicker.
6/26