CMOS Imaging Sensors

The LM9627 (color) and LM9617 (monochrome) CMOS imaging chips are designed to produce brighter pictures, smoother video sequences and longer battery life in cell phones, PC cameras, digital still and dual-mode cameras. The chips, with integrated 12-bit ADCs, are capable of capturing still or full-motion video images up to 30 frames per second and converting them to a digital datastream. The ICs consume 90mW of active power at full frame rate when operating from a 3.3V supply, and 80mW when in a power management mode.

The image array uses a 7.5 micrometer square pixel and offers a total array of 664 x 504 pixels and active area of 640 x 480 pixels. The surrounding black pixels are provided for automatic black level calibration. The sensor core architecture attains a high fill factor of 47% without the aid of micro-lenses, resulting in a high sensitivity level up to 11kLSBs/lux.sec. In monochrome applications, the LM9617, with additional sensitivity boosting micro-lenses, can improve the performance of security cameras and machine vision at low light levels or in the IR-range.

The Analog Front End (AFE) architecture produces noise-free images at low light levels. The 12-bit datastream from the ADC can be reformatted into 8-bit or 10-bit datastreams. A fully programmable on-chip timing and control system offers design-in support, allowing digital image processors to either control and read out data from the CMOS image sensor (sensor slave mode) or to receive the already formatted data from the sensor (sensor master mode).

The timing and control system is programmable via an I2C interface and the functions are automatically synchronized. Two read-out modes -- video and snapshot -- can be used to control the datastream into the digital image processor. Users can tailor the sensor configuration and manage the sensors power consumption at different light levels.

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