MicroSemi’s Precision Colour Sensor AS73211

Precision colour sensing made easy

Austrian MicroSemi recently divested itself of its transceiver portfolio, leaving standards such as AS-I stranded. Sensors were selected as the new main field of business, leading to the introduction of a few extremely interesting products such as the JENCOLOR colour sensor ICs.

In principle, the sensor is laid out according to the schemes shown in the two figures accompanying the screen. The main priority is that the part contains but three photo-diodes, all three of which are conveniently located behind a filter to eliminate unwanted spectral components.

The three diodes are located in seperate areas of the main die…

…AMS provides a relatively complex set of signal conditioning circuits

To clarify a few aspects: first of all, the AS73211 is strictly an one-pixel color detector – it has nothing to do with the traditional linear or two-dimensional CCD chips which are well-known from digital cameras. Secondarily, the chip’s intended usage is processes – think about quality control, sorting of goods and similar tasks where accurate color sampling is required.

Finally, the AS73211 is intended to reach extreme high accuracies – its internal DACs can work at 24bit if required.

When compared to a homebrew solution, benefits pop up. ADC linearity and temperature issues are handled by AMS – the chip contains various bits of logic which ensure that issues affecting resolution adversely are handled effectively.

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