light to frequency converter

Thread Starter

thavamaran

Joined Feb 21, 2008
67
Hi guys, i currently been working on this sensor TCS230, there is a portion of this sensor where is converts light to frequency, the datasheet is attached, so the
problem is i dont get the theory behind this conversion and through my
research i couldnt find any appropriate findings on this particular part, do
help me please.
 

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thingmaker3

Joined May 16, 2005
5,073
Photovoltaic output current is directly proportional to illumination. A capacitor charged with constant current will have a constant rate of voltage increase over time. A comparator reading this voltage increase can discharge the capacitor. This makes a ramp-generating oscillator, thereby converting current (therefore light) to frequency. Converting the ramp to a square wave with 50% duty cycle could be accomplished in several ways.
 
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