light to frequency converter

Discussion in 'General Electronics Chat' started by thavamaran, Apr 17, 2009.

  1. thavamaran

    Thread Starter Active Member

    Feb 21, 2008
    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.
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    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.