I'm looking for a photosensor/photo IC part (combination of photodiode, linear amplifier, Schmitt trigger and output transistor) that can be powered with 3.3V. Fairchild QSE256/257/258/259 is almost exactly what I need, except that it requires 4-16 volts supply voltage and not working very stable at 3.3. I know that there is a number of parts usually used in the infrared receivers, but they contain demodulator (from 38KHz) which I don't need. Anyone here knows a good alternative to Fairchild part?
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In this thread is explained that a photodiode doesn't need a voltage across it to generate a photocurrent:
Do you need all the functions integrated into one IC? You have plenty of options if you would pick a common photodiode plus a comparator. Comparators exist for DLV (Damn Low Voltages™) these days; Digikey lists more than a thousand which will happily run at 3.3 V or less. The MCP6546 is the cheapest I found:
If the 30 mA current sink is not sufficient you can use the MCP6541, which has a push-pull output, from which you can drive an external transistor. This would also allow you to switch much higher voltages, as well as set your own hysteresis levels. In this answer I explain how to calculate the required resistances. |
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