Photodiode Signal Conditioning

Thread Starter

electronicsguy7810

Joined Jan 7, 2016
3
Hi,
For a project, i'm wanting to use a photodiode and a microcontroller to log ambient light levels in my garden.
I need an op-amp circuit that will output 5v to the microcontroller when ambient light is equivalent to 5mW/cm^2.
The photodiode I have is TEMD6010FX01
Below is what I have for a start
photodiode.png
Can anyone advise me on weather this is right, and if so how can I work out what C1 and R1 need to be

Tim
 

crutschow

Joined Mar 14, 2008
25,247
According to the data sheet the diode has a nominal sensitivity of 1μA per 1mW/cm^2 with a 5V reverse bias.
It does not give the current with zero bias as your circuit shows.
So if you apply a 5V reverse bias to the diode anode than a value of 1megΩ for R1 will give a nominal output of 5V for an illumination of 5 mW/cm^2.

But note that the diode sensitivity tolerance is -25% to +225% so, if you need better accuracy then that, you will need to calibrate the circuit or get a diode with a better sensitivity tolerance.
 
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