Home > Components, Electronics, Tutorial > OPL530 – Sensing Light (or so I thought)

OPL530 – Sensing Light (or so I thought)

The OPL530 (click here for the datasheet (.PDF)) and the OPL5## series are “Photologic Sensors“. Unfortunately, I bought two of these when what I was actually looking for was a simple photodetector/photoresistor. Turns out that my datasheet comprehension is not as great as I thought, and this sensor is something entirely different. This sensor is actually a photodiode with an integrated circuit intended to be paired with a infrared LED with a wavelength of 935nm, and provides logic output, meaning; HIGH or LOW (1 or 0). I believe that the use of photologic sensors is intended for applications such as non-contact object sensing (think detecting rotating fan blades), end of travel sensing, and door position sensing.

As I understand it, the basic function of this sensor is; if it detects the light of an infrared LED, past a certain threshold, it will output the signal HIGH or 1, otherwise it will output LOW or 0. If this is true, and there is only two possible outputs, then this sensor most definitely cannot be used in a way similar to a photoresistor, which provides a variable analog output.

The projects that I had in mind required a sensor that would measure general lighting of the environment, something like a photoresistor. Perhaps this ambient light sensor (.PDF) was more in line of what I needed, or I can just go and buy a couple actual photoresitors off Digikey.

I do have a photoresistor … somewhere around here … and will follow up with a brief tutorial on its use as soon as I can find it.

Continue for more information about the sensor…

More about the component:

This sensor contains an IC which incorporates a photodiode, a linear amplifier, a voltage regulator, and a schmitt trigger on a single silicon chip housed in a 3 pin “side looking” package with a integral lens. Operates from 4.5VDC up to 16VDC. Has inverter, totem pole output to provide output low with “light on”. OPL530 includes a 10 K Ω pull-up resistor (RL) from output to VCC.

Here is a representative internal diagram of the sensor:

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