Reflective Object Sensor, Design with the QRE1113GR

Hello,

I'm trying to design a circuit to sense an object for a project. I'm using the QRE11113GR reflective sensor to accomplish this. Basically what I want to do is get a < 0.8V output when there is reflection from the object and the output has to be greater than 2V when the object is not reflecting/not in path. The circuit I've attached can do this, but I'm having some issues calculating what my output should be assuming a distance of 1.5mm from the object. I can take the measurements fine with a meter but want to be able to calculate the output values depending on the If, Ic, and value of R19.

For thi particular circuit I'm using a 150Ohm resistor to get a If of about 25mA.
If = (VCC - Vf) / R18
If = (5V-1.2) / 150
If = 25mA

Is there anyway I can calculate the approximate output voltage with the given parameters?

hi,
Looking at the datasheet , it shows only typical values, so your calculations will be typical and not specific.
E

Yes, I understand, but how do I go about doing the calculations.

Hi,
Looking at the datasheet plots, attached, it indicates a collector current of 1.27mA with your Vsupply and If.
So if you have a 47K collector resistor, the Vce will be ~0v

To calculate the Vce its 5V - (R19 *0.00127)
So if you choose a lower value for R19, say 2k2 that would be, 5V- ( 2200*0.00127) = 5V - 2.784V = 2.2V

Use an R19 value which will give the widest Vce range
E