What is the minimum range in millivolts in a linear optocoupler

I would like to know how many minimum millivolts can pass through the optocoupler, for example in a working range of 1mv to 10mV (input output) will there be problems in its operation?

Where in the LOC110 linear optocoupler data sheet is it specified?

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0 scottiebabe over 2 years ago

In case you missed it I would recommend you skim through: https://www.ixysic.com/home/pdfs.nsf/www/AN-107.pdf/$file/AN-107.pdf

The optocoupler operates based on photocurrent. So in you would selected R1 & R2 such that the LED current is in it recommended operating range of 1 to 10 mA. Selecting the right op-amps is going to be a major performance factor operating at just 1 mV to 10 mV above the ground rail.
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0 A3JBNE over 2 years ago in reply to scottiebabe
So the operating range of the LED is from 1mA to 10mA, I have an input signal of "0 to 2.5V", so I have to scale from "1V to 2.5V" so that 1V is the minimum voltage it will give me the minimum current 1mA approximately and 2.5V the maximum current. To adjust the minimum current I will have to calculate the resistor referring to K1 until I obtain 1mA of LED current for 1V input.

Because in the schematic example it uses a "0 to 2V" input signal. It is assumed that 0V is equal to 0mA for the LED.

What if I use different voltages for VCC1=5V and VCC2=18V will it affect the K3 gain?
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0 scottiebabe over 2 years ago in reply to A3JBNE

The 1mA to 10mA LED current rating is where the servo-linearity is guaranteed. The LED and photodiodes/transistors are absolutely still going to work on lower photos currents. I just can't say how well, if you built this on a breadboard I'm sure it would work just fine (though vout will be 0-2V for R1=R2).

Surprisingly the datasheet doesn't list a voltage rating for the photodiodes/transistor so I can only assume 18V is okay...
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0 scottiebabe over 2 years ago in reply to A3JBNE

The 1mA to 10mA LED current rating is where the servo-linearity is guaranteed. The LED and photodiodes/transistors are absolutely still going to work on lower photos currents. I just can't say how well, if you built this on a breadboard I'm sure it would work just fine (though vout will be 0-2V for R1=R2).

Surprisingly the datasheet doesn't list a voltage rating for the photodiodes/transistor so I can only assume 18V is okay...
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