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Help me interface a 0 to 20mA sensor to a microcontroller

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evl_inside

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Hello,

I want to interface a 0 to 20mA sensor to my micro controller, buut i need to isolate the signal before use and the availabe supply voltage is 3V.

Kindly suggest the possible circuit or chip.

Thanks in advance.
 

Re: 0 to 20mA Interface

Maybe you would like to provide us more detail on your sensor.
How it works?
Your information seems insufficient for any reply.

Best Wishes.
 

Re: 0 to 20mA Interface

provide signal conditioning to ur senors o/p (assuming that ur pointing to noise)

need to clarify ur question
 

Re: 0 to 20mA Interface

Use 150Ω resistor to convert 0-20mA current to 0-3V voltage ..
Next, you may use 12-bit (or whatever you need) A/D 3-wire converter such as LTC1288, connect its /CS pin to GND, and use 3 optocouplers to isolate CLK, Din and Dout .. see picture below ..
Of course, to provide total isolation between ADC and µC you will also need 3V-to-3V dc-dc converter ..

https://www.ortodoxism.ro/datasheets/lineartechnology/lt1285.pdf

Regards,
IanP
 

Re: 0 to 20mA Interface

i think there are two possible ways to over come this problem

first one

use opto coupler at the end of the 0-20mA or convert in to voltage by using opAmp then feed into the optocoupler then calculate the value of resistor in such a way that u get the approximate change at the output with respect to input .... i know it is difficult but not impossible

second method

use ADC with isolated Analog GND then there is no problem for u

but first method is prefered when u are using the Microcontroller (with ADC built in)

thanks
Ashad
 

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