INA326: Volt In/Current Out

Miguel Partida

Part Number: INA326
Other Parts Discussed in Thread: TIPD107, OPA333, OPA2333

Hello,

I am trying to get the output current to configure 10uA/Volt input. So far this design works, until I try to go higher than 2V. It seems to be having some convergence issues. I believe it has to do with INA326. I wanted to see if someone had more insight on the subject. Maybe how I need to set some Analysis Parameters? Any information can be helpful.

Best Regards.

over 4 years ago

0 Tamara M Alani over 4 years ago

TI__Genius 10850 points

Hi Miguel,

Thanks for your post. I can help. It looks like you are referring to TIPD107: http://www.ti.com/lit/ug/slau507/slau507.pdf

What is your expected input range?
What is your desired output range?

This design is for 0-5V in, 0-5µA out but we can try to tweak this for your requirements.

0 Miguel Partida over 4 years ago in reply to Tamara M Alani

Prodigy 60 points

Hello Tamara,

You are correct, I am referring to TIPD107. My expected input range is from 0V-3V. Which I want to be able to output 0-30uA. I was able to design is as such to give me 10uA per volt input, but after 2V input, TINA TI seems to give me convergence errors. It doesnt specify completely, but it says Operation point not found. Any help will be appreciated.

0 Tamara M Alani over 4 years ago in reply to Miguel Partida

TI__Genius 10850 points

Hi Miguel,

Your circuit looks right to me. I did make two changes to my attachment below:

I changed C2 my circuit from 1nF to 500pF.
1. For Gain = 10V/V; R1=40kohm, R2=200kohm, C2=500pF
2. This is on page 5 of the design
I changed OPA2333 from your circuit to OPA333.

Take a look.

INA326 TIPD107.TSC

0 Miguel Partida over 4 years ago in reply to Tamara M Alani

Prodigy 60 points

Thank you so much Tamara, one quick question. The change from OPA2333 to OPA333, is that just to make the simulation work? Theoretically isn't OPA2333 just two OPA333 on the same chip? Or would using the OPA2333 for applied purposes actually vary that differently from OPA333?

0 Tamara M Alani over 4 years ago in reply to Miguel Partida

TI__Genius 10850 points

That's right, Miguel. The OPA2333 is just 2 OPA333 in one package.

Since you are only utilizing one OPA333, though, I switched it out to the correct package.

-Tamara

0 Miguel Partida over 4 years ago in reply to Tamara M Alani

Prodigy 60 points

Thanks Tamara, not sure why my design didn't work for me, but the one you sent worked well.

Best Regards.

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INA326: Volt In/Current Out