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I wanna read 0.5uA to 50mA

SANG HYOUK KIM
Prodigy 20 points

Hello?

My name is Sag Hyouk Kim from Korea.

Please understand my english.

Anyway.... i wanna read 0.1uA  to 50 mA.... 6Ch....

I saw OPA-129.... and 24bit ADC....

If ADC have 5V Ref... than can read 0.0000003 V / 1 bit....

But I need more simple (easy...) and more cheap....

I never use OP Amp and ADC... only use AVR....

Please help~ me~~~~~~

Thank you for read...

  • 0
    TI__Expert 7185 points

    Sang,

    There are many ways to go about this; however, many of the options are not "cheap." Here is one way you can go about doing this; you can pick the OPA based on your accuracy and cost constraints.  The transistor will give the cheap OPA the current-carrying capacity that it needs to handle 50mA. 

    You can achieve the same thing with a selectable shunt resistor and an INA, a couple selectable shunt ranges and a PGA, or a LOG AMP.

  • 0 in reply to Matthew Hann
    Prodigy 20 points

    Dear Matt.

    Thank  you for reply.

    I'll use AVR Mega8... so... I can't use s/w.... If use S/W or Relly... they have R value... about under 1ohm.

    If I use OPA-129 and 20bit ADC(24Bit ADC) ....

    What is good match.... for OPA-129....

     

    and... If I buy OPA-129 and ADC... under 10 PCS... where can I buy?

  • 0 in reply to SANG HYOUK KIM
    TI__Expert 7185 points

    I don't really understand what your question is.  What exactly do you want to match to the OPA129?

    You cannot use an OPA129 for the 50mA current setting as it can only source/sink up to 10mA.  You will need to attenuate your current by at least 10x which will put your max current reading around 5mA.  Also, if you do not switch your resistor settings, your dynamic range will not allow for precise current measurements at your low currents.

    One of the best places to purchase devices in small quantities is a licensed distributor such as Digikey.