Measuring small current with INA199

Hi,
My goal is to measure very small currents(1uA-5mA) from my esp32 without any special addons.
This chip seems to do the job, but I can’t understand how to choose Rshunt.
What are the considerations for this?
This is the datasheet:

Thanks

Why the INA199.
There are more advanced types available (on breakout boards), like the INA219 and INA226.
Leo…

This amplifier is not a good choice for the very low currents you want to measure. To have an upper limit of 5mA you would have to use a shunt of about 3Ω (INA199x3) which is usually too big for most applications.

BTW, both the INA219 and INA226 are also no valid alternatives as they don't measure current in the µA range using reasonable shunts.

What exactly do you want to measure? Maybe there are other ways to accomplish that.

Hi,
Thanks for the replies. I want to measure the current of the esp32 during sleep and active mode(meaning what's going out of the battery).
I'd like to add that measuring the active mode(or more than 300uA i.e) is less important so I can minimize the range significantly.

Nothing wrong with a 3 ohm shunt for 5mA full-scale - 3 ohms only dropping a tiny 15mV which isn't going to be an issue for almost any circuit or device you can think of.

The difficulties arise when you want a wide dynamic range (say 1µA to 100mA). This
can only be done by ranging, or using a logarithmic converter (ie a diode).

Hi,
This might help.

There is a YouTube video on its use.

Tom.... :grinning: :+1: :coffee: :australia:

1 Like

Hi,
Thanks! I will try the CurrentRanger