INA190EVM: How to set-up this EVM when measuring few uA to 30mA current?

Hey Archie,

10uA to 30mA (dynamic range = 3000:1) may not be possible with just one INA190. You may need two INA190. For example one INA190A5 to sense 10uA to ~5mA and another INA190A1 to sense ~5mA to 30mA.

INA190 output dynamic range is only about 500 = 5V/0.01V assuming a minimum 10mV VOUT at low current level.

Next problem is the size of shunt resistor. 0.25Ohm*10uA=2.5uV. The INA190A5 (500V/V) would amplify to 1.25mV. This is a very small signal given the few mV of noise on INA190 output. If you cannot increase this minimum signal, then you will need to provide a small bias voltage to REF pin(~>50mV) to keep VOUT from saturating into GND rail when current is low.

Given small signal and noise I ideally recommend increasing the shunt resistor as large as possible/allowable for system.

Next, decide what the minimum allowable BW so you can place input and output filters with lowest allowable fc. This to reduce noise floor as low as possible to you can resolve smaller signal and thus use a smaller shunt.

I actually go over this noise/BW trade off in this post where you can use TINA simulation tools to determine best balance. Also here is a circuit note on measuring low currents with INA190.

https://e2e.ti.com/support/amplifiers-group/amplifiers-internal/f/amplifiers-internal-forum/1435670/ina310a-q1-sensing-current-accuracy-and-quiescent-power-in-12v-auto-bms

https://www.ti.com.cn/cn/lit/an/sboa551/sboa551.pdf 

Sincerely,

Peter