INA290: 5mA level accuracy current sensor solution

Kai Lai

Part Number: INA290
Other Parts Discussed in Thread: INA228, INA236, INA190, INA229

Hi Team,

My customer is investigating a 5V rail / 5~650mA(Imax) level current sensor solution, they would like to design an sensor can sense low to 5mA with high accuracy, BW is don't care here.

Do you think INA290 is a good choice here ?
If I select A1 devices: 20 V/V, and use 250m ohm precision resistance, 5mA*250m ohm * 20 = 25mV.
The VOS of INA290-A1 is 25uV*20=0.5mV. It is really smaller than 25mV, so the result should have high enough accuracy, am I right ?
Compare to digital output solution INA228 or INA236, which one can perform more highly accuracy at 5mA ?\
If digital solution is more better here, could you provide your suggest solution ?

Thank you so much.

Kai

over 2 years ago

+1 kai klaas69 over 2 years ago

Guru 140200 points

Hi Kai,

sounds good to me. But as the output voltage swing to ground is limited to 25mV, you might not be able to see a difference between the two conditions

1. Isense = 5mA

and

2. Isense < 5mV.

Kai

0 Mitch M over 2 years ago

TI__Genius 17990 points

Hey Kai,

Here are my responses to your questions:

If you're wanting more accuracy, and still want an analog device, then the INA190 would be a better choice if you.
Kai has a good point about the worst case swing to ground. you would have enough resolution, but anything lower that 25mV and you may not be able to detect it. It's also important to note other error sources and noise level.
The INA228 (I2C) and INA229 (SPI) are our most accurate digital current sensors that we have, and would perform better at 5mA than the INA236.
If you want the best solution possible here, then you may want to look into the INA228/9, as they have a lower IB and are highly accurate. Since you don't care about bandwidth, you'll want to use a longer conversion time and built in averaging to get an even more precise result.

0 Kai Lai over 2 years ago in reply to kai klaas69

TI__Expert 5856 points

Hi Kai,

Thanks for the reply!

Kai

0 Kai Lai over 2 years ago in reply to Mitch M

TI__Expert 5856 points

Hi Mitch,

Thanks for your input, let me discuss with customer and then feedback to team!

Kai

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INA290: 5mA level accuracy current sensor solution