Electronics > Microcontrollers

Measuring current with a microcontroller

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peter-h:
I don't understand why anyone would use those single sourced and expensive Hall current probes, unless they want galvanic isolation, or don't care about costs or long term manufacturing.

But in this case we have so little information on the OP's criteria.

Avelino Sampaio:
The ACS712, 30A version, seems to serve its purpose very well. Its cost is 2$ at LCSC.

https://datasheet.lcsc.com/lcsc/1811061532_Allegro-MicroSystems--LLC-ACS712ELCTR-30A-T_C9932.pdf

samu1214:
Thanks everyone, i decided to bought 2 resistor SMD, one is 4 terminal and the other 2. I will check how much this changes and if its convinient to buy a 4 terminal resistor. Then i bought 3 dedicated op amps, TSC210 ( 200 Gain ), ACS712ELCTR-30A-T ( 30A version ) and INA199C3 ( 200 gain ). With them and some LM358 that i have i will be testing the reliability and precision in all of them. I will be back after checking all of this. Thank you for you help!

nctnico:
You can't derive precision or reliability from just a few parts. For determining the resulting precision of your design, you'll need to work with the worst case specs (spread and temperature coefficients) in the datasheet and do the math.

A problem with the ACS712ELCTR and related devices is that the output depends on the supply voltage so you'll need to power it using a voltage reference chip in order to achieve the specs from the datasheet. Normal regulators are 1% at best (typically 2% to 3%). Alternatively you can use the same supply as the reference for de ADC; the error will cancel in that case.

tooki:
Why not just use a digital current/voltage sensing chip like the INA219 or INA226. They’re better than the ADCs in a MCU.

Or, if this is for lithium batteries, please just use a lithium charging chip with appropriate protection ICs.

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