INA181: INA vs. OPA current sensing for BLDC motor drive solutions

Genius 16285 points

Part Number: INA181

Hi all

My customer is working on a BLDC-motor design (48V / 1kW) and they have these questions:

-What are the pros and cons of using an INAxxx vs. OPAxxx for the current sensing on the low-side shunt resistors ?

-What do we recommend as to implementing the filter ?

Best regards

Ueli

over 3 years ago

+1 Javier Contreras4 over 3 years ago

TI__Mastermind 26515 points

Ueli,

For Pros and Cons take a look at these.

https://e2e.ti.com/blogs_/b/analogwire/posts/system-trade-offs-for-high-and-low-side-current-measurements

https://www.ti.com/lit/an/sboa190/sboa190.pdf

For filtering I would look at the datasheet for the device selected. For the INA181 like most current sense amplifiers we recommend a Rfilter smaller than 10 ohms due to input bias current of the CSA(Current Sense Amplifier). This is in section 9.1.3 in the INA181 datasheet.

Also on low side please make sure to be aware that the input of the CSA can only go 0.2V below the GND pin so connection of the GND needs to be carefully done as you can get drops on the GND.

Javier

+1 Ue over 3 years ago in reply to Javier Contreras4

TI__Genius 16285 points

Javier

Thank you for the quick reply and for pointing to the post covering the topic.

Best regards

Ueli

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INA181: INA vs. OPA current sensing for BLDC motor drive solutions