Load cell amplifier: OPA or INA?

Davide Romeo1

Other Parts Discussed in Thread: ADS1232, OPA277, INA333, INA828, INA317

Hi, I'm an electronics novice, I wanted to work on a load cell and I'm considering which amp is best suited.

Load cell 1Kg (max), 1mV / V, ADS1232 to read the values, working voltage 3.7V (lithium battery).

I wanted to use the one in the OPA277 datasheet as an amplification circuit, to be connected to my ADS1232, but recently I saw that the INAXXX amplifiers are much more practical and complete, all in a single package, so I would like some advice: it's better to use 2 OPAs or an INA for a load cell? And which INA is more suitable for a load cell? I was currently reading the documentation on the INA333, could that be fine?

Thank you

over 3 years ago

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi Davide,

can you tell a bit more about the load cell? Is it forming a Wheatstone bridge?

Do you have a datasheet of the load cell?

Kai

0 Davide Romeo1 over 3 years ago in reply to kai klaas69

Prodigy 50 points

Yes sorry, I forgot to specify, the cell is a Wheatstone bridge. Unfortunately, there is no cell datasheet, I currently have an inexpensive version taken online on AliExpress, just to start working on the circuit. I'm looking for a cell of at least + -2mV / V of class C3 or higher. So I'm designing the circuit for a good quality cell

0 Davide Romeo1 over 3 years ago in reply to kai klaas69

Prodigy 50 points

0 Raymond Zhang1 over 3 years ago in reply to Davide Romeo1

TI__Guru 51421 points

Hi Davide,

You may take a look at INA333 micro-power instrumentation amplifier, but it will be very helpful if you are able to find the specification of the sensor. Google the sensor model number over the internet, perhaps you are able to find the specification.

The following thread that may be helpful in selecting the applicable INA instrumentation amplifier for your application -->

How do Instrumentation Amplifiers (INAs) fit into my design?

https://e2e.ti.com/support/amplifiers/f/14/t/818894

If you have any questions, please let us know.

Best,

Raymond

0 Davide Romeo1 over 3 years ago in reply to Raymond Zhang1

Prodigy 50 points

This is the cell I intend to buy

0 Raymond Zhang1 over 3 years ago in reply to Davide Romeo1

TI__Guru 51421 points

Hi Davide,

The image did not load properly. Please try the following.

Please click on the icon circled in red to upload an image file. Please use the icon circled in green to upload a standard file.

Have you decided what instrumentation amplifier you are going to use? If you do, I may be able to put a simulation together for you.

Best,

Raymond

0 Davide Romeo1 over 3 years ago in reply to Raymond Zhang1

Prodigy 50 points

I inserted the image, but I don't know if it was loaded correctly, the preview is empty. I attach a second link for the image uploaded online.

Regarding the choice, I was directed to the INA333. I also read the INA828 datasheet, which should perform better. The INA2XX and INA1XX versions should be outdated and inferior to the newer models right?

i.ibb.co/.../1320856495-812709032.webp

0 Raymond Zhang1 over 3 years ago in reply to Davide Romeo1

TI__Guru 51421 points

Hi Davide,

I do not recommend INA828, since you have a single supply rail at 3.7Vdc. Your input Vcm does not have the range per your application.

Based on your early design requirements and compression transducer's datasheet, I did the following simulation for you. I think that INA317 may be good Op Amp for your application. I configured Gain = 101. Also, enclosed is Tina simulation that may help to decide.

/cfs-file/__key/communityserver-discussions-components-files/14/INA333-INA317-Compression-Sensor-07282020.TSC

Best,

Raymond

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Load cell amplifier: OPA or INA?

How do Instrumentation Amplifiers (INAs) fit into my design?