TLV9004: Single-supply strain gauge bridge amplifier circuit using TLV9004

Vasu Poojary

Part Number: TLV9004
Other Parts Discussed in Thread: TINA-TI, TLV9002

Hello,

I have considered TLV9004 amplifier circuit to be used for amplifying the strain gauge bridge output and i am referring to application note "SBOA247"

This circuit i simulated in TINA-TI and it is working as described .

Is any practical board/eval board developed with this configuration ?

Since it involves uV/mV signal amplification (strain gauge ) and practical limitation involved in 2 opamp instrumentation amplifier explained in the application not SBOA247 ?

Thanks

Regards

Vasu

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Vasu,

can you post your simulation file?

If your input signal is very low, I would recommend the use of an ultra low input offset voltage OPAmp.

Kai

0 Tim Claycomb over 5 years ago

TI__Genius 15410 points

Hi Vasu,

The DUAL-DIYAMP-EVM has a 2 op amp instrumentation amplifier circuit configuration that can be used with the TLV9002 (dual channel version of the TLV9004).

Some practical limitations would be related to the error sources of the amplifier. You wouldn't want to choose a high noise amplifier because the noise of the amplifier would dominate the signal you are trying to measure. Offset voltage errors of the amplifier can also effect the performance. Offset voltage will add or subtract to the signal you are trying to measure. I recommend watching our TI Precision Lab Videos. Specifically, the videos on noise and offset voltage/input bias current will go into more detail about what I mentioned above.

Lastly, PCB layout can also effect the measurement accuracy. Improper PCB layout can introduce errors and additional noise into your system. I recommend taking a look at "How to layout a PCB for an instrumentation amplifier" and "The basics: How to layout a PCB for an op amp" for information on recommended PCB layout practices.

Thank you,

Tim Claycomb

0 Vasu Poojary over 5 years ago in reply to kai klaas69

Intellectual 390 points

two opamp INA.TSC

0 Vasu Poojary over 5 years ago in reply to Vasu Poojary

Intellectual 390 points

Hello Kai,

Attached is the simulation file.

Regards

Vasu

0 Tim Claycomb over 5 years ago in reply to Vasu Poojary

TI__Genius 15410 points

Hi Vasu,

The design seems to function like I would expect. As I change the resistor values in the bridge the output voltage changes. Is there anything else you would like us to check?

Thank you,

Tim Claycomb

0 kai klaas69 over 5 years ago in reply to Tim Claycomb

Guru 140200 points

Hi Vasu,

keep also in mind that the manufacturing tolerances of feedback resistors have a direct influence on the common mode rejection ratio. Here the worst case with +/-1% resistors:

Kai

0 Vasu Poojary over 5 years ago in reply to kai klaas69

Intellectual 390 points

Hello Team,

Thanks for your valuable inputs.

Yes, we have considered 1% tolerance .

We also considering to use of 3 opamp INA . Attached is the circuit.

Thanks

Regards

Vasu3 opamp INA Connected wa.TSC

0 kai klaas69 over 5 years ago in reply to Vasu Poojary

Guru 140200 points

Hi Vasu,

you still need very low input offset OPAmps with low drift. And you still need very precises resistors. I would go for +/-0.1% resistors.

Kai

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TLV9004: Single-supply strain gauge bridge amplifier circuit using TLV9004