INA 156 Gain selection Problem

Ganesh Singh Jayaram

Other Parts Discussed in Thread: INA156, ADS1247, INA826

Hi,

I got a sample INA156 from Texas. I kept 1st and 8th pi of the INA156 open and i am giving a input from 10mV to 200mV and i am getting proper output 100mV to 2V . when i tried to get gain 50, by Short circuiting the 1st and 8th pin . the output is still in 10 times the input as mentioned above. The Supply voltage is +5V and ground. Ref pin is connected to ground. can any body tell me why i am not able to get 50 times output(gain 50)?

over 12 years ago

0 Pete%20Semig over 12 years ago

TI__Mastermind 25825 points

Hello Ganesh,

Can you please post a schematic of your circuit? Also, what is your input common-mode voltage? I ask this because the input common mode voltage range of the INA156 is 0.3V to 5.2V (Vs=5.5V) but your input voltage is 10mV-200mV.

0 Ganesh Singh Jayaram over 12 years ago in reply to Pete%20Semig

Prodigy 50 points

hello Pete Semig,

.5238.INA156 PT100 3 wire.pdf

please find the schematics in PDF file , in which i am trying to measure temperature using PT100 RTD.Please let me know what is Problem in that.

0 Pete%20Semig over 12 years ago in reply to Ganesh Singh Jayaram

TI__Mastermind 25825 points

Hello Ganesh,

It does not appear as though your 3-wire RTD is connected correctly. Please take a look at the following application note (Figure 6 in particular):

http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=slyt442

Also, you may be interested in the ADS1247. It is a very nice integrated solution for this application. Here is an app note that may be of help:

http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sbaa180&fileType=pdf

Finally, since this is a temperature sensing question, I'm going to move this to our temperature sensing forum.

0 Ganesh Singh Jayaram over 12 years ago in reply to Pete%20Semig

Prodigy 50 points

Thank you for giving me a useful solution. i got another solution my net .. ina826 instrumentation amplifier. i will try that.

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INA 156 Gain selection Problem