This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

  • Resolved

TINA/Spice/INA333: INA333 Pin 5 Reference Bias Fault

Part Number: INA333

Tool/software: TINA-TI or Spice Models

Tech Support,

I have been working with the Tina sim program. I was using an outdated sim model... since corrected... 

I have 2 issue...

1) The Ref pin 5... on my PCB card seems to be sourcing +VCC .... I should be able to swing the pin using OPA333 ... The Tina program shows the Ref, but in the real PCB the pin never changes..?

2) I still can't get the real chip to flip its output... regardless which part of the bridge resistor I change..?INA333 WSB Sensor Redundant Circuit Oct 1B 2017.TSC

  • Eddie,

    FYI, We're still looking into this.

    Herman
  • In reply to Herman Theodorus - WEBENCH Design Center:

    Hi Eddie,

    I thought I understood your question, but as I read again and again, I guess I am not 100% sure if I understand the problem you have here. But let me try to answer here, if my answers do not make sense, please help me by describing your problems in a different way.

    So for #1, if I understand correctly, you are having problem with the symbol? If you do have problem with the symbol after updating the model, I would recommend you redownload the .TSM file or the symbol from the following website: www.ti.com/.../toolssoftware

    For #2, I am not sure what you mean by "flip its output". If you meant how to flip the symbol, you can right click the symbol for the model and choose the "mirror" option. If you meant flip certain electrical node voltage, can you help me to understand which node are you monitoring or trying to flip? Do you mean to flip like from +1V to -1V something like that?

    If you think it might be helpful for me, can you describe to me a little bit what are you trying to achieve with your attached circuit? What's the objective? Perhaps this way I can understand what you mean by "flipping output, etc".

    Herman
  • In reply to Herman Theodorus - WEBENCH Design Center:

    Greetings Herman,

    Over the past few weeks I have enjoyed working with the INA333 WSB chip.  The chip is working very nice.  I did how ever see something in the technical specification sheet that makes me wounder?

    My boss as me to write and get a response to this question. On the first page, Section 3 description, it suggest that only one resistor is needed to set the gain from 1-1000... On Page 5, Section 6.5 specification

    list the "Range of Gain", =1000 V/V, yet on page 13, Section 7.3, the "Feature Description", summary states that the chip has the capacity to have a gain of 10,000?  

    Would you be kind enough to explain the difference in operations... I have operated the chip with a gain setting of ~3000 and it works just fine... is there any reason to limit the Gain to just 1000 or can this chip

    operate at a higher gains without causing any problems?

    With warm regards,

    -eINA333 WSB Circuit Nov 11 2017.pdf

  • In reply to Eddie Sines:

    Hi Eddie,

    Glad you like our product. Your latest question is product/datasheet specific. I am going to move this question from this forum to another forum so that somebody can help you with it.

    Herman
  • In reply to Eddie Sines:

    Hello Eddie,

    I will investigate this discrepancy in the maximum gain specification. A gain of 10,000V/V, or 80dB, is not unreasonable for an amplifier so I would not be surprised some units of INA333 could manage it, over a very low bandwidth of course.

    That being said, aside from section 7.3 everywhere else in the data sheet gives a maximum gain of 1,000V/V. It's likely we only guarantee operation to that level since not all units might be able to achieve higher performance over temperature, process and other variables.

    Best regards,

    Ian Williams
    Applications Engineer
    Precision Amplifiers

     

  • In reply to Ian Williams:

    William,

    Thanks for looking into this... The application is low frequency and did a prototype circuit and set the Gain to 2800 and it worked fine. Personally I think the chip can do more... the out put was low noise and stable.

    Now I am turning my attention to finding a electronic means of changing the Gain or using the INA333 as the front end for a microprocessor design. I look forward to

    reading your response.

    Warm regards,

    -e

  • In reply to Eddie Sines:

    Hello Eddie,

    I can confirm that the information in section 7.3 is a typo. The official specification for maximum gain on the INA333 is 1000V/V. While some units may achieve higher gain, we do not guarantee any level of performance past 1000V/V. If you need a precision INA with higher gain, you can select from the devices listed here.

    Best regards,

    Ian Williams

     

  • In reply to Ian Williams:

    Thanks Ian... the chip was doing great.... but we decided to back off on the gain and stay within the specifications.

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.