• State TI Thinks Resolved
  • Locked Locked
  • Replies 11 replies
  • Answers 1 answer
  • Subscribers 49 subscribers
  • Views 4032 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

Strain-gauge measurement

Markus Krenn11
Prodigy 100 points
Other Parts Discussed in Thread: PGA308, PGA900, PGA309, INA333, USB2ANY

Hello all,

I'm searching for a One-Chip solution to measure a strain signal.
I have looked at the PGA308 and PGA900, which from my Point of view are nice choices.

Does anyone of you has experience with those ICs or maybe a better choice?

My requirements are:

Less space
programmable gain
programmable Offset compensation
low power
high precision
temperature stable
max. Temp 125°C

Output Signal can be analog or digital

Thanks in advance

BR
Markus

  • 0
    TI__Genius 12100 points
    Hi Markus,
    I'm not as familiar with the PGA900, but the PGA308 should work well for this application.

    Both appear to be pretty close in terms of analog specifications, although the PGA308 is lower power (1.3mA vs. 2.6mA) and available in a smaller package. The PGA900 is a more complex part, but does integrate an ADC, microcontroller, and DAC, so could offer some advantages for calibration or linearization of more unusual sensors.
  • 0 in reply to Alex Davis
    Prodigy 100 points
    Hi Alex

    Can you suggest another IC's with integrated Features like PGA308 or PGA900 with maybe better analog performance?
    What I've forgot is, that i need 1kSps.

    BR
    Markus
  • 0 in reply to Markus Krenn11
    TI__Genius 12100 points
    I think either PGA308 or PGA900 would work for that sampling rate. At its highest gain setting, the PGA308 has around 10kHz of bandwidth, and the PGA900 should be able to sample at ~7.8kSa/s.

    You might also consider the PGA309. It's functionally very similar to the PGA308, but adds some lookup-table functionality to allow bridge calibration over temperature. I'm not sure what your size constraint is, but the PGA309 is only available in a TSSOP package.

    In terms of analog performance, is there a particular specification of most concern to you? There are small differences between the parts in terms of noise, bandwidth, offset voltage, input bias current, and other specifications.
  • 0 in reply to Alex Davis
    TI__Intellectual 1840 points

    For force strain-gauge application, the front bridge sensitivity is low typical 1mV/V. I am thinking it is too low to PGA900. if you need both analog and digital output capability, you need add more amplifier before PGA900 for better system performance.  INA333+PGA900 are recommended for your reference 

  • 0 in reply to Hawk Tong
    Prodigy 100 points

    Hello all,

    Thanks for all your answers, I think i would try both the 308 and the 900 with an Evaluation kit.

    Thank you very much.

    BR

    Markus

  • 0 in reply to Markus Krenn11
    Prodigy 100 points
    Is that true, that both of the ICs can operate up to +150°C?
  • 0 in reply to Markus Krenn11
    Prodigy 100 points
    Can you suggest me any swd debug probe for the PGA900?
    The USB2ANY connector should be included right?
  • 0 in reply to Markus Krenn11
    TI__Genius 12100 points
    Hi Markus,
    It looks like both PGA900 and PGA308 will operate from -40 to 150°C, though it looks like many of the drift specifications on the PGA308 are guaranteed only to 125°C.
  • 0 in reply to Markus Krenn11
    TI__Genius 12100 points
    It looks like the PGA900 EVM can use either a USB2ANY or an XDS200 interface.
  • 0 in reply to Alex Davis
    Prodigy 100 points

    Hi Alexander,

    Thanks for answering, yeah I read the drift specification but in this temperature area it's more the fact that the chip get not damaged.



    For me it's sounds more like, that the USB2ANY IF is for reading any communication data from the IC's and the XDS200 is for programming and Debugging the M0 Core of the PGA900. Are you sure it's like that?

    BR

    Markus 

  • 0 in reply to Markus Krenn11
    TI__Genius 12100 points
    Hi Markus,

    My apologies for not replying sooner. It looks like for PGA308, the 150°C rating is an absolute maximum spec. While the part will operate at that temperature, reliability isn't guaranteed if the part is operated continuously at that limit. PGA900 appears to have a 155°C Abs Max, with a 150°C max operating temperature.

    I believe you're correct that the USB2ANY is used for measurement communication with the PGA900, while the XDS200 is used for debugging. I'll see if I can confirm this with someone more familiar with the part.