• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 445 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.

ADS1262 - Can I supply to AVDD and AVSS, 2.8V and -2.5V respectively?

Sung ho Cho
Prodigy 190 points
Other Parts Discussed in Thread: ADS1262

The problem is that I want to use PGA in ads1262 at the range of from +2.5V to -2.2V for precise gain calibration of 2.5V.

For this reason, I will adopt LDOs, +2.8V and -2.5V. However, recomendation ratings of AVDD - AVSS is 5.25V..

In this situation, if I use 2.8V at AVDD, will the ADS1262 work properly?

Please help me...

  • 0
    TI__Mastermind 44720 points

    Hi Sung ho,

    A 5.3V analog supply would be outside of the ADS1262's recommended operating conditions. The device should work up to the absolute maximum ratings (up to 7V analog supply) without damaging the device; however, it would not be good design practice to operate in this region and performance would likely degrade.

    What are the range of input voltages you would be measuring on AINN and AINP?
    I need to know both the differential AND common-mode input voltages you would be measuring - there will be a limitation on each of these. Also, if AVDD = 2.8V, then AINP wound not be able to exceed 2.5V; therefore, you would not be able to measure inputs of 2.51V without operating the PGA in the non-linear region. I think you would want to have additional headroom to account for slightly larger input signals...

    What are you planing on using for a reference voltage?
    If you use the internal 2.5V reference then again you would be limited to only measuring signals up 2.5V and no larger. Are you planning on using an external 5V reference, for example, to account for inputs larger than 2.5V?

    Do you need the AVSS to be -2.5V?
    If you want to be able to connect AINN to 0V, then you would still need a negative analog supply voltage; however, if you made this -1V instead of -2.5V it would provide you with additional headroom. (Additionally, it might be easier to use a standard 0-5V analog supply and level-shift your input signal.)

    There is an PGA input range calculator that you can download from here: http://www.ti.com/lit/zip/sbac137

    It should help you set the appropriate supply voltages for a given input signal. For example, if know that AINN will be set to 0V, try using AVDD = 4V, AVSS = -1V. With an external 5V reference and PGA = 1V/V, AINP would be able to swing from -0.7V to 3.7V.

     

    Best Regards,
    Chris