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Original question:

ADS7952: Analog input problem

ADS7952: Analog input problem

xujian huang
Prodigy 20 points
Part Number: ADS7952


Dear :

I have used the ADS7952 to sample  3.3V  but the output only 2.5V ,  the REFP power supply by REF5025IDR (2.5V)  and the VA supply +5V  and i have config  DI06 to Setting input voltage range   5V（range2）  the input voltage below 2.5V can convert succesfully

Should i increase the vref voltage beyond 3.3V so it can sample 3.3V succesfully ?

In other words  does it can sample 3.3V when Vref=2.5V VA=5V and select  range2 ? 

please help me , thanks 

  • 0
    TI__Expert 5575 points
    Hi

    Welcome to TI E2E forum !

    ADS7952 can sample 3.3V with 5V supply and 2.5V reference and when used in Range 2 (2xVREF)
    I would like you to check couple of things

    1. When you are operating in Range 1 or Range 2, please monitor MXO and AINP voltage. If you are not using any signal conditioning block between input signal and the ADC then you should observe same voltage on MXO/AINP pins. Apply 3V at the input and see if you get same voltage on MXO and AINP or not. If you get 3V on these pins then we have to look in to the way you are configuring this device in Range 2

    2. It could be the case that DI06 bit is not getting written properly when you configure device for range 2. Please capture CS, SDI, SCLK pins to see the activity on these pins.

    3. Which mode are you operating in (Manual/Auto 1/ Auto 2). The Range configuration changed in "n" frame gets reflected in conversion result of "n+2" frame. Please refer to device functional mode flow chart given in section 9.4.3 of the datasheet. Please see if you are following this


    Thanks & Regards
    Abhijeet
  • 0 in reply to Abhijeet Godbole
    Prodigy 20 points

    Thanks Abhijeet , i will follow your advice to check out the real problem