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ADS114S08: 3V0 powering issues (3V3 OK)

Jan Chalupa
Prodigy 20 points
Part Number: ADS114S08
Other Parts Discussed in Thread: CC2652P

Tool/software:

Dear Mr./Mrs.

I have encountered problematic behaviour with different voltage supply. Design was made with 3V0 linear regulator but ADS wont start and its function of SPI seems stucked. When i use 3V3 regulator instead, everything runs normal (ads setup measurement biases etc.)

At the power up of the whole device, reset pulse is issued and than waiting few milliseconds to request device ready state over SPI communication and it always fails. (3V0 regulator)

When 3V3 regulator used, the same sequence results in successfull device ready bit reading.

Both ADS and uC(cc2652p) are supplied from the same 3V0 or 3V3 rail. SPI mode selected according to datasheet (CPOL0 CPHA1)

Few experiments were carried out (startu up timing, reset etc.) always fail with 3V0 supply.

schematic included

Looking forward to your response. Thanks!

  • 0
    TI__Mastermind 41631 points

    Hi Jan Chalupa,

    Can you try removing the inductor from AVDD, replace with a 0ohm resistor or otherwise short the pads together, and try again with the different power supplies? Also, you can try with a bench supply instead of the LDOs just to make sure there is not an issue with the power supply circuit.

    You should also add a pull-up to DVDD on RESET so the ADC starts in a known state

    -Bryan