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Original question:

ADCS7476: About Read access

ADCS7476: digital Data maxing out at middle of the voltage range

Darshan K
Prodigy 10 points
Part Number: ADCS7476

Tool/software:

Hi,

The ADCS7476 which I have is giving data as expected. To test the SPI signal, I have connected a variable power supply which can vary from 0 to Vdd(3V). The digital data which I am getting is double the corresponding applied voltage. I have verified the data recieved with a logic analyser as well and still I see that The received 12bit data is  doublt the voltage value applied at Vin. At 1.5V it is showing max value i.e. 4095 and then starting from zero to 4095 from 1.6V to 3.3V. I have replaced the chip and still am getting the same result. 

The pcb design is done as per the reccomendations in the datasheet. Can someone explain why it is happening that way and what is the solution?

this is the footprint where the chip is soldered

  • 0
    TI__Expert 5510 points

    Hi Darshan,

    Thanks for your question! To better understand your use case, what kind of application are you using this ADC for?

    Is the variable power supply connected to VIN? What is the voltage at VDD? Could you share an oscilloscope or logic analyzer screenshot of the digital pins? Is there a different condition you tried where the data was as expected?

    Best regards,

    Samiha

  • 0 in reply to Samiha Sharif
    Prodigy 10 points

    Hi Samiha,

    Thankyou for the response. Was experimenting with the sensor couple and figured out that the hardware is working well. I hooked up the sensor to an arduino and used the libs provided by arduino to verify.
    The problem was in my firmware and how I was reading the data. Thanks a lot for the quick response tho.