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.

ADS1299 SCLK Voltage level

Other Parts Discussed in Thread: ADS1299

Hi,

I'm using the ADS1299 with a bipolar analogic power supply (+2.5,-2.5V) and a 3.3V digital power supply, as suggested in the datasheet. A microcontroller, also powered by a 3.3V powe supply, is in charge of the SPI communications. I observed the SCLK signal with an oscilloscope and I found that the voltage level was not 3.3V but approx. 1.5V. I didn't find a short circuit in the PCB. I've tested the microcontroller, and the SPI work fine; the problem comes when I connect the ADS1299. I've checked the design and apparently everything is according to the datasheet. Do you have any idea of what I am doing wrong? Thank you in advance.

Juan Manuel.

  • Hola Juan,

    Thanks for your question.

    Just to be clear, when you probe the SPI pins from the microcontroller (without connecting the ADS1299) all signals measure 0V - 3.3V? But only the SCLK is attenuated to 1.5V upon connecting the ADS1299?

    It's not immediately clear what might be causing this. Are the microcontroller and the ADS1299 DVDD referenced to the same ground?

    Saludos,

  • Hi Ryan,

    Yes, you're right, all the signals are 0V-3.3V but only the SCLK is attenuated. The digital ground is the same for the microcontroller and for the ADS1299.