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ADS7828: ADS7828 resolution output

Blaz Jakob
Prodigy 60 points

Part Number: ADS7828

Hi, everyone.

I am using the IC ADS7828EB for ADC. It in the single mode with the external reference voltage of 3.3V, and COM connected to GND. My problem is when I set command byte for ch0 or ch1 with internal reference voltage OFF of and ADC conversion ON, the input does not sense correctly. An always get the value between 3200 and 3400 bits on I2C bus. It doesn't matter if the input voltage is 0 or 3.3V on the channel.   

Please advice.  

  • 0
    TI__Expert 3805 points
    Hi Blaz,

    What values are you sending as "Write Addressing Byte" and "Command Byte"? Here it is important to keep the bit PD1 = 0.
    Could you please provide a digital scope shot of the I2C bus when reading data from the ADC?

    Thanks.
  • 0 in reply to RahulVK
    Prodigy 60 points

    Here is the picture. Now the write address is 0b10010000 and the read address 0b10010001. I am calling the ch0 on this example with the external reference voltage of 3.3V (Vcc = 3.3V main power) and COM connected to GND.