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ADS1113: No output from device

Marvin Gasis Arcangel
Genius 9475 points
Part Number: ADS1113

Hi Experts,

A customer is having trouble using this part for their design.

If they set the address to 0x48/0X49, the part works well, but if they connect the address to SCL/SDA (0X4A/4B), the part doesn't work.

In the datasheet, there is a note stating: "Use the GND, VDD and SCL addresses first. If SDA is used as the device address, hold the SDA line low for at least 100 ns after the SCL line goes low to make sure the device decodes the address correctly during I2C communication."  The customer have 700nSec between SDA and SCL > 100nSec but still, there is no output from ADS1113.

I attached two pictures for reference.

I hope you can help to solve the issue.

Regards,

Marvin

  • 0
    TI__Mastermind 22950 points

    Hi Marvin,

    SDA needs to be held low for at least 100ns after SCLK goes low. In the scope image, SCL is the yellow trace, correct? If so, we need to check the time from the first falling edge to the first rising edge of SDA. So the cursor on CH. 4 needs to be moved over to the first rising edge of SDA. Eyeballing it, it looks like it should be okay but it would still be good to measure. 

    Additionally, the schematic shows two 10kohm resistors on the ADDR pin. I assume this is there to check the address when pulled high and low. Are these resistors populated when the ADDR pin is connected to SDA?

    Regards,
    Aaron Estrada

  • 0 in reply to Aaron Estrada
    TI__Genius 9475 points

    Hi Aaron,

    Thanks for the support. Here is the update from the customer:

    I sent you the schematics that by default address was connected to the SDA, the two 10K ohm resistors were not populated (N).

    And in this case that address was connected to SDA, although even we hold the SDA line low for at least 100ns after the SCL line goes low, it doesn’t work.

    Address=SDA  -> (~500ns)

    What I don’t understand is why if I do rework and connect the SCL to the address, it still doesn’t work!!?

    Address=SCl  -> (~440ns)

    Only if I do rework and we connect pull up or pull down to the address, the device start working well.

    I hope to hear from you soon.

    Regards,

    Marvin

  • +1 in reply to Marvin Gasis Arcangel
    TI__Mastermind 22950 points

    Hi Marvin,

    Thanks for your response. We will take this offline for now. 

    Regards,

    Aaron