• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 46 subscribers
  • Views 1337 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

ADC128D818: I2C ADDRESS A1/A0 STATUS IF MAKE THESE TWO PINs JUST OPEN

Iven Xu
Intellectual 2090 points
Part Number: ADC128D818

Dears

Here just would like to check with product line about the I2C address A1/A0 (pin8/pin7 of ADC128D818) status if just let these two pins just open without any connection?

Please help check if there is any weak pull down or pull up of these two pins internally of ADC128D818?

Whether these two pins is fix H or L during the open without any connection?


thanks.

Best Regards

Iven

  • 0
    TI__Guru**** 181091 points
    Hi Iven,

    The structure of the A0 and A1 pins in the ADC128D818 are shown on page 4 of the datasheet. Beginning on page 17, section 8.5.1.1 (and Table 2) there is a description of how the address pins should be configured. There are also examples in Figure 38 and Figure 39 that provide flexible options. If you want to set a specific address, you should either pull up or down the pins, or use a resistor divider to set the mid supply level. Leaving the A0 and A1 pins float is not advised.
  • 0 in reply to Tom Hendrick
    TI__Intellectual 2090 points

    Hi Tom,

    thanks for your response. 

    yes, I do understand how to do the configuration through the datasheet. 

    the main reason why ask this question is that customer have made a mistake on the I2C address configuration and just left open. Have suggested customer modify the PCB in the next version. 

    But I am thinking about whether the status might be a fix H or L if left A1/A0 open based on the IC design internally, so that they can do the software development with system level debug. just for debug.

    If no fix status at this condition, then I will let customer add fly resisters on the board to configure the correct address. thanks.

    Best Regards

    Iven 

  • 0 in reply to Iven Xu
    TI__Guru**** 181091 points
    Hi Iven,

    The address lines are 'latched' when the ADC128D818 does its internal power on reset. Without fixed voltage levels on A0/A1, you won't be able to guarantee that the same I2C address is latched into the device each time you power up. There is no 'fixed' default address in the ADC128D818.