• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 373 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

ADS1118: Is the weak pull-up overdriven by DOUT/DRDY output pin driver when CS is LOW

Randhir Kalsi
Expert 4545 points
Part Number: ADS1118

Hello team,

Hope you are well. Would you be able to help out with customer question below: 

When the CS input is LOW I am assuming that the DOUT/DRDY signal drives both HIGH and LOW. (complementary output drive in both directions)

This would seem to be the standard way to doing things but when I read the PULL_UP_EN section of the “Table 7 - Config Register Field Descriptions” I became a bit confused over the sentence: “This bit enables a weak internal pullup resistor on the DOUT/DRDY pion only when the CS is high.”

I am assuming that when CS is LOW the weak pullup is overdriven by the DOUT/DRDY output pin driver.  Is this true? 

I am also assuming that the weak pullup is made available so that it keeps the DOUT/DRDY signal PCB trace from floating when the ADS1118 is an idle not transmitting data.

  • 0
    TI__Guru* 95195 points

    Randhir,


    The weak pull-up resistor is enabled only when /CS is high. Without the weak pull-up, the DOUT/DRDY is normally in a high-Z mode and could potentially float high or low.

    When the /CS pin is low, the DOUT/DRDY actively drives the output high or low, without the use of the pull-up.


    Joseph Wu