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ads13108: avdd vs avdd1, Charge pump block

Hector Martinez
Prodigy 20 points

I am having trouble understanding what is the purpose of AVDD1 and AVSS1.  In the datasheet it says;

"AVDD1 provides the supply to the charge pump block and has transients at fCLK. Therefore, it is
recommended that AVDD1 and AVSS1 be star-connected to AVDD and AVSS."

Is this to provide other internal voltage in the case that analog voltage supply is less than 5 volts?

1. Is it a feature we could use or not use? 

2. How do we connect the pins if we don’t use it?

3. How do we connect the pins if we do use it?

Thank you for your time and help.

  • 0
    TI__Mastermind 38745 points
    Hello Hector,

    1. The internal charge pump will be activated no matter what. You cannot disable it and the device will not operate without it.

    2. N/A

    3. Basically the idea is that you don't want to expose the other AVDD/AVSS inputs to the transient noise from the AVDD1/AVSS1 inputs without putting some decoupling in between. The way to think about it is that you want to branch to AVDD and AVDD1 from the source separately and decouple the supplies respectively after the branch rather than just decoupling all with one set of capacitors.

    I hope this makes sense.

    Regards,
    Brian Pisani
  • 0 in reply to Brian Pisani
    Prodigy 20 points
    Thank you for the reply and your time. This helps me better understand and move forward with my project. Thank you.