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ADS9227: AVDD_1V8 and DVDD_1V8

Urs Probst
Intellectual 290 points
Part Number: ADS9227
Other Parts Discussed in Thread: ADS9218

Tool/software:

Hi TI-Team

The datasheet of the ADS9227 mentions AVDD_1V8 and DVDD_1V8 supply pins, but it is not clear which of the VDD_1V8 pins belong to analog and which to the digital supply. Looking at the "big brother" ADS9218, it seems that pin 13 and 37 are AVDD_1V8 and pins 14, 35 and 36 are DVDD_1V8. Is that correct?

Question: Would it not be advisable to separate the two 1V8 supplies by at least a ferrite bead or even an own LDO for each of the two? In the datasheet all 1V8 supply pins are connected together.

Thanks and best regards,

-Urs

  • +1
    TI__Intellectual 1620 points

    Hello Urs, 

    Thank you for your question. We have found that performance wise there is not need to separate these supplies nor have a ferrite bead between them, they can all be grouped together, hence the new naming convention of VDD_1V8. As long as both groups of VDD_1V8 (pins 13 &14 as well as pins 35-37) be decoupled like shown in Figure 8-10 on the datasheet, it should work as expected. 

    Best regards, 

    Yolanda