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DS90UB935-Q1: PDB RC network selection

Jiawei Hu1
Expert 5555 points
Part Number: DS90UB935-Q1

Hi team,

For UB935 PDB delay, TI recommend RC network to make it. From reference schematic, the value of Cap is  >10µF, but from 9.2, the value of Cap is 1µF. My question is can I use 1uF cap for fast start up requirement? If not, do we have the recommended value? How about 2.2uF? Thanks!

 

BR

Jiawei

  • 0
    TI__Expert 5555 points

    Hello team.

    Pls give feedback today, Byd are pushing this. Thanks.

    BR

    Jiawei

  • 0 in reply to Jiawei Hu1
    TI__Mastermind 23555 points

    Hi Jiawei,

    I believe an older datasheet is being referenced in the pictured portion of section 9.2 Power Down from the datasheet. This was corrected to list the capacitor as being greater than 10uF. The DS90UB935 datasheet is currently on revision B. 

    Regarding capacitor values, the device requires PDB to go high after VDD18 becomes stable. The RC represented in the datasheet are the recommended values to ensure proper power up sequencing. These values can be lowered to 1uF or 2.2uF if the the power up sequencing is confirmed to be met in the system context. 

    If you are using software to control the status of the PDB pin, you do not have to change the cap. Just ensure that the power up sequence is being followed. 

    Let me know if any further clarification is desired.

    Best,

    Zoe