• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 406 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.

TPS23754 capacitor and VDD

PAN-M
Mastermind 8375 points
Other Parts Discussed in Thread: TPS23754EVM-383, TPS23754

Hi

In TPS23754EVM-383, may I change C10 capacitor?
eg. 0.1uF -> 0.047uF

And, may I connect  VDD to VDD1 line?
(D3 cathode)

Regards,
PAN-M

  • 0
    TI__Mastermind 42795 points

    D3 (and C25) is needed when a PoE preference (with adapter present) function is desired. If this is not the case, then D3 can be omitted with a connection of VDD1 to VDD.

    The standard requires the PD input capacitance to be between 0.05uF and 0.12uF. This will typically include C10 + C9 + Cbs / 2 (Cbs is the value of the line termination caps in the J3 connector). So, if Cbs=0.01uF then the total input capacitance is 0.047 + 0.001 + 0.01 / 2 = 0.053uF which is close to the low end.

    C10 also provides protection for U1 so ensure that the 0.047uF is located close to U1.

  • 0 in reply to Eric Wright
    Mastermind 8375 points

    Eric-san

    Thank you for answer.
    Please let me know a little in more detail about D3.
    "Removing the short at CL1 allows certain power source priority schemes to be tested" is written In SLVU301 EVM User's Guide,
    Is D3 necessary for PSE?

    Regards,
    PAN-M

  • 0 in reply to PAN-M
    TI__Mastermind 42795 points

    Hello,

    Please refer to the TPS23754 datasheet description on page 31 as well as the application report, SLVA306A (start on page 5) which describe the usage of Dvdd (D3 on the EVM).