• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 64 subscribers
  • Views 160 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.

TPS3808: Reset Timing formula related issue

Miteshkumar Dalabhai Patel
Intellectual 2260 points
Part Number: TPS3808

Hi Team,

One of my customer is using TPS3808 for their design & they have raised the queiry related to Ct calculation formula.

As per datasheet, foprmula is given as 

Now as per the formula if we use 131pF in design then reset timing is  1.25mS so if we consider the statement that Ct >= 100pF is wrong. If we use 100pF in design then reset timing will be well less than 1 mseconds, can you help calrify why formula is not matching with the mentioned capacitor values?

Mitesh

  • 0
    TI__Expert 6060 points

    Hi Mitesh, 

    Thank you for your question and thanks for pointing out this inquiry. 

    I checked with my team and the equation is correct, and that is a typo in the EC table. 

    You can also use TPS3808E datasheet since it is P2P with TPS3808. 

    I hope this helps!

    Best,

    Sila

  • 0 in reply to Sila Atalar
    TI__Intellectual 2260 points

    Sila,

    There is no change in equation and the EC table in both the device datasheet, even if any changes TPS3808E is also not matching.

    We are saying that CT value has to be equal to or grater than 100pF and for the programmable timing range is given as 1.25mseconds as min. typical. If we calculate using the formula mentioned then capacitance comes out is 131pF. That means value of CT has to be grater than 131pF not the 100pF.

    Pls. Clarify.

    Mitesh

  • 0 in reply to Miteshkumar Dalabhai Patel
    TI__Expert 6060 points

    Mitesh,

    I understand the confusion and want to let you know that we are looking into this. What I learned from my team is we will look into the EC table value, and change the datasheet in the next revision, and the equation is correct so that you can use it to calculate the cap value.

    Can you please tell me what is your delay requirement? Is it 1.25ms?

    Regards,

    Sila