• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 30 subscribers
  • Views 428 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.

TM4C123GH6PGE: VDD and VDDC Decouple caps flexibility

yihe
Guru 63780 points
Part Number: TM4C123GH6PGE
Other Parts Discussed in Thread: EK-TM4C123GXL

Hello Champs

We have a customer follow the old Stellaris® LM4F232 Evaluation Board design, please refer the below snapshot from LM4F232 Guide(spmu272.pdf)

They are looking to use 0201 caps so they can place as close to these pins but they are only using one type of 0201 caps on this project, 4.7uF 6.3V cap. 

Is it ok to replace below 3x1uF and 2x1uF decoupling caps with a single 4.7uF cap respectively? 

I do not think it shall be a problem but wanted to confirm from you before getting back to customer?

Regards

Yihe

  • 0
    TI__Guru 72500 points

    On the LM4F232 Evaluation Board those capacitors are 1.0uF 25V 10% X5R 0603. On the EK-TM4C123GXL LaunchPad the capacitors are , 0402, X5R, 10 V, Low ESR. Two things besides total capacitance are to be considered. Voltage rating. 6.3V is minimum for the 3.3V supply. (Higher would be better.) The other is ESR. You get a lower ESR using multiple smaller capacitors in parallel. 

  • 0 in reply to Bob Crosby
    TI__Guru 63780 points

    Hello

    Thank you.  Will it impact the normal operation? if you do not recommend this, what's the best reason to convince them?

    Regards

    Yihe

  • 0 in reply to yihe
    TI__Guru 72500 points

    They need to evaluate the Equivalent Series Resistance (ESR). If it is the same or lower, then OK. They also need to evaluate the risk of only 80% margin on the capacitor voltage. We used a larger margin in our designs. I don't see any big problem, but they must evaluate their design and make decisions based on their requirements.