• State TI Thinks Resolved
  • Replies 2 replies
  • Answers 2 answers
  • Subscribers 64 subscribers
  • Views 42 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

Original question:

UCC21755-Q1: Gate drive signal problem

UCC21755-Q1: About UCC21755 VDD cap slection

Gabriel Wang1
Genius 4325 points
Part Number: UCC21755-Q1

Tool/software:

Dear Expert

Use UCC14141 and UCC21755. UCC21755 requires VDD to add at least 10uF to COM. For UCC14141, when the capacitance between VDD-COM is 10uF, VEE-COM needs to add 50uF.

The current question is whether the capacitance between UCC21755 VDD-COM can be reduced to 2.2uF. There is still 2.2uF near UCC14141, and an additional 10uF will be added near UCC21755 VDD-VEE? Configure as shown in the following figure
Drive frequency 70kHz, Qg 600nC.

  • 0
    TI__Expert 4908 points

    Hi Gabriel,

    Thanks for reaching out. Our expert is currently out of office, and we'll get back to you before end of day tomorrow US central time. Appreciate your patience and understanding.

    Best,

    Pratik

  • 0
    TI__Expert 5070 points

    Hi Gabriel, 

    With this switching frequency and Qg, I believe the risk is small by using 2.2uF on VDD-COM of UCC21755. The capacitor recommendation is in place to make sure the supply rails stay stable when switching. If during testing, the ripple on VDD is acceptable and does not affect normal device operation, then the system is ok. 

    Be sure to put small decoupling capacitors (~0.1uF) as close to the power supply pins as possible. 

    Thanks, 

    Vivian