• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 63 subscribers
  • Views 980 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.

TPS54302: TPS54302 design question

Jason Hu27
Intellectual 910 points
Part Number: TPS54302

Dear Sir, I have some question about the TPS54302. Please refer to below Figure. Does C3(0.1u Bootstrap Capacitor) can be change to 0402 size? Because on TI EVB, the C3(0.1u Bootstrap Capacitor) is 0603

size. How wide for PCB Layout trace from TPS54302 to C3(0.1u Bootstrap Capacitor) is suitable? Second question,can I delete the R1(49.9 Ohm) on my schematic? Final question, If I want to reduce EMI

interference, what the switching frequency of DC/DC Buck is suitable? The lower switching frequency of DC/DC Buck(such as TPS54302) is better than higher switching frequency of DC/DC

Buck(the grade of switching frequency is MHz)?  Thanks.

  • 0
    TI__Genius 9550 points
    Hi Jason Hu,
    1. C3 can be used 0402 size
    2. 20 mil is ok
    3. yes you can delete R1
    4. optimize your layout can reduce EMI; lower EMI also can reduce EMI. If your application is very sensitive for EMI, suggest to add snober circui (Add RC at SW note to GND)
  • 0 in reply to Jason Wang (BSR-MV)
    Intellectual 910 points
    Dear Jason, Thanks for your reply. About question 4, you mean the lower switching frequency of buck can reduce EMI? Some documents suggest to select 500KHz to 700KHz switching DC/DC device on high voltage applications(such as output voltage is higher than 12V). But TI has some DC/DC device that switching frequency is about MHz. The higher switching frequency can reduce external passive components' size and improve current ripple, but will increase switching lose. If I select lower switching frequency DC/DC device, what's the benefit I can get? Lower switching frequency will increase external passive components' size and cost but it can reduce switching lose. Thanks.
  • 0 in reply to Jason Hu27
    TI__Genius 9550 points
    hi Jason Hu,
    All the selection is the result of trade off.
    you are right:
    The higher switching frequency can reduce external passive components' size and improve current ripple, but will increase switching lose;
    Lower switching frequency will increase external passive components' size and cost but it can reduce switching lose.
    So how to select Fsw, depend on what you are care.
  • 0 in reply to Jason Wang (BSR-MV)
    Intellectual 910 points
    Dear Jason, thanks for your reply.