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TPS560430: TPS560540YQDBVRQ1

jie liu
Prodigy 30 points
Part Number: TPS560430

Hello,

During our test, I found power efficiency is very low and only up to 20%. Vin=13.5V, Vout=3.3V, Iload_nor=20mA, Iload_max=60mA.

Baesd on datasheet, efficiency should be up to 65%. I also did a simulation with inductor using Murata dc-dc convert tools. The results

showed efficiency is about 89%. More strangely, based on my test data, the SW frequency is 1.022MHz but TPS560540YQDBVRQ1 frequency should is 2.1MHz based on datasheet.

Pls find my SCH design and test data,  help to check what happened and how to improve it.

TPS560430_efficiency_issues.pdf

  • 0
    TI__Genius 13735 points

    Hi, Jie,

    Looking from your package this is YQ version ,at light load the device work in PFM mode with high efficiency and frequency drop, the SCH looks good, only the inductor is a little large, 4.7uh around should work.The waveform of SW is not stable, could you also try increase to 100mA, your point is 20mA. Also, compare the layout with EVM, and make sure your measurement point is right, voltage of Vin /Vout from the Vin/Voucap , input current measure is right.

    Elena

  • 0 in reply to Elena Gao
    Prodigy 30 points

    Hello Elena,

    Thanks for your support.

    I will try to change a little inductor. for the light load, I'm confused about how to select inductor. Do you have some recommendation about it?

    Baesd on the formula of datasheet, Lmin is very big at light load.

    in addition, I'm confused about frequency drop. How to ensure frequency stable and does't drop?

    Thanks in advance. 

  • 0 in reply to jie liu
    TI__Genius 13735 points

    We have a webench tool for you select inductor, use 36V 0.6A for TPS560430 for calculation.

    Frequency drop of PFM mode please read in DS part PSM mode. this happens in light load for improve the efficiency.

    Elena