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TPS54331EVM-232: TPS54331EVM-232

Hale Tan
Expert 3160 points
Part Number: TPS54331EVM-232

Hi! I have some question about TPS54331EVM.

Q1: When I test TPS54331EVM-232, output ripple doesn't look like User Guide providing waveform. What's wrong with it?

                                            

my test(Green: DC output voltage; Yellow: output ripple; Purple: Output current; Blue: SW or PH node)                                                                             User Guide

Q2: The output voltage has large glitches.

Q3:When I test TPS54331EVM-232 Eco-mode, the output current is unstable .There is oscillation at SW(PH) node and it does not decrease to 0V. Is this normal?(Green: DC output voltage; Purple: Output current; Blue: SW or PH node)

 

Q4:When I test Slow Start mode, it works as shown in the image below. Why?(Green: DC output voltage;  Purple: Intput current)

  • 0
    TI__Expert 8100 points

    Hi Hale,

    My colleague Ruby will give you response by tomorrow!

    BR

    Zixu

  • 0
    TI__Expert 7430 points

    Hi Hale

    Sorry for the delay.

    I would like to confirm some details here: 1. did you change anything on the EVM? 2. When testing the output ripple, did you use the smallest test loop?

    Regarding Q1 and Q2, the switching noise is coupled to the output, did you use full bandwidth to test the ripple? and a smallest test loop may help here.

    Regarding Q3, what is the load current of your test? There is some current point where multipulse may happen. "it does not decrease to 0V", this is because that both high side and low side FETs are turned off, the PH voltage is equal to Vout.

    Regarding Q4, would you please do me a favor to capture the input voltage and also check the set up of the DC source, I think this may be related to the slew rate and the initial voltage setting allowing power flow of the DC source.

    Hope this helps.

    BR

    Ruby

  • 0 in reply to Ruby Li
    TI__Expert 3160 points

    Hi, Ruby! Thanks for your reply.

    I didn't change anything and I test output voltage ripple  with a ground ring.

    And I use full bandwidth to test the ripple, bandwidth is 350Mhz. I can choose 20MHz, and output voltage don't have voltage burrs. But I am not sure whether the actual output voltage has burrs .

     

    As for multipulse, I know little about it. Could you tell me something more about it?  And what is its characteristic? "the PH voltage is equal to Vout",thanks for your explanation, and I'll test PH voltage again.

    Regarding Q4, I'll test it again later. "Capture the input voltage and also check the set up of the DC source,"

  • 0 in reply to Zixu Wang
    TI__Expert 3160 points

    OK, thanks for your reply