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CCS/LM34936: output capacitor of LM34936 decide the PD charge normal or not

Jianping
Intellectual 550 points
Part Number: LM34936

Tool/software: Code Composer Studio

Hi,TI's expert:

  we're run into a trouble for the output capacitor choose.

becuase it's PD charge fail on Dell_5370(inrush issue,see the capture) when using low ESR(30mR) capacitor,special the temperature rise to 57°C.

it work normal when the temp fall to 38°C.

if change the capacitor to tantal capacitor( higher ESR.900mR),it'sn't impact by temperature.

but can't support large current (ie:lenovo Y900K,20V/5A)of  PD charge handshake. must change to low ESR capacitor(30mR)be normal.

i tried tune the RT/SYNC pin and SS pin on LM34936,but get the result didn't compatibility them（Dell_5370 and Lenovo_Y9000K).

and change the Coil(4.7uH) or change the DC input( original adaptor 19V/8A) to 22V.  these solution don't cover them(two type NB).

as below circuit show to you reference.kindly advise you give me some comment or solution for the issue.

thanks!

  • 0
    TI__Mastermind 21720 points

    Hi Jianping,

    Thanks for reaching out with your question and for using the LM34936.

    What is the inrush current level are you trying to be below? Also can you please zoom in on the inrush current and probe the following pins of the LM34936 {COMP, SS} along with the input current and the output voltage?

    Thanks,

    Garrett