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LMR14203: Device shutdown above 60C

Part Number: LMR14203

Hi Team,

We have received this inquiry from our customer,

I have designed the LMR14203X into a prototype board and it's shutting down above 60C ambient.  It will restart once cooled to 22C, so I'm probably tripping its internal shutdown.  In reviewing the part selection, the output cap is not a low ESR electrolytic.  Its actually 0.7 ohms esr much greater than the web-bench rec.  While I await the correct part to try, do you think this is the source of my problem?  Note that my load is 150mA, part designed for 18-28V DC IN, 15.5V DC Out.  Also, my inductor may be too high (220uH versus 120uH).  Output cap is 68uF.  

Upon checking the PCB layout, I noticed that the components such as inductor, output capacitors and other major parts are not properly laid out. Can you please confirm if there are other causes of the issue?



  • Hi,

    Thank you for providing the schematic and layout for your design. It looks like your design may hit somekind of current limit and shrink the duty cycle.

    Here are my comments on your design:

    1) Make sure that the 220uH inductor does not go into saturation at your maximum current

    2) Check the diode D9, the diode looks quite small and it has to be schottky diode

    3) Shorten routing of bootstrap capacitor C20, and use larger traces from SW pin to the inductor

    4) Is there anything downstream that may pull more current at higher temperature? Or something that causes the LMR14203 to hit current limit?

    5) You may want to put the output capacitor ground closer to the IC. Or at least put a ceramic capacitor from VOUT to GND near the inductor 

    You can take a look at this user guide for layout reference

    Thank you


  • Hi Arif,

    Thank you for your insights. Here is our customer's feedback.

    1. The inductor is not 220uH (it was originally, but we reduced it to 68uH) and the pics correspond to 68uH and 68uF (you are looking at the art of the original board, new L & C were kluged in trying to overcome this shutdown issue).  It is a shielded inductor from Coilcraft MSS1048-683ML with a saturation current rating from 1.28A to 1.7A.  The CAP was changed to a 68uFx50V OS-CON type (low esr), but it was too difficult kluging the second in.

    2. Diode D9 is a Schottky rated for 40V and 1A, Central Semi CMPSH1-4L

    3. I will ensure this is done in rev B of board.

    4. The load was a fixed electronic load that we set the maximum on.  The part still shuts down at much lower currents (as low as 20mA).  The in-circuit load is ~160mA MAX and very well-defined (8 0-20mA current mirrors).

    5. I will review this in rev B.

    Thank you for your help.  Also, very disappointed that we suddenly can’t buy most TI parts, which makes it difficult to design you in (The LM14203X here is NA for > 1 year).



  • Hi Danilo, 

    Do you know if the part can pull 150mA at room temperature? 

    You can also try to put an input ceramic capacitor around 1uF directly at pin 5 and 2 (VIN and GND) and see if that helps

    Yes, just like most of the semiconductor industry, supply issue is quite challenging. 

    Thank you


  • Hello

    I will close this post due to inactivity


  • Hi Frank,

    The customer will switch to another device due to the long leadtime of LMR14203X. Thank you for your support!