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LM2731: Heating/Failing Issues on Start-Up

Intellectual 1940 points

Replies: 3

Views: 235

Part Number: LM2731

Hello Team,

I am working with a customer who is using the LM2731 in their circuit to boost 5Vin to 12Vout. They noticed that they would every now and then have heating issues on their output capacitor, and also have catastrophic failures on the circuit. 

After reviewing the schematic I noticed that their output capacitors did not meet the requirements of the datasheet. 

For the external capacitors they are using a 2.2uF X7R and a 100uF tantalum capacitor in parallel. Since both of these caps are outside of the 4.7uF to 10uF recommended range, could the heat/failing issues be stemming from this?

I was thinking that the heat issue may be related to the ripple current entering the polarized capacitor depending on the cap's max rating, but I am not sure if that would cause failures either.

Any guidance or input would be appreciated here. 

Best Regards, 

JP

3 Replies

  • Any feedback on this?
  • In reply to Javier Palomo:

    Hi Javier,

    From the description above it seems like this has to do with the RMS current rating of the output capacitor. What is the condition that the over heating occurs? Is it just at full load? Is this the x or y option of the LM2731?

    During the case where the output capacitor is overheating, is there any oscillation on the output voltage?

    Thanks,

    Garrett
  • In reply to Garrett Roecker:

    Hello Garrett,

    I am waiting on the scopeshots of the output voltage from the engineer, and I will need to ask what version is used and if it is occurring at full load.

    I'll follow up once I gather that information.

    Best Regards,

    Javier Palomo

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