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L5987A Regulator Noise and Voltage issues

LLawr.1
Associate II

Hello,

I am using an L5987A voltage regulator to power a ublox LISA-U200 cellular module as specified in the LISA-U200 integration manual on page 23, figure 7. I have been having issues regarding high noise under load and completely incorrect voltages after operating for some time, as much as twice the expected output voltage, and this behavior has seemingly been killing some LISA-U200 modules. I have two PCB designs, V1.2 and V1.3. V1.2 boards work as expected, without any issue, but V1.3 boards have the above issues, and there is little change between the two boards with regards to the PCB layout. Any ideas as to why this may be happening?0693W000004IrJXQA0.png0693W000004IrJNQA0.png0693W000004IrJ8QAK.png0693W000004IrIyQAK.png

1 REPLY 1
Peter BENSCH
ST Employee

Hi, @LLawr.1​,

I'm sorry that I've only seen this question after such a long time.

Have you solved the problem in the meantime or can I still help?

Regards

/Peter

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