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LM25088: LM25088 power up stability issue

Part Number: LM25088

I have a power up stability issue with the LM25088MH-1. The input is +20 V, output is 6.7V, current is 4.5A, switching frequency 1 MHz and frequency dithering is enabled.

Failure was observed intermittently while the unit was hot +50C.  During power up the output voltage was 4.3V instead of 6.7V. I can reproduce the issue by slowly ramping up the +20V input at room temperature. If I disable dither, it consistently fails.

I am not able to reduce the failure if I reduce the switching frequency to 532 KHz. Could the stability issue be due to operating at the maximum switching frequency?

  • Hello, to best advice you, please share:

    steady-state osccilloscope captures of (VIN,VOUT, SW)

    schematic, layout, and BOM

    I am not able to reduce the failure if I reduce the switching frequency to 532 KHz. Could the stability issue be due to operating at the maximum switching frequency?

    Loop response changes with switching frequency. Device stability could be affected.