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LMR36015-Q1: Behavior when bootstrap capacitor is open

Part Number: LMR36015-Q1


We are using the LMR36015FSC3-RNXQ1 to generate 3.3V. Our client is requesting us to do measurements with failure injection. Among other, we have to test the open mode failure of the bootstrap capacitor.

I have desoldered the bootstrap capacitor from out PCB, but the DC/DC converter is still functional, it produced around 1.63V on the output with a 3.3 Ohm resistive load, the switching frequency is around 5.5MHz. See below my measurements.

What should be the expected behavior if the bootstrap capacitor fails open? I would have expected the DC/DC to no longer switch the output because there is no power supply available for enabling the high-side MOSFET inside the converter. Not shown in the measurements, but during the tests, PG is LOW.