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TPS54821: low resistance between PH and GND

Part Number: TPS54821
Other Parts Discussed in Thread: TPS54620

Hi team,
we recently discovered one faulty piece of TPS54821 after some time of operation. Behaviour is that DCDC does not work and PH pin seems to have 0.6Ohm to GND on un-powered board (same measurement on OK board shows >1k). High side switch seems to still be working (scope shows normal waveform to feed inductor from Vin). Thermal camera images shows very quick heat up of the chip upon power-up.  We are using mode of operation similar to this (constant current source based on PWM applied to VF pin, just DCDC PN is different):

Could you think if any mode of operation (enable, disable, ...) would case a stress on the circuit? We basically want to ensure that this was just a random part failure, not a design/software control issue.

Kind regards,

Petr