Part Number: DRV11873
Hello,
We are currently investigating field failures of a BLDC motor driver used in a water purifier application.
During our root cause analysis, we monitored the input/output waveforms to identify potential noise or surge issues. We observed an intermittent abnormal start-up current behavior during a 3-day continuous stress test.
1. Observation:
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Normal Operation: Start-up current typically peaks at 1A (Max) for 0.05s.
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Abnormal Issue: During repetitive testing (3 occurrences over 3 days), the 1A (Max) peak current duration extended to 0.5s.
2. Technical Analysis: Based on the waveform measurements, it appears that the FETs remain in a conducting (ON) state for the full 0.5s duration during start-up. We suspect that this extended high-current state leads to thermal stress and eventual FET burnout, which aligns with the field failure symptoms.
3. Requests:
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Please review the attached start-up current waveform and confirm if this duration (0.5s at 1A) falls within the acceptable operating range for the device.
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Could you provide a technical analysis of the conditions or internal logic states (e.g., stall detection, gate driver behavior, or BEMF sensing issues) that might cause such an extended start-up current duration?
Please refer to the attached waveform files for more details.
Best regards,
