Part Number: LMX2594
Dear TI Support Team,
I am currently using the LMX2594 in a frequency multiplication application and have encountered a critical issue. The device gets damaged immediately upon power-up, before any register configuration is performed.
The following measurements have been taken:
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VCC measurement: During power-up, the VCC voltage cannot reach the nominal 3.3V, measuring only approximately 2.6V.
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Supply current: With a 5V input, the combined current drawn by the OCXO and the LMX2594 is only 700mA, which remains below the LDO’s maximum rating.
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Internal LDOs: The measured voltages on various internal LDOs are incorrect compared to the expected values.
At this stage, no SPI commands have been sent to the device, and yet the LMX2594 appears to be damaged. Given these observations, I would appreciate your guidance on the following:
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Could the insufficient VCC voltage during power-up be responsible for damaging the device?
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Are there any known startup timing or inrush current characteristics that could explain the observed behavior?
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What are the most likely design issues that could cause such a failure, particularly regarding power supply decoupling, layout, or the connection between the OCXO and the LMX2594?
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Do you have any specific recommendations for debugging the internal LDOs to identify the root cause?
I have attached the relevant section of my schematic for your reference. Please let me know if additional information or measurements would be helpful for the analysis.
Thank you very much for your time and assistance.
Best regards
