Tool/software:
Hi,
We are currently evaluating the AMC1351 for use in our design, and during initial prototyping we have observed device failures. We would like to ask for your guidance regarding our circuit implementation and possible countermeasures.
Questions
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Could you please review our circuit configuration and confirm if there are any issues that might cause device damage?
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If there are known precautions or recommended countermeasures, could you kindly advise us?
Background
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Application: Isolated transmission of an external 0–5 V analog signal from a variable resistor to a microcontroller.
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Configuration:
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Input side: VDD1 = 5 V
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Analog input: 0–5 V (generated by 10 kΩ variable resistor, but during some tests a 1 kΩ resistor was used)
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Output side: VDD2 = 5 V (galvanically isolated from VDD1)
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Outputs VOUTP and VOUTN connected to MCU input
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Observed Failures:
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The device failed with an internal short between VDD1 and GND1.
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No short observed between INP and GND1.
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Failure Cases
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First failure:
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Test circuit without output RC filter (1 kΩ + 0.01 µF).
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Device had worked the previous day.
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Upon powering VDD1, the bench supply went into current limit and shut down.
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Post-inspection: internal short between VDD1 and GND1.
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Second failure:
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New AMC1351 installed, with output filter added (1 kΩ + 0.01 µF).
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Powered with limited current on input side only (VDD2 was OFF).
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Worked initially, but after 3–4 ON/OFF cycles of VDD1, the supply again went into current limit.
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Post-inspection: internal short between VDD1 and GND1.
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At this time, the input voltage from the variable resistor was set to maximum (minimum resistance).
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We would greatly appreciate your advice on whether our use conditions are within the safe operating range of the AMC1351, and what protective measures (such as input current limiting, sequencing requirements, or filter considerations) you would recommend to avoid this type of failure.
Best regards,
Conor