Do Not Touch Warning

A Cautionary Tale

Sometime in 2017, a major university incorporated our XEM7310 in a sensing lab, offering students real-world engagement with high-tech sensors and the design of digital logic to work with them. After a few field failures, both the educators at the university and the staff at Opal Kelly were concerned with the extremely high failure rate (we typically see none). We collectively reviewed application information and schematics only to find nothing of concern.

Months later, we discussed the project again with the instructors. As it turns out, one of the sensors on their peripheral was an ambient temperature sensor. In order to “stimulate” the sensor, teaching assistants suggested that students “warm their finger” on one of the power regulators on the board, then apply some pressure to the temperature sensor to watch the real time measurement. This turned out to be a bad idea.

The power regulator in question is a very small, very high-efficiency switching regulator. The light touch from a student’s finger would often contact devices surrounding the regulator disturbing the sensitive feedback circuits and causing the regulator to “self destruct”. After checking with the manufacturer of the regulator, it was confirmed that this was a known behavior.

While most regulators are somewhat more sturdy, we agree that touching unprotected (e.g. conformally coated) circuits while powered on and in operation is not suggested practice and should be avoided.

General Warranty

Unsuitable or unprofessional application and handling are not covered by our warranty. Our products include sensitive electronics and should be handled with care at all times.

Field failure of our products is exceedingly rare under normal operating conditions. In our experience, nearly all failures are due to mishandling, misapplication, or operating out of design specification.

The most common causes of hardware failure are:

  • Over-voltage on a power input – This can cause permanent damage and cause the board to become non-functional. Due to the possibility of multiple component failure diagnosis and repair is not typically practical.
  • Over-voltage or over-current on a signal line – FPGAs have very high-performance I/O. These devices are not tolerant of voltages out-of-specification and are not designed as high current drivers. Exceeding the device specifications can cause I/O failure or device failure.
  • Touching sensitive components – Many of our devices have high-performance power converters with sensitive feedback networks. Small external influences (such as human touch) can cause these devices to “self-destruct”. It is important not to touch these devices during operation.
  • ESD events – ESD can cause product failure that can be difficult or impractical without extensive (and expensive) root cause analysis. Exercise common sense and professional engineering practices at all times.
  • Hot-plug events – All handling and adjustments must be performed when the device is powered off.

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