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MSP430FR2433: Short Duration Input Voltage Spikes During Transient Signals

Part Number: MSP430FR2433

Do I need to worry about damaging a digital I/O channel with input voltage spikes which range from -2 to +7 VDC but only last from about 30 to 100 nanoseconds? These would be about two or three spikes produced by a tactile switch which is already filtered by an RC circuit.

  • Hi Thomas,

    This is a tricky one, and there probably isn't a definitive 'yes', 'no' answer.  These voltages clearly violate the absolute maximum ratings for voltage applied to any other pin (other than VCC) as shwn here.

    Now, with regard to the +7v and -2v applied to an IO pin, there are ESD protection diodes that are designed to handle ESD strikes of several thousand volts and they are designed to handle up to 2mA of continuous current, but fortunately this not what you are seeing in your design.  I will refer you to pages 2 and 3 of document "ESD Diode Current Specification, SLAA869.  Based on what it says there, there is probably a low risk of damage under your conditions. 

    At the end of the day, however, it is impossible to predict if these conditions will cause an early failure in the device, especially over time, across temperature and from device to device.  Officially, I would recommend you do what is necessary to mitigate the problem as best you can, but the decision is ultimately up to you.

    Are you in a design phase or production phase with this device?  In other words, can you make modifications to your PCB at this point?

  • Document number SLA869 answered all my questions. I learned about the diode current at the pin, which had been vague to me, and the timing requirements for applying power to Vcc and to the channels. That information will help me produce a reliable design.

    I'm in the design phase, so changes can easily be made.

    You have always been a great help.

    Thank you.