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TM4C1230C3PM: ESD failure

Miranda Gu
Genius 14827 points
Part Number: TM4C1230C3PM
Other Parts Discussed in Thread: STRIKE, UNIFLASH

Hi team,

 

Our customer find TM4C1230C3PM ESD failure, failure rate 2/3. When the board under 6kV, TM4C1230C3PM cannot work. If customer download code again, the bad IC will work normally. Customer test many times, confirm the failure is recoverable.

I assumed it is caused by memory issue. Could you give some comments?

Thanks,

Miranda

  • 0
    TI__Guru*** 128185 points

    Hello Miranda,

    Please see Section 20.1, Table 20-2 of the datasheet which states maximum ratings for ESD is 2kV. 6kV exceeds this by a great margin, so it is not surprising issues are arising. The customer should not subject that device to such large ESD voltages as that violates specifications.

  • 0 in reply to Ralph Jacobi
    TI__Genius 14827 points

    Hello Ralph,

    Customer did 2kV ESD test, but the device also failed. Test details is as below.

    • Stress:        ±2000kV,  20times
    • Method:      IEC61000-4-2
    • Test Point:  GND

    Miranda

  • 0 in reply to Ralph Jacobi
    TI__Genius 14827 points

    Hi Ralph,

    Additional problems:

    1. Customer want to read bad IC’s flash data. Do you know how to read flash?
    2. Do you think changing the code storage location or configuring flash as ‘write protection’ could solve this problem?

    Miranda

  • 0 in reply to Miranda Gu
    TI__Guru*** 128185 points

    Hello Miranda,

    Thank you for this, the test details are very important here. There is a large difference between the standards our device datasheets guarantees vs the IEC61000-4-2 test methods.

    IEC61000-4-2 tests at a full system level which means the stress is beyond just stressing a single device. As such, the ESD tolerance for the device alone is not the only factor here. A device can be protected from far higher amounts of ESD than spec with a well designed system that has proper protection. The intent of IEC61000-4-2 is to test the full system for ESD.

    It is also important to understand that the ESD testing for IEC61000-4-2 is a lot different than the ESD testing for HBM or CDM that is spec'd in the datasheet, so without proper protection, a 2kV strike from a static gun used for IEC61000-4-2 testing can impact the TM4C device, and that would not violate our device specifications because it is a system level test with different parameters - and most importantly, different discharge pulses - than the HBM test that we have tested the device specs to be up to a max of 2kV. To best explain this to your customer, you may want to read the first few pages of this document from the MSP430 team which explains the differences in the testing and why we have to make a distinction between device spec vs system testing: http://www.ti.com/lit/an/slaa530/slaa530.pdf

    Now then, to solve the issue for their system, simply put it sounds like they don't have adequate system-level ESD protection in place. We have design guidelines that cover all the required points for this, and I would recommend they review the guidelines and assess what portions of their PCB design/layout is not properly guarded against ESD: http://www.ti.com/lit/an/spma059/spma059.pdf

    As this is a system level issue, changing code storage location or using write protection will not help, they need to address the system flaw because the ESD damage could present differently on different PCB's or in different situations.

    As far as reading flash data, I don't think it's relevant due to the above details, but if they want to it should be possible if they can connect with JTAG. Uniflash would be the best tool to use for that.