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TMS320F28335: I/O Input issue.

Reed
Expert 2310 points

Part Number: TMS320F28335

Hi Team,

1. Poor production testing, approximately 6% defective
2. As shown in the figure below, confirm that pins 100 to 89 are faulty (no defects were found in other pins). These pins are all used as input I/O. Voltage changes were detected in the chip pins, but the software did not monitor them. After replacing the TMS320F28335A chip, the test was normal
The following is a partial schematic diagram of the TMS320F28335A chip.

  • 0
    TI__Mastermind 24491 points

    Hi Reed,

    What is the end application? Is there possibility that there was manufacturing defect or that the voltage input exceeds rated voltage of these input pins at any point in time, in turn damaging the pins/device? Do you have information such as lot codes for these devices

    Regards,

    Peter

  • 0
    Prodigy 10 points

    1. This pin is used as a normal GPIO input signal, connected to the secondary side of an optocoupler, with a voltage of 3.3V.

    2. Only when the 3.3V supply is unstable could the voltage at the input pin potentially exceed the limit. Based on testing, the 3.3V supply remains stable below 3.4V.

    3. The chip batch codes are 3ACQNFW and 39A7YNW.

    4. Is it possible that the chip's I/O pin is not damaged, but damage occurred elsewhere on the chip?

  • 0 in reply to xuegong song
    TI__Mastermind 24491 points

    Hi Xuegong, 

    Thank you for the additional information. Based on what you are showing, it is not possible for the input of this particular pin to exceed the 3.3V. The device features internal ESD protection diodes shared across multiple pins. If this is damaged, the error could propagate to multiple other GPIO pins. So I would recommend to check the connection of all the pins you mentioned experiencing issue with to confirm their input also cannot exceed 3.3V. Also, please check that all analog inputs do not exceed 3.3V as that can also damage the device

    Regards,

    Peter