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SN74HC244: Regarding the malfunctioning behavior of the SN74HC244PWR

Kyohei
Expert 1646 points
Part Number: SN74HC244


Hi team,

My customer is considering using the SN74HC244PWR for data bus connections.

However, on their pre-mass-production board, some devices are exhibiting behavior where all input and output pins appear to be pulled down to GND. When a known-good device is mounted on the same board, normal operation resumes, so we believe this is a device-dependent issue rather than a board-related one.

First, we would like to have the circuit connections checked. Since this involves the schematic of a mass-production board, we would prefer to share it via private message. If anyone is able to assist, please send me a Friend request so I can share the schematic with you.

Best regards,

Kyohei

  • 0
    TI__Intellectual 2290 points

    Hi Kyohei,

    Logic has an internal-only forum that you can post on. If that's not acceptable, you can also feel free to send me the schematic.

    Regards,

    Nikki

  • 0 in reply to Nikki Dengel
    Expert 1646 points

    Hi Nikki,

    Thank you for your reply.

    Could you please share the URL of Logic’s internal forum that is for internal use only? Is this internal forum visible only to the sender and the TI representative?
    Also, I’ve sent you a friend request—could you kindly accept it?

    Best regards,

    Kyohei

  • 0 in reply to Kyohei
    Expert 1646 points

    Hi Nikki,

    We received devices from the customer that reportedly exhibited malfunctioning behavior, and we conducted terminal-to-GND characteristic analysis at our company. As a result, we confirmed the following:

    • For two devices:
      • Device 1: Pins 11, 16, 17, and 18 were shorted; Pin 20 was open.
      • Device 2: Pins 7, 14, 16, 17, 18, and 19 were shorted; Pin 20 was open.

    A significant number of pins were found to be shorted, suggesting that the failure was likely caused by EOS (Electrical Overstress). It is highly probable that the issue was due to improper usage. The customer is requesting the manufacturer's opinion on what kind of usage conditions could lead to such failures.

    We will share the circuit diagram of the mass production prototype via private message, so we kindly ask for your support in investigating this matter.

    Best regards,

    Kyohei

  • 0 in reply to Kyohei
    TI__Intellectual 2290 points

    Hi Kyohei,

    I've sent you contact info via private message. I will consider this thread resolved, and you can address any follow-up questions or send additional information via email.

    Without waveforms or schematic, I can't say for sure what caused the problem. Based on your description, I would agree that the likely cause is over-voltage or over-current beyond the Absolute Maximum listed in the datasheet. For example, SN74HC244 does not have over-voltage tolerant inputs and if the input voltage is greater than VCC, it can cause these kinds of problems.

    Regards,

    Nikki