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Original question:

SN74LVC1G175: Pin FMEA

SN74HC138: About SN74HC series FMEA information

Tsukui Yusuke
Guru 21930 points
Part Number: SN74HC138
Other Parts Discussed in Thread: SN74HC244, SN74HC245, SN74HC273

Hi,

Could you tell me the FMEA information of SN74HC series?
The specific parts number is as follows.
・SN74HC138
・SN74HC244
・SN74HC245
・SN74HC273

Competitor have prepared the following materials.
https://assets.nexperia.com/documents/application-note/AN11044.pdf

Customers want such materials or FMEA information.
If you can provide this information, it will be useful for replacement activities.

Best regards,
Yusuke

  • 0
    Guru 242810 points

    TI makes FMEA analyses only for safety-critical devices.

    The following is an unofficial FMEA analysis for all HC/HCT devices.

    class A: possible damage to device; likely affects application functionality
    class B: no damage; possibly affects application functionality
    class C: no damage; does not affect application functionality

    short circuit to VCC:

    pinclassnotes
    input B behaves as if input set high
    output (high) C
    output (low) A damage due to high current
    output (hi-Z) C
    GND/thermal pad A damage due to high current

    short circuit to GND:

    pinclassnotes
    input B behaves as if input set low
    output (high) A damage due to high current
    output (low) C
    output (hi-Z) C
    VCC A damage due to high current
    thermal pad C

    short circuit of neighbor pins:

    pinclassnotes
    input/input C if same voltage
    input/input B if different voltages; see open input above
    output/output C if same voltage
    output/output A if different voltages; damage due to high current
    input/output C if same voltage
    input/output A if different voltages; damage due to high current (depending on the drive strength of the device driving the input)
    any/VCC or GND see the tables above

    pin left open:

    pinclassnotes
    input B input undefined, high cross currents; see [FAQ] How does a slow or floating input affect a CMOS device?
    input (Schmitt trigger) B input undefined
    output (high) C
    output (low) C
    output (hi-Z) C
    VCC B undefined operation: device might be partially powered through any input or output with high voltage applied
    GND/thermal pad B undefined operation: device might be partially powered through any input or output with low voltage applied

    This analysis applies also to devices from other manufacturers; where AN11044 is different, it is wrong.

    This analysis applies also to devices in other logic families. (But devices with overvoltage-tolerant inputs or outputs cannot be powered through those if VCC is left open. And auto-bidirectional voltage translators are entirely different.)