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LM4040B: Recommended Operating Temperature

John Leahy63
Prodigy 20 points

Part Number: LM4040B

The recommended range is -40 to 85 degrees.  I would like to know the impact of operating closer to an ambient temperature of -55 for a short period of time (<2 hours)  Is the risk that the component will fail or will the operating parameters be wider than is normally acceptable?  I'm having the same issue with the LM2901M which appears to be tested at -55 but is rated at -40.

  • 0
    TI__Expert 3835 points
    Hi John,

    To ensure normal operation, the LM4040B is spec to -40 degrees C. Even if it is for a short duration and the component does not fail, there are no guarantees the LM4040B will operate in other conditions (25C, 85C, long-term stability). What is the application for this device?

    In regards to the LM2901 datasheet, it is possible that the testing done at -55 is for the LM139 which is also on the same datasheet.
  • 0 in reply to Ethan T
    Prodigy 20 points
    This is a safety critical component, part of a current control circuit for firing a squib. The things I need to know is if it is likely to fail at -55 or is performance degraded? Is the regulated voltage going to be higher or lower at -55? It is currently tested at -55 and we have seen no problems and would like to discontinue testing at cold temperature but I'm am trying to determine what a failure would look like.
  • 0 in reply to John Leahy63
    TI__Expert 3835 points

    Outside of recommended operating conditions, we can not ensure if anything is likely to fail or have degraded performance. Based on the temperature drift graph on the datasheet (Figure 1), Vz seems to be lower than the fixed regulated voltage at colder temperatures.

    If you have personally tested at -55 and see no problems, then it is up to you. Failures at low temperature can range from anywhere from mechanical stress causing the IC to be inoperable or have unspecified operations that can damage your circuit. Again, we do not characterize it outside of its rated temperatures.

    If this can fit in your applications, I recommend the LM4040C25-EP which is characterized to -55C.

    Here is a link to other shunt voltage references rated for -55C:
    http://www.ti.com/lsds/ti/power-management/shunt-voltage-reference-products.page#p1192=-55 to 125

    Hope this helps
    Ethan