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LM2941C: Temeratures

Part Number: LM2941C
Other Parts Discussed in Thread: LM2941

LM2941 is Tj-max=150C, what's the meaning of "Temperatures" in Recommended Operating Conditions? Is it Ta?

Thank you for your help.

  • Hi Tahara,

    These are the recommended operating temperature ranges for each device.
    150C is the maximum junction temperature of the device, and 155C is where the nominal thermal limit protection circuit kicks in.

    In the Electrical Characteristics table it is stated that the "specifications apply over the full operating temperature range".
    The "Operating Temperature Range" is shown to be the same as these "Recommended Operating Conditions" on Addendum page 1, on page 20 of the datasheet.  In one of the columns to the right it lists the "Op Temp (C)" which is the Operating Temperature Range.

    As devices get hotter the reliability or lifetime of the component diminishes.
    As such the component electrical characteristics table only lists the recommended operating conditions.
    This also means the tolerances of each performance metric may go beyond what is listed in the tables, at temperatures above the recommended operating conditions.  Keep this in mind for any long term operating conditions above 125C.

    Thanks,

    - Stephen

  • Hi Tahara,

    The recommended operating conditions are TJ. The absolute maximum is a threshold above which the device could be damaged. To predict the TJ in your application, the RTJA number can be used.

    The Junction temperature would be (VIN-VOUT)*ILOAD*RTJA+TA. For example, if VIN is 12V and VOUT is 5V with a 300mA load and using the TO-220 package, you have (12-5)*0.3 or 2.1W of power dissipation. 2.1W*32.1C/W is a 67.4C rise above ambient. If your PCB ambient temperature is 40C, then the die temperature TJ would be ~107.4C.

    I hope this helps to clarify.