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OP27: Maximum operating junction temp

Andrea Bordonali
Prodigy 190 points
Part Number: OP27

Tool/software:

The datasheet shows that temperature limits for free-air temperature, but my application is for space where air doesn't exist.  Is there a operating junction max/min temperature limit?  

  • 0
    TI__Guru 69891 points

    Hi Andrea,

    Andrea Bordonali said:
    Is there a operating junction max/min temperature limit?  

    I assumed that the question is related to OP27AJG heat dissipation for Space application. 

    All power device in Space application is mounted on a "cooling" block, where excessive heat will be dissipated to. The "cooling" block temperature could be 80C or similar, but it is a fixed regulated temperature. Since the Space temperature and inside of device compartment has a wide range of temperature delta, the "cooling" block's temperature can be regulated to a fixed thermal state. 

    So OP27AJG can be mounted onto such device, if you are concerned about the thermal dissipation in the op amp. This is a standard technique used to dissipate heat in space. 

    If you have other questions, please let us know. 

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    Prodigy 190 points

    Hi Raymond,

    Thanks for the information.  We are using TECs on a couple places, so that will be something to consider.  Is there a operating min/max junction limit though?  Or is there only free-air limits?

    Thanks,

    Andrea

  • 0 in reply to Andrea Bordonali
    TI__Guru 69891 points

    Hi Andrea,

    Andrea Bordonali said:
    Is there a operating min/max junction limit though?  Or is there only free-air limits?

    You may need 2 stage of TEC temperature regulator for your space application. The Tj < 125C probably will be the max. limit, and lower Tj will be better. The issues are the temperature regulating efficiency for the Space application (which is a part of system requirements). 

    If a chuck of metal or thermal conducting substrate in Space can maintain a known temperature or readily controlled, then the cooling/heater side across the TEC interface may be regulated without dissipating excessive power at TEC controller. TEC controller is only able to have 5-15% energy conversion efficiency for the thermal/electricity energy transfer, and there is a fix temperature temperature delta may be maintained across the TEC cooler/heater. So TEC efficiency is the main concerns. 

    If the application is able to regulate cooling/heating interface at the OP27AJG's interface, say top surface, then the op amp should behave a relative constant, and all Vos deviation may be subtracted or calibrated out, and system thermal drift will be the minimum. 

    If you have additional questions, please let me know. 

    Best,

    Raymond