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OPA551: OPA551FAKTWTG3

Jose Medranda
Prodigy 10 points
Part Number: OPA551
Other Parts Discussed in Thread: OPA552, OPA549-HIREL

I would like to know if there is an alternative for the op amp with the complete reference:  OPA551FAKTWTG3 to stand a low temperature to -55ºC.

The reference OPA551FAKTWTG3 according the datasheet has a range of operating temperature from -40ºC to 125ºC.  

Thanks,

Jose Medranda

  • 0
    TI__Guru 67761 points

    Jose,

    A standard industrial temperature range is specified from -40ºC to 125ºC and for  -55ºC you would have to use a military, or high reliability products.  having said that, OPA551/OPA552 do work down to -55ºC (see below) but some of the maximum specifications like input offset voltage or drift may not be met.  

    If you absolutely need a specified temperature range down to -55ºC, the only part to meet this requirement would be OPA549-HIREL - see comparison table below:

  • +1 in reply to Marek Lis
    Prodigy 10 points

    Thanks Marec for your promt response. Is there any chance to know the list of parameters that may not be met. You mention the input offset voltage and the drift, but if TI could provide a confirmation of the exact parameters and we check they do not affect the performance of our aplication, we could provide that rationale to our coustomer to aprove our current desing. Would that be possible?

    Thanks again 

  • 0 in reply to Jose Medranda
    TI__Guru 67761 points

    The OPA551 specs that may not be met at -55ºC are simply those that are specified in datasheet only for Tj from -40ºC to 125ºC - see below.

    However, if the OPA551FAKTWTG3 is meant to work under -55ºC ambient temperature on +/-12V power supplies or higher, there may be no reason to be concerned because in such case under quiescent condition (no load) and with SOIC package junction-to-ambient thermal resistance of 96.7 [ºC/W], the actual junction temperature, Tj, will be above -40ºC due to self-heating; Tj = -55ºC + (24V*7mA)*96.7 [ºC/W] = -55ºC + 16.3ºC = -38.7ºC

    All these means that even under -55ºC ambient temperature OPA551 SOIC will meet all of the over temperature specs because its junction temperature,Tj, would stay within the specified range of -40ºC to 125ºC.

  • 0 in reply to Marek Lis
    Prodigy 10 points

    Thanks a lot Marek. Very useful.

  • 0 in reply to Jose Medranda
    Prodigy 10 points

    Marek, just one more comment. We are using the OPA551 with package DDPAK/TO-263-7 (Its Rja is 22,7 ºC/W), so in this case Tj = -55ºC + (24V*7mA)*22.7 [ºC/W] = -55ºC + 3.8ºC = -51.2ºC.  For our aplication we should change the OPA551 to select the SOIC package if we want to meet the Tj above -40ºC. Is it correct?

  • +1 in reply to Jose Medranda
    TI__Guru 67761 points

    Yes, your calculation is correct for DDPAK/TO-263-7 package under no load conditions. Using SOIC package would assure junction temperature above -40ºC, under quiescent conditions, for as long as supply voltage are +/-12V or higher while +/-25V supply voltage or higher, and no load, would also raise the PDIP junction temperature to -39.6ºC.  In case of DDPAK/TO-263-7 package, in order to raise the minimum junction temperature above -40ºC, one would need to assure a minimum power dissipation inside the package of ~0.66W or higher; min_Power = 15[ºC] / 22.7[ºC/W] - this could be accomplished with a combination of output current and/or higher supply voltage.

  • +1 in reply to Marek Lis
    Prodigy 10 points

    Thanks a lot Marek