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UA747: About use in low temperature conditions

Daisuke Higa
Genius 3825 points
Part Number: UA747

Hi support team.

I received a question from my customer.

Could you tell us what are the characteristics that deteriorate under low temperature conditions below 0 ° C?

We understand that it is out of warranty, but I have to use the uA747CD as a replacement because competitors' products are not available.

It would be greatly appreciated if you could cooperate.

Thanks and Best Regards,

Higa

  • 0
    Guru 140200 points

    Hi Higa,

    first of all the "full range" specifications are only valid for the temperature range between 0°C and 70°C. But please note that this temperature range can also be found in the "absolute maximum ratings". This has the deep consequence, that the manufacturer does not guarantee that the OPAmp is working properly outside of this temperature range, yes, that the OPAmp is even in danger to be damaged then.

    What does this concretely mean? The OPAmp may still work "somehow" outside of the specified temperature range, mostly. But some of the OPAmp can show issues and can even be damaged. This might be an acceptabnale risk for an amateur. But for a professional this can become expensive because of eventual damage claims.

    Kai

  • +1
    TI__Guru**** 151276 points

    Hello Higa-san,

    I was a young child in the 1970's. Back then uA747 might have been the only choice. However, it's strange pinout makes replacement with a new device impossible without hacks or a re-made circuit board  uA747M is -55C to +125C, so a variant of this product worked over a wide temperature. There is no uA747M in soic package. 

    For repair work, it is worth trying uA747CD. Verify the repair over temperature. Then calculate the risk, because it is yours.

    For new production, redesign the board to use a modern op amp.

  • 0 in reply to Ron Michallick
    Genius 3825 points

    Hi Ron-san

    Thank you for your advise.

    We really appreciate it.

    Best Regards,

    Higa