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OPA551: Connect pins 1,4,5 to V- or not?

Part Number: OPA551

Page 3 of the spec shows that I should connect pins 1 and 4 and 5 to V- but the note on page 17 recommends not to.

It vaguely states that it will result in a performance reduction.  What does that mean?

  • Hi Mark,

    The OPA551 pins 1,4 and 5 connect internal to the metal package leadframe. Each of these pin's connection point are at different corners. The reason pin 4 is specified as the primary current carrier on Pg. 17 has to do with directing current flow out through this pin which appears to produce optimum performance. If pins 1 and 5 are connected to a separate, floating copper thermal mass, then the primary current can't flow through them and it is forced to flow through the pin 4 connection.  

    Although I can't find anything specific about the mentioned performance reduction, I suspect it is with regard to the op amp's distortion performance. I wouldn't expect much of a change in it if pins 1,4 and 5 are connected together as Fig. 34 shows.

    Regards, Thomas

    PA - Linear Applications Engineering