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LM4140: Accuracy after PCB assembly

Zack Schwarz
Prodigy 260 points
Part Number: LM4140

Tool/software:

I am working on a design with the LM4140BCM-2.5 voltage reference and I am having an issue with the accuracy of the reference. The datasheet lists the initial accuracy of V_REF to be +/- 0.1% but with the note that:

(4) High temperature and mechanical stress associated with PCB assembly can have significant impact on the initial accuracy of the

LM4140 and may create significant shifts in VREF.

 

Is there data or guidance on the accuracy of the reference post PCB assembly? I am currently assuming the accuracy is within +/-0.5% but I’m not sure if that is a reasonable assumption to make. I appreciate an informaiton you can provide.

Thanks,
Zack

  • +1
    TI__Expert 6150 points

    Hi Zack,

    Thanks for reaching out. What you are wondering about here is what we would call solder shift. This is further explained in this application note ( https://www.ti.com/lit/an/snaa320b/snaa320b.pdf ) on page 3:

    LM4140 is an old device. Since it is an older device, its datasheet does not have as much information on the solder shift. Our newer voltage references quantify this in the datasheet. For example, this can be seen on page 13 of the REF34 datasheet:

    I would strongly recommend moving to a newer voltage reference. I will reach out over email for more specific details.

    Thanks,

    Jackson