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LM4040 Drift issue & How similar is it to LM4050?

John Tillotson
Prodigy 50 points
Other Parts Discussed in Thread: LM4040

I have a mature application using the National Semiconductor LM4040CEM3-5.0/NOPB.  Recently within the last year my yield has decreased. The datasheet CTE is +/-20 ppm/C  typical and +/-100ppm/C maximum.  Part to part variation from the same lot varies considerably within this range, from -85 to +10 PPM when measured over  -25C to +90C.    Has there been a change that would affect the either the average CTE or allow this variation to increase?

I am considering upgrading to the LM4050AEM3-5.0/NOPB, which specifies +/- 50ppm max. .  Both data sheets claim the use of fuse and zener zapping trim, so from this identical description I am guessing there is a high degree of similarity in the die.  Is the internal schematic the same?   Are there differences in speed that would make them respond differently during electromagnetic interference?  I would like to avoid a repeat EMI test and need to know exactly how similar they are.

  • 0
    TI__Intellectual 2320 points

    Hello John,

    Both are 0.1% spec for the A-grade part. LM4050’s tempco spec is better with 50ppm/C while LM4040 is 100 & 150 ppm/C depending on the grade. LM4050 A, B & C grade can do 125C, but LM4040 has only the C, D & E grade that can be used at 125C.

     The internal cicuitry is same. The design is the same; thin film resistors were being used in LM4050 to improve tempco.

     The process and layout has some difference. LM4040’s process is LFAST and implant resistor. LM4050’s process is LFAST and Thin Film resistor.

     At present, we do not run/have any EMI data for both the parts.

    Regards,

    Sourav