Internal reference accuracy of LT3086MPFE#PBF

Hi All,

We are looking at generating a very tight regulated 1.2V power supply with 1.5A current capability. We need to achieve <2.5% overall accuracy. I have shortlisted LT3086MPFE#PBF for this application.

Internal reference voltage has 2% variation (392mV to 408mV) over full line and full load regulation per datasheet. However in our application we do not see any line voltage variation at the input. So, we feel accuracy should be better than 2%. So, in order to independently calculate, I need Reference voltage accuracy over temperature. Is the reference voltage  (396 mV to 404mV) provided in datasheet over temperature range of -55C to 125C or only at 25degC? If not over temperature, request you to please share reference voltage error over temperature.

Please help us clarify this question to understand if LT3086 is suitable or not in our application.

Thanks

C.Pradeep

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  • 0
    •  Analog Employees 
    on Apr 27, 2020 4:39 PM 8 months ago

    Thank you for the post.  I will forward this post to the design group and update my post with any additional information that I receive.

    From my understanding, the LT3086 is essentially +/-2% accurate over everything.  That is what I believe is meant when the LT3086 datasheet page 1 description text says the LT3086 is +/-2%.  I show the applicable text in the image below.

    LT3086 DS Descrip_1.png

    I agree with you that the specifications for Reference Voltage and Reference Current in the LT3086 datasheet Electrical Characteristics table seem to indicate that accuracy should be +/- 2% and +/- 2% in some RMS combination, but in reality I believe the overall accuracy will still be at worst +/-2% as I mentioned earlier.   I show the Reference Voltage and Reference Current line items from the Electrical Characteristics table in the image below.  The line items with the dots are over the full operating temperature range, as the text in the image states:

    LT3086 DS Elect Char_2.png

    I may misunderstand you, but the datasheet does provide SET pin Reference Voltage and SET pin Reference Current curves versus temperature - the curves are shown in the image below.  You may be asking for SET pin Reference Voltage and SET pin Reference Current distribution data at room temperature.  I'm sure that data is available, but we normally only share distribution data with field support and not directly with customers.  I don't think the distribution data will contradict the +/- 2%   overall accuracy I mentioned earlier. 

    LT3086 DS Typ Perf_1.png

    Line and Load Regulation do not seem to contribute significantly to the LT3086's +/- 2% overall accuracy, so I don't think your relatively constant VIN improves the +/- 2% overall accuracy significantly either.  I show the datasheet Electrical Characteristics line items for Line and Load Regulation in the image below:   

    LT3086 DS Elect Char II_1.png

Reply
  • 0
    •  Analog Employees 
    on Apr 27, 2020 4:39 PM 8 months ago

    Thank you for the post.  I will forward this post to the design group and update my post with any additional information that I receive.

    From my understanding, the LT3086 is essentially +/-2% accurate over everything.  That is what I believe is meant when the LT3086 datasheet page 1 description text says the LT3086 is +/-2%.  I show the applicable text in the image below.

    LT3086 DS Descrip_1.png

    I agree with you that the specifications for Reference Voltage and Reference Current in the LT3086 datasheet Electrical Characteristics table seem to indicate that accuracy should be +/- 2% and +/- 2% in some RMS combination, but in reality I believe the overall accuracy will still be at worst +/-2% as I mentioned earlier.   I show the Reference Voltage and Reference Current line items from the Electrical Characteristics table in the image below.  The line items with the dots are over the full operating temperature range, as the text in the image states:

    LT3086 DS Elect Char_2.png

    I may misunderstand you, but the datasheet does provide SET pin Reference Voltage and SET pin Reference Current curves versus temperature - the curves are shown in the image below.  You may be asking for SET pin Reference Voltage and SET pin Reference Current distribution data at room temperature.  I'm sure that data is available, but we normally only share distribution data with field support and not directly with customers.  I don't think the distribution data will contradict the +/- 2%   overall accuracy I mentioned earlier. 

    LT3086 DS Typ Perf_1.png

    Line and Load Regulation do not seem to contribute significantly to the LT3086's +/- 2% overall accuracy, so I don't think your relatively constant VIN improves the +/- 2% overall accuracy significantly either.  I show the datasheet Electrical Characteristics line items for Line and Load Regulation in the image below:   

    LT3086 DS Elect Char II_1.png

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