I have a problem with LT3999.

I simulate LDO with parameters:



Iout=800 mA.

I use Coilcraft PA6384 with turns ratio 1:1.4 and diaode with Vf=1V.

I do not understand, why the output violtage rises more than 12v?

 Then I add a load and Vout equal 12 V

  • 0
    •  Analog Employees 
    on Sep 21, 2021 11:49 AM


    first of all you should ask this question in the 'Power' section of the engineerzone, the section interface and isolation is intended for signal isolation.

    2nd you should have a look in the datasheet on the output voltage regulation section:

    If you have no load attached the output voltage will slowly increase as you have ssen within your simulation. Output voltage regulation is dependent on load current, as can be seen in some of the diagrams as well:

    If you need 'better' Vout regulation a post LDO is necessary (and recommended in the datasheet)