• LT3999


    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…

  • LT3999 light load operation


    When using LT3999 with a light load, the output voltage became higher than the set value.

    I also tried it with LTspice and I saw a similar waveform.

    Is there a way to  regulate the output voltage at light loads?

    Best Regards,


  • Problem with LT3999


    Iam using the LT3999 in series with a push Pull Trafo from würth (750315371) to generate 12VDC isolated.

    After a powerup, the first few seconds all works fine but then the output voltage begins to oscillate and as a result, the LT3999 is getting…

  • LT3999 adjacent Tranformer


    i want to use LT3999 to build 12V and 0.8A power supply. according to datasheet i have to use a  COOPER BUSSMANN CTX02-19062  to adjust LT3999. but there isnt any transformer in this name around the internet. does anyone has information?

  • LT3999 Simulation


    I am running a LTSpice simulation using in-built LT3999 macro model test fixture available. The test fixture is designed for a 12V input, 12V output, 0.4A load which seems to be working well.

    However, when the load is changed to 1kohm and Rdc set…

  • Minimum primary inductance LT3999

    Hello everyone, 

    I am designing a DC-DC converter with the LT3999, input voltage is 24V and output voltages are 5 and 15V.

    I am facing some problems. What should be the minimum inductance of the primary side? and what are the parameters of the LT3999 that…

  • LT3999 transformer

    Dear Sir/Madam,

    I am looking for some available transformer options.

    For nominal 12V input and 12V output the data sheet recommends Coilcraft PA6384.
    This part does not seem to exist. 
    The EVM uses Wurth 750314781. I cannot find stock.

    Are there any other…

  • LT3999 primary inductance

    I am designing a DC-DC converter with LT3999, input Voltage is 24V and output voltages are 15V and 5V, what should be the minimum value of the primary inductance

  • Simulation of LT3999


    I am simulating the LT3999 with : Vin = 13V, Rt = 35k, Rdc = open, Txfr=200uH n=1:1.  The problem is that the output voltage won't ramp to its final value unless I add an output inductor after the output diodes.  Why is it required?


  • LT3999 and flux imbalance

    Is there any mechanism in LT3999 which forbid flux imbalance in the converter?