• LT3999 RT Pin

    Dear experts,

    I would like to know if it is possible to change the Rt=49,9kOhm - recommended value by the datasheet - to reduce the base bias current and all over the quiescent power consumption of the device? My application uses a simple push pull architecture…

  • RE: LT3999 Sim failure

    Hi my company policy forbids my from publishing any design files. I can describe the circuit in this text.....

    2 stage converter 17V input -> LT8609S converter ( RT 86.6K, SS 1u ) -> 10u inductor, feedback to gen 15.7V -> 30uF -> LT3999 push-pull (Rdc…

  • 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,


  • 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…

  • 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 and flux imbalance

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

  • 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

  • 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…

  • About the primary inductance of the LT3999

    In the link: www.analog.com/.../high-frequency-push-pull-dc-dc-converter.html, equation 14 and equation 15. They both have a factor "Ts/4". I wonder how the figure '4' come from? Thanks.

  • LT3999 switch node voltage

    Hi All,

    I am using LT3999MP part in my design. As per datasheet, SW node voltages (at SWA and SWB) should be between -0.3V and 80V (screenshot below).

    The transformer that I am using has leakage inductance of 0.45uH. Based on simulations with LT3999…