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LT3483A very poor performance

Category: Hardware
Product Number: LT3483A


I've just tried to check the performance of LT3484A regulator

Quite mediocre. It's setup to output -40V.

Indeed it output -40 without any load.

With load the output is hardly dependent on load value ... e.g. with 100 Ohm the output is only -8V.

Any comments ?


  • FormerMember
    0 FormerMember
on Oct 13, 2022 7:24 PM

Load is too high. Keep in mind that this part is a micropower application.

Switch current limit is around 420mA which is NOT equal to the output load. The output load would be much smaller than this.

  • Thanks Jhun,

    It is a pity that the datasheet does not provide information on the maximum load current and that a simulation must be carried out to see if the regulator meets the load conditions.

    So the only way to choose a regulator that meets the load specifications is to run several simulations of different regulators that, after going through the selection chart, might meet the requirements?

  • FormerMember
    0 FormerMember on Oct 14, 2022 3:04 AM in reply to Pavel47

    Not necessarily. You can download LTPowerCAD. You just need to fill in the input/output requirements and it will suggest ICs that fits your design needs.

    It can aid in your design and then use LTSpice to have a general idea how your design works.



  • FormerMember
    0 FormerMember on Oct 14, 2022 3:06 AM in reply to Pavel47

    I would just like to add further that only monolithic devices, meaning it has integrated switches, that usually have a current limit as the load current will be dependent on the current stress on the device. So the output current is limited.



  • I've just tried LTpowerCAD. 1st experience is rather disappointing: With specification Vin=5V, Vout = -30, Iout = 10mA, the tool found only one device LTC3896. Doing my exploration of Analog Device regulators, I did some simulations. At least ADP5073 and ADP5074 meet such specifications.

  • Reply Children
    • FormerMember
      0 FormerMember
    on Oct 14, 2022 4:40 AM in reply to Pavel47


    Not all devices are available in LTPowerCAD.

    You can also use this site to search: Selection Table for Inverting Regulators | Parametric Search | Analog Devices

    You can try exploring the website more to search for the IC that suites your design the most.



  • Sure, I use it, but there are no key parameters !

    I couldn't find how to specify Iload_max, Vout.

    I use this table to get a complete list of inverter regulators, then I would have to proceed one by one by opening the datasheets and looking for that missing information.

  • Well ... finally I see that selection table can provide with more or less relevant data ... in any case it looks much better than LTPowerCAD.

    Here is my case ...

    Unfortunately all these 8 regulators feature external switch Frowning2

  • FormerMember
    0 FormerMember on Oct 16, 2022 7:23 PM in reply to Pavel47