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UC1842: Reference Design

Part Number: UC1842
Other Parts Discussed in Thread: , UC1843, POWERSTAGE-DESIGNER


I want to design DC\DC convertor with UC1842A

Can you pleas provide any reference design?

In the datasheet I don't see the value of the components.

+ How to set the FB resistors?


  • Hello Moshe,

    We do not have a reference design for this exact part. However, the following links may be useful as they are for similar parts. In general the UC1842 will require some design work to implement but will therefore allow increased flexibility to adapt to the system needs (see the datasheet as well for some of the needed design steps).

    Hopefully that helps. If you have more specific questions let me know what your power supply requirements are.



  • Hi,
    In those link I see Flayback. I need to design Buck or Boost.
    + What is the formoula for set the FB resistors? What is the recommended values for the other resistors/capcitors?

    There is any more information regarding UC1843?
  • Hello Moshe,

    The feedback resistors will be set with regards to the non-inverting side of the error amplifier which is 2.5V. This is what should be seen at the inverting input of the error amplifier (pin VFB).

    Other component selection will depend on your design requirements. This controller allows lots of flexibility with key design decisions. Therefore, there is no standard recommended value or configuration. Looking up general literature on designing a buck or boost converter will be applicable to helping your design with this part. For example see this application note on buck converter calculations ([]). Additionally, you may be interested in our Power Stage Designer which helps with calculations for switch-mode power supplies ([]). Lastly, our Webench tool helps with designing power supplies online ([]).

    If you do not need the flexibility of this part you may be interested in a more complete solution in some of our other parts (for example see Modules in the above mentioned Webench).