• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 524 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UC1843A internal 1V Zener in continuous zener breakdown

Pradeep Chitirala
Prodigy 150 points
Other Parts Discussed in Thread: UC1843A

Hi All,

I am planning to use UC1843A in my circuit.

Internal 2.5V connection to the non-inverting pin prohibits me from using the internal Error amplifier of this IC in my application. So, I am planning to configure the error amplifier such that the 1V zener inside the controller always will be enabled (the inverting pin of current sense comparator will be maintained at 1V zener voltage through-out the operation of the IC).

Can I operate the IC this way? Operating temperature range for my circuit is -55deg to 85deg C.

Please let me know your thoughts on this.

  • 0
    Genius 3295 points

    Pradeep,

    Just to clarify, you want to use an external error amp because the internal error amp has a 2.5V reference connected to it and you want to use a different reference voltage?

    If that is the case, then yes I have operated this chip by pulling the Vfb pin to ground and pushing the output of the internal error amp to the rail and effectively clamping the inverting pin of the internal comparator to 1V. Then I add the external op amp with its external reference and connect its output to the Comp pin.

    This has worked for me on other designs.

    -Chuck