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UC2843: application problem

Reed
Expert 1730 points
Part Number: UC2843

  I use UC2843 desige the BOOST application,  i want to limit the Max duty cycle at 80%, according the datasheet'figure7 ,the RT need to choose about 1.8k.

But at the PIN functions table recommends like that :



So if must need to limit the Max duty cycle at 80%,how to choose the RT and CT parameter? By the way In my application the swicth frequency desige at 63kHz.

  • 0
    TI__Guru 64965 points

    Hi,

    Can you attach the data sheet you are using since the data sheet on ti.com does not show the figure you cited?

  • 0 in reply to Hong Huang
    Expert 1730 points

    Sorry,

    it's use UC2843A,  

    So if must need to limit the Max duty cycle at 80%,how to choose the RT and CT parameter? By the way In my application the swicth frequency desige at 63kHz.

  • 0 in reply to Reed
    TI__Guru 64965 points

    Hi,

    So basically, you cannot get 63kHz while limit Dmax =80%, based on the datasheet recommendations. These curves just show some trends while the data sheet limit the selection within the recommended range to make sure the reality stays similar to the curves. Outside the recommendations, it usually means the reality may have large variation from the typical curves.