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  1. #1
    Full Member level 6
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    mc34063

    What's the constant current configuration and how do I boost MC34063 output current to 2A using a PNP power transistor? Frequency as high as better.

    Regards,

    Fernando

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  2. #2
    Advanced Member level 5
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    mc34063 current source

    Boosting output current to 2A, or more, with the MC34063 and external PNP transistor is not a problem .. see: http://www.onsemi.com/pub/Collateral/AN920-D.PDF for examples of voltage regulators with MC34063 IC ..

    As far as current limiting is concerned you have to be aware that:

    .. current limiting will only protect the switch transistor from overcurrent due to inductor saturation. If the output is severely overloaded or shorted, D, L, or Rsc may be destroyed since they form a direct path from Vin to Vout. Protection may be achieved by current limiting Vin
    Having this in mind one can say that building a costant current source based on switching voltage regulators is not an easy task, and in many applications you will find SMPS as voltage pre-regulator followed by a linear, costant current source ..

    Regards,
    IanP


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