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External Current-Boost for MC33063 buck converter

Renjith Narayanan
Prodigy 10 points

Hi

For my project i want to use a dc-dc converter

input 24V

Output 5V,1.5A

I am using MC33063 with external current boost transistor (npn), is anybody worked in this circuit

Also please share the critical points to be taken care

Any answer in this will be appreciated

 

With Best Regards

Renjith K Narayanan

  • 0
    TI__Guru**** 164496 points

    Hello Renjith,

    The formulas on page 10 of the data sheet still can be used.
    Add the external transistor as shown in figure 9a of the data sheet. The external resistor is better placed between the external NPN base and emitter.
    The transistor should be rated for max input voltage and peak current.
    The resistor pulls the base low when the output turns off. Lower values make the turn off quicker. 100 ohms is a good starting point.

    Regards,
    Ron Michallick