UCC28221: Regarding minimum Dmax limit of UCC28221

Waqar Khan

Part Number: UCC28221

Tool/software:

Hello,

I intend to use UCC28221 in an interleaved boost converter application. To limit inrush currents during start up, I would like to clamp the duty cycle at some minimum value (Lets say 10%). Is it possible to acheive this low duty cycle by adjusting the resistors on PIN 10(CHG) and PIN 9 (DISCHG)? Thank you.

11 months ago

0 Hong Huang 11 months ago

TI__Guru 74115 points

Hi,

You can clamp soft start pin voltage to limit the duty cycle. But since there is no mechanism for accuracy so 10% duty cycle is with variations from units to units.

0 Waqar Khan 11 months ago in reply to Hong Huang

Prodigy 30 points

Hi Hong,

Thanks for your reply. Is there a clamping circuit recommended by TI? The variation in clamping accuracy of the duty cycle is acceptable to me as long as its within +-5%.

BR,
Waqar

0 Hong Huang 11 months ago in reply to Waqar Khan

TI__Guru 74115 points

Hi,

No recommendations. Your application is not typical and not intended by this device. Tolerance also is not able to assume as not tested. A simple clamp would be Zener or regulated. But even a clamp voltage is accurate the resulted duty cycle may not be accurate since no test or mechanism for such use.

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UCC28221: Regarding minimum Dmax limit of UCC28221