UCC28951-Q1: Max duty cycle determination in UCC28951-Q1

Dewang Gupta

Part Number: UCC28951-Q1
Other Parts Discussed in Thread: UCC28951

Hi all,
I am trying to find the transformer turn ratio (section 8.2.2.2, page 37). In this example, (Max Duty cycle) Dmax is 70%, but the specification of controller (page 5) shows Dmax as 95% at Fsw=100kHz.

Does the Dmax changes according to the application (like the one in the above example)? If yes, how to calculate that?

over 6 years ago

0 Teng Feng over 6 years ago

TI__Genius 13660 points

Hi Dewang,

I have contacted my colleague to answer your question.

Regards,
Teng

0 Bliss Zhou over 6 years ago

TI__Expert 3470 points

Dear Gupta,

The maximum duty is set according to you want. it is experience value,70% Dmax in page 37, which will get better regulation or better efficiency in possible. You can set it 80% or 90% when you calculate turn ratio. Anyway, the Dmax depends on your turn ratio on the min input and max load.

UCC28951 can support 95% Dmax show in page 5.

Thanks

Power management

Power management forum

UCC28951-Q1: Max duty cycle determination in UCC28951-Q1