UCC28251PWR

Serg Smirnov

On UCC28251PWR datasheet is info how to set tine delay betwen input and output pulses (SP and PS pins).

datasheet: "Dead time between primary-side switch
and secondary-side synchronous rectifiers can be
independently programmed"

I did not find information about dead time betwen primary side pulses in case of 50% duty cycle.

In assembled converter i can see 110 ns dead time. It suits for my converter, but would be good to understand how to calculate primary side impuls dead time.

Thank you

Serg

over 6 years ago

0 Mike O' over 6 years ago

TI__Guru* 86286 points

Hello Serg,

They don’t give equations but graphs for TD(sp) (Figure 27) vs RSP and TD(ps) (Figure 27) vs RSP. With these graphs and figure 26 it should be possible to estimate the delays.

Regards,

Mike

0 Serg Smirnov over 6 years ago in reply to Mike O'

Prodigy 110 points

Thanks Мike

Information about dead time in the primary pulses is missing.

Maybe they mean that the output pulses are basic with a duty cycle of 50%, and thus the delay in the input pulses forms the input dead time?

But this is not directly indicated in the datasheet.

0 Mike O' over 6 years ago in reply to Serg Smirnov

TI__Guru* 86286 points

I believe that you are correct.

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UCC28251PWR