UCC28C43: UCC28C43

colin reason

Part Number: UCC28C43

Are you able to supply the slope compensation formula for the UCC28C43 controller when using a 1:100 current transformer

Thanks in advance

Regards

Colin Reason

over 5 years ago

0 Teng Feng over 5 years ago

TI__Genius 13660 points

Hi Colin,

I think it is not relative with the turn ratio of transformer.
For peak current mode control, sub-harmonic oscillation occurs with a duty cycle greater than 50%, which occurs when the inductor ripple current does not return to its initial value by the start of next switching cycle. Sub-harmonic oscillation is normally characterized by observing alternating wide and narrow pulses at the switch node. By adding a compensating ramp equal to the down-slope of the inductor current, any tendency toward sub-harmonic oscillation is damped within one switching cycle.

Hope attached files can help you.

An Intuitive Approach to Nonlinear Slope Compensation.pdf slua101 Slope compensation.pdf

Regards,

Teng

0 colin reason over 5 years ago in reply to Teng Feng

Prodigy 140 points

Ok Thanks Teng

Looking at the app note for the controller, calculation used for the required slope comp uses Rs (series switch current sense resistor) in the calculation for the up slope. Assuming that s CT is used instead of the series resistor, the Rs value with will be CT secondary loading resistor / CT turns ratio.

Regards

Colin

0 Teng Feng over 5 years ago in reply to colin reason

TI__Genius 13660 points

Hi Colin,

Yes, you only need to add the turns ratio of current transformer in the calculation.

Regards,

Teng

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UCC28C43: UCC28C43