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UCD3138 Burst Mode Problems

Hi,

after successfully closed the Loop of my flyback design I run into further problems.

At light load conditions I want to use burst mode to prevent over voltage conditions at the Output. Here what I get:

Settings:

DPWMMINDUTYLO = 1500 to have stable switching conditions

DPWMMINDUTYHI = 1570 some threshold

DPWM0-MIN_DUTY_MODE = 1

Result: No pulse

As far as I understand the documentation, MIN_DUTY_MODE stops the DPWM if the filter Output is less DPWMMINDUTYLO and restart pulsing (pulswidth determined by filter Output) after the filter Output is greater than DPWMMINDUTYHI, correct?

I watched my filter Output for some operating Point, and get readings in the range 1600 to 2000, so no reason th stop the DPWM, but after Setting MIN_DUTY_MODE = 1, DPWM is stopped for infinite time.

Filteroutput reaches upper Limit, cause the Loop is open and the error amplifier try all he can to correct the Situation. My max. is 12000, so Little higher than DPWMMINDUTYHI (1570), isn't it?

Whats my mistake?

Thanks for helping.

With best regards

Gerhard