UCD3138: Related to Burst Mode

Merih Eren

Part Number: UCD3138

Hello guys,

I set the minimum duty as 400 ns but when UCD3138 goes into burst mode, it generates smaller pulses like 150 ns. When I disable the burst mode and decrease the duty, it gets no smaller than 400 ns which is what I expect. Why does it generate smaller pulses than the minimum value when the burst mode is enabled?

I would be appreciated if someone helps me.

Thanks in advanced,

Regards,

Merih

over 8 years ago

0 Brian Johnson96 over 8 years ago

TI__Expert 3200 points

Hi Merih, An AE will respond soon to your question.

0 Sean Xu over 8 years ago

TI__Genius 14580 points

Hello, Merih,

What is DPWM turn on threshold and DPWM turn off threshold at burst mode? Have you run EVM at the closed loop?

Thanks,
Sean

0 Merih Eren over 8 years ago in reply to Sean Xu

Intellectual 440 points

Hello Sean,

My threshold configuration is:

LoopMuxRegs.LLENTHRESH.bit.TURN_ON_THRESH = 2000;
LoopMuxRegs.LLDISTHRESH.bit.TURN_OFF_THRESH = 3500;

Also minimum duty configuration is:

Dpwm0Regs.DPWMCTRL0.bit.MIN_DUTY_MODE=2; // no pwm less than minduty
Dpwm0Regs.DPWMMINDUTYHI.all = 1600;
Dpwm0Regs.DPWMMINDUTYLO.all = 1600;

I am running it at the closed loop. Output voltage follows the reference pretty good, everything is ok but those small spike-like pulses are looking serious

Regards,
Merih

0 Sean Xu over 8 years ago in reply to Merih Eren

TI__Genius 14580 points

Hello, Merih,

I think the values of TURN_ON_THRESH and TURN_OFF_THRESH needs to be exchanged. Please try it and let me know.

Thanks,
Sean

0 Merih Eren over 8 years ago in reply to Sean Xu

Intellectual 440 points

Hello Sean,

It worked. Thank you so much.

Regards
Merih

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UCD3138: Related to Burst Mode