I want to know how to use the current reset PWM of eflexPWM module DSP MC56F82748. I want to utilize this pwm mode in order to drive a transition mode or critically discontinuous Boost PFC converter. Thank you!

kienfrancis_ure · ‎03-21-2019

xiangjun_rong · ‎03-24-2019

Hi, Kien,

You gave me the section "3.1.8 current-reset PWM", can you tell me the documentation name?

Regarding the current mode control solution, I suggest you refer to an4716.pdf, which I attached, you can see the Comparator generate signal to disable PWM signal as a Fault pin function.

You can download an4716.pdf from here.

https://www.nxp.com/docs/en/application-note/AN4716.pdf

Hope it can help you

BR

XiangJun Rong

kienfrancis_ure · ‎04-04-2019

Hi XiangJun,

Is the PWM external sync can be used in the scenario that I need? Or should I use the fault pins?
After a fixed on time set from INIT to VAL2. I want the PWM to be reset until the comparator output is set. Once the comparator output is set, the fixed on-time will be pulsed again. But the PWM will wait for another comparator output set to be able to continue the cycle.

Thanks,

Kien

xiangjun_rong · ‎04-07-2019

Hi, Kien,

Regarding your question, I am not clear about your required timing, can you draw a timing which is required by your application so that I can understand your timing?

BR

Xiangjun Rong

kienfrancis_ure · ‎03-24-2019

Hi the document name is "Using eFlexPWM with MC56F82xx DSC". We hope that

we can have a tutorial on this pwm. We think this will be the best solution

for our control. Thanks

On Mon, Mar 25, 2019, 10:56 AM xiangjun.rong <admin@community.nxp.com>

xiangjun_rong · ‎03-21-2019

Hi, Kien,

I see that you want to use current signal to reset eFlexPWM counter, in the case, you have to use a shunt resistor to transform current to voltage and use an on-chip or off-chip CMP to get a digital signal when the current exceeds a threshold.

If you use on-chip CMP, you can use crossbar to route the CMP signal to PWM0_EXT_SYNC as the following screenshot in the MC56F827xxRM.pdf.

If you use off-chip CMP, you can connect the CMP output signal to any XB_INx pin, use the crossbar to route to PWM0_EXT_SYNC.

You can set the INIT_SEL bits as 2b'11 in PWMA_SMnCTRL2 so that the PWM0_EXT_SYNC signal can reset the PWM sub-module counter.

Hope it can help you

BR

Xiangjun rong

kienfrancis_ure · ‎03-22-2019

Hi. I want to know how to implement this one. Thanks for the help!

xiangjun_rong · ‎03-22-2019

Hi, Kien,

I am sorry, I misunderstood you.

For the waveform, I think you have to use FAULT pin function, the CMP output is connected to eFlexPWM fault pin, the fault signal disable PWM output pad signal only immediately, but the PWM module and PWM output signal works as usual.

Hope it can help you

BR

Xiangjun Rong

kienfrancis_ure · ‎03-22-2019

Hi,

is there references for this kind of eFlexPWM mode? i hope that I can get one to serve as reference for our research. and also for its configuration in this kind of mode.

Thank you!