UCD3138064A: Problems with peak current mode DPWM configuration

Hi Jun,

Your query is under review.

I will respond in a day or two.

Regards
Hemanth

Hi Jun,

We have not implemented this in UCD3138 before. So, it is taking time. 

Please allow us a week to see what is the correct way of implementation and update you.

Regards

Hemanth

Hi Hemanth，

Thank you for your help and look forward to  your reply.

Regards

Jun

Jun,

Sure..

Regards

Hemanth

Jun,

Can you share more technical background here? topology? application? what is DPWM2AF and 0A tied to? or schematic?

If you are not comfortable to share the information online, please get connected with our local FAE team. 

We need those info to proceed the assessment.

Thanks,
Ning

Ning，

I changed DPWM2AF to DPWM0AF

Topology： buck converter.

 Application：Point-of-Load Converter

what is DPWM2AF and 0A tied to：valley current mode constant on time control（Fig.1）and its modulation waveforms（Fig.2）。Since COT control is a variable frequency control that produces a constant on-time every time the valley of VIL is equal to VC, I would like to implement the above operation in UCD3138，However, the peak current mode in the UCD3138 can only switch off the DPWM via the CBC when the peak current reaches the target value，So I can only turn on DPWM by using Edge Generator Module。

 When the valley value of VIL is equal to VC，PCM triggering signal (fault ) chops DPWM0AF generate a falling edge, This falling edge serves as the turn-on signal for DPWM0A（Fig.3）.

Regards

Jun Lin

Jun,

I will get back to you in few days.

Ning

Jun,

In principle, you can invert the current polarity using external circuits and leverage PCM like you described. But I am not sure if you can force COT afterwards. 

You could also use the general ADC to sense the valley and trigger PWM by firmware but you need to validate if the delay from sensing to action is acceptable.

Unfortunately, we don't have an example code or hardware to verify the concept.