Bandwidth control loop TPS40140 in parallel set-up

Louka Taymans

Other Parts Discussed in Thread: TPS40140

Hi everyone,

Would it be possible to provide some feedback on the below request from a customer, in the absence of local support with the holidays:

"When designing a converter, it is normally advised to have the bandwidth of the control loop below 1/5 of the switching frequency.

For a new design, I am using the TPS40140 to interleave several buck converters to control a single output.

As described in the datasheet, the control loop of 1 buck converter can be used and the others can be connected to the same control loop.

Can this control loop bandwidth be increased when paralleling more phases for a single output? And if so, what is advised?"

Thanks in advance,

Kind regards,

Louka

over 10 years ago

0 JohnTucker over 10 years ago

TI__Guru**** 191445 points

Each of the parallel devices will be running at the same Fsw as the master, but will be out of phase. You will set the loop BW with the master and it will be the same for all, both loop response and operating frequency. This assumes that your output power stages are identical for each phase. You cannot increase it because the "perceived" frequency is fsw X number of phases. The Fco < 1/5 Fsw is a good rule of thumb. The hard limit is 1/2 Fsw. You absolutely cannot allow that under any circumstance.

Let me know if you have further questions.

0 Louka Taymans over 10 years ago in reply to JohnTucker

TI__Prodigy 470 points

Thanks a lot John, that seems like a pretty straight forward feedback to me.

I shared this link with the customer in case he wants to ask follow-up questions.

Happy Holidays!

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Bandwidth control loop TPS40140 in parallel set-up