Multiple PTH08T2xx modules w/ & w/o SmartSync

rainer03

I'm using several PTH08T2xx modules in my design, which include one PTH08T210 that doesn't have SmartSync. Does it still benefit if I enable SmartSync on other modules (PTH08T220/PTH08T230)? In the datasheet of PTH08T210, I see such a mixed design (Fig.24) where SmartSync is not activated on PTH08T220. Any suggestions on this?

over 11 years ago

0 Tom Guerin over 11 years ago

TI__Mastermind 38230 points

One reason for using smart sync. out of phase on PTH08T220 /PTH08T230 would be to have a common input ripple frequency between the two modules.

However, PTH08T210 has no external control function. The average input ripple is reduced due to its dual phase operation .

If input ripple is a concern, adding input PI filters to each PTH will reduce reflected ripple.

I attached a filter note which can apply to each PTH module.

The smart sync.. can be used or shorted to ground if not required.

Tom

General PTH08T210 and other modules input filter .pdf

0 rainer03 over 11 years ago in reply to Tom Guerin

Prodigy 130 points

Thank you Tom. I'm not quite sure how to select the parameters of the PI filters. If the PTH modules work at different frequencies, should the filters be set to attenuate the beat frequencies, or I can just use the 4.7uF+1~5uH+470uF for PTH08T210 and 4.7uF+Bead for other PTH modules, just as shown in the document?

0 Tom Guerin over 11 years ago in reply to rainer03

TI__Mastermind 38230 points

Rainer03.

The PI filter per the diagram attenuate all beat ripple and switching frequencies between 100kHz and 10MHz by 10-15db.

The low frequency ferrite bead listed is from Fair-rite with a part number of 2773021447. The PI filter requires ceramic capacitors of at least 4.7uf or greater to 10uf

Tom

0 rainer03 over 11 years ago in reply to Tom Guerin

Prodigy 130 points

Are there special considerations for choosing between the two types of PI filters for a specific PTH module? E.g., can I choose the filter with inductor for PTH08T220/230?

0 Tom Guerin over 11 years ago in reply to rainer03

TI__Mastermind 38230 points

Rainer3:

The Ferrite bead PI filter or the inductor PI filter will attenuate the reflected input switching pulses by 10 to 15db.

Tom

0 rainer03 over 11 years ago in reply to Tom Guerin

Prodigy 130 points

Does it mean this filter fits all PTH modules?

0 Tom Guerin over 11 years ago in reply to rainer03

TI__Mastermind 38230 points

Rainer03:

Yes the inductor type PI filter can be used for all power modules . The only other consideration would be the limiting saturation current rating on the power inductor.

Tom

0 rainer03 over 11 years ago in reply to Tom Guerin

Prodigy 130 points

Got it. Thank you!

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Multiple PTH08T2xx modules w/ & w/o SmartSync