WEBENCH® Tools/TPS563200: Max Duty cycle question

Vasily Milin

Part Number: TPS563200
Other Parts Discussed in Thread: TPS560200, TLV62585, TLV62568, TPS62821, TLV62569

Tool/software: WEBENCH® Design Tools

Hello! Could someone explain what is real duty cycle limit for TPS563200? On product page I see 80%, WEBENCH allows only 70% and 65 % is recommended in datasheet. I'm use it to supply GSM modem from 5V to 3.5 V, that is vely close to lower modem supply limit. In previous design tps563200 got 3.8V from 5V well. So, 65% recommendations in datasheet looks like old "copy-paste" from first devices(like tps560200) and WEBENCH limitations looks like a bug. But I need a documentally substantiated design and ask TI help me to revolve this question.

over 7 years ago

0 Vental Mao over 7 years ago

TI__Expert 5745 points

Normally, the max duty cycle is determined by the frequency and Toff-min, for this part, the Toff-min=260ns(Typ.) 310(Max) and Fre=650KHz(Typ), So the D-max is nearly (1-310ns*650K)=80%. But at this time (Duty=80%), the transient of the part is not good, so the DS recommends to use 65% as max duty cycle to make sure the part can have a good load transient performance. So if you want to use the Duty=80% ,the load transient will be not good.
For WEBENCH set sthe Duty-max=70%, i'll double check with WEBENCH team and give you respond later.

0 Chris Glaser over 7 years ago

TI__Guru**** 150610 points

Hi Vasily,

If you have a 5V input, there are generally more optimal solutions. See TLV62585 for 3A and TLV62568/9 for 1A and 2A options.

If you need better transient response, see the TPS62821/2/3 family.

0 Vasily Milin over 7 years ago in reply to Vental Mao

Prodigy 30 points

Thank you, Vental!

Your answer is very helpful!

I've just checked Webench, its limitations was corrected according datasheet recommendations.

0 Vasily Milin over 7 years ago in reply to Chris Glaser

Prodigy 30 points

Hi, Chris.
Thank you for this nice and interesting parts. TLV62569 is most suitable for me!

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WEBENCH® Tools/TPS563200: Max Duty cycle question