Output voltage limit on PI Expert

Posted by: Fabio Foltran on 08/20/2018

hello, i'm a beginner and i decided to dive into the world of SMPS and i thought that starting with the PI ICs would be a good idea since the support that you offer is more than fantastic.

PSU specs
AC 195-230 standard european ac voltage

output1 5V 1A 1.5 amp peak 7.5Wpeak
output2 170v 20ma 40ma peak 6.8Wpeak

so we have a 14.3w of peak power, i was thinking about using the tny279 TinySwitch-III Family beacuse i have it on hand but other suggestion are well welcome.

here it is the real question, pi expert doesnt let me select 170v as output voltage infact the max is 100v. there is any workaround or its a limitation of the flyback topology / IC ??

should i change the topology or the ic family? thanks in advance to everyone that will answer, i'm not native english so if you do not understand i'll try my best to explain it again

Files

Attachment	Size
TinySwitch-III_PIDesign1.pdf	426.66 KB

Comments

maybe i know why i can't go over 100V ....the tny 279 datasheet says that it has a max duty cycle of 65% with the switch open, so 35% switch closed.

soo----- 325v : 100% = x : 35%

x = 113V max so roughly 100v

can someone confirm this? what would be the alternatives that PI offers?

Correct, the duty cycle limitation will not let you design for VOUT=170V.

So which one of your product do you reccomend for doing a 230v ac in to 170dc volt out?

Thanks

Unfortunately, the products offered by PI do not support a multi output design with an output voltage as high as 170V.