Post by thread:[EE] 28v boost converter

--- Bob J <spam_OUTrocketbobTakeThisOuTgmail.com> wrote: > Would anyone happen to have any schematics adaptable to build a 12V > to > 28V boost converter? I've looked at many of the switchers available, > but none are rated to supply the 10A required for my application. > > Regards, > Bob You are looking to make a 280W boost convertor? Medium power applications are a bit tricky. You may wish to look at controling IC's that can be synchronised into a multi phase converter scheme. Have a look at Linear Technologies page I think www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1042,C1031,C1115,P8850 might be a good start to look at there offerings. http://www.linear.com/pc/viewCategory.do to look at there product selection as well. They have as an example circuit for the LTC3782 a 12V to 50V 4A boost converter. This is in the range of power you are interested in no? Stephen ===== Stephen R. Phillips was here Please be advised what was said my be absolutely wrong, and hereby this disclaimer follows. I reserve the right to be wrong and admit it as well. :) __________________________________ Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard. http://promotions.yahoo.com/new_mail

Bob J wrote: > Would anyone happen to have any schematics adaptable to build a 12V to > 28V boost converter? I've looked at many of the switchers available, > but none are rated to supply the 10A required for my application. > > Regards, > Bob At the risk of being called anti-engineer ;) I would recommend a push-pull design using an LM3525 or a more modern controller chip. Check this page out to see what I'm talking about: <http://schmidt-walter.fbe.fh-darmstadt.de/smps_e/smps_e.html> -- Martin K http://wwia.org/sgroup/biofuel/

On Tue, 11 Jan 2005 13:19:19 -0800 (PST), Stephen R Phillips <.....cyberman_phillipsKILLspam@spam@yahoo.com> wrote: > selection as well. They have as an example circuit for the LTC3782 a > 12V to 50V 4A boost converter. This is in the range of power you are > interested in no? Actually the range I need is greater. Minimum 6A, 10A nominal. There is nothing off the shelf I've found that can work with my power requirements, unless I could work with a switcher where that supports chaining bypass mosfet's. I'm beginning to think I could roll one together with a with a pic and a couple of mosfet drivers, some n-channel mosfets (of course with the normal littany of discrete parts in the mix). The only 28V commercially-available boost converter I'm aware of costs about $500. I figure I can do it for much less... Regards, Bob

Bob J wrote: {Quote hidden}>On Tue, 11 Jan 2005 13:19:19 -0800 (PST), Stephen R Phillips ><cyberman_phillipsKILLspamyahoo.com> wrote: > > > >>selection as well. They have as an example circuit for the LTC3782 a >>12V to 50V 4A boost converter. This is in the range of power you are >>interested in no? >> >> > >Actually the range I need is greater. Minimum 6A, 10A nominal. There >is nothing off the shelf I've found that can work with my power >requirements, unless I could work with a switcher where that supports >chaining bypass mosfet's. I'm beginning to think I could roll one >together with a with a pic and a couple of mosfet drivers, some >n-channel mosfets (of course with the normal littany of discrete parts >in the mix). The only 28V commercially-available boost converter I'm >aware of costs about $500. I figure I can do it for much less... > >Regards, >Bob > > Why can't you create three 3A 28V (90W) units and have them drive the load through a schotkky diode in series with each output? You'd have to fine-adjust them to match by monitoring the diode drop of each supply. Its set correctly when all 3 exhibit the same diode drop at median load (1.5A each leg). That looks pretty cheap to me...NOTE: make sure the layouts are as identical as possible, and don't let the coils get close to each other, they'll interact.. --Bob -- Note: To protect our network, attachments must be sent to .....attachKILLspam.....engineer.cotse.net . 1-866-263-5745 Tollfree

--- Bob J <EraseMErocketbobspam_OUTTakeThisOuTgmail.com> wrote: {Quote hidden}> On Tue, 11 Jan 2005 13:19:19 -0800 (PST), Stephen R Phillips > <cyberman_phillipsspam_OUTyahoo.com> wrote: > > > selection as well. They have as an example circuit for the LTC3782 > a > > 12V to 50V 4A boost converter. This is in the range of power you > are > > interested in no? > > Actually the range I need is greater. Minimum 6A, 10A nominal. > There > is nothing off the shelf I've found that can work with my power > requirements, unless I could work with a switcher where that supports > chaining bypass mosfet's. I'm beginning to think I could roll one > together with a with a pic and a couple of mosfet drivers, some > n-channel mosfets (of course with the normal littany of discrete > parts > in the mix). The only 28V commercially-available boost converter I'm > aware of costs about $500. I figure I can do it for much less... > > Regards, > Bob Did you look at the URL and information I pointed too? Did you look at the application information provided on the data sheet? Your peak input current is 29A with 11.5V lowest voltage input if you drop it too 11V it because 30.5A. You can use Fairchild Semis FDI3652 Fets for that application 100V 61A 0.016 on resistance. etc etc. Just go through the numbers. It won't take 5 minutes, more like an hour or two. Remember there examples are just that examples not something to necessarily decide weather it will work for your application or not. Look at page 16 I assume that's what you want to make? Stephen Stephen __________________________________ Do you Yahoo!? Yahoo! Mail - Easier than ever with enhanced search. Learn more. http://info.mail.yahoo.com/mail_250

OK I've just built an active load for testing PSU's ( I even used pic for the display and fan control) which I've tested at upto 60A or 100V and 500W cooling capacity. so I thought I'd try to build a Low Voltage boost converter to test it out and see how easy it is, as I've never actually needed to do one before(not including PFCU'S). I managed to get it to work at 28V and 9A ( I would have tried 10 A but I'm having a problem with my 8 year old 7Ah 12V lead acid battery as it drops down below 9 volts and its way over 30A) I've used some components that were lying around The parts are. IR SD51(obsolete part) as I remember 50A 50V IRFP064 (probably bigger than needed) 60V 9mR (520A peak !) ~100uH air cored inductor litz wire 3x(120x0.1) uc3843 with slope compensation and I used a current transformer as a resistor is getting impractical. It seemed just fine, I just need a decent battery now to fully test it. Richard ----- Original Message ----- From: "Bob J" <@spam@rocketbobKILLspamgmail.com> To: "Microcontroller discussion list - Public." <KILLspampiclistKILLspammit.edu> Sent: Tuesday, January 11, 2005 5:52 PM Subject: [EE] 28v boost converter > Would anyone happen to have any schematics adaptable to build a 12V to > 28V boost converter? I've looked at many of the switchers available, > but none are rated to supply the 10A required for my application. > > Regards, > Bob > --