Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

choosing mosfet for my buck boost

Status
Not open for further replies.
D

dalalennahli

Newbie level 3
Joined
Jun 18, 2016
Messages
3
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
18
hello
i'am doing an undergraduate project of designing a buck boost converter 48v to 12v ,i did the basic circuit but i need some help choosing my mosfet
 

Switched-coil converters are able to create high voltage spikes in case of mistakes when building and testing. Start out with devices which are robust. If you wish to use less robust (and less expensive) devices, then wait until you see whether the operating envelope can permit it.
 

Design equations tell you about expected transistor average and peak current and peak voltage. You should also know the switching frequency and be able to estimate switching losses. You have already thought about heat-sinking and have an idea of preferred transistor packages. With all these information, go to major manufacturers selection tables.
 

can you please explain more ?
what shoud i do to choose the correct mosfet ?
i have a buck boost converter 48v to 12v and i=60A

- - - Updated - - -

and f=30kh
 

For 60A circuit will not be basic and not single phase. Show your schematic, please.
 

The mosfet has waveforms going through it with peaks in the area of 150 A.

Parasitic resistance is likely to take a toll. It cannot be more than 1/6 ohm. Therefore you might consider interleaving two or more converters.
 

the "elephant in the room" is why a buckboost and not a buck....or rather , interleaved buck as above said

- - - Updated - - -

I presume it is a 4 switch buckboost or three switch…..so anyway you get 2 diodes with reverse recovery in them instead of just one with a buck.
However, The reason to do buck boost would be that sometimes your vin goes below your vout, say

- - - Updated - - -

here is a buckboost sim in ltspice, you can see the voltages..put some stray L in to see the overvoltage ringing. BTW you can put sync fets in in place of the diodes if you wish...or use an LT8705 which facilitates this.
 

Attachments

  • BuckBoost _GND output.txt
    2.9 KB · Views: 67

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top