symmetrical SMPS

[franksterb92]

all right I'm still doing a ton of research on this project before I even get a pcb made up as I'm still unsure what type of bobbin to use I'm thinking the e25 or the controller ic no wonder companies always out source the smps to someone else so am I right in my assumption that all I have to do to add a negative voltage to these ti workbench designs is add a center tap on the secondary and reverse the diodes and the side I want to be negative  there doesn't seem to be away in ti workbench to select a +- output

[Faringdon]

If its isolated output, you can put your secondary ground anywhere you like. But sorry i havent used Texas workbench.
In post #17 i gave you a design with ETD44 transformer core and bobbin......it was a conservative design i admit.......i mean, a smaller core woudl also be ok....but was the ETD44 too big for you?......the #17 gives turns and everything.
Are you asking about something to power the primary  side controller with?......you could just use a LNK302 for that if you want. A high voltage buck converter.

Attached is the flyback of post #17 now done isolated and with 0v at the centre rail of the output. Its in the free LTspice sim.

If this is your first go at SMPS....id feed the bias supplies in from isolated wallwarts, and just concentrate on the power stage to start off with.

Do some research, then just build it....you will make mistakes but if you try and research so much that you do it right first time...then you will never get started.

[franksterb92]

ok cool ive ben playing with ltspice and simulating transformers honestly i never knew you could simulate a transformer with ltspice

[franksterb92]

i had downloaded a 3d model for that transformer and it is def to big for what im planning thinking about the  ee 25 i think that one would be ok for 100W

[Faringdon]

ok remember to check its got enough room for the windings on its bobbin.