hello forum. i want to make a simple isolated dc/dc converter, that has Vin from 10 to 16v (Car battery ) and fixed 12v outpout. (and 3A ).
can anyone share with me a simple schematic, with some basic explanation ??

because in all the schematics i find, i have a hard time, understanding how the feedback is done...

 

A buck converter is not isolated. For that you need a circuit with a transformer, such as a flyback design. Why do you need isolation?

 

i have an LCD in my car, tha i power from a non-isolated switchg converter, but i have a ground loop somewhere, but in 2 years now i cant find it to break it...

so the only way to break it, would be to make the LCD power supply, isolated from the rest of the system !!

 

hello forum. i want to make a simple isolated dc/dc converter, that has Vin from 10 to 16v (Car battery ) and fixed 12v outpout. (and 3A ).
can anyone share with me a simple schematic, with some basic explanation ??

because in all the schematics i find, i have a hard time, understanding how the feedback is done...

Use a 2 transistor push-pull forward converter. Flyback could also work, but with low VIN like 12V, we always used a push-pull to get best utilization of the available input voltage.

 

Use a 2 transistor push-pull forward converter. .

hm? can you expain a bit more please?? remember, i need an isolated dc-dc converter...

something like this :

only , much more simple, and without a chip, becouse it limits the outpout...

 

bountyhunter. after a bit of search, i see that flyback and push pull that you mentioned, are exactly what i was looking for!!

but why not flyback?? since i dont require much power (30watt) OR efficiency (After all, this is my first attempt in power supplies, so it dosent have to be the best) , i could even use a linear voltage regulator (like 9v or something ) to make calculations easier!! the only thing that is a must, is the isolation

in a flyback design, how would i modify the pulse width and frequency, with an optocoupler??

and the two coils i will be using, what exactly do i look for?? (2 coils side by side, or a coil, with enother coil around it in 1-1 ratio?? )

 

Flyback would probably be OK, just lower efficiency. I recommend you go to the TI website and use the simple switcher software on the LM-2577 or similar devices. They will design the whole flyback converter for you and give the part numbers. They have transformers in their parts data base.

 

i also found LT4748 to be nice... can you tell me exactly what is the software you speak of? because, i downloaded something, but it dosent implement any IC's...

 

i also found LT4748 to be nice... can you tell me exactly what is the software you speak of? because, i downloaded something, but it dosent implement any IC's...

Cant find the LT4748 listed, but several others isolated regulators..

 

crap. i mean LT3748.

well just now, i found out, that even finding IC's like this, where i leave, would be a bit hard...

is there any current driven PWM source, i could use, as a controller?? ( a pretty common one)

 

crap. i mean LT3748.

well just now, i found out, that even finding IC's like this, where i leave, would be a bit hard...

is there any current driven PWM source, i could use, as a controller?? ( a pretty common one)

Where do you live,?

 

i leave at greece!!

 

actually, i now have another problem.

if the isolated dc/dc converter, powers an LCD.

and the LCD gets the signal from a PC, that is grounded somewhere else.

inside the LCD, the signal cable grounds, are connected to the power cables ground....
so , wouldent that , short the 2 different grounds, into one??