hi every body
please i need a project circuit of DC to DC converter
to step down from (48V @ 40A) to (36, 24, 12V @ 40A)
can any one help me please

 

a linear device would work, as you don't need to step up the current, also, im going to assume heat is not an issue. for up to 40A, i think you would have to make your own from opamps and mosfets, rather than buy an off the shelf product.

basically this:
http://i.cmpnet.com/planetanalog/2008/08/C0334-Figure1.gif
but instead of 1 bjt, i think you may want 40 mosfets in parallel (with applicable control circuitry, and maybe some mosfet drivers).

i hope you like heat sinks, because pulling 12v at 40A is going to generate 1.44 kW of heat (and for this reason, a linear regulator is probably a pretty bad choice).


another option is to make a buck converter (step down), and i'm not exactly sure how you would go about making one of those to handle 40A, as they are a bit more complex.

the last option i see is to convert the DC to high frequency to AC, and then use different taps on a transformer. similar to a computer power supply.

by the way, this seems like a very high power converter. if you don't understand how dc-dc converters work, then i suspect you don't know enough about electronics to do this safely.