dc to dc conversion - will the circuit work well?

[bt87]

dc to dc conversion...

i haved designed a software which need 4.2V and 2.5-3A in it's input i want to make a circuit to run this circuit with normal car battery. so please give me some help...
i know hat current divid inparallel but will the resistor be able to handel such high current of car battery?

i have made these circuit for this purpose.. please tell me that will thay work well?
thanks in advance.

 

[santosh.bongane]

Re: dc to dc conversion...

as per our need i suggest you to use or go through National semiconduator ic's
like LM5118

or you can use Murata power module for fast result