12v, 5V, 3A dual power supply based on the LM2596

Hello, I'm trying to design a 12v, 5V, 3A dual power supply based on the LM2596 voltage regulator. Now I need about 2A on both the 12V and the 5V rails. This is supposed to power a SATA HDD and a raspberry pi board. I've attached a schematic here and I was hoping you folks could tell me if it would work? Also can I use the 5V rail to power a raspberry pi along with the HDD in parallel? Feel free to dismantle this circuit completely if necessary. The goal is to provide enough power for all devices the right way!

Any help would be really appreciated. Thanks.

Every thing else is fine except for the input 40V unrectified source. It should be rectified and filtered and able to provide atleast 5A.
With unrectified the output voltage will be zero when the input signal drops to zero. Average output voltage will hence be lower the rated.

Hi electrophile
in your image you wrote UNRECTIFIED DC but i think you meant Unregulated DC as it can't be DC if it's Unrectified
if you have properly calculated the values of inductors and capacitors(specially output ones) then your circuit looks fine. but you should pay attention to passive components' other characteristics too (beside their voltage and current ratings). e.g. Capacitors' ESR & ripple current ratings and inductors' Volt x microsecond rating, frequency rating & core type. These things will help you improve output max p-p ripple and EMI.
Plus if you are going to use this circuit to power a SATA drive, I would recommend using some protections too, like reverse voltage, over-voltage and over-current protections
Then there are some general precautions like you should never operate these IC's near their absolute maximum ratings and should pay attention to heat dissipation during board design.
And yes you can use 5V rail to power raspberry pi but i would again stress protections

is there a reason for such a high Vin?

the Cout values might be on the low side - see table 1, page 12 **broken link removed**

Thanks folks! this was really helpful!

salmanliaquat said:

Every thing else is fine except for the input 40V unrectified source. It should be rectified and filtered and able to provide atleast 5A.
With unrectified the output voltage will be zero when the input signal drops to zero. Average output voltage will hence be lower the rated.

Click to expand...

shihab_leo said:

Hi electrophile
in your image you wrote UNRECTIFIED DC but i think you meant Unregulated DC as it can't be DC if it's Unrectified

Click to expand...

Yes this struck me a little later This has to be filtered rectified input. This input will be from a toroid transformer with the output side giving out 15V-0-15V and a current rating of 5A. Thanks for the other tips too shibab_leo. The datasheet shows a circuit where output ripple is reduced through another LC circuit but how would you take precautions for over voltage and current? I'm still a noob when it comes to advanced concepts.

kam1787 said:

is there a reason for such a high Vin?
the Cout values might be on the low side - see table 1, page 12 **broken link removed**

Click to expand...

Yes I realized this after I read a couple of datasheets of the same IC from National Semi and OnSemi. They too list the Cout values as 470uf which is what I intend to use. Thanks for noticing this!