Choosing a SMPS controller IC

[kkeeley]

Hi,

I'm looking to design/build a SMPS for a home project and therefor needs to use components that can be hand solder. I've been looking at a few different manufactures and I'm trying to work out which device or devices would be best suited to my needs.

My basic design goals are to use 230Vac 50hz Input and produce 2 output voltages ( 5V @ 13A and 3.3V @ 10A ) the max current values can vary a little if design requires it. I'd alike to be able to simulate the design in LTspice to help verify the design before building.

I've looked at the following manufactures:

Power Integration, there Topswitch family appears to have some good documentation and design tools but I haven't been able to find any SPICE models which prevents simulating the design in something like LTSpice.

Linear Technology, something like the LT3748 but fear that this will not be suitable for hand soldering. The documentation and design tools make it a little harder to find the most suitable devices.

OnSemi, Something like the NCP1380, once again fear it will not be suitable for hand soldering. The documentation and design tools make it a little harder to find the most suitable devices, but at least the do appear to have a number of Spice models.

I have found that there appears to be enough information available to determine the component values and transformer requirements regardless of which device I choose, although some are easier to work with than others.

Can anybody recommend which devices might be most suitable to my needs.

Thanks
Ken

 

[dick_freebird]

If the goal is to obtain these two supply voltages then it
seems to me you want to rip an ATX power supply out of
any of a bazillion cast-off PCs.

If the goal is to amuse / educate yourself by building a
power supply yourself, that is another matter.

I'm sure you can find many, many designs for supplies
that use the well understood, rather old Unitrode /
Silicon General 35xx (voltage mode) or 38xx (current
mode) PWM controllers. You will be able to find many
SPICE (macro)models for all of them (picking the best
one, may be a challenge) and probably in the Yahoo!
LTSpice group archives, full projects to play with and
modify to suit.

Since it'a s hobby thing I doubt you are concerned
with attaining the highest possible efficiency, smallest
size, highest operating frequency or even lowest BOM
cost (sure, nobody likes to waste money, but for a
one-off it can't be helped really). So I'd recommend
sticking with tried and true (not to say "way crusty")
general purpose parts and all the developed design
knowledge base (TI/Unitrode app notes, for starts).

 

[kkeeley]

Thanks for the suggestion, I've started looking at the UC3845 as another option, seams to have a lot of documentation too.

 

[KlausST]

Hi,

There are many things to consider.
* safety. For a hobbyist it is very difficult to design a SMPS that fufills the safety regulations of your country
* EMI/ EMC regulations. Again very difficult for a hobbyist. Especially with modern SMPS ICs, PCB layout....The cost for test is high.
And so on.

To avoid this all I recommend to buy a AC to 5V / 20A power supply. (They should be good available and cheaper than you can build it on your own)
And just add the 5V to 3.3V DC/DC part. Either as ready to buy module or design it on your own...it wll be difficult enough, though.

Klaus

 

[kkeeley]

Thanks for the suggestions,

I'm aware of the safety and EMI aspects and these will be taken into account as part of the design, as this is a one off design for personal use I don't believe that the design would have to fully meet the EMI regulations, although the better the EMI design the less this supply will effect other items around the house. As with all designs, safety will most certainly be the highest priority as I won't be able to use the end products if I or anybody else is dead as a result of ignoring safety.

Ken