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Best switch mode design to step down 5-12v to 5v at 1A?

Former Member

Hi,

I'm trying to design a switch mode step down buck regulator on my ATmega-based microcontroller board that will take 5-12+v from a LiPo or other power source and convert it to 5v with max current 1A.

I'm new to the field of power supplies/regulators, so I don't yet know exactly what would work well and what wouldn't.

 

I've looked at TI's TL2575 ICs, which are 1A "simple step-down switching regulators." Only four external components are needed (inductor, 2 caps, schottky diode), and it's 85+% efficient. The problem, however, is that it requires a big 330uH inductor that is expensive.

 

I then moved on to looking at another TI chip, the TPS63061 (kind of hard to find...just released in Dec. 2011). It is a buck-boost converter with 2A max current. This will allow for an input lower than 5v, as well as above it, so it would work great with 1/2-cell LiPo batteries. It uses a 1.5uH inductor, some small caps, a resistor, and a pretty big 66uF ceramic. Overall, the footprint is much smaller, but the total cost is a bit higher. Here's a basic schematic.

 

I've also been on WEBENCH and desiged a 6-18v input, 5v/1.6A output regulator with the TI LM20333.

 

What design would you suggest?

 

Thanks for the help!

Michael

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  • 0 in reply to Catwell

    I initially thought about using a simple linear regulator, but with the amount of current I would be using I'd probably have to put a heatsink on the board. I think it would be better to use a switch mode regulator to aim for most efficiency and low power dissipation (albeit a more complex design!)

    The LM20333 looks like a good solution, but I'm thinking maybe the TPS63061 would be even better because of its buck-boost SEPIC design and smaller inductor? I've never soldered SON/QFN packages before, but I just ordered a few Schmartboard breakout boards to help with the initial prototype.

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