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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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    It depends on what you need. LM20333 is buck converter, so you cannot have input voltage lower than 6V perhaps alittle bit lower). There are available less buck-boost converters than buck only. TPS63061 is interesting, however do you have experience soldering tiny SON packages? If you plan to use 1 LiPo, you need boost converter. If 2 LiPo - buck. If 1 or 2 LiPo - buck-boost (SEPIC).

     

    You can look at Linear:

    http://parametric.linear.com/switching_regulator#!1038_yes!1646_Buck-Boost|SEPIC!1032_%3C=3!1033_%3E=12!1105_%3C=5!1034_%3E=5!1035_4:24!1107_1:6!vinmin_3!vinmax_12!mono_mono!vout_5!iout_1

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  • 0

    It depends on what you need. LM20333 is buck converter, so you cannot have input voltage lower than 6V perhaps alittle bit lower). There are available less buck-boost converters than buck only. TPS63061 is interesting, however do you have experience soldering tiny SON packages? If you plan to use 1 LiPo, you need boost converter. If 2 LiPo - buck. If 1 or 2 LiPo - buck-boost (SEPIC).

     

    You can look at Linear:

    http://parametric.linear.com/switching_regulator#!1038_yes!1646_Buck-Boost|SEPIC!1032_%3C=3!1033_%3E=12!1105_%3C=5!1034_%3E=5!1035_4:24!1107_1:6!vinmin_3!vinmax_12!mono_mono!vout_5!iout_1

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