Modern switcher?

[miceuz]

I need to make a switching DC to DC converter that will be powering Rasberry Pi and some WS2812 leds. Input voltage - 12VDC, output - 5V @ 2A max. Ripple is not hugely important, probably would be nice to keep below 0.1Vp-p. Efficiency is not hugely important too, I just want to keep the power dissipation to the minimum. The system will be using ~400mA constantly.

Can someone recommend me a modern switching regulator for the task? There is a huge selection of them, I'm at loss. I'm also considering using MC34063 with an external transistor, but I'm not sure, I have never designed a switcher before. Please help 

[rx8pilot]

One off?
Target package?
Hand Soldering?
Cost sensitive?
Isolated?
integrated or controller?



I have been using TI's TPS53915 and it has been working quite well. i2c/SMBUS for monitoring and trimming. .4mm QFN package is not for beginners. Up to 1 Mhz Fs so you can use tiny inductors if efficiency is not critical. Output caps are ceramics so the overall size is very small. I use 7x 10uf 0805 caps. Overkill for your application at 12A, but is is efficient and robust. No heat sink needed.

[miceuz]

One off?
Target package?
Hand Soldering?
Cost sensitive?
Isolated?
integrated or controller?

I have been using TI's TPS53915 and it has been working quite well. i2c/SMBUS for monitoring and trimming. .4mm QFN package is not for beginners. Up to 1 Mhz Fs so you can use tiny inductors if efficiency is not critical. Output caps are ceramics so the overall size is very small. I use 7x 10uf 0805 caps. Overkill for your application at 12A, but is is efficient and robust. No heat sink needed.

We will be manufacturing in hundreds, so no, not one-off, but not super mass production. Hand soldering using paste stencil and oven is a must for now. Non-isolated. Cost - wise I want to end up not much more expensive than LM7805 with a huge heatsink they are using now (1.46€ total)

I'm looking at TPS54339 now..

[SteveyG]

What's driving your need for 12V input? Automotive use?

[miceuz]

What's driving your need for 12V input? Automotive use?

No, not automotive use. The most power hungry component in the system is 5 meters of 12V LED strip, that's why we have a pretty beefy 12V power supply.

[langwadt]

One off?
Target package?
Hand Soldering?
Cost sensitive?
Isolated?
integrated or controller?

I have been using TI's TPS53915 and it has been working quite well. i2c/SMBUS for monitoring and trimming. .4mm QFN package is not for beginners. Up to 1 Mhz Fs so you can use tiny inductors if efficiency is not critical. Output caps are ceramics so the overall size is very small. I use 7x 10uf 0805 caps. Overkill for your application at 12A, but is is efficient and robust. No heat sink needed.

We will be manufacturing in hundreds, so no, not one-off, but not super mass production. Hand soldering using paste stencil and oven is a must for now. Non-isolated. Cost - wise I want to end up not much more expensive than LM7805 with a huge heatsink they are using now (1.46€ total)

I'm looking at TPS54339 now..

lots of tiny boards with mp1584 on ebay at less than that price

http://www.ebay.co.uk/itm/291146781922

you can build you own, though it might be hard to beat the price

[T3sl4co1l]

TPS54xxx are usually good, an LM26xx SimpleSwitcher would also do.  Both are pretty small on components, and perform well.  Follow the appnotes for parts selection (they probably have a standard 5V 2A design all ready to go for you..) and layout and you should be fine.

If you want to design/build boards, you might as well buy the dev kits instead.  If you're going to dead-bug them, do use a ground plane method.

Tim

[tonyarkles]

I'm more than happy to admit that I'm pretty lazy when it comes to power supply design and love to use TI WEBENCH. I've built a few supplies using it and have never had a problem.

I punched in Vin_min = 11V, Vin_max = 15V, Vout = 5V, Iout_max = 2A and got this design: http://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=1A09CC4364A3A0D0

Gives a BOM cost of $1.14 usd for 1k units.

[rx8pilot]

TI's Webbench is a good tool to rough in a power supply, but it does not help much with PCB layout or other elements that are non-ideal. When I started learning about power supplies about 18 months ago, I learned that slapping a schematic on a PCB gives a predictably low performance result.

It took many, many  hours of study to get a high performance design worked out.

[tonyarkles]

TI's Webbench is a good tool to rough in a power supply, but it does not help much with PCB layout or other elements that are non-ideal. When I started learning about power supplies about 18 months ago, I learned that slapping a schematic on a PCB gives a predictably low performance result.

It took many, many  hours of study to get a high performance design worked out.

Absolutely. The best part about WEBench is that it helps pick out appropriate parts, because... there's so damned many of them and I don't really want to become an expert in all of them. WEBench gives me a nice list of different designs, I'll pick the one that best meets the requirements and then pull down the datasheet and learn as much as possible about it.