I love really small things. I ran across this little thingy the other day. A Texas Instruments TPS62601. It's step down dc-dc converter perfect for point of load regulation in small low-power devices. Although, the term "low power" can get take latitude here. It can deliver up to a half an amp. That wouldn't be impressive if it were a big TO-226 form factor or something like that, but it's a chip scale microBGA.
The actual part size is approximately 1mm x 1.5mm with a .4mm ball pitch. That's less than three dime ridges long. All it needs to convert your 3 or 5 volts down to 1.8 is two 0402 ceramic capacitors and one little 0805 chip inductor. It's only available in this six bump SAC RoHS package.
I got a sample part from TI to take a look at and of course, I thought I lost it first thing. It came in a standard black plastic cut tape and the part is black on top too. It's like a flake of ground pepper. Except not as spicy. I did find it though.
If you do use this part, be sure to go down to near the end of the data sheet - page 17 - and check out TI's recommendations for layout. There's nothing that we can't handle for a prototype assembly here, but given that the regulator runs at 6MHz, TI is concerned about layout-based performance issues. Like many high speed parts, you kind of have to treat it like a radio to get the full performance out of it.
Andre says "hi" to Wally Bee.