High efficiency 5V converter

[cpcp68]

Hello,

I got bored, so I came up with another (possibly useless) circuit. The use of a resistor or a regulator for 5V mods is widely accepted, but inefficient and requires two batteries in series that give, at best 1Ah. So, I thought of using a step up DC-DC converter to generate efficiently (89% eff) a nice 5V output from a single Li-ion or Li-po cell like a 18650.
Mind you, it takes quite a bit of parts, but with the proper component selection and layout can be made reasonably small. The added benefit is that it can use any switch you like as there are no power requirements for it.

If you dwell into the MAX1708 datasheet, do not use the parts suggested as they are too big. For our application we can use smaller and cheaper parts as our stuff is rougher than the applications this device is for.

I hope someone will have the time and interest to play with it (I lack the time). Personally, I would like to see it used as a little module inside a Chuck.

Happy modding!
CP

 

[SurvivorMcGyver]

Hello,

I got bored, so I came up with another (possibly useless) circuit. The use of a resistor or a regulator for 5V mods is widely accepted, but inefficient and requires two batteries in series that give, at best 1Ah. So, I thought of using a step up DC-DC converter to generate efficiently (89% eff) a nice 5V output from a single Li-ion or Li-po cell like a 18650.
Mind you, it takes quite a bit of parts, but with the proper component selection and layout can be made reasonably small. The added benefit is that it can use any switch you like as there are no power requirements for it.

If you dwell into the MAX1708 datasheet, do not use the parts suggested as they are too big. For our application we can use smaller and cheaper parts as our stuff is rougher than the applications this device is for.

I hope someone will have the time and interest to play with it (I lack the time). Personally, I would like to see it used as a little module inside a Chuck.

Happy modding!
CP

Interesting... plus free samples

Not quite where I need to be (background-wise) to FULLY evaluate or purport it's usefulness -- but it looks promising...

Awesumely small 1/4w x ~5/8L x THIN

Keep us posted -- anyone who may endeavor.


Thanks for the thought and the post

 

[cpcp68]

Thanks for your comments!

The same circuit can also be based on a (better) TI part (TPS61086). This would be in a 3mm x 3mm package, so it requires some serious soldering skills and equipment. The TI would also allow to have the output variable from 5V to 6V or even 7.5V.

 

[Ericfixit]

I work on very small SMD's at work, when I get a chance I will make a small PCB for this and see how it goes. Should be able to get the form factor down.

Nice find

 

[Ez Duzit]

How much smaller then the TI 4050c boost converter, would that actually be? Or about the same size?
(the 4050c is 22x13mm)

 

[FlipnOut]

Seems to me that the max8677 could be the end all solution to charging and output at 5V... What am I missing here? (Other than the 4mm x 4mm package with 24 pins on it?)

QuickView - MAX8677A 1.5A Dual-Input, USB/AC Adapter Charger and Smart Power Selector

 

[SurvivorMcGyver]

Seems to me that the max8677 could be the end all solution to charging and output at 5V... What am I missing here? (Other than the 4mm x 4mm package with 24 pins on it?)

QuickView - MAX8677A 1.5A Dual-Input, USB/AC Adapter Charger and Smart Power Selector

It's amazing what one can get "off the shelf" these days

Great find -- taking "the mod" to the next level.......

 

[FlipnOut]

Yeah, I like the chip, don't like trying to design the board to use it. My crappo PCB Cad software doesn't have it built in, and I can't get it to cooperate to design the pads from scratch. I ordered a sample on Friday, hopefully it'll get here this week and I can get lucky enough to actually etch a board and throw it together. It's been sooo long since I've etched a board, should be an exciting exercise in futility.

 

[cpcp68]

I work on very small SMD's at work, when I get a chance I will make a small PCB for this and see how it goes. Should be able to get the form factor down.

Nice find

Sorry all, I was out buried under 1.5" of snow

That would be great. Let me know if you need any help.

 

[FlipnOut]

Sorry all, I was out buried under 1.5" of snow

Southerners

 

[cpcp68]

Seems to me that the max8677 could be the end all solution to charging and output at 5V... What am I missing here? (Other than the 4mm x 4mm package with 24 pins on it?)

QuickView - MAX8677A 1.5A Dual-Input, USB/AC Adapter Charger and Smart Power Selector

I do not think you are missing anything. The output current may be a little on the edge, but I am sure it will work anyway.

 

[cpcp68]

How much smaller then the TI 4050c boost converter, would that actually be? Or about the same size?
(the 4050c is 22x13mm)

It will be up to the ability of whomever does the layout. My guess would be comparable in area but much thinner. With the 3x3mm TI device, probably smaller.

 

[cpcp68]

Yeah, I like the chip, don't like trying to design the board to use it. My crappo PCB Cad software doesn't have it built in, and I can't get it to cooperate to design the pads from scratch. I ordered a sample on Friday, hopefully it'll get here this week and I can get lucky enough to actually etch a board and throw it together. It's been sooo long since I've etched a board, should be an exciting exercise in futility.

Have you tried Eagle? I have been using the pro version for a long time, but they have a limited free version. It is ridiculously simple to learn and to make new libs.

LOL, you are right about the comments on the southeners. I grew up in northern italy where snow was 1/2 meter at a time... never been blocked by it.

 

[FlipnOut]

OT: I grew up in Detroit metro, and didn't hesitate to go out in 6+ inches of snow. However, here in Greenville, I won't go out if there's snow or ice. Too many hills and curves. Usually, someone gets stuck on a hill, then everyone behind them is stuck too. Last Feb, I must've helped neighbors push 30 cars up the hill on the main road behind my house.

Back On Topic: I got a copy of DipTrace freeware, that seems to have the component. Now to get back to reading the specs and trying to make the circuit.

 

[cpcp68]

great to hear. Good luck with the layout and let me know how it goes. Count on my help if you have any questions.