Alternative 3v3 power supply

I am working on a board where I would like to have a 3v3 power supply on, with same specs as on the april board…

However, the switching voltage regulator used on the april board, is outside of my smd soldering skills. Any suggestions to something with familiar in specs, but in a smd package easier to work with?

FWIW, I stumbled across the following a few weeks ago and hope it may be the answer when I need to do some SMD soldering:

Looks like some kind of breakout board? I need something that can be put through reflow in one go.

I use this 1 often

Looks like a nice one too, going to order a few. :slight_smile:

Patcher, have you used that with the Imp? Looks like only 250mA output, which is the bare minimum.

MikeyDK I bought a rework station similar to this on Amazon.
It makes rework and SMT really easy. Flux the board, get a little solder on the pads with your iron, heat it with the gun and pop it in place.

@MakeDeck I got a reflow station, and I can do 0805, but so far it isn’t easy. I don’t see how I should be able to get a component same as the one on the april board lined up properly.

It’s easier than it seems. I use the method Tom recommended to me. Place flux around the pads, I use a syringe with liquid/gel flux. Using a fine tip on your soldering iron with a little solder on it, get a tiny bit of solder on each pad. Don’t put any extra on the GND pad, as there is usually plenty there. Then heat the pad quickly with your rework gun and place the chip with tweezers. I use a 10x magnifying lens to build, which helps. I got mine at Radio Shack on clearance, but they are pretty easy to come across. After you do it a few times its easy. Just don’t pull on the chip if you have to pull it back off to re-adjust it, you can tear pads off… make sure the solder is hot and lift gently.

if used it many times, if u refering to the startup peak, i have no troubles whatsoever.
I wouldnt advise MikeyDK it if i didnt use it myself :slight_smile:
Here the link thats using it rigt now :

edit : updated stream link

What size caps do you place around it? That seems to be the key to making sure you can get past the startup spikes.

1uF both ends
i think this answers the startup wurries:
datasheet :
6.5 Pulsed Load Applications
For some applications, there are pulsed load current
events that may exceed the specified 250 mA
maximum specification of the MCP1702. The internal
current limit of the MCP1702 will prevent high peak
load demands from causing non-recoverable damage.
The 250 mA rating is a maximum average continuous
rating. As long as the average current does not exceed
250 mA, pulsed higher load currents can be applied to
the MCP1702. The typical current limit for the
MCP1702 is 500 mA (TA +25°C)

edit: added some spec’s

250mA must be a pretty conservative rating for the chip. I’ve had some issues with running too close to 250, which is why I ask. In any case, that should be a very easy chip to build with.

Edit… Yep, no worries there.

Current layout I made for the MCP1702. Haven’t routed anything yet because I am still moving parts around.

Still struggling with Eagle, it just does not want to make that polygon into a pad.

I finally got around to try that regulator, but it seems to be a bit unstable?

Booting the impee isn’t any problem, and it also runs just fine, but the voltage goes from 3.471v and all the way down to 2.926v, measured by the impee.

But after having tested reflow soldering, with a stencil for helping with putting the solder down, I am more confident in being able to use the one on the reference design.

hi Mikey,
strange u get such a difference, i did notice some fluctuation in volts not much tgh.
i’am pritty sure we can blame the c’s on front and end that says ‘ceramic’ in the datasheet.
Imho this should be a tantalum or polyprop.

anyways mine works 24-7 no problems.

It runs just fine too, the voltage is just unstable. I am going to add some more caps to it to try and fix it. Then change to the other on the next device I make.

If you are powering from a 5 volt rail a linear rather than switching converter has fewer components… 1.7 volts at 100 mA = not much wasted power

Such as

I got the regulator to run stable… I just had to add a big ass capacitor to the 3v3 rail. :wink:

Right now it goes from 3.304v to 3.269v, so that is just fine. But that is also after I put a 27000uF capacitor on. A friend calculated a bit, and came up with around 30uF was needed, so I am going to give that a shot, since 3x 10uF 0805 capacitors are a lot easier to fit on a pcb. :wink: