FREE DIY open source BOOST driver!!! Tested & working!!

Something I forgot to point out -

The way we positioned the MOSFET makes it very easy to reflow the boards with or without reverse polarity protection. If you don't want it, you just leave it off, and bridge SMD pads 4 and 5.

Guys... you have some explaining to do. How. The. Hell. Did. You. Manage. To. Parallel. Them?! I was testing that and I wasn't getting anything over 600mA! Not to ruin your "sales", but my experiments showed that these guys overheat a lot. I'd recommend adding OVP to prevent them burning out when there is an open circuit. That mosfet idea of yours is very creative!

Mohrenberg said:

So far it's look like production cost of $5.01ea without counting the cost of the PCB board.

That's with a Mouser part list.
http://www.mouser.com:80/ProjectManager/ProjectDetail.aspx?AccessID=b43371e29c

not sure if others can view the project parts list....
sense resistors for
495mA
879mA
1.2A

using .768,.316, and .432 ohm resistors
So you could actually get the following combinations.

247mA
495mA
601mA
687mA
879mA
1041mA
1.2A

Click to expand...

Don't forget shipping, Mouser likes to take you from behind with shipping. But I guess at 100 pcs it should only add around 8 cents per driver.

Johnyz said:

That mosfet idea of yours is very creative!

Click to expand...

You guys may want to set the record straight on that as well!!!

Johnyz said:

Guys... you have some explaining to do. How. The. Hell. Did. You. Manage. To. Parallel. Them?! I was testing that and I wasn't getting anything over 600mA! Not to ruin your "sales", but my experiments showed that these guys overheat a lot. I'd recommend adding OVP to prevent them burning out when there is an open circuit. That mosfet idea of yours is very creative!

Click to expand...

Parallel is a straight forward concept, what do you want explained?
EDIT: Sorry, misread your post. I though you meant that you needed the concept of "paralleling" explained. Maybe you made an error in the reflowing? What boards are you using? I can't imagine you got PCBs fabricated that quickly?

What current-set resistor did you use on each driver?

Johnyz said:

Guys... you have some explaining to do. How. The. Hell. Did. You. Manage. To. Parallel. Them?! I was testing that and I wasn't getting anything over 600mA! Not to ruin your "sales", but my experiments showed that these guys overheat a lot. I'd recommend adding OVP to prevent them burning out when there is an open circuit. That mosfet idea of yours is very creative!

Click to expand...

Thanks, but I didn't come up with the mosfet polarity protection all by my self. I've seen it used before.

I had a design with OVP, but we decided to leave that off.

It was just a straight parallel, not even any balancing resistors. Try comparing your designs and parts lists with ours to see what is different.

yea reflow soldering is a very easy thing to do.
Just make sure your pads dont have to much copper connected to them or else you run the risk of tombstone some of the small resistors.
I did alot of my work via a 22in electric skillet with a cover.
No fancy electric temp controllers, just a simple thermometer and an egg timer.
And with reflow you can do 2 sides just do small things like resistors first then do the heavy components last, also make sure all heavy components are on the same side.
So i could solder a bunch of board all at one.
Yea solder masks are nice but for the design posted doing it by hand with the solder paste is easy.
im very excited to see how well these do.
Im getting some board made via the GB however i have a place in china that is will ing to do a panel for very cheap.
So maybe we should look into doing a LPF panel.
I have about 100 board that are 21mm by 23mm i need made.

I've redesigned the board to make it 16mm diameter, one-sided with a battery pad and ground pad on the other side ^_^ Once I find the right inductor (only LPF is working on my laptop for some reason), I will post the new board

benmwv said:

From what I've found, this is hooked up correctly.

As soon as power is applied the diode will pass the current flow over the mosfet. Since the gate is connected to ground that makes the Vgs somewhere around -3v, turning the mosfet on. Now that it is on the Vgs will be around -4v lowering the resistance further. And all of that will happen extremely fast. But if the battery is connected backwards the mosfet wont turn on because it will never get a negative Vgs.

Please correct me if I am wrong about this :thinking:

Click to expand...

Sorry to disagree with you but Q1 is connected in reverse on the
schematics..

Look at page four Figure 4 of this .PDF it shows the correct way of
connecting a P-Channel transistor...
Notice the direction of the internal protection diode.. The cathode
towards +V...

http://www.irf.com/technical-info/appnotes/an-940.pdf

The internal diode is there to protect the Drain/Source junction
from back EMF if a relay or inductive load were connected as a
load..

Now look at the first page of your P-Channel transitor's data sheet.

http://www.vishay.com/docs/69947/si3473cd.pdf

It is common practice when showing transistors in schematic form
that positive potentials are at near top and ground potentials are
near the bottom...


BTW... for a proper reflow time/temperature sequence have a look at
page 8 of the P-Chanel data sheet. Using this Time/Temp sequence
will assure that you don't thermally stress the electronic component.


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

Again - I'm going to let Jerry and Ben chat about the MOSFET because that's outside of my knowledge base.

But I've created in post #2 a running agenda of a few things that I want to change. Mostly some small sizing things so far, to make the driver easier to fit in an Aixiz module. It will now, but it's tight.

Anything non-controversial, I'll add to that running agenda. Stuff like OVP etc, that's a bigger change, and exactly why we made this design open - so that people can grab the board, fork it, make versions the behave differently (like Wolfman has already done). So that's the idea - OVP isn't on our board, but you can add it! You can even post the changes in a new thread etc. This is open - so everyone can play around with it.

If he MOSFET is indeed wired incorrectly, we'll change that in the board here of course, because that's an error we'd want to correct. But if someone wants to swap in a different type of polarity protection they can fork the design, etc.

Also, if the MOSFET is incorrect, and anyone has already ordered boards prior to Jerry's bringing it to our attention here, I'll happily cover the cost of anyone's boards. We perhaps should only have posted the BRD design for the actual revision that I had tested. I think we thought the MOSFET was so straight forward that it didn't warrant waiting another 3 weeks for more boards to arrive to test again - that may have been our error.

Rhd, at one point JohnnyZ was designing his own lm3410 boards.

Can't wait to see it wolfman! Will the inductor we've chosen not work? I can tell you right now you aren't going to find any smaller ones if that's what you are looking for!

lasersbee said:

Sorry to disagree with you but Q1 is connected in reverse on the
schematics..

Look at page four Figure 4 of this .PDF it shows the correct way of
connecting a P-Channel transistor...
Notice the direction of the internal protection diode.. The cathode
towards +V...

http://www.irf.com/technical-info/appnotes/an-940.pdf

The internal diode is there to protect the Drain/Source junction
from back EMF if a relay or inductive load were connected as a
load..


Jerry

Click to expand...

Usually you connect it that way, but not when you are using it for reverse polarity protection. Google "p-channel mosfet polarity protection" or check out this website: Power Protection Circuits - A Closer Look at the P-Channel MOSFET Circuit [424] | General Electronics | Electronics

So rhd would you guys be up for getting a LPF pcb panel done?
That way anyone with boards here can get one done for a good price.

benmwv said:

Usually you connect it that way, but not when you are using it for reverse polarity protection. Google "p-channel mosfet polarity protection" or check out this website: Power Protection Circuits - A Closer Look at the P-Channel MOSFET Circuit [424] | General Electronics | Electronics

Click to expand...

Thanks for the Link... I now understand how the P-Channel is
configured as voltage protection in this unusual way after reading
the link....

I've learned a new trick... Thanks...:beer:

My only other question would be how much current can be driven
through that internal Back EMF diode. The Current rating of the
P-Channel transitor is between Source and Drain in a standard
configuration...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

kiyoukan said:

So rhd would you guys be up for getting a LPF pcb panel done?
That way anyone with boards here can get one done for a good price.

Click to expand...

In theory... but what's the benefit to that over Dorkbot?

I mean, the PCBs are so darn cheap through Dorkbot. I can see not wanting to use Dorkbot for a lot of small orders (out of courtesy to him), but I'm not sure I really see the price of PCBs as being an impediment to anything at this stage. I would really be surprised if we could get the price down so much that it would be a benefit?

rhd said:

In theory... but what's the benefit to that over Dorkbot?

I mean, the PCBs are so darn cheap through Dorkbot. I can see not wanting to use Dorkbot for a lot of small orders (out of courtesy to him), but I'm not sure I really see the price of PCBs as being an impediment to anything at this stage. I would really be surprised if we could get the price down so much that it would be a benefit?

Click to expand...

Even if you would have achieved a $1.00 total cost someone would
want to know if you could do it for $0.50....:crackup::crackup:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

lasersbee said:

Thanks for the Link... I now understand how the P-Channel is
configured as voltage protection in this unusual way after reading
the link....

I've learned a new trick... Thanks...:beer:

My only other question would be how much current can be driven
through that internal Back EMF diode. The Current rating of the
P-Channel transitor is between Source and Drain in a standard
configuration...


Jerry

Click to expand...

Your welcome :beer:
I don't know how much current it can handle, but I dont think it matters because the mosfet will turn on practically instantly and then it would conduct all the current flow.

rhd said:

In theory... but what's the benefit to that over Dorkbot?

I mean, the PCBs are so darn cheap through Dorkbot. I can see not wanting to use Dorkbot for a lot of small orders (out of courtesy to him), but I'm not sure I really see the price of PCBs as being an impediment to anything at this stage. I would really be surprised if we could get the price down so much that it would be a benefit?

Click to expand...

And just imagine the shipping times if the boards had to come from china, then get sorted out and shipped again!

For now at least I'm content with the dorkbot pdx group buy. They are great quality and reasonably fast.