Astral Driver - Buck, Boost, & Buck-Boost

[badboybilly]

Just a question will your driver boost to 7+ volts at 500ma. On a single 4.2v battery!
For these new diodes!

 

[Astralist]

Theoretically speaking, it should be able to output about:

806mA when powered with 4.2V to generate 5V output.
576mA when powered with 4.2V to generate 7V output.
504mA when powered with 4.2V to generate 8V output.

576mA when powered with 3V to generate 5V output.
411mA when powered with 3V to generate 7V output.
360mA when powered with 3V to generate 8V output.

 

[badboybilly]

Awesome that's what we need for know, a higher current boost would be awesome later!

 

[paul1598419]

Thanks, CDBEAM.

@astralist
Do you have an ETA on any of the drivers you have coming yet? I know you have to do some testing, so just a round about guess would be fine. :thanks:

 

[Astralist]

They will be finished about 15 to 20 days according to the factory (weekdays included)

 

[Benm]

I guess that anything that can do boost and buck mode is welcome.

Consider a 445 nm diode running from 2 cells, factoring in losses over wires, contacts and such.

In such a case it would be great to have a driver that can both buck and boost, since you will need both as the battery starts over, but ends under, the dropout voltage for the laser diode.

Drivers that can actuallly d o that are somewhat rare.

 

[Astralist]

I've come across so many ICs that are capable of doing such, including >20A boost IC which only 3x3mm.
The thing is that those magnificent ICs are needs a minimum quantity to buy (min of 1k or so) and the datasheet are not posted online (needed registration using company email to request download of datasheet), quite crazy isn't it?

I already design another buck/boost driver capable of such things (3A when buck & 2A when boost), i will update the thread later.

 

[paul1598419]

I was checking out TI and saw a bunch of good ICs that could be used as drivers with very tiny footprints. It has gotten me to start thinking about designing some for cheap because as far as I know there aren't any US builders at the moment. I have gone back and forth with this idea for a few years. Might have to build some prototypes and then see how much it would cost to get them built en mass.

 

[Astralist]

That would be great!
The actual challenge however, lies on the soldering/reflow process IMO, not the calculation at design time :crackup:

So even when you do prototyping, you might want to use automated assembly machine, or else you may de/resolder the component back and forth using hot air just to align the QFN footprint, which may degrade/break the IC itself AFAIC

 

[paul1598419]

IDK, I'm pretty good with the reflow station I have. I think I can do a few myself, but you never know until it's done. :crackup:

 

[Benm]

Those package are problematic indeed, especially the leadless ones like QFN or BGA, especially when the chips are -only- available in that form factor and you cannot get any samples in more suitable packages for prototyping.

You could try mounting them on breakout boards, but even that's not overly simple unless the ic's can handle high temperature soldering. And even they you don't really know if heating them up that badly changed them somehow.

One option is to use QFN socket breakout boards, but those are not very good for high current application as the connections rely on a mechanically pushed contact instead of a solder joint, generally having much higher contact resistance which is a problem when pushing several amps through such small areas.

 

[Astralist]

I didn't know the QFN adapter exists until you mentioned it.
It seems the adapter is only good for QFN digital IC

Using it for QFN power IC would be worsening the output capability and stability
Also usually the high powered buck/boost IC are using a non standard footprint

 

[CDBEAM777]

Well....reading what you guys are saying....is....well....humbling !!! I understand maybe....every 10th word ....HAHAHA...But then....we each have our talents !! I know.... the few times I have tried to reconnect a surface mount resistor....Well....Things did not work out well....

I can put on head gear....to see the components magnified....but then....it looks like there is a Earth Quake when I view my Solider tip...Shake, shake....and more shake....rattle and roll !!!

Anyway....I want to do a very small, EDC...corrected 044 build....and your High Amp boost drive is just what I need....One 26650 cell will be the LiPo....Anyway...Good Luck !!!

CDBeam

 

[Benm]

I didn't know the QFN adapter exists until you mentioned it.
It seems the adapter is only good for QFN digital IC

Using it for QFN power IC would be worsening the output capability and stability
Also usually the high powered buck/boost IC are using a non standard footprint

Those breakout boards exist, but are not valid for all applications.

They are mostly used to use a small form factor chip on a breadboard, but the chip often is something lik a microcontroller requiring low current at limited frequency etc.

How they will perform in a high frequency, high current application is not that obvious. The breadboard will add significant resisances, inductances and capacity compared to a real world application. For something like a laser driver this is not ideal at all.

Breakout boards are not that good for building things like power supplies at all. They are mainly intended for slow response applications where you prototype things using sensors and such at a slower speed.

It doesn't mean they cannot be succesful to produce though: the entire arduino platform is essentially a breakout circuit for that litte atmel processor. Apart from the USB nterface it just routes pins from the uC to bigger pins and sockets, without any level shiftiing, isolation or anything like that.

 

[Astralist]

I can put on head gear....to see the components magnified....but then....it looks like there is a Earth Quake when I view my Solider tip...Shake, shake....and more shake....rattle and roll !!!

LOL earth quake :crackup: couldn't agree more! earth quake is dangerous for small SMD components :crackup:

Those breakout boards exist, but are not valid for all applications.

It sure is, and not to mention those adapter is quite pricey.
for me, creating something in breakout is more difficult than just printing & mounting all the things in one PCB.
because when the things works in breakout, doesn't mean it will works in real PCB, and vice versa.
especially with frequency/noise-sensitive circuit


BY THE WAY.. i just create another driver, it's LINEAR driver,
runs with 3-12V, output current is adjustabe and limited to 0mA-2200mA although the mosfet can be driven to >15A

I'll update the thread later :beer:

 

[paul1598419]

I'm anxious to see what you've come up with. I will be buying at least one of each to test.