Tiny GE 12 Amp Regulator

[Claviger]

I am trying to make a mod that will use 2x18650. The goal is to keep it super small.

For my goal is this going to work: http://apps.geindustrial.com/publibrary/checkout/PVX012A0X?TNR=Data%20Sheets|PVX012A0X|generic

It is very small and seems to have good environmental characteristics, both heat tolerance and vibration/impact tolerance. 

After multiple attempts at fixing here is the temporary "final" draft   Once I get it put together and tested out we shall see what needs to change on it.

[Breaktru]

The Input caps are wired wrong.
The 1.91k trim resistor will give you approximately 6.9V. You're over spec. See the chart in the datasheet. Why not use a trimmer for more flexibility

Update: Claviger has updated his schematic diagram as suggested

[Claviger]

Breaktru, the chart is based on a 12v input I assumed. I did the 1.91k resistor based on 8.4v input from the series batteries using the formula in the data sheet, did I screw that up?

Updated the diagram could you give it a quick once over again?

[CraigHB]

The output caps are rated for 6.3V which is going to be a problem for DC Bias.  MLCC caps are great caps with the one exception you want to use a higher voltage rating than you need to minimize the effects of DC bias.  What happens with MLCC caps is the capacitance drops as DC voltage increases.  Those caps will drop to about 10uF with an applied 6V DC.

I looked at the data sheet for the 10% tolerance part and I didn't see a DC bias curve, but the data sheet for the 20% tolerance part does show the DC bias curve which should be the same;

http://psearch.murata.com/capacitor/product/GRM31CC80J476ME18%23.pdf

I didn't read the data sheet for that regulator, but you really shouldn't need that much output capacitance, that's a lot.  Also, step down regulators typically need more input capacitance than output capacitance so you should be using at least as much capacitance on input as output. 

A couple 22uF 16V MLCC caps in a 1210 size (3225 metric) on both input and output should do the job and those won't exhibit excessive capacitance loss at higher DC voltages.  You can probably just use the same capacitor array on output as you're using on input.  Those parts should have a good DC bias curve (high voltage rating, large size), but I couldn't find one with a quick look.

It's always best to check the DC bias curves in the data sheets for MLCC caps.  They can vary widely.  Larger parts have less DC bias so the bigger the better there, in other words, a 1210 size is going to have less DC bias than a 1206 size.  For example, here's an MLCC cap with a good DC bias curve for our application;

http://www.mouser.com/ds/2/400/C3225X5R1C226K250AA-265476.pdf

The fuses can provide reverse polarity protection in that they should trip when a reverse polarity condition is applied, however there's no guarantee.  For some regulators in certain configurations, one of our resident modders (mamu) found reverse current is not high enough to trip the fuses.  You really should check that, but unfortunately that means you risk burning out a part to test it.  Otherwise, you can just add a transistor.

Li-Ion batteries get heavily damaged when they are discharged below their minimum allowable voltage level.  It depends on the cell, but it ranges from 2.5 to 3.0V.  The problem is the damage incurred when a cell is over-discharged makes the cell unsafe to use.  It can be tricky setting up over-discharge protection for series cells, but it's definitely a good idea if you can work it out.  Some regulators have an under-voltage lockout above minimum battery voltage so that's always handy.  Check the data sheet for that part.

Without over-discharge protection, you can probably tell when input voltage drops too low since output voltage falls off too.  You should check your cells when you change them out to make sure you're not over-discharging them.

Well, best of luck with your build.  Looks like a nice setup.

[Claviger]

Craig thanks for the look and feedback. Following the OKL/OKR/TI builds I read, I found it odd that GE called for significantly more output capacitance than input. I guess it's because the regulator has some built in on the input but none on the output side.  I found the 6.3v rating strange myself, but was trying to not stray too far from the GE example build (because I only have a rudimentary understanding of circuit design).

I added in a 5.9v zener diode to cut at a input voltage of 6.2, after reading about mamu's batteries discharge unevenly (lower one at 2.75) I figured it was better to be a tad over 6v (thought the VTC 5 batteries are rated down to 2.5). 

The reason I am not really concerned with reverse polarity protection is really simple. I am building this for myself, I know which way they go and will label the holder for blonde moments.


With an input voltage range from 6.2-84 volts, can someone who knows better than I please help with the resistor and trimmer?  I have a resistor at 1.91kohm and trimmer at 5kohm. As I use the formula they have in the data sheet:

Rtrim = input voltage / (Vout - .6) kohm

so Rtrim = 8.4 / (5 - 0.6) kohm solve and rtrim = 1.909 khom which as I understand it should set max voltage to 5 volts.

The 5kohm trimmer should set the lowest voltage setting at 1.2 volts, probably lower than needed tbh.  I think 2.5kohm would but me right at 2.5 volts minimum.

Am I doing that correctly?!

[CraigHB]

You have to keep in mind the data sheet assumes the converter is going to be used to power other electronics that are sensitive to voltage transients and ripple.  We have the luxury of not being concerned with this in powering an atomizer.  Voltage can spike and ripple all it wants to with zero effect on atomizer performance.

The high capacitance values you see in the data sheet are stated in terms of reducing undesirable output characteristics.  We only need what we need for things to operate within the parameters of what the regulator can handle itself which is pretty liberal.

I would go ahead and try the 22uF capacitor array on both input and output.  I would be highly surprised if there's any issue with it. 

On reverse polarity protection, it's your work and it's up to you one the level of protection build into it, but for me, that's something I would absolutely account for.  When it comes to things being idiot proof, I'm the biggest of them all.  If something can be done wrong, I'll do it wrong at some point.

[Visus]

It is a sweet tiny and powerful pcb mod incoming.

I saw that chip and wanted to be the 1st to use it but dang lol...

I still have many chips I still haven't used to make mods with   
waiting on my own home build for my workshop 

Break makes a good argument,  just trim it out, use one or two trimmers and have a good versatility but your math is sound.

I am doing that with any new switch I try lol...

If you look in Craigs post about a voltage detector its kinda sweet and easy to implement maybe instead of the zener (its kinda small).. 
http://breaktru.com/smf/index.php/topic,1212.msg14237.html#new




I

[Breaktru]

It should not matter what the input voltage is as long as it is 3Vdc –14.4Vdc input. If that was true, the output voltage would not be locked into what you set your pot at as the battery weakens.
The DC-DC converters that I have used, never take the input voltage in to consideration for the trim formula and that also goes for the Naos Raptor 20A.

If I was building it I would use a 2.45K ohm fixed resistor and a 1.4K ohm trimmer pot which would give you an output range of 3.7v to 5.5v
The exact resistance with the formula calls for a 2.4489K ohm for 5.5v and 3.87K ohm for 3.7v. Subtracting the two would give you a fixed resistor value of 1.4211K ohms. They are not practical values so that's why I said to use what I mentioned above.

When you correct your schematic, update the one above so not to confuse someone that may want to try their hand at building one.

[Claviger]

Will do. Thanks a TON for your second look break!

[Visus]

woot break with the awesome
12 represent the amperage,  vo is the changing figure.  It doesn't say anything about Vi in that equation....

The POL
Programming Tool, available at www.lineagepower.com
under the Downloads section, also calculates the values of
Rmargin-up and Rmargin-down for a specific output voltage and %
margin.

Linux wont open the file its a xls file my gnumeric is not working properly..  Try their tool.

http://www.geindustrial.com/tools-and-calculators

[Claviger]

Just want to thank everyone for being helpful with a noob trying to self educate. Now I surely know enough to get myself in trouble :-)

Parts are ordered as well as a full setup to build the okl-20t using mamus post. Also got an email from Texas instruments today that my 10amp regulator shipped! Looks like I'll be doing 3 first next week Lol.

For someone interested in learning with some very basic electronics knowledge there is an incredible amount of good info on this forum!!

Actually have an idea on something I have not seen done by anyone so far. If it works it will be incredible, I'll do a build walk through when the mystery 4th setup gets here, providing it actually works.

[Claviger]

woot break with the awesome
12 represent the amperage,  vo is the changing figure.  It doesn't say anything about Vi in that equation....

Linux wont open the file its a xls file my gnumeric is not working properly..  Try their tool.

http://www.geindustrial.com/tools-and-calculators

When I read the equation with the 12 as amperage instead of voltage it makes more sense. Dangers of trying to design a circuit for the first time at 2am.

[Visus]

When I read the equation with the 12 as amperage instead of voltage it makes more sense. Dangers of trying to design a circuit for the first time at 2am.

Yeah your math was good but because it was applied wrong, we both just learned a whole lot about how they implement a switch..  If 12A is constant, like our atomizers when using a mechanical, lower ohm atty's are hotter quicker; so we floor the throttle of induction by freeing the slaved electrons by what they call a loop and on that chip its tuneable to so many digits..  So,  it should be bang on when dialed at the pot loaded/unloaded, the output/atomizer,  but quite a few chips say this and are not unless you dial in the caps that clean up the tune,  its an awesome lesson learn here..

But since we are only firing an atomizer it doesn't need to be accurate to the third, fourth, or fifth digit lol...  So we are paralleling to already created resistance internal on the chip that creates 0.6v output and modifying it with our pot and set resistor.    woot more understanding..

[c1truz]

I have personally used this board.  And if i missed it in reading im sorry but I hope you are making a breakout board for it and not trying to solder to those small pads.  The smallest is 1.01mm x 1.01mm pretty darn small. 

I was using the digital one not the analog though so maybe you dont have those small pads(edit this one has mostly small pads).  I do have ONE breakout board left that I had made for the digital one if you want it.  Have to mount it with a hot plate or something though.  Pin out is the same on digital and analog. 

Wire is 24 gauge if that helps with size of module. 

[c1truz]

or you can order 3 boards for $3.45 shipped.  http://oshpark.com/profiles/c1truz

[Breaktru]

Nice find on the breakout boards c1truz

[c1truz]

Makes it much easier to work with.  Especially when prototyping. 

[Rico]

Hey c1cruz,

Thank you so much for sharing with us this nice PCB for prototyping purposes!
It's and incredible job you did so far with this chip (I also saw your mod project in another post :p).

I just ordered a batch so that I can experiment myself with this nice converter

PS:
I suppose this PCB is also compatible with the 6A version (PDT006A0X) of the chip, im I right?

[Rico]

Hi c1truz,

Thanks again for the nice prototyping PCBs, they did the job well:)

The second try to solder it using the hot plate technique worked (the first try the temperature was too hot and every components unsoldered, LOL) and I now have a working chip for prototyping: so advice number 1, buy an infrared thermometer to monitor the temperature, its very usefull
Its breadboarded with an Arduino pro mini 8MHz and i can power it on/off using the OPERATION PMBUS command

What I saw is when power is on (with 3.2V output), and even if the vout pin is not connected to anything, the module is quite warm to the touch: I can leave my finger on it no problem, but I see that its rather hot.
Did you also saw that on your side?

And how is your current DLynx project progress?

Best Regards,