Wide output TI Voltage 90w Buck controller PTN78020W

[Claviger]

Fun stuff on order!  7v min input voltage, 90 watts, 6A, large output voltage range.  Thinking of making a triple 18650 box mod for 3-4 day endurance before charging is required, will probably be my first using an integrated charging solution, probably the circuit developed by breaktru.  Also considering using the digital pot circuit breaktru put upAfter rethinking it, I would rather twist a knob then press a button repeatedly or wait for it to auto-press.  Thinking dual LCDs a simple 2 wire for output voltage and a 1s-6s screen for cell monitoring or perhaps the tiny solution that is on hobby king.  Has anyone done any work using the 8020W series yet?
 
Box - https://www.fasttech.com/products/1373301
Chip -
http://www.ti.com/product/PTN78020W?keyMatch=8020w&tisearch=Search-EN

[Visus]

 

[SilenTDoGz]

hehe....ditto

[Claviger]

Ok I have done some quick reading. The intent of this device compared the OKL2-T20 and Texas Instruments 221W is to allow for a wide range of output voltage.   Being able to sweep from 2.5 to 10 volts will allow for a very wide range of atomizers with significantly varying resistances to achieve high power levels.  Actually, this 2.5-10v range is perfectly suited for a 1.65 ohm coil, a very easy target to hit in rebuild-able tanks using 28 gauge kanthal a1 on a 7/8 wrap 1.5mm microcoil.   It would also run the higher ohm off the shelf coil heads and carto, usually 2-3 ohm range at fairly high power, significantly higher wattage than any existing device I have seen, which are all limited by their output voltage (SX-350/DNA - 30 included).  The table below illustrates my point. Current x - 6 volt offerings being widely used cannot push higher ohm coils/cartos to the wattage I am looking for (I usually vape from 20-40 watts).

Current Table in Amps
Output   Resistance of Coil
 Volts  - 0.6 - 0.8 - 1.0 - 1.2 - 1.4 - 1.6 - 1.8 - 2.0
2.5        4.1   3.1   2.5    2.1   1.8    1.5   1.3   1.25   
10        16.6  12.5   10    8.3  7.14 6.25  5.5     5






Here is the parts list I have come up with:
Resistor to set max voltage output to 10 volts - http://www.digikey.com/product-detail/en/MFP-25BRD52-2K7/2.7KADCT-ND/2059130
470k POT which allows for 2.55 minimum voltage, fitting for running very sub ohm coils(I like these pots despite their ridiculous price) - http://www.digikey.com/product-detail/en/P16NP474MAB15/P16NP-470K-ND/1587868
Output Capacitor - http://www.digikey.com/product-detail/en/GRM1555C1H301GA01D/490-6230-1-ND/3845427
2x Input Capacitor - http://www.digikey.com/product-detail/en/C1210C475J3NACTU/399-5777-1-ND/2236784
2 x PTC Fuses - http://www.digikey.com/product-detail/en/2920L300%2F15DR/F2875CT-ND/1833229
Battery Holder - http://www.digikey.com/product-detail/en/BK-18650-PC6/BK-18650-PC6-ND/2330514
Case - https://www.fasttech.com/products/1373301
Heavy duty button to cut Vin instead of using on/off function - http://www.digikey.com/product-detail/en/GPB553B2L01BU/CWI278-ND/3193544
P FET for reverse polarity protection - http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=151097628&uq=635373318922396828
Fat Daddy Vapes SS 510 Connector w/locking washer
Battery Monitor - http://www.hobbyking.com/hobbyking/store/__22693__FrSky_Lipo_Voltage_Sensor_FLVS_01.html
Output Voltage Monitor - http://www.hobbyking.com/hobbyking/store/__18825__On_Board_LED_RX_Voltage_Display.html
3 x The only battery I will use - http://www.orbtronic.com/sony-18650-2600mah-vtc5-30a-high-drain-hybrid-imr-li-ion-battery

more to come when everything arrives.

Parts are on order, and TI sent me a free sample of the 8020W

[Jasen]

 

[timesarerough]

3 x The only battery I will use - http://www.orbtronic.com/sony-18650-2600mah-vtc5-30a-high-drain-hybrid-imr-li-ion-battery

But may not be the best battery choice?

http://dampfakkus.de/akkuvergleich.php?akku1=507&akku2=490&akku3=523&akku4=&akku5=&akku6=&a=5

The Sony VTC5 is toast at 800mah (3.3V) in a 20A drain and the cell's temperature will reach 200+ degrees F if discharged to 2.5V.

http://www.intaste.de/community/dtf/VTC5-discharge.png

The LG HE2 is toast at 1000mah (3.3V) in a 20A drain, cell temperature not shown in this graph:

http://i01.i.aliimg.com/img/pb/178/169/948/948169178_181.jpg

And the Samsung INR-25R is so new that I cannot find any comparable graphs other than this one:

http://abload.de/img/5abis2.5vhochstrombhgj9w.jpg

It's beats one of my favorite batteries, the Panasonic NCR18650PF, to 3.3V and keeps it's voltage higher for longer off the charger...in a 5A drain.

The Sony is not actually rated for 35A....it's only a 20A cell, as are the LG and the Samsung.

But the most surprising of the 3, is that the Sony is $1.50/ea MORE per cell wholesale than the LG or the Samsung....and IMO, is the last battery that I would choose out of the 3.

My first choice would be the Samsung, then the LG.

The S. Koreans are building far superior batteries over the Japanese in recent years.

As much as I love my Panasonic and Sanyo cells, the SK's are currently making the best batteries on the planet!

[Claviger]

Those graphs directly contradict testing I have seen done on the Sony.

The Sony data sheet also provides discharge duration for extreme loads all the way up to 100 amps!

Anyway not a battery thread, don't care if god himself handed out a battery that was 9999mah and could handle 99amps, I'm using VTC 5s because I have seen loads under 0.1 ohm put on them repeatedly and they don't even get warm


IN OTHER NEWS:

I have a self switching, internal usb charging circuit for dual and triple 18650s designed, will post when I am happy/confident with it.  Essentially it will run in series for vaping until the USB plug is inserted, then it auto switches to parallel to charge, and switches back when unplugged or when the batteries reach full charge.  With a Push switch attached to Vin instead of the on/off pin, it should basically sit with no draw on the batteries when left on its' own.  Should be about 3 or 4 components Will end up being quite a few more unless I can find the perfect IC.

[CraigHB]

To take this regulator to the maximal output of 90W requires an input approximately 100W.  With 3 cells in series, minimal input voltage will be 9V assuming an ideal cutoff 3V per cell.  So, worst case input current is 11 Amps.  That's well within tolerance for a 20 or 30A 18650.

In terms of battery loading, a cell should never be taken over its burst limit when used in an e-cig.  Typically burst limits are about 50% over the continuous limit.  Anything higher than that for a 20 or 30A cell is irrelevant for vaping and shouldn't be done anyway.

A single cell at 30A is at least 90W and two cells at 30A is at least 180W.  Maybe 90W, but there's no way you could ever vape at 180W.  Though, I'm sure someone will prove me wrong at some point.  People have jokingly vaped with a fog machine and those are commonly 600W, but that doesn't count, that's not an actual e-cig with an e-cig atomizer.

[Claviger]

Well, this has been twirling around in my head, inspired by Craigs mention of a solid state version of Breatru's series to parallel internal charging circuit using a 3PDT switch.  I have been trying to self educate as fast as possible on it, but EE is a serious knowledge deficiency of mine. Here is my idea.


Problems I am running into:

1: I do not know where to wire the resistors for the Gates on the FETs.
2: I do not know exactly which FETs to use for items 7,8,9. I have found the right ones for 1-6 though (I have also found a single FET array that will work with one chip to do all the 1-6 switching, that is 3x3 mm)
3: No idea where to connect the ground on the MCP73831T #1 lmfao. Pretty sure it needs to be kept separate from MCP73831T #2 to avoid a short circuit. FETs 1-6 grounded to the USB #1 controller when they should be low and 7-9 grounded to the series circuit ground when they should be low.

Enough of the don't knows, here is the circuit I could use a helping hand to check if it is in fact correct and free of shorts as well as safe if anyone is interested  
Would be a great little setup for all your box mod charging needs


Updated to ground the FETs and the #1 power module.






Here is my concept for the auto switching series to parallel internal USB charging to allow vaping while plugged in to the USB charger.

FETs 1-6 would not allow current from D to S until voltage is applied to G. FETs 7-9 are the opposite and allow voltage from D to S until G is powered. 

When powered from the Mini USB connection the MCP73831T #1 attached to the switch would power all the FETs, changing the configuration from series to parallel. When the switch is depressed the voltage would be cut to the FETs, putting the batteries from parallel to series and grounding 7-9 FETs to the 12.6 volt ground pulling them low, allowing you to vape while connected to the USB plug and it will resume a parallel charging configuration as soon as the switch is released and energizing the G  on all the FETs.

The 1 amp fuses are to prevent high currents between the batteries during charging and avoid overheating possibilities due to uneven discharge.   The charging circuit (MCP73831T #2) only charges at 500ma, so the whole parallel charging circuit can be built with very small components and thinner wire.

If I get the circuit down and safe, as well as finding the right parts, I'll prototype using the board in this thread and 3 18650s, then probably move onto miniaturization using Li-Po batteries to to a 4s version. 4s is where the DC-DC converter options start to get really interesting.

[Visus]

Maybe this will help 

http://www.batteryspace.com/prod-specs/7758.pdf

[CraigHB]

What you're trying to do is not a trivial task so don't feel bad about burning brain cells over it.  I would be burning them too and it's why I'm not going to analyse your circuit.  Though I'm sure you would appreciate it, I don't have to time to do it right now.  Maybe someone else can help you with it.  Should be possible though and you should be able to work it out at some point.

If it were me, I would just give up on the idea of a USB charger and simply provide a 3S plug in the mod for a hobby charger, problem solved, and you can charge and vape at the same time.  There are several small "plug in the wall" 2S/3S LiPo chargers you can get for cheap from Hobby King.  Terminals and connectors are available too, I've looked them up before.

[Claviger]

I have started construction. This will be the last non MCU mod I do, and the last mod in an off the shelf box. All future projects will go the route of custom 3d printed boxes so it is all a perfect fit with premade holes and cut outs. 

Enough of that, here are some pics. I am using 4 Orbtronic 3c 3100 mah protected 18650s in series and plan to charge in 4s mode at 16.8 volts at 1amp using an intelligent charger from tenergy.  Each battery has its own overcharge cut off and over discharge cutoff so it should be fairly safe.  It won't balance but I'll pull the pack in a month and evaluate to see if I need to redesign and add a parallel charging switch.

Visible and added to the board is the 20k pullup resistor, the 2nd SMT 47uf cap (TI leaves a spot unpopulated from the factory). 

Box size is 100x66x43 externally. Inside is more like 98x60x39



Screwdriver for scale



Converter in its' position. Fits in the rail and against the battery pack (which is a friction fit) and should stay put nicely without having to goof around with adhesives and such.



From the top. Still to be fit into the box: 2 x 2 wire 3-30v meters one for batt voltage enabled off a nfet connected to the fire button, and one to the dc-dc output circuit.  The pot, similar to the Axiz mod pot, 300 degree turn and will range from 3.1 volts to 11.99 volts.  FDV 510 connector (last one I have till he restocks ).



More to come tomorrow

[mamu]

Have you tried soldering to the TI board yet, Claviger?  With the TI 16A board, the pins just fell right off when I touched the soldering iron to them, except for pin 3 (Vin ground) - it was solid and didn't budge.

[Claviger]

Ya, they dropped off the instant they got some heat   Fine by me, as it would not have fit in that spot if the pins were still on it!

Look at the Cap design on the board. You can see my meddling I'm sure, but aside from that, they already have a filter on the input stage.  I'm skipping input caps on this one, despite what the datasheet says, my instinct tells me it doesn't matter in our application to filter the input. Time will tell I guess

[Claviger]

Well, the construction is nearly completed, however, the home made battery pack was not stable. I ended up deciding to use Orbtronic protected 3100 mah 18650s in a 4s setup for 14.8 nominal voltage. The battery pack clearly had a short as one of them kept going into protect and causing the mod not to function. Rather than screw around with home made packs etc, I have order 2 4s1p 1500 mah LiPO 20c batteries to run in parallel. Charging will be done via parallel balance chargers run to a mini din which I will wire to plug into a balance charger. At 72x35x23 they will fit perfectly. On a plus note, I can eliminate reverse polarity protection:P

On a side not, the 20k pull up resistor did nothing for the inihibit pin, it must be grounded to turn off, so I had to add a pfet to control grounding the inhiibit pin for the fire button, so when it is depressed it turns on since I don't like the idea of a normally open push switch.  For the short time I was able to test voltage swept nicely from 3.15 to 12.1 at the 510 connector.

Picture will come when it's done, which will be as soon as the parts get here.  3000 mah, and 16ua idle current when inhibit is low, it should last quite awhile!

[Claviger]

Well, because I wanted to make sure the board still worked and that all my connections were good, I went ahead and wired the 2 2S liPO 900mah 10c batteries I had here in series and threw them in for an evening of vaping.  Still have to get the Voltage Displays, Mini-Din charging connector, and new batteries into Eve before she is complete.

So far she vapes quite nice. Being able to toss nearly any atty on and turn it up to the power level I like is nice. Running .8-3 ohm attys at 30 watts, roughly where I normally vape, is pretty kick ass!

Here is a picture of Eve (the new chip) sporting a my favorite atty a Rose V2, next to Adam (OKL2-T20) rocking my 2nd favorite atty, the Expromizer.


At 6'2" I have pretty big hands. Eve is more of a full bodied size or BBW if you will 

[Visus]

Nice mods, no internal view?


They look like a helga and norman. 

Adam and Eve were the most beautiful in creation even the angels whom absolutely beautiful wanted in on the babies.

Eye of beholder I guess. 

[katrev]

I use it with 1 capacitor and 1 100k pot from december as my "desktop" mod .Flawless , the sense is really doing it's job ,i am almost ashamed for using such a product for something trivial as this.
( also a radiator on it,for ~ 0.40 ohm builds)