NejTech Evolution - a new BOOST driver - Nearly finished!

Re: NejTech Evolution - a new BOOST driver - It lives!!! (sorta)

Maximum sustainable current output tends to decrease as output voltage increases. Most of the stuff i've simulated with a 4.4V output shows roughly a 40-50% correlation with the various IC's datasheets listing of 'maximum switch current'. So my guess is if the circuit was designed properly. It's capable of 1.2-1.4A into a 445. Though this is easily tested with a test load and using a fully charged battery.. Just hook it to a string of 5 1n540x diodes and a 1ohm resistor and crank it up. Finding maximum output doesn't really involve any 'high tech equipment' and running it off a battery, especially an 18650, would be a lot better real world test than running it off a high current bench psu that won't have any voltage sag. After all. What matters is how these drivers will act in the real world in use, not what they'll do under 'perfect' conditions.

Also.. You can't really go by 'datasheets showing it driving long strings of LED's' as being able to deliver high currents in the real world. After all, 10 10mA LED's would only be 100mA of load....

Re: NejTech Evolution - a new BOOST driver - It lives!!! (sorta)

Kay... of to charge some 18650's I guess... About the datsheet driving long strings of LED's, I was replying to Wolfman, because he was asking about max voltage.

I wanted to take some photos of these pretty purple boards, but my camera's batteries are discharged. As soon as recharging finishes, I'll upload some photos.

EDIT: And there go two dead drivers... Death by running it without load... Reason: darn alligator clips too wobbly... Anyway, one gave me with a 4.1V 18650 a bumpy 1.2A most likely due to heat... I glued some heatsink to the third, just waiting for the thermal glue to dry. Interesting is, that when dead, both supply a pretty stable 120mA. I might add a little protective circuit to it, so it would become the first switched supply that can be ran without load.

EDIT2: After heatsinking it, the driver gives a STABLE 1.2A from a 4.07V 18650!!! Success! --- In memory of: two prototypes and one single IC

EDIT3: Finished adding the OVP to the design, so they shouldn't die if a LD fails open or ran without load. I even made it another mm smaller!

EDIT4: I just found another little IC. It is a very similar design. However, it can only do about 0.6A. The advantage? ASTONISHINGLY low price. Probably lower than a DDL from Radioshack.

Re: NejTech Evolution - a new BOOST driver - Photos added!

can the output be adjusted? Running two in parallel at 900mA each would be a cheap solution for 1.8A assuming the prices are low.

Re: NejTech Evolution - a new BOOST driver - It lives!!! (sorta)

Johnyz said:

EDIT4: I just found another little IC. It is a very similar design. However, it can only do about 0.6A. The advantage? ASTONISHINGLY low price. Probably lower than a DDL from Radioshack.

Click to expand...

Very very interested! .6A is plenty for anything needed in a portable :angel:

Re: NejTech Evolution - a new BOOST driver - Photos added!

Helios: I do have an adjustable version designed, I will order it after the OVP prototypes arrive.
Pontiac: The parts for the "BudgetBoost" are already here and boards are ordered. It's more likely to do only about 550mA, but still darn good I think. It also has an internal OVP and a soft start.

Re: NejTech Evolution - a new BOOST driver - Photos added!

Any chance these are getting closer to production level

Re: NejTech Evolution - a new BOOST driver - Photos added!

@johnnyz... member cyparagon can test your drivers. pm him if you are interested. he is really friendly.

michael.

Re: NejTech Evolution - a new BOOST driver - Photos added!

Cam453 said:

Any chance these are getting closer to production level

Click to expand...

You bet! I'd love to start making them right away, but I seriously need to do more testing atm... I'm not even really decided about the inductor now...

chipdouglas said:

@johnnyz... member cyparagon can test your drivers. pm him if you are interested. he is really friendly.

michael.

Click to expand...

Thnx for the info.

Re: NejTech Evolution - a new BOOST driver - Photos added!

That would be a limiting factor can't wait for it to be finished.

Re: NejTech Evolution - a new BOOST driver - Photos added!

Alright, just finished my OVP prototypes, and sure enough, they can be ran without load without dying! Next up is the adjustable prototype.

Re: NejTech Evolution - a new BOOST driver - Photos added!

Bumpity bump. Update: I am currently testing an adjustable version (with a pot) - waiting for new parts to come in from Farnell - eta tomorrow. Oh and, the "another cheaper IC" plan has blown up - it can only do around 0.36A.

Re: NejTech Evolution - a new BOOST driver - Photos added!

.36 A is good. That's more than enough for pen pointers which is mostly what I build. If you've given up hope on producing them could I convince you to make me a few board for me to put together?

Re: NejTech Evolution - a new BOOST driver - Photos added!

Nope, not giving up. I will be attending the Farnell Techological Day at ČVUT FEL in Prague, so hopefully I will have a chance to discuss with some other people why is this design so underspec... BTW, I even tried swapping the resistor for less resistance, and the only effect was more heat...

Re: NejTech Evolution - a new BOOST driver - Photos added!

Cool! Just glad to see that there might be some cheap low power boost drives sometime in the future!

Re: NejTech Evolution - a new BOOST driver - Photos added!

Heh, when I first saw the price of it (10 pcs) I almost fell off my chair... Really looking forward to that day - people from Cadsoft, STMicroelectronics, Freescale etc. In case you were wondering, ČVUT FEL = Czech Technical University - Faculty of Electrical Engineering.

:bumpit:
Any Update ??