Texas Instruments boost converter frying m401 atty's @ 5 volts

[Ez Duzit]

Here's one for you electronics guru's. I don't know what the hell is happening here.
I got some of the 5v regulators, and some of the 4050 boost converters from Texas Instruments. Haven't used the regulators yet, but built a decent looking 5v box using one of the 4050's and the dam thing keeps frying atty's after 2-3 seconds every time.
I used the 100µF caps on the input and output, as specified in the 4050 data sheet. Pretty basic circuit, but I still rechecked it to make sure it's wired properly. The output is exactly 5.04 volts. It stays constant under load, which I checked as it blew the 3rd atty. I'm using 401 atty's and they're all around 3 ohms, or should I say.... were around 3 ohms.

Why is this thing popping attys like that? The first 2 it blew were used, but both worked awesome on my 3.7 nicostick. I figured maybe they were just ready to die, so I tried a brand new one, and got the same result. Dead atty after about 2-3 seconds. Tried one more atty that was almost dead anyway, and it lasted all of 2 seconds.

So is anyone else out there running a 401 atty at 5 volts? Is the 401 just to fragile for 5 volts? I can't believe that could be it, but not sure what else it could be. Could this particular 4050 somehow be faulty? I mean, the output is spot on, so it appears to be working right, except for the part about frying atty's.

I know that a few people run these without the input and output caps, and they work ok, but that couldn't have anything to do with it, could it? Wish I had a scope to look at the output. I can't figure out what wtf is going on. Any help is appreciated.

Thinking about trying one of the other 4050 units I have, without the caps. Of course that won't happen until after I get more atty's dammit. Down to 3 now and won't risk anymore till I get new ones. Should be here Wed or Thurs.

 

[emus]

Is there any chance more than 5VDC is building up in the cap?

My M401 passthru puts out 3.4VDC.

It is hard to believe 5VDC is to much? Maybe?

 

[Nuck]

I found 401's become increasingly fragile after 4.4v. I won't go above 4.5v with them.

The caps should be low ESR..can't see from the pics. The datasheet has a list of caps that work well.

The other thing you have to do is test the voltage under load. The boards usually increase by 0.1 to 0.15v under load over nominal so it is very possible you are approaching 5.2v for the 401 which is pretty much atty suicide.

 

[Ez Duzit]

I found 401's become increasingly fragile after 4.4v. I won't go above 4.5v with them.

The caps should be low ESR..can't see from the pics. The datasheet has a list of caps that work well.

The other thing you have to do is test the voltage under load. The boards usually increase by 0.1 to 0.15v under load over nominal so it is very possible you are approaching 5.2v for the 401 which is pretty much atty suicide.

You might be right about 401 atty's sucking ... at 5 volts. But I had to know, so I yanked out the booster, switched the battery connections, and wired in the 5v regulator instead. It works awesome. TONS of vapor, and perfect throat hit. Still has all that great flavor that 401's are known for. OMG it's so good.
Lasted all of 4 minutes.................Stop laughing.

I have 5 dead atty's now!

So, since I obviously can't use 401 atty's at 5v, what size resistor would I need, between the regulator output, and the atty, to bleed off about 1/2 volt? I'll be ordering other atty's besides 401's later today, but I do like the flavor from the 401's so I wouldn't mind having at least one 401 setup with a little extra kick.

As far as the caps on the booster circuit, I doubt they were low equivalent series resistance caps. Just plain old 100microfarad electrolytic caps from the shack. What effect would that have? Just wondering since I might still use this circuit.

 

[emus]

I know RN4081 will work for months at 4.5 VDC and hits similar to M401.

Thanks for finding 5 VDC kills M401; I'll try to remember that

How much current does your 4050 boost converter produce?

I would consider using the 4050 on a 510, then build a 3.6 VDC mod for the M401 instead of chocking the current with a resistor.

 

[Nuck]

You might be right about 401 atty's sucking ... at 5 volts. But I had to know, so I yanked out the booster, switched the battery connections, and wired in the 5v regulator instead. It works awesome. TONS of vapor, and perfect throat hit. Still has all that great flavor that 401's are known for. OMG it's so good.
Lasted all of 4 minutes.................Stop laughing.

I have 5 dead atty's now!

So, since I obviously can't use 401 atty's at 5v, what size resistor would I need, between the regulator output, and the atty, to bleed off about 1/2 volt? I'll be ordering other atty's besides 401's later today, but I do like the flavor from the 401's so I wouldn't mind having at least one 401 setup with a little extra kick.

As far as the caps on the booster circuit, I doubt they were low equivalent series resistance caps. Just plain old 100microfarad electrolytic caps from the shack. What effect would that have? Just wondering since I might still use this circuit.

You can use a 0.3 ohm resistor to take the edge off (about 1/2 a volt).

My first caps were regular electrolytic caps and I couldn't get reliable performance with them...didn't see much difference as with no caps. The power tends to "flicker" when you don't use the caps particularly on smaller bats.

If you do find an issue with it you can try these ones:

Digi-Key - 495-1529-1-ND (Manufacturer - B45197A2107K409)

They are quite small and work really well.

 

[Ez Duzit]

I know RN4081 will work for months at 4.5 VDC and hits similar to M401.

Thanks for finding 5 VDC kills M401; I'll try to remember that

How much current does your 4050 boost converter produce?

I would consider using the 4050 on a 510, then build a 3.6 VDC mod for the M401 instead of chocking the current with a resistor.

Thanks emus but I think I'm try and go bigger. The converter puts out up to 2.4a, and you can actually 3 or 4 free samples. Even the shipping. Just register with TI. Plug-in Power Modules - Non-Isolated POL - PTN04050C - TI.com.

I will probably try a 510 but I've gotten spoiled by the flavor with a 401, so I probably won't like a 510, but I'm gonna try it anyway.



Nuck - How do you get a 401 to run at 4.4v on batteries? It's got to be better then what I came up with below.

Also, I figured out my resistor question, I think. (Studied electronics in high school but that was a long time ago lol).
I figured to drop the voltage to the atty down to about 4.5, I would need a really low ohm resistor. 1/3 of an ohm, or .4ohms. By my figures, a .3 ohm resistor would drop just under .5v, and if I used .4ohms, it would drop about .59 volts.

So basically the .3ohm resistor has the atty getting just over 4.5v. If I use a 4ohm resistor, the atty gets just over 4.4v. There's that 10th of a volt difference that might save my atty.

Anyway, I doubt i could find those values, but either way, I can get exactly .33ohms by putting three 1ohm resistors in parallel (1/2 watt should be fine by my calculations and they're tiny).

If I want 4.4 volts instead of 4.5, just to play it safe, it's two 1ohm resistors in parallel with a 2ohm. Gives exactly .4ohms.
ALL of my figures use a value of 3ohms for the atomizer.

The only problem I see with doing it this way is the resistors are drawing the same amount of current as the atty, (about 1.5a), so it will chip away pretty good at my battery life. I think I'm still going to try it anyway. It still might outlast a standard 401, even with the added current drain.

If I'm wrong about the way I figured that, someone please let me know. Like I said it's been a long time since I've played with electricity.

Excuse the MS paint rendering.

 

[Ez Duzit]

Nuck, you posted as I was finishing mine. But at least I know I figured it out properly.
Thanks

Is this the method you use to get a steady 4.4 volts?

 

[Nuck]

Nuck, you posted as I was finishing mine. But at least I know I figured it out properly.
Thanks

Is this the method you use to get a steady 4.4 volts?

I use these at the moment:

Digi-Key - B280-FDICT-ND (Manufacturer - B280-13-F)

and they drop it 0.6v at the level I vape at.

There is another way to do it without wasting power but it keeps burning out the boards so I won't bother posting it until I know why. I'm sending some burnt out chips to RjG who is infinitely better with this stuff than I am.

 

[WillyB]

Is there any chance more than 5VDC is building up in the cap?

My M401 passthru puts out 3.4VDC.

It is hard to believe 5VDC is to much? Maybe?

Same here 3.4V on the PT. Even at 3.4V if I hit it too hard and long it has over heated and actually melted/distorted the top of the juice cup. And 3.4V is definitely higher than my fully charged batts that come in at about 3V.

I like my M401 but for higher voltage mods it's the wrong choice.