Jib77 Driver?

Wolfman29 said:

Turns out there is also a 3.2A spike on start-up... I am starting to think that this driver isn't as effective as I thought it was o.o

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Depending on what you're measuring, I could see the spike very simply being attributable to the charging of the IC's input cap, and thus nothing to worry about.

But I still want to know how a constant current driver can have non-constant current. What is the driver actually set to?

Turns out it's actually set to 2.5A... just did some testing. They were paralleled, equal to .5 Ohms. So yes - it's limited by the heatsinking on the driver.

So for all those who read this and buy a Jib driver - make sure you remove a resistor.

DTR said:

:thinking: I do?

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:wtf: i would of thought so :spank: i dunno if im somehow drunk, tired or freaking delirious.....

u only do it in your Saik build (which i love ) and somehow i though that related to most of your builds... Silly me

Wolfman29 said:

So for all those who read this and buy a Jib driver - make sure you remove a resistor.

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Uhhhh, hold on for a second before you go cannabalizing his driver Lets wait and get Jib's input. For one, if you remove a resistor, we don't know if the remaining resistor can handle the 1.5W + that a regulated 1.25A would create. So lets get the designer's input before assuming there's a problem!

Having said that, I am semi-convinced that his driver uses an LM117 and NOT and LM1117 as specified - take a peak:

I'm just going by photos - I don't have one - but it looks like a 117 not a 1117 (two 1s versus three 1s)

Well they aren't the same IC

The LM1117 (what Jib lists)
- LDO Low Dropout
- 800mA current limit (that always confused me about his 1.3A drivers)

The LM117 (what the photos look like the drivers actually use)
- Not LDO Low Dropout (closer to 3.25V with resistor factored in - basically an LM317)
- 1.5A current limit (again, like an LM317)

MY THEORY
Here's what I think is going on. Jib is using an LM117 instead of LM1117. He's NOT using a low dropout IC. So even though his resistors are set to supply 2.5A of current, that will never happen because the DROPOUT voltage is preventing it. In other words, two cells give you ~8V, his circuit drops 3.25V. That leaves somewhere around 4.75V for the 445nm diode. Based on the 445's PIV curve, it is the VOLTAGE that stops the diode from sucking up 2.5A (and probably massive-over-current protection on the IC that would shut it down if that ever happened).

To test my theory, try using 3 cells with Jib's driver. USING A TEST LOAD! (don't kill a diode).
- I would be willing to bet that you see way more current than whatever you normally get with 2 cells. You may not get 2.5A since the IC will probably overheat, but I bet you'll far exceed what the current "limit" was thought to be.

My theory could be wrong - but that's what I'd put my money on.

Wow i never noticed that ..... Jib you've got some explaining to do

im comfused Jib any input on this cause it clearly states 117 im not saying your doing anything wrong just asking

Whoopsie daisy....
Still a good driver when used for 445nm diodes and with 2x LiIon.
But apparently it is operating OUTSIDE of regulation.

Whoops! This may not end well for jib :O

anselm said:

Whoopsie daisy....
Still a good driver when used for 445nm diodes and with 2x LiIon.
But apparently it is operating OUTSIDE of regulation.

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Well - I really want to hear from Jib.
But if my understanding (post above) is correct, then this is not largely different from direct drive (IE, relying on the voltage supply capabilities, and/or current supply capabilities of the batteries to keep the diodes safe).

LaZeRz said:

:wtf: i would of thought so :spank: i dunno if im somehow drunk, tired or freaking delirious.....

u only do it in your Saik build (which i love ) and somehow i though that related to most of your builds... Silly me

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It is all good. That was a special request to see how much of a bump it would give.

Did anyone get to the bottom of the issue with this driver? I lost track.

DTR said:

:thinking: I do?

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one time you turned the saik build, or another build up to 1.9A just to push it past the 2W mark.

Don't know if it's been posted already, but, you did it hahaha

Wow, was not aware of this thread ... it would have been nice to be alerted to its presence.

1) The IC is self regulating ... it has both an internal current limiter and thermal protection. My resistors are there to make it a current mode driver, and nothing else. The reason its 1.3A without heatsink is because that is where its internal limiter kicks in. When you add heatsinks, its internal are not getting as hot, so internal current limiting does not kick in until1.5-1.6A.
Taking out a resistor is ok since they are rated for 2W, this make it a strict 1.25A driver.

2) There is no current spikes, it is DMM artifacts. This is the driver scoped:


As you can see it does a nice soft-start as its supposed to do ... no current spikes. I too get a spike on my DMM but only to 1.8A.

3) It is in fact a LM1117 LDO ... not a LM117. The part number is NCP1117DT.

I just found out about it when I posted jib, or I would've holla'ed

Makes sense -

One Q still confusing me: Why do the photos show an IC that says 117 not 1117?

Because that is an internal manufacturing code for ON Semi, not a part# or an IC series name: