NJG-18 Driver Questions

[metlarules]

If anyone can explain the workings of this driver I would appreciate it.
In the link below it states that " if the output setting is exceeded by the input it will go in to direct drive". Does this mean that if I use a li-ion cell at 4.2v it will be operating in direct drive? Further down he does a test with the input voltage at 4.1v@540mah stating that the output is 3.2v @500mah. What's going on here? http://e-lectronics.net/boost-driver-board-input-voltage-8v7v-njg18-p-422.html

 

[metlarules]

Anyone? :shrug:

 

[Justin Case]

The data presented doesn't make sense. The NJG-18 is supposed to be a boost converter. Typically, they can withstand a small amount of overdrive, say about 0.5V or 0.7V above Vf, such as when using 1xLi-ion to drive a single LED with Vf~3.5V. In that case, the board should run in direct drive. When the battery voltage drops below Vf, then the regulator kicks in.

Deal Extreme sells the same product for a lower price (though backordered). Search for SKU 7882. DX also has more information on the NJG-18 on their forum: http://www.dealextreme.com/forums/Forums.dx/Forum.7882

What is it that you want to build?

 

[metlarules]

The data presented doesn't make sense. The NJG-18 is supposed to be a boost converter. Typically, they can withstand a small amount of overdrive, say about 0.5V or 0.7V above Vf, such as when using 1xLi-ion to drive a single LED with Vf~3.5V. In that case, the board should run in direct drive. When the battery voltage drops below Vf, then the regulator kicks in.

Deal Extreme sells the same product for a lower price (though backordered). Search for SKU 7882. DX also has more information on the NJG-18 on their forum: http://www.dealextreme.com/forums/Forums.dx/Forum.7882

What is it that you want to build?

I want to use it in a d26 drop-in driving a Cree Q3 5A emitter.. I want to set the high mode to 700mah using a li-ion 18650.I also want to use it with 1 4/3a or 4/3af cell(nimh single cell) as I have a bunch of those.I was afraid that if I put 4.2v into that it would overdrive the led and burn it up.

 

[Justin Case]

Hard to say if the Li-ion will work or fry the board based on the scant information provided by these vendors. I would think that odds are it will work.

What you can do is partially discharge the cell so that its resting voltage is say 3.9V or 4.0V and try that first.