Calling All Current Regulation Masters - Unique Driver Needed

This IC requires a complex design but can handle up to 70W. It uses an external FET so your switch current is determined by the your FET selection: http://www.micrel.com/page.do?page=/product-info/products/mic3230.jsp

MIC3230 is a good chip, but if you look on the datasheet, on the "design procedure for a led driver" table, you can see that also this is rated for a maximum capability of 7 leds with 4V FV each, for a maximum voltage output of 28V


EDIT: also, following the datasheet posted from the OP about the LED model, it's rated for 100W (and it will consume more ..... 34V * 3.5A = almost 120W)

What about one of these?

120W DC-DC 10-32V Boost 35-60V Adjustable Power Supply | eBay

150W DC-DC 10-32V Boost 12-35V Adjustable Power Supply | eBay

Then I wouldnt need as many batteries and could use A123 26650s instead!

I wish they were 20-40V since I need 32-36. Could I use some diodes (non laser) on the 35-60 to get the voltage down or some how get the 12-35 to boost 1 volt higher?

I dont think they are current regulators but I should be able to get away with voltage regulation I would imagine.

What do you guys think?

1 volt won't make much of a difference. It is likely to draw full current at 34V anyway. You don't need to run LEDs at their max current. In fact, it's generally bad for them.

The 150W one looks promising

Cyparagon said:

1 volt won't make much of a difference. It is likely to draw full current at 34V anyway. You don't need to run LEDs at their max current. In fact, it's generally bad for them.

The 150W one looks promising

Click to expand...

True.

Is there a way to make the output adjustable? AKA set the pot to the max voltage I want it to run and then be able to adjust from lowest voltage of driver to that preset maximum voltage from a knob on the exterior?

Yes, the pot seems to be hooked up as a rheostat. So changing the resistance the board sees there will change the voltage and therefore the current and brightness.

You would need to tinker with it to find optimal values.

Ok unless someone tells me a reason not to I am going to go ahead and order it.


I think I will run it off of 5-8 LiFePO4 cells.

They ship everywhere except Italy ..... normal

Anyway, looking at them, they seem only voltage-regulated drivers, with a sense resistor for the max current shutdown ..... but this may mean that changing that sense resistor, you can set a maximum current, and then use the trimmer for lower the voltage for dim the led (at least, seeing the pics)

Anyone know what chip they are using ?

Or my thought was to open through circuit at one side of the pot and insert either a variable resistor that can be turned to 0ohm and up or a multi switch that could change between several resistor and a simple wire. This way the max voltage could be set by the pot and then dropped down with the other adjustable resistance.

Not so good, as solution ..... how much voltage do you have available ?

If higher than the led required voltage, i still suggest you the mosfet/opamp system, if lower than that, you need a boost driver, and this will be a killing (both for current required from batteries, and for the wallet )

HIMNL9 said:

Not so good, as solution ..... how much voltage do you have available ?

If higher than the led required voltage, i still suggest you the mosfet/opamp system, if lower than that, you need a boost driver, and this will be a killing (both for current required from batteries, and for the wallet )

Click to expand...

Well I havent built it yet so I can use any battery configuration. However I like the idea of a boost driver because:

1. The driver is only $9
2. I dont have to buy 12 Batteries
3. I dont have to build the driver (I am not an electronics expert - just have basic knowledge)


Do you not think that this driver and 6 lifepo4 18650 batteries would be a good setup? The lifepo4 cells are made by A123 systems and have been test vigorously by RC enthusiasts. They are rated at 1100mAh and 10C!

Just keep in mind that the energy don't come from nowhere

If that 150W driver (the one that have the limit resistor, as far as i can see from the pics) is capable to give you 35V at 3A from 12V, it can require also 10A from the 12V part (the 105W, plus some extra current, cause 100% of efficence is not existing) ..... or around 5A if you power it with 24V input ..... and so on.

Does those LiFePo batteries survives, to repeated stresses like these ones ?

HIMNL9 said:

Just keep in mind that the energy don't come from nowhere

If that 150W driver (the one that have the limit resistor, as far as i can see from the pics) is capable to give you 35V at 3A from 12V, it can require also 10A from the 12V part (the 105W, plus some extra current, cause 100% of efficence is not existing) ..... or around 5A if you power it with 24V input ..... and so on.

Does those LiFePo batteries survives, to repeated stresses like these ones ?

Click to expand...

They are supposed to be incredible batteries and in all honesty I will not use this light daily. I could go with larger lifepo4 cells that are rated higher. Also with this driver I could hook the light to a 12V car plug! Would be amazingly useful camping etc!

The more I think about it the more I see myself using it 90% of the time hooked up to a car or outlet (I already purchased a 110AC power supply). Its almost a an impractical amount of light for using fishing or hiking and I have other lights for that.

I will end up making a battery pack for it just so that I can say it is portable and for the few times I will want it to be :beer:

^ in this case, 8 x "C" or "M" size cells in serie will give you some authonomy without blow up

And you don't need to switch them in banks for charge them ..... just be sure that they sell you the cells all from the same production lot (the serial number must be identical for all of them), and then you can also recharge them as a single 26V cell (and if you don't need "quick charge" option, the CC/CV charging circuit is very simple and can be built inside the torch with the battery pack)

HIMNL9 said:

^ in this case, 8 x "C" or "M" size cells in serie will give you some authonomy without blow up

And you don't need to switch them in banks for charge them ..... just be sure that they sell you the cells all from the same production lot (the serial number must be identical for all of them), and then you can also recharge them as a single 26V cell (and if you don't need "quick charge" option, the CC/CV charging circuit is very simple and can be built inside the torch with the battery pack)

Click to expand...

I do not care about charge times so thats a great suggestion!

As far as blowing up I really suggest checking out the A123 cells. As far as I know no one has even been able to get one to blow. They are used all the time in high drain RC applications as well as ultra high drain EV car applications so if there was a risk of explosion we would know by now. :wave:

I can already see myself converting over to them as we speak. They are safer, have longer shelf life, Higher discharge, and the only thing you lose is some capacity.

Then these ones are ok ..... and for the slow charger, i will suggest you a very easy and efficent solution.

Get a transformer with a 24V 1A secondary (relatively small and common), followed from a rectifier bridge and a 1000uF 50V capacitor ..... then build a voltage regulator, followed from a current regulator (you can use a pair of LM317 in serie, for this, with a pair of small heatsinks) ..... set the first one (voltage regulator) for get 28.5 / 29V (the max nominal voltage of the 8 cells pack plus the dropout of the second IC and the diode), then set the second (current regulator) for 1/8 to 1/10 of the rated current of the cells (like, if the cells are rated as example 2Ah, set it for 200 to 300 mA), and finally a silicon rectifier diode (high current, 3 to 5 A rated) in serie, connected directly to the cells pack.

The diode prevent te discharge of the pack through the regulators (so you don't need a switch for change from use to charge), the regulators acts as CV/CC charger ..... when the cells are undercharged or weak, they become charged in current, until they reach the nominal value and start to "eat" always less current til it become constant voltage maintaining at low current ..... this also cannot overcharge the cells, cause when they are at the full voltage, the current draining will virtually stop.