Does anyone know if the Potrans 6.5A psu can be adjusted down more than 20V?
Yes, I've had it down below 19v, though iirc that's out of spec so might not be achievable on every single unit.
The 5 volts would come from the arduino.
So what your saying is that when i stack a few CAT4101's the current demand goes up not volts.
So in my case I need a 18.5 volt PSU(I forgot to mention the drivers are current set at 800 MA, is it an issue by feeding it 2 amps for 2 drivers?),
so more like a 24 volt supply unless I can get an adjustable transformer.
I know they get rather warm when you put too much voltage,
I do not know how a of as voltage difference would heat up the driver chip.
It would be temping to put the arduino right on the PSU(problem solved about too much voltage) but they can really only use 20 volts tops because the regulator can only on it's max use that high of a voltage.
Thanks for all the help,
I've spent maybe $20 and I can build 6 CAT4101 drivers and that's way less than what's out there.
Quick question.
Say(for instance..) I'm going to run two CAT4101's that will power 5 Crees on one and 4 on the other.
Wouldn't I need a 27 volt 1 amp plus PSU at one amp?
Or would it be a 15 volt 2 amp PSU?
Thanks for the awesome driver
A few thoughts related to these two posts:
1) keep in mind that the max the CAT4101 is rated for is 25v. So, DO NOT connect a power supply and/or LED string that needs more than that.
2) Powering 4 LEDs on one driver and 5 on another, and connecting them to the same power supply, means the power supply will have to have enough voltage to run the driver with 5 LEDs. This means the driver with only 4 LEDs will be dropping an extra 3 - 3.5v, and will likely get very hot (maybe hot enough to trip, unless you provide a heatsink or cooling for the IC).
3) As indicated in terahz's post, many "industrial" power supplies have adjustable voltage - so if you get a 24v supply but only NEED 21v, you'd definitely want to turn it down to 21v. Don't kill yourself looking for a 21v supply, the 24v unit will be happy trimmed down.
4) Regarding running the Arduino from the 24v supply - depending on how much current you're pulling on the Arduino, it may be just fine. If all you're doing is feeding a control signal to the CAT4101 chips, then I'd say it's almost certainly fine - that's only going to be an mA or two more load than the AVR on the Arduino takes, which isn't much at all. Worst case, get a voltage regulator around 10 - 15v and build a little breakout to knock down the 24v to something small enough to keep the reg on the Arduino from cooking itself. IMHO this is preferable to setting up another power supply just for the Arduino, if you're trying to keep things simple.
You need about 1/5 volt over the LED drop. Anything more is just turned into heat the CAT as to dissipate.
I think you meant 1/2v?
