5000lm bridgelux power supply questions

[Axkiker]

what would you all think about using this power supply to run the big bridgelux led array

the bridgelux specs are 25.4 v 2.1A 5000 LM


driver below

http://cgi.ebay.com/12V-24V-Step-up...DC-DC-New-/250680842823?pt=LH_DefaultDomain_0


What would you think about running 2 of the 5000lm bridelux in parallel ????? see any issues

 

[Steve K]

and the search goes on....

while the ebay site doesn't have much useful info, they do provide a useful link:
http://www.nbglin.com/dc.htm

and the "LM2577" on the boost converter IC tells you that this is one of National Semiconductor's early "Simple Switchers". Nice, well behaved parts.

You can dig up the datasheet too:
http://www.national.com/ds/LM/LM1577.pdf

The datasheet tells you what the device can do, for the most part. In your case, I think the biggest issue is the power that you are wanting to convert. It sounds like you want to convert about 100 watts of power (two of the leds, each of which is drawing about 50 watts).

The problem is that the switch transistor can handle up to 3 amps. This is the current that the converter will draw from the 12v supply. Ignoring the current ripple, this means that it will only convert 36 watts of power, and not the desired 100 watts. Heck, it won't even drive one of the Bridgelux leds that you are looking at.

There are other limiting factors too, such as the current rating for the inductor and flyback diode. Only the factory in China knows what parts are used on the circuit board.

So.... unless I've overlooked something, this is not the converter for your application.

OTOH, you could always run one or two of these in parallel to get the desired output current. You'd need to run a small resistance between each converter output and the common load (or led) in order to get the converters to share the load properly.

regards,

Steve K.

 

[Axkiker]

and the search goes on....

while the ebay site doesn't have much useful info, they do provide a useful link:
http://www.nbglin.com/dc.htm

and the "LM2577" on the boost converter IC tells you that this is one of National Semiconductor's early "Simple Switchers". Nice, well behaved parts.

You can dig up the datasheet too:
http://www.national.com/ds/LM/LM1577.pdf

The datasheet tells you what the device can do, for the most part. In your case, I think the biggest issue is the power that you are wanting to convert. It sounds like you want to convert about 100 watts of power (two of the leds, each of which is drawing about 50 watts).

The problem is that the switch transistor can handle up to 3 amps. This is the current that the converter will draw from the 12v supply. Ignoring the current ripple, this means that it will only convert 36 watts of power, and not the desired 100 watts. Heck, it won't even drive one of the Bridgelux leds that you are looking at.

There are other limiting factors too, such as the current rating for the inductor and flyback diode. Only the factory in China knows what parts are used on the circuit board.

So.... unless I've overlooked something, this is not the converter for your application.

OTOH, you could always run one or two of these in parallel to get the desired output current. You'd need to run a small resistance between each converter output and the common load (or led) in order to get the converters to share the load properly.

regards,

Steve K.

Good greif just as soon as I think I have something I find out I dont. LOL

So let me see if im reading all this correctly. I can run 2 of these in parallel to run 2 of the bridgelux in parallel??? What exactly would I need to do to do that.

Do you know of another driver that would run either one or two of the bridgelux leds. I would even be happy if it only ran one. I could just use 1 driver per LED

any thoughts

 

[Steve K]

Good greif just as soon as I think I have something I find out I dont. LOL

So let me see if im reading all this correctly. I can run 2 of these in parallel to run 2 of the bridgelux in parallel??? What exactly would I need to do to do that.

Do you know of another driver that would run either one or two of the bridgelux leds. I would even be happy if it only ran one. I could just use 1 driver per LED

any thoughts

It would take two of these to run just one Bridgelux. You would need to insert a modest resistance between the two converters and the LED in order to get the converters to share power. This would also allow the converters to see a more consistent load.... ideally, you'd have some sort of current regulator, since a voltage regulator is really not appropriate when driving an LED.

Unfortunately, I'm not that knowledgeable on what an appropriate converter would be. My approach would be to look at the converter IC's from different semiconductor companies, but that's probably not your best option. If you are lucky, you might find a part that does the job, and the supplier will have an evaluation board for sale. That might be good enough. I know that National Semiconductor used to make eval boards for their Simple Switcher family of parts.

I'd look at Linear Technology, National Semiconductor, OnSemi, ... ummm.... well, maybe just browse thru Digikey and see who else makes LED drivers (maybe Texas Instruments too)

I'm just not a lot of help, but maybe I can help avoid throwing away money on one or two things.

good luck,
Steve K.

 

[Axkiker]

It would take two of these to run just one Bridgelux. You would need to insert a modest resistance between the two converters and the LED in order to get the converters to share power. This would also allow the converters to see a more consistent load.... ideally, you'd have some sort of current regulator, since a voltage regulator is really not appropriate when driving an LED.

Unfortunately, I'm not that knowledgeable on what an appropriate converter would be. My approach would be to look at the converter IC's from different semiconductor companies, but that's probably not your best option. If you are lucky, you might find a part that does the job, and the supplier will have an evaluation board for sale. That might be good enough. I know that National Semiconductor used to make eval boards for their Simple Switcher family of parts.

I'd look at Linear Technology, National Semiconductor, OnSemi, ... ummm.... well, maybe just browse thru Digikey and see who else makes LED drivers (maybe Texas Instruments too)

I'm just not a lot of help, but maybe I can help avoid throwing away money on one or two things.

good luck,
Steve K.

you are most definitly a lot of help and I appreciate the time you take to help me out..

Im starting to think that maybe my best bet is to step down to the 1300lm bridgelux units and run 4 of them off of the taskled.com hyperboost module