Matching Drivers and COBs

captainmorgan

captainmorgan

Well-Known Member
Wouldn't 9 CXB3590 CD 36v 3500k COBs at 1050ma add up to 355 watts?

Guess I could run 8 on the HLG 320H and use a single driver for the 9th.
 
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SupraSPL

SupraSPL

Well-Known Member
Yes it is rated to out put 8.9A, divided by 9 COBs that would be 989mA per COB. But in practice it will put out up to 9.7A or 1080mA per COB when adjusted to max. The driver would probably pull 367 watts total at almost 95% driver efficiency.

As far as pros and cons, using the HLG-185 series approach you get up to 190V on the heatsinks so they probably should be grounded for your safety. Wiring in series is simplifies the wires routed through your space.

The HLG-320 with parallel setup would be less than 36V so not as likely to be able to get through skin. Each COB might be getting a slightly different current but probably not a significant difference. Wiring in parallel results in more wires overall.
 
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bassman999

bassman999

Well-Known Member
SupraSPL said:
Yes it is rated to out put 8.9A, divided by 9 COBs that would be 989mA per COB. But in practice it will put out up to 9.7A or 1080mA per COB when adjusted to max. The driver would probably pull 367 watts total at almost 95% driver efficiency.

As far as pros and cons, using the HLG-185 series approach you get up to 190V on the heatsinks so they probably should be grounded for your safety. Wiring in series is simpler.

The HLG-320 with parallel setup would be less than 36V so not as likely to be able to get through skin. Each COB might be getting a slightly different current but probably not a significant difference. Wiring in parallel results in more wires overall.
Click to expand...
I can vouch for the wiring nightmare for wiring in parallel
 
captainmorgan

captainmorgan

Well-Known Member
SupraSPL said:
Yes it is rated to out put 8.9A, divided by 9 COBs that would be 989mA per COB. But in practice it will put out up to 9.7A or 1080mA per COB when adjusted to max. The driver would probably pull 367 watts total at almost 95% driver efficiency.

As far as pros and cons, using the HLG-185 series approach you get up to 190V on the heatsinks so they probably should be grounded for your safety. Wiring in series is simplifies the wires routed through your space.

The HLG-320 with parallel setup would be less than 36V so not as likely to be able to get through skin. Each COB might be getting a slightly different current but probably not a significant difference. Wiring in parallel results in more wires overall.
Click to expand...
I know about the risk of higher voltage with a large driver in series but I'm not very versed in parallel and have heard of thermal runaway. What are the risks of using the the HLG-320H in parallel with my COBs? If the driver fails or a COB fails or do I have to worry about thermal runaway? What's needed to adjust the driver to max,any special tools or skills?
 
welight

welight

Well-Known Member
If your going to runs leds in parallel you should consider balancing resistors to account for variations in vf, led to led
bear in mind if one led fails the total current load will be spread over the surviving leds, may or may not be desirable if your already pushing the envelope
Cheers
Mark
 
bassman999

bassman999

Well-Known Member
captainmorgan said:
I know about the risk of higher voltage with a large driver in series but I'm not very versed in parallel and have heard of thermal runaway. What are the risks of using the the HLG-320H in parallel with my COBs? If the driver fails or a COB fails or do I have to worry about thermal runaway? What's needed to adjust the driver to max,any special tools or skills?
Click to expand...
Basically same use of driver with external pot on the (B) series
You could run a fuse maybe to each cob...1 amp slow blow?
I am NOT well versed on this either. Mine is doing fine so far
 
bassman999

bassman999

Well-Known Member
welight said:
If your going to runs leds in parallel you should consider balancing resistors to account for variations in vf, led to led
bear in mind if one led fails the total current load will be spread over the surviving leds, may or may not be desirable if your already pushing the envelope
Cheers
Mark
Click to expand...
I would love to know how and what resistors to use?!?
 
bassman999

bassman999

Well-Known Member
welight said:
You would need some fairly large wattage resistors so I am not sure of the practicality of it if your happy to use series
Cheers
Mark
Click to expand...
I was looking into mirroring etc...and I dont understand the schematics. I didnt see one that gave a formula to determine the right values of components either.
 
welight

welight

Well-Known Member
bassman999

bassman999

Well-Known Member
welight said:
One of our suppliers Recom wrote a good piece on this based around RCD24 which is a DC/DC led driver, the same basic concept applies however you would need to modify values for the COB style circuit. Its a bit component heavy so would require a PCB to support this as a function
http://www.ledsmagazine.com/articles/print/volume-6/issue-2/features/led-design-forum-avoiding-thermal-runaway-when-driving-multiple-led-strings-magazine.html
Cheers
Mark
Click to expand...
That is one that I read, and am not that electronics savvy to manage that circuit I am afraid at this point.
 
bassman999

bassman999

Well-Known Member
welight said:
I hear you, I wonder if we should consider to make a PCB that does this?? interesting thought
Cheers
Mark
Click to expand...
If there was something simple where I just switch values in a given circuit I could easily achieve that.
I wonder of efficiency loss from driver with the circuitry.
 
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