BOBBY_G
Well-Known Member
based on several different discussions, im trying to spec the most universal driver for my CXB3590 system so i thought id think out loud and start a discussion on it
my parameters:
typical use = 49W 56.3% eff
'efficient' mode - would like to be able to turn down to 15W/cob efficiently
minimum load = 10W (at some driver efficiency penalty)
'overdrive' mode - would be like to drive up to 75W (~50% efficient)
tough to find a driver that can do all of the above so where do we make compromises, lets see....
HLG-240H-C2100 will soon be available to run 36V cobs at 2.1 A, but has the following disadvantages:
-at 115V, is less efficient across the board than a 185H series
-runs an odd number of cobs at that current - (3.3). running 4 would top them out at 1.75A
in this case, despite the driver cost, it might be best to double up on HLG-185H-C1050 and run 72V cobs instead of 36V
running at full current of 1.05A = 75W, 2 cobs per driver
looking at the datasheet for the HLG-185H-C series: (http://www.mouser.com/ds/2/260/HLG-185H-C-SPEC-806161.pdf)
efficiency at 93% for 115V operation is damn near linear down to 55%. so what is 55%? 0.58A
looks like it can go down to 39W @ 59% cob efficiency. with no penalty on driver efficiency. eggcelent.
so what happens when we try to turn it down to 15W?
current = 0.24A
% of full load current = 0.24/1.05 = 23%
driver efficiency at 23% = a respectable 89%
cob efficiency at 15W = 67%
overall driver+COB efficiency = 59.6%
ultimate eff. at same wattage with smaller driver at max 93% eff. at that current = 62.3%
for occasional low wattage use at that low load, ill take a little efficiency hit (id rather they be more efficient at high wattages and in the ranges im more likely to use
at minimum 10W/cob
current = 0.17A
% of full load current = 0.17/1.05 = 16%
driver efficiency at 16% = a fair 85%
cob efficiency at 10W = 69%
overall driver+COB efficiency = 58.7%
ultimate eff. at same wattage with smaller driver at max 93% eff. at that current = 64.2%
here were starting to see an efficiency hit as im really out of the range of my driver's efficient zone. but you know what? it really doesnt matter to me to lose 5% of efficiency when im turning the cobs down from 15W to 10W and saving almost 50% of dissipation.
but if i was going to run like this all the time id be better off with a 700 or 500 mA driver....
-----------------
but what about heat sinks, you say?
well how about a dual active/passive configuration?
a nice sized heatsink that can handle passive cooling of the cobs at 49W, with some fans on there that only get used when run at 75W. surface area TBD based on actual hat load as thread develops
thoughts? tweaks? flames?
my parameters:
typical use = 49W 56.3% eff
'efficient' mode - would like to be able to turn down to 15W/cob efficiently
minimum load = 10W (at some driver efficiency penalty)
'overdrive' mode - would be like to drive up to 75W (~50% efficient)
tough to find a driver that can do all of the above so where do we make compromises, lets see....
HLG-240H-C2100 will soon be available to run 36V cobs at 2.1 A, but has the following disadvantages:
-at 115V, is less efficient across the board than a 185H series
-runs an odd number of cobs at that current - (3.3). running 4 would top them out at 1.75A
in this case, despite the driver cost, it might be best to double up on HLG-185H-C1050 and run 72V cobs instead of 36V
running at full current of 1.05A = 75W, 2 cobs per driver
looking at the datasheet for the HLG-185H-C series: (http://www.mouser.com/ds/2/260/HLG-185H-C-SPEC-806161.pdf)
efficiency at 93% for 115V operation is damn near linear down to 55%. so what is 55%? 0.58A
looks like it can go down to 39W @ 59% cob efficiency. with no penalty on driver efficiency. eggcelent.
so what happens when we try to turn it down to 15W?
current = 0.24A
% of full load current = 0.24/1.05 = 23%
driver efficiency at 23% = a respectable 89%
cob efficiency at 15W = 67%
overall driver+COB efficiency = 59.6%
ultimate eff. at same wattage with smaller driver at max 93% eff. at that current = 62.3%
for occasional low wattage use at that low load, ill take a little efficiency hit (id rather they be more efficient at high wattages and in the ranges im more likely to use
at minimum 10W/cob
current = 0.17A
% of full load current = 0.17/1.05 = 16%
driver efficiency at 16% = a fair 85%
cob efficiency at 10W = 69%
overall driver+COB efficiency = 58.7%
ultimate eff. at same wattage with smaller driver at max 93% eff. at that current = 64.2%
here were starting to see an efficiency hit as im really out of the range of my driver's efficient zone. but you know what? it really doesnt matter to me to lose 5% of efficiency when im turning the cobs down from 15W to 10W and saving almost 50% of dissipation.
but if i was going to run like this all the time id be better off with a 700 or 500 mA driver....
-----------------
but what about heat sinks, you say?
well how about a dual active/passive configuration?
a nice sized heatsink that can handle passive cooling of the cobs at 49W, with some fans on there that only get used when run at 75W. surface area TBD based on actual hat load as thread develops
thoughts? tweaks? flames?
