Help: Xp-g3 Led. How Do I Calculate Non-listed Currents, Voltage And Temperature?

[Horto]

Help: XP-G3 LED. How do I calculate non-listed Currents, Voltage and Temperature?
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XP-G3 LED DATA SHEET:
Maximum DC Forward Current - 2000 mA
Maximum Forward Voltage - 3V

Forward voltage (@ 350 mA, 85 °C) V 2.73
Forward voltage (@ 700 mA, 85 °C) V 2.83
Forward voltage (@ 700 mA, 25 °C) V 2.93
Forward voltage (@ 1000 mA, 85 °C) V 2.89
Forward voltage (@ 1500 mA, 85 °C) V 2.99
Forward voltage (@ 2000 mA, 85 °C) V 3.06

Note: Cree Product Characterization Tool is limited to 700 mA.
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Data Sheets show operating voltage lowering with increasing temperatures.
EG: Forward voltage (@ 700 mA, 85 °C) V 2.83
. . . .Forward voltage (@ 700 mA, 25 °C) V 2.93

I wish to drive the XP-G3 LED’s at 1050 mA. (Which is non-listed).
My Ambient Room Temperature can get to 35 °C.
Lets assume a Heat Sink with the same heat dispersion specifications as the Cree Horticultural Reference design.

Questions:
1/ How does the Junction temperature/voltage relate to room temperature for a given current?
2/ How do I calculate Junction temperature/voltage for 1050 mA at 35 °C room Temperature?

The Project:
2 x 54 XP-G3 LED’s in series.
Driver Candidate: HLG-320H-C2100 76 ~ 152V - 319.2W
OPEN CIRCUIT VOLTAGE (max.) 156V.

My concern is how high of ambient room temperature could overload the Driver!
Will the Driver or LED’s be damaged?
Will the driver just cut out, or just drive the LED’s at lower capacity?

Help is appreciated,
Horto.

 

[Horto]

Temperatures/Voltages above 700 mA extrapolated from DATA SHEET and Cree Product Characterization Tool.

Temperature - - 85°C - 50°C - 45°C - 40°C - 35°C - 30°C - 25°C
Fv @ 350 mA = V 2.73 - 2.78 - 2.78 - 2.79 - 2.79 - 2.80 - 2.81
Fv @ 700 mA = V 2.83 - 2.88 - 2.88 - 2.89 - 2.90 - 2.90 - 2.91
Fv @ 1000 mA = V 2.89 - 2.94 - 2.94 - 2.95 - 2.96 - 2.96 - 2.97
Fv @ 1050 mA = V 2.90 - 2.95 - 2.95 - 2.96 - 2.97 - 2.97 - 2.98
Fv @ 1500 mA = V 2.99 - 3.04 - 3.04 - 3.05- 3.06 - 3.06 - 3.07
Fv @ 2000 mA = V 3.06 - 3.11 - 3.11 - 3.12 - 3.13 - 3.13 - 3.14
--------------------------------------------------------------------
Math for Currents above 700 mA.
1000 mA - 700 mA = 300 mA
2.89V - 2.83V = .06V
.06V/300 mA = 0.0002V per mA Change.
--
Math for Currents above 1000 mA.
1500 mA - 1000 mA = 500 mA
2.99V - 2.89V = .10V
.10V/500 mA = 0.0002V per mA Change.
--
Math for Currents above 1500 mA.
2000 mA - 1500 mA = 500 mA
3.06V - 2.99V = .07V
.07V/500 mA = 0.00014V per mA Change.
--
Math for 1050 mA
0.0002V x 50 mA = 0.01 additional Volts.
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If the Math above is correct, it paints a better picture of the XP-G3 LED across operating conditions ????

 

[Horto]

Note: The Cree Horticultural Reference Design is more like a Reference Hack regarding electrical design, in the use of XP-E Red diodes to limit the current to XP-G3 LED’s.
Cree’s use of 1050 mA drivers must have been second to the LED design.

I am hoping the idea of omitting LED’s is a solution for DIY.

HLG-320H-C2100 76 ~ 152V - 319.2W - 94.0%
OPEN CIRCUIT VOLTAGE (max.) 156V

Operating Conditions 25-85°C
51 LED’s x 2.98V (25°C) = 151.98V (99.99%)
51 LED’s x 2.95V (50°C) = 150.45V (98.98%)
51 LED’s x 2.90V (85°C) = 147.90V (97.30%)

9x PCB Layout
- - - - - - | - - - - - - | - - - - - -
- - - - - - | - - - x - - | - - - - - -

- - - - - - | - x - - - - | - x - - - -
- - - - x - | - - - - x - | - - - - - -

- - - - - - | - - x - - - | - - - - - -
- - - - - - | - - - - - - | - - - - - -
PCB: SinkPAD – Part No. 1950-A (2x6).

x = Jumper wire (No LED)
Boards are wired 2x 6 LED’s.
Each side of boards makes up the 2x 51 LED’s in series.

=====================

Please let me know if the maths is correct.
I am eager to commence building.

Horto

 

[Toaster79]

For the xpg3 you should be looking at the 50°C data, so this should work and also the driver should be running at the highest efficiency considering your mains (110V will be slightly less efficient than 240V). Also when wiring for 1050mA output off a 2100mA driver, wire a series string first then put two of those in parallel, should be well balanced this way even if there are some higher or lower Vf chips in those strings.

Use direct to copper MCPCBs like sinkpad or noctigon. This should up the efficiency some as there is no dielectric layer between the chips heat pad and MCPCB and also if one string fails and the other one gets full 2100mA, those chips won't mind much (I've got an xpg2 running at 2500mA in a wee little flashlight). And please don't use self adhesive thermal tape. Either thermal glue of high quality or even better thermal compound and screw those bitches to the heatsink.


If you're looking to use red xpes keep the lover forward voltage and lover drive current in mind. I wouldn't push them past 350mA.

 

[Horto]

For the xpg3 you should be looking at the 50°C data

What Ambient room temp is the 50°C recommendation based on?

when wiring for 1050mA output off a 2100mA driver, wire a series string first then put two of those in parallel

Yep, that is the basis of my design.

Use direct to copper MCPCBs like sinkpad

Are you referring to the SinkPAD used in Cree reference?
Got 9 SinkPAD – Part No. 1950-A (2x6) on the way!

How do DIY members solder these surface mount LED's?
I don't mind spending a few dollars for equipment, but keen to hear what people are using for one-off jobs.

Thanks

 

[Horto]

For the xpg3 you should be looking at the 50°C data

I have used a 25°C reference point to set the driver at 100% capacity!
If you were to use 50°C for 100% reference point the LED's Voltage would exceed Driver for any lower temperature.

Is what I have done, what you are saying?
Please add some specifics and explain if you have a different approach.

Ty

 

[sixstring]

if your hell bent on low power diodes why not just use a few of these boards?
at low power they dont even need heatsinks and if run a little higher you can use cheap flat aluminum and a fan to cool them.plus it takes away all the soldering issues. i think cree is the only one that ever built that ref design lol.

 

[Toaster79]

50°C is junction temperature. That's the core temperature of the LED which you can calculate based on the room temperature, thermal resistance of the LED package and thermal resistance of the heatsink.

Sinkpad or noctigon, like I said, copper based MCPCB without dielectric layer. I'm sure @Welight will be able to help you there.

Soldering chips on the MCPCB is pretty easy. You can do it at home on your stove or in the oven. Put a thin layer of solder paste on the MCPB and put the emitter on top of it. Put all of it on your stove or in the oven and wait till the paste melts then let it cool slowly. Solder paste will pull the emitter towards the MCPCB and center it. Just watch out that the terminals are oriented in the right direction. You could also ise soldering iron to do it but it's time consuming and a bit tricky with the copper as it absorbs the energy from the pad too quickly so you'd need at least a 50W iron if not 80W to do it right.

 

[Horto]

you can use cheap flat aluminum and a fan to cool them.plus it takes away all the soldering issues.

I am considering flat aluminum as it is more readily available.
Making inquiry with Cutter for future "solder free board" options.

For this build I am soldering XP-G3 LED's into SinkPAD – Part No. 1950-A (2x6).

Can you help me with the operating voltage at which the XP-G3 3700 K (Code: S4) provides maximum lm/Watt?
Tried to extrapolate from the data, but my knowledge is not up to it.

XPGDWT-01-0000-00LF6

Put a thin layer of solder paste on the MCPB

Solder Paste I have on hand is just for preparing surfaces for solder.
Are you including solder. or does the Flux contain solder.
What gives?


Thanks

 

[sixstring]

I really cant help on those smaller diodes.

 

[Horto]

I really cant help on those smaller diodes.

@Randomblame on rollitup forum makes reference to 175,5lm/w @55°C for S4 bin.
And +3% eff for S5 Bin, making this very close to the 179lm/w.

diy version of low profile led propagation fixture for small area? Here: https://goo.gl/HfT0by

Quote:
If you choose 30XP-G3, 4.000°k, S4 bin and drive them with this HLG-C driver you should get Ø10530lm total or 175,5lm/w @55°C,
~54% eff.(+3% eff. is you get S5 bin)
59,5w LEDs/(x0,91%=)65,3w total from the wall,
27,4w heat, heatsink for passiv cooling should have at least 3300cm²
(a 3mm thick Alu-Sheet 75x 25cm in more than enough(3850cm²) and ultra-flat)
32,1PAR/w,
x 4,52μMol/j(4.000°k)= 145μMol/s PPF
or
PPFD without wall losses: Ø 520μMol/s/0,28m² (3 sft).


Any help to narrow it down?

 

[CoraDias]

Hi...i am a new user here. As per my knowledge you should use direct to copper MCPCBs like sinkpad or noctigon. This should up the efficiency some as there is no dielectric layer between the chips heat pad and MCPCB and also if one string fails and the other one gets full 2100mA.

 

[Toaster79]

Hi...i am a new user here. As per my knowledge you should use direct to copper MCPCBs like sinkpad or noctigon. This should up the efficiency some as there is no dielectric layer between the chips heat pad and MCPCB and also if one string fails and the other one gets full 2100mA.

Read post #4

 

[Horto]

For the xpg3 you should be looking at the 50°C data, so this should work and also the driver should be running at the highest efficiency considering your mains (110V will be slightly less efficient than 240V). Also when wiring for 1050mA output off a 2100mA driver, wire a series string first then put two of those in parallel, should be well balanced this way even if there are some higher or lower Vf chips in those strings.

Use direct to copper MCPCBs like sinkpad or noctigon. This should up the efficiency some as there is no dielectric layer between the chips heat pad and MCPCB and also if one string fails and the other one gets full 2100mA, those chips won't mind much (I've got an xpg2 running at 2500mA in a wee little flashlight). And please don't use self adhesive thermal tape. Either thermal glue of high quality or even better thermal compound and screw those bitches to the heatsink.


If you're looking to use red xpes keep the lover forward voltage and lover drive current in mind. I wouldn't push them past 350mA.

I have Surface Mounted White LED - XLamp XP-G3 White 4000 K, 70 CRI - XPGDWT-B1-0000-00L5E.

And the new Red LED - XLamp XP-E High Efficiency Photo Red - XPEEPR-L1-0000-00B01.

Into Sinkpad 1950.
Running at 1000MA CC the High Efficiency Photo Reds age leaves within days at 30cm or less, even in ambient temperatures of <25 Degree C.

Quote: I wouldn't push them past 350mA.

I was thinking to run the High Efficiency Reds seperatly at 500ma, which might get me operating safely at 30cm?
At the end of day, I will find the best answer from experiment.

Have you done anything similar to chime in?
Why 350ma and are we talking the same LED's.
No right or wrong answers, just wanting to drill down into this.

Cheers