Plans for the MC-E

[TigerhawkT3]

Sweet pics!

Is the pad on the bottom solderable?

 

[Nos]

btw, is the max current on the mc-e really only 700ma? or did someone try more......like 1A ? :thinking:

 

[saabluster]

btw, is the max current on the mc-e really only 700ma? or did someone try more......like 1A ? :thinking:

Don't have mine yet but I will be sending WAY more through it than that. FYI that spec is per die so 4x 700mA=2800mA total.

 

[TigerhawkT3]

Don't have mine yet but I will be sending WAY more through it than that. FYI that spec is per die so 4x 700mA=2800mA total.

The 700mA figure is accurate if the dice are in series. Of course, that's not gonna prevent me from running around 1200mA through each die. :devil:

 

[JB01245]

Not very good alignment of that die on the upper left of the picture :thinking:

Is the dome silicone or glass?

 

[saabluster]

The 700mA figure is accurate if the dice are in series. Of course, that's not gonna prevent me from running around 1200mA through each die. :devil:

The spec from Cree is a max of 700mA per die. Doesn't matter how you accomplish that series or parallel. I'll be testing them at 2A per die.:nana:

 

[TigerhawkT3]

Yes, but in your post that I quoted, you said "4x 700mA=2800mA total." If dice are in series, it doesn't make sense to add the current running through each one (unless you want to compare it to a single die running at a higher current). If someone reads your post and thinks, "oh, 2.8A is within spec, great," then puts a series-wired MC-E on a merely modest heatsink and runs 2.8A through it, they'll fry it pretty quickly. I just want to make sure that people know that your 2.8A max spec figure is only applicable to parallel-wired MC-Es.

 

[MorpheusT1]

Any chance these would fit on a Tower module in say a SF M6 and still retain the possibility of using a converter.


Benny

 

[Aircraft800]

OH, I almost forgot this pic, nice comparison picture:

Helps to visualize just where you can fit this small emitter.

 

[saabluster]

OH, I almost forgot this pic, nice comparison picture:

Helps to visualize just where you can fit this small emitter.

This is the picture I've wanted to see most. Awesome work. Notice that Cree actually packs their dies closer together than SSC? And is it just me or does the MC-E's dome have more clarity to it?

 

[TigerhawkT3]

I think it's funny that the dice in the Cree packages look bigger because of the collimating dome (the one that causes the narrower beam pattern).

Those P7s are just huge.

Is the MC-E's silicone dome the gummy kind like the SSC P4's and P7's, or the hard kind, like the Lux's and XR-E's? Is it floating, like the XR-E's dome?

 

[Gryloc]

I made some measurements based off of Aircraft800's beautiful image and I was able to determine both the gap size between dies (in mm) and also the relative "apparent" die sizes between the three emitters using the EZ1000 dies...

OH, I almost forgot this pic, nice comparison picture:

Helps to visualize just where you can fit this small emitter.

Again, wonderful closeup!

So, I took that image and physically traced it onto a transparency sheet using a fine-tipped Sharpie marker. My hard drive failed this weekend, but my motherboard has a built on SSD (USB flash) that contains a simplified Linux OS specialized for web browsing (it is called 'Express Gate' and was implemented on newer Asus motherboards). I do not have any paint program, or my beloved Paint Shop Pro to make these measurements, so please understand that my measurements were made using a steady hand and a trace off of my LCD monitor. By the way, could anybody guess as to how nervous I was when I was tracing the LED package and die outlines onto a clear transparency taped in place? Agh! I have done it before, but I was still worried about making lines or dots right outside of the transparency sheet. oo:

Anyway, to the data. I measured the X and Y dimensions of each of the four dies for the MX-C and P7, and compared it to the relative apparent size to that of the XR-E. I used a nice metric ruler (flat and transparent) to measure the different dies and the gap sizes. There is an error of +/-0.5mm for each measurement, so the finished numbers are not perfect! My raw numbers are measured on the millimeter scale, but for now on, I will refer to them as "units" to avoid confusion. I averaged the die sizes for each LED emitter, and used that average when making direct comparisons. Actual die sizes are the same (~1mm x ~1mm), but the apparent die sizes may make a difference when placed behind a smaller sized reflector.



So, the raw data:

Averaged apparent size of the dies on the Seoul P7: 11.1 units

Averaged apparent size of the dies on the Cree MC-E: 14.19 units

Averaged apparent size of the dies on the Cree XR-E: 15.88 units

Averaged apparent gap between the dies on the Seoul P7: 1.94 units

Averaged apparent gap between the dies on the Cree MC-E: 1.44 units

So, from the raw data, we can compare the apparent die sizes of the three LED emitters:

P7 ... 11.1 units
------------------- = 69.9% (the apparent size compared to the XR-E)
XR-E 15.88 units

MC-E 14.19 units
------------------- = 89.4% (the apparent size compared to the XR-E)
XR-E 15.88 units

So, that means that the apparent die size of the P7 is only 78.2% of the MC-E (or the MC-E appears to be 27.8% larger).

The apparent size of the dies will vary depending on the viewing angle, as the XR-E has tighter beam angle. I do not have the P7 and MC-E in front of me to see how the dome distorts the die shape depending on angle.

------------------------------------------

Finally something useful: Actual gap size between the dies on the MC-E and P7!

I was able to find the gap size (in millimeters) for both the P7 and MC-E by comparing the apparent gap size and the apparent die size.

I have not looked at the specs for the EZ1000 die for a while, and my PC at its current state will not allow me to download anything (and I cannot view PDF files), but I know that the die is approximately 1mm by 1mm in size (more like 980nm by 980nm I think). So if I divide the measured apparent gap distance by the measured apparent size of the die, and multiply by 1mm, we should get the actual gap between dies in millimeters, right?

P7:
1mm * (1.94 units / 11.1 units) = 0.175mm

MC-E:
1mm * (1.44 units / 14.19 units) = 0.101mm

So, that means that the actual gap between dies on the MC-E is only 57.7% of that of the P7 (the gap on the P7 is 73.7% larger). However, this is when the domes are sheared off to see the raw dies (the bond wires would be ruined by this).

The apparent size of the MC-E die gaps are still 74.2% of the size compared to the apparent size of the P7 gaps (or the P7 gaps appear to be 34.7% larger).

Apparent gap distances:

MC-E 1.94 units
------------------ = 74.2%
P7 ... 1.44 units

Does this seem correct? I was hoping it would be useful. Please feel free to tell me if I made a big mistake on my calculations.

Finally, is anyone able to take a nice close-up picture of the Seoul P7 or Cree MC-E next the good old Luxeon V? From that, I can find the gap distance between those dies and the relative apparent die size. The Luxeon V will have to be colored, and not white (but green, cyan, blue, royal blue), because on the white emitters, the phosphor covers up the dies so uniformly, it is not as easy to see the separate dies. On any of the colored emitters, you can clearly see where one die stops, and the next starts. I would appreciate it! I would take the picture, but I cannot post anything at this moment from this PC. Thanks!


-Tony

 

[Aircraft800]

Well,

I learned something today, you can not DD a Parallel wired Cree MC-E with one C Sized Li-Ion (charged to 3.8V resting) for more than 4 sec. It draws 3.42A and quickly burns up.

Definitely going to need some good heatsinking and a Constant Current driver < 2800mAh...

Any suggestions on such a driver? I may use 3 Ni-MH (3.6v) or one Li-Ion (3.7v), just need to keep the current down...

I'm glad I have a few more, but I don't want to make that mistake again....

I didn't get any chance to test out reflectors :sigh:

Maybe I should series wire, that way I will have a better selection of drivers, Shark, MaxFlex, but all of those wires will be hard to conceal.

 

[Gryloc]

Aircraft800,

Oh, that is really too bad to see a MC-E go.

Even if you have it pressed against a good heatsink with some thermal paste used as the thermal interface, it shouldn't overheat too quickly. Of course, I say this based on powering the bare P7 with such thermal paste attached to a PIII heatsink and running 3-4A. If it was bare or the star by itself, then I can see it overheating very quickly. Do not feel bad, though. Many of us lost many nice LED emitters in the learning process.

I see that you are trying to figure up how to power them up still. So, are you trying to test them further, or are you trying to find a permanent solution? Why do you have to conceal wires so you cannot use a driver? Is there a target current you are reaching for? Use 11 NiMH cells to give each die 3.3V, or use 12 and a resistor to reduce the current. Wiring them in parallel is tricky, especially when trying to change the voltage very slightly (which changes the current draw quickly). In series, it may be easier to reach the target voltage to get the desired current, and you have more driver options...

 

[TigerhawkT3]

Well,

I learned something today, you can not DD a Parallel wired Cree MC-E with one C Sized Li-Ion (charged to 3.8V resting) for more than 4 sec. It draws 3.42A and quickly burns up.

Definitely going to need some good heatsinking and a Constant Current driver < 2800mAh...

Any suggestions on such a driver? I may use 3 Ni-MH (3.6v) or one Li-Ion (3.7v), just need to keep the current down...

I'm glad I have a few more, but I don't want to make that mistake again....

I didn't get any chance to test out reflectors :sigh:

Maybe I should series wire, that way I will have a better selection of drivers, Shark, MaxFlex, but all of those wires will be hard to conceal.

I hope that failure was without a heatsink, because I'm planning on DDing an MC-E at about 3.7V per die with fresh cells.

 

[MikeRD03]

By the way - the MC-E does not have a silicone dome! Ist has a glas dome just like the XR-E emitter. Only with a glas lens such a narrow collimation is possible in this little space.

And it is amasing how close the collimation comes to the XR-E beam - the apearent die size is a good hint for that. This should mean MC-E reflectors are quite close to the XR-E ones. Good work, Cree!

greets
MikeRD03

 

[saabluster]

By the way - the MC-E does not have a silicone dome! Ist has a glas dome just like the XR-E emitter.

How do you know this?

 

[FredM]

I want to put one in a KL4 head but am scared of the electrical connections. Want to see one on CPF first.

 

[MikeRD03]

Hi saabluster,

How do you know this?

Cause I´m already testing enigeering samples of the MC-E ;-)

greets,
MikeRD03

 

[ahorton]

By the way - the MC-E does not have a silicone dome! Ist has a glas dome just like the XR-E emitter. Only with a glas lens such a narrow collimation is possible in this little space.

That is good news indeed. I was upset when I heard about the silicone dome. I really like the glass on the XRE.

...I just hope my 2 from Cutter turn up soon... I've been patient for 7 weeks but now you guys have them I'm envious.