FloEFD LED module - RC ladder data
 

Hi there,

I currently use Mentor graphics FloEFD to thermally simulate automotive LED lamps. We have the LED module but don't find it very useful because the few Pre-defined LED's in the database we don't use therefore we have to use the two resistor function. (very inaccurate)
Does anybody know where I can get the RC ladder data for LED's?
The current LED I am simulating is a Cree XHP-50.

If you have any questions or need further information please let me know.

Many thanks

Cameron

Hi Cameron,

Most of the RC Ladder model data can be extracted in some way from datasheets. The only thing you usually don't get in detail is the RC ladder itself as this only comes from measurements as the vendors don't supply such depth.
You might get a single value such as the Rth also for the Cth from the vendor but usually not as a curve, but you can use only a single value from junction to board.
The other data such as luminous flux is often in dependency defined in the datasheet in some way or another, that's often dependent on the vendor.

If you need the information in detail but don't have a T3Ster TeraLED to measure it, Mentor also offers such measurements.
The 4 LEDs that are included are only examples as it is simply impossible for Mentor to provide that data for all possible LEDs on the market. You might only be interested in 2-3 but another company is interested in 3-4 other LEDs than you are plus than the next generation that comes out in a year or differences in the binning etc.

The LED "module" is more than just the LED "model". The LED model, especially the RC ladder model, has been introduced because there is also such measurement equipment offered by Mentor and some companies use it for that. The key features in the LED module are the Monte Carlo radiation model with all its capabilities and the condensation/evaporation and icing model. Those are the actual core of the LED module, besides some other features that come along with it.

Regards,
Boris

Hi Boris,

Thank you for your reply. So am I right in saying that my options are as follows if I want to accurately simulate a lamp using a Cree XHP-50 is to either buy the T3Ster and do this testing in-house or get Mentor to test this LED for us?
Would you know what the costs are involved with these options and who I would need to contact?
Finally regarding the binning of the LED; would the figures be diferent depending on which binning we used?

Many thanks

Cameron

Hi Cameron,

Partially, it depends if you need the details of the RC Ladder, if you are ok with just a single value rather than multiple layers, then the Rth can be found mostly in the datasheets already. The Cth, however, is often not mentioned in the datasheets but you might get it from the supplier.
But if you want detailed models then yes, either buying the T3Ster and TeraLED or getting Mentor to measure it for you. For a contact information, I would need to know where you are based, you can send me a PM with your location or your contact details so I can forward them or send you the contact details of a person you can contact.

I know of companies that take these experiments serious and test also different binnings as slight changes can appear due to manufacturing processes etc.
As for the prices, I wouldn't be the right person to ask and it depends on the system requirements which depends on the LED performance regarding current requirements and the corresponding cooling performance etc.

Regards,
Boris