The TM21 test is mainly to predict the life of LED light sources. And use the data of LM-80 to estimate the long-term life performance of LED components and lamps/bulbs.

What’s TM21 Test? TM21 provides processing methods for the data measured by LM80, which mainly including the following:

a. The data fitting method in the form of exponential function is given.

b. The correction method of fitting life (70% light decay life) is given.

c. The detailed expression method of life is given.

d. The interpolation method for calculating the lifetime at a given point temperature is given.

Note: Before TM21 calculation, the LM80 report of the lamp bead must be prepared. And then the whole lamp can be subjected to the ISTMT temperature rise test before the calculation can be carried out.

Steps to use TM-21 to estimate the life of LED lamps

1: The LED component supplier conducts an LM-80 experiment at 3 temperatures (55/85/optional temperature) for at least 6,000 hours on its LED Source (Package/Array/Module).

2: Estimate the long-term life data of 3 test temperatures (55/85/optional temperature) according to the TM-21-11 formula.

3: Obtain the In Situ Temperature of the LED lamp bead placed in the LED lamp. And refer to the ISTMT (In Situ Temperature Measurement Test) test program to obtain the temperature of the LED lamp bead in the LED lamp. And the test temperature position must be the same as the Ts setting position of LM-80-15.  As the temperature measurement point position is called TMPLED (LED Temperature Measurement Point).

4: Interpolate the calculated results of the measured TMPLED and TM-21 to obtain the estimated lifetime value of the TMPLED.