instantaneous luminous flux (i.e. at initial turn
on) when the LED emitter is driven at a constant
forward current at a constant ambient
temperature. Equation #3.8A models the
thermally stabilized luminous flux at any forward
current compared to the instantaneous
luminous flux prior to heating at a specified
forward current and a constant ambient
temperature. Equation #3.9A models the
thermally stabilized luminous flux at any forward
current compared to the thermally stabilized
luminous flux at test conditions of
I
F TEST
,
V
F TEST
,
and
R
θ
JA TEST
at a constant ambient temperature.
A good example of an application for Equation
#3.9A is the normalized luminous flux versus
forward current graph shown in Figure 3 of the
SuperFlux LED Data Sheet. Finally, Equation
#3.10A models the thermally stabilized luminous
flux over temperature compared to the thermally
stabilized luminous flux at test conditions of
I
F TEST
,
V
F TEST
, and
R
θ
JA TEST
, at 25°C. Note for Equations
#3.8A, #3.9A, and #3.10A, that for forward
currents over 30 mA,
m
≈
1.0.
Figure 3.4A. Maximum DC Forward Current versus
Ambient Temperature for HPWA-xxOO LED Emitter
with Different System Thermal Resistances.
5
LUMILEDS [ LUMILEDS LIGHTING COMPANY ]
