Characterization of LEDs and other semiconductor devices
demands at least accurate junction temperature (Tj) monitoring
and also control in more sophisticated cases. One of the most
common causes is that in practical LED lighting appliances
“hot lumens” are meaningful – most lamps are used in power on
steady state and cold analysis provides only indirect
information about intended operation. On the other hand direct
TJ measurement is not trivial – the most viable way is to
measure the forward voltage (VF) which is a function of
junction temperature. In this paper we compare two ways of VF-
based TJ regulation of LEDs capable for electrical-optical-
thermal characterization in a single session in terms of
accuracy and time consumption.
