Document UT-MT-0778_EN
Page 17 of 39
Edition 11/03/2014
Supersedes edition 02/03/2014
LED INSET THRESHOLD/END LIGHT L
THE04
INSTRUCTION MANUAL FOR USE, INSTALLATION AND MAINTENANCE
2.3
ELECTRONIC SECTION
The electronic section consists of the following circuits:
Current / current conversion circuit
LED command circuit
Control circuit
2.3.1
Current / current conversion circuit (patented)
This electronic section provide a conversion from the input current value (within
range from 2.8 A to 6.6 A) to the specified LED current value.
This conversion, performed in one transformation only, allows to achieve several
benefits:
minimize the power losses
significant increase of efficiency
high input power factor
independent form the CCR topology: the CCR may have any output current
waveform
no percentage of load dependent: the CCR can feed without any problem also
few lights in the series circuit
isolation transformers of smaller size can be used, respect to those used with the
equivalent fixtures equipped with halogen lamps
To meet the previous features, the conversion circuit is based on the MOSFET
technology. This circuit has been designed to withstand the several field stresses (like
withstand at elevated current peak) determinate by:
defective connections along the series circuit
sudden variations of the CCR power supply voltage; in many cases the CCRs don’t
provide suitable response time in order to compensate these variations
use of circuit selectors
The input circuit is protected against over-voltage, tested in accordance with the
requirements in FAA “Engineering Brief N°67” document.
2.3.2
LED command circuit
A PWM technique is used to command the LEDs. As known LEDs need to be supplied
with a constant current; therefore in order to vary the luminous emission with a
proper linearity is necessary the supply current will be applied at impulses. In other
words, the LED luminous output depends on the time of application (duty-cycle) of
constant current impulses.
