TLE4242G Datasheet, PDF (4/13 Pages) Infineon Technologies AG – Adjustable LED Driver

TLE 4242 G
Application Information
V_BAT
I
RO
TLE 4269 G SI
µC
RADJ GND
Q
D
100
10
nF
µF
10 kΩ
ST
I
PWM
Q
TLE 4242 G
GND
REF
D
47 nF
LED
Dragon
0.47 Ω
0.25 W
R_REF
AEA03499.VSD
Figure 3 Application Circuit
Figure 3 shows a typical application with the TLE 4242 G LED driver. The 3 LEDs are
driven with an adequate supply current adjusted by the resistor R_REF. Thus brightness
variations due to forward voltage spread of the LEDs are prevented. The luminosity
spread arising from the LED production process can be compensated via software by an
appropriate duty cycle applied to the PWM pin. Hence selection of the LEDs to forward
voltage as well as to luminosity classes can be spared. The minimum supply voltage
calculates as the sum of the LED forward voltages, the TLE 4242 G drop voltage (max.
0.7 V at a LED current of 300 mA) and the max. voltage drop at the shunt resistor R_REF
of max. 185 mV.
The status output of the LED driver (ST) detects an open load condition enabling to
supervise correct LED function. A LED failure is detected if the voltage drop at the shunt
resistor R_REF falls below typ. 25 mV. In this case the status output pin ST is set low after
a delay time adjustable via an optional capacitor connected to the pin D.
Data Sheet
4
Rev. 1.0, 2004-01-01