Data Sheet

4

Rev. 1.1, 2007-03-20

TLE 4242 G

Application Information

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

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

a delay time adjustable via an optional capacitor connected to the pin D.

AEA03499.VSD

TLE 4269 G

100

nF

GND

D

RADJ

SI

Q

RO

10

µF

10 k

Ω

µC

TLE 4242 G

V

BAT

I

I

47 nF

GND

D

ST

PWM

Q

0.47

Ω

0.25 W

R

REF

LED

Dragon

REF