TLE4242G

Adjustable LED Driver TLE 4242 G Features • • • • • • • • • • Adjustable constant current up to 500 mA (±5%) Wide input voltage range up to 42 V Low drop voltage Open load detection Overtemperature protection Short circuit proof Reverse polarity proof Wide temperature range: -40 °C to 150 °C Green Product (RoHS compliant) AEC Qualified P-TO263-7-1 Functional Description The TLE 4242 G is an integrated adjustable constant current source driving loads up to 500 mA. The output current level can be adjusted via an external resistor. The IC is designed to supply high power LEDs (e.g. Osram Dragon LA W57B) under the severe conditions of automotive applications resulting in constant brightness and extended LED lifetime. It is provided in the surface mounted PG-TO263-7-1 package. Protection circuits prevent damage to the device in case of overload, short circuit, reverse polarity and overheat. The connected LEDs are protected against reverse polarity as well as excess voltages up to 45 V. The integrated PWM input of the TLE 4242 G permits LED brightness regulation by pulse width modulation. Due to the high input impedance of the PWM input the LED driver can be operated as a protected high side switch. Type TLE 4242 G Data Sheet 1 Package PG-TO263-7-1 Rev. 1.1, 2007-03-20 TLE 4242 G Circuit Description I 1 Bias Supply 7 Q PWM 2 Bandgap Reference Comparator 5 REF 3 Status Delay ST 4 GND 6 D AEB03500.VSD Figure 1 Block Diagram An external shunt resistor in the ground path of the connected LEDs is used to sense the LED current. A regulation loop helds the voltage drop at the shunt resistor on a constant level of typ. 177 mV. Selecting the shunt resistance permits to adjust the appropriate constant current level. The typ. output current calculates V REF I Q, typ = -----------R REF (1) where VREF is the reference voltage with a typical level of 177 mV (see Page 10). The equation applies in a range of 0.39 Ω ≤ RREF ≤ 1.8 Ω. The output current is shown as a function of the reference resistance on Page 10. With the PWM input the LED brightness can be regulated via duty cycle. Also PWM = L sets the TLE 4242 in sleep mode resulting in a very low current consumption of