TLE4241GM_07 Datasheet, PDF (2/15 Pages) Infineon Technologies AG – LED Driver with Adjustable Current

TLE 4241 GM
Circuit Description
I
Q
Regulation
High
ST
PWM
SET
Regulation
Low
Reference
Voltage
REF
GND
AEB03003
Figure 1 Block Diagram
An internal reference voltage of typ. 1.20 V supplies the REF pin which is connected to
GND via an external resistor. In the SET = H mode the reference current flowing on the
REF pin is mirrored with an amplification to form the desired output current. The typ.
output current in the SET = H mode calculates:
I_{Q, typ}/mA
=
------1---.--2---0-------- × 487 + 0.1
R _{R E F} /k Ω
(1)
The output current is shown as a function of the reference resistance on Page 10 for the
high as well as for the low current mode.
With the PWM input the LED brightness can be regulated via duty cycle. Also PWM = L
sets the TLE 4241 in sleep mode resulting in a very low current consumption of << 1 µA
typ. Due to the high impedance of the PWM input (see timing diagram I_PWM versus V_PWM
on Page 12) the PWM pin can thus also be used as an Enable input.
Data Sheet
2
Rev. 1.3, 2007-03-19