ILD4071 Datasheet, PDF (5/25 Pages) Infineon Technologies AG – LED Driver for High Power LEDs

ILD4071
Block Diagram
2
Block Diagram
The ILD4071 regulates the LED current by monitoring the load current (Peak Current Measurement) through the
internal switch cycle by cycle. When the current through the switch reaches the threshold I_peak the switch is shut-
OFF and it is kept OFF for a time equal to t_OFF. Both I_peak and t_OFF can be fixed through few external components.
The peak current I_peak is fixed by a resistor connected to the SET pin while the t_OFF is fixed by RC network. As t_OFF
is fixed and the duty cycle depends on V_REC, the frequency depends on V_REC as well. Refer to Chapter 8.2 for the
evaluation of the switching frequency.
PWMI 5
FREQ ^EN
6
3
OFF-Time
Control
ON/OFF
Logic
VREC
1
Internal
Supply
UV+OV
Lockout
8 SW
internal
PWM
Generation
Thermal
Protection
ST 2
Open Load
Detection
Logic
Power-
Switch Driver
Peak Current
Adjustment
Peak Current
Measurement
Power
Switch
4
SET
Figure 1 Block Diagram ILD4071
7
GND
Datasheet
5
Rev. 1.0, 2011-11-16