ILD4071 Datasheet, PDF (22/25 Pages) Infineon Technologies AG – LED Driver for High Power LEDs

ILD4071
Application Information
8.3
ILD4071 in LED Application
Figure 13 provides a simplified application with two high brightness LEDs in series. A µC is controlling the EN pin
to put the device into sleep/active mode. Also the PWMI pin can be directly controlled via a µC port if PWM
dimming of the LED current is required. The open load ST pin monitors the load condition of the application and
gives feedback to the µC. An external pull up resistor is recommended to achieve a logic HIGH signal during an
open load error (internal status transistor is switched OFF and the ST pin is high ohmic).
The external low power resistor R_SET is used to set the required peak current for the LED load (refer to Figure 9
for more details).
To set the desired switching frequency of the buck regulator the external R_FREQ and C_FREQ network must be
connected to GND (reference values are given in Figure 11).
Vs = 5V to 40V
I_LED
C_REC
VREC
1
open load status
connected to µC
V_DD
R_ST
ST
2
SW
Driver
Open
Load
L_SW
SW
8
V_REC
FREQ 6
R_CLAMP
R_COMP
C_OUT
D_CLAMP
connect to µC pin
R_SET
3 EN
4 SET
GND
7
R_FREQ
C_FREQ
PWMI 5
PWM dimming via µC
Figure 13 Simplified Application Diagram ILD4071
Note: This is a very simplified example of an application circuit. The function must be verified in the real application
Datasheet
22
Rev. 1.0, 2011-11-16