ILD4071 Datasheet, PDF (15/25 Pages) Infineon Technologies AG – LED Driver for High Power LEDs

ILD4071
Enable, Dimming Function and Thermal Protection
6.2.2 Internal PWM dimming Function
The ILD4071 has an integrated PWM dimming engine. Via an external R_PWM and C_PWM network it is possible to
achieve a PWM LED current waveform. The duty cycle and dimming frequency is depending on the size of the
external components (see formula in Figure 7). This feature is specially designed to achieve a stand alone PWM
dimming function without the usage of micro controllers or external logic. This allows a flexible and cost effective
usage of the device in a decentralized light module application.
The advantage of a PWM dimming (to reduce the LED load current) is the change of light intensity only, at constant
light color.
With an external RC network a PWM programming between 100Hz and 1200Hz and Duty Cycles between 4%
and max. 20%. is possible. Figure 6 displays the external components corresponding to the desired PWM
frequency and duty cycle.
The following setup applies for the table displayed in Figure 6: V_REC=12V, V_LED=7.2V, L_SW=220µH, R_SET=14kΩ.
PWMI 5
GND
7
R_PWMI
C_PWMI
R_PWMI
216k_Ω
216k_Ω
216k_Ω
216k_Ω
87k_Ω
87k_Ω
87k_Ω
87k_Ω
44k_Ω
44k_Ω
44k_Ω
44k_Ω
Figure 6 R_PWMI and C_PWMI versus f_PWMI and DC
C_PWMI
64nF
32nF
21nF
16nF
150nF
75nF
50nF
37nF
265nF
132nF
88nF
66nF
f_PWMI
100Hz
200Hz
300Hz
400Hz
100Hz
200Hz
300Hz
400Hz
100Hz
200Hz
300Hz
400Hz
DC
4%
4%
4%
4%
10%
10%
10%
10%
20%
20%
20%
20%
Datasheet
15
Rev. 1.0, 2011-11-16