TLD5045EJ_15 Datasheet, PDF (16/30 Pages) Infineon Technologies AG – 700mA High Integration - DC/DC Step-Down Converter

Infineon® LITIX™ Power
TLD5045EJ
Enable, Dimming Function and Thermal Protection
6.2.2 Internal PWM dimming Function
The TLD5045EJ 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 6-4). 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 (refer to application drawing ).
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 6-3 displays the external components corresponding to the desired PWM
frequency and duty cycle.
The following setup applies for the table displayed in Figure 6-3: V_REC=12V, V_LED=7.2V, L_SW=220µH, R_SET=14kΩ.
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
C_PWMI
64nF
32nF
21nF
16nF
150nF
75nF
50nF
37nF
265nF
132nF
88nF
66nF
Figure 6-3 R_PWMI and C_PWMI versus f_PWMI and DC
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%
Data Sheet
16
Revision 1.0
2015-05-28