AN216: RGB Wall Washer Using ILD4035

RGB Wall Washer Using ILD4035
A pplication Note AN216
Revision: 1.0
Date: 2010-04-23
RF and Protection Devices
Edition 2010-04-23
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2010 Infineon Technologies AG
All Rights Reserved.
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Application Note AN216
RGB Wall Washer Using ILD4035
Application Note AN216
Revision History: 2010-04-23
Previous Revision:
Subjects (major changes since last revision)
Application Note AN216, 1.0
Application Note AN216
RGB Wall Washer Using ILD4035
This project combines three constant current “buck” converter ILD4035 to drive a 15W RGB Wall Washer using
OSRAM high power RGB LEDs. By driving the red, green and blue LEDs with varying pulse widths, the
controller can generate up to 16 million colors.
The circuit can drive 5 or 6 LEDs in each of the three channels and will also work with the LEDs from Cree,
Nichia, Philips Lumileds, Seoul and others.
In this project, the use of surface mount components and the low power dissipation in the three current sources
allows for a very compact design.
Application Note AN216, 1.0
Application Note AN216
RGB Wall Washer Using ILD4035
Application Information
The schematic of the RGB Wall Washer driver circuit as shown below:
Figure 1
RGB Wall Washer Schematic
Application Note AN216, 1.0
Application Note AN216
RGB Wall Washer Using ILD4035
The circuit consists of 3 LED drivers – ILD4035 which can drive the constant current up to 350mA. A diode
bridge form by BAS3020B is needed for the purpose of reverse polarity protection. The operating voltage range
for this circuit is from 24V ~ 30V, due to the reverse breakdown of the schottky diodes for the reverse polarity
protection is up to 30V. In the case for the application which not requires the reverse polarity protection, the
operating voltage range can go up to 40V.
The components list for the RGB Wall Washer driver:
1. BAS3020B
2. ILD4035
3. BAS3010A-03W
4. 330uH Inductor
5. 1.2Ω Resistor
The value of the sense resistor is chosen by the following equation:
Rsense =
Vsense 125mV
By setting the ILED to 350mA, the Rsense is equal to 0.35714Ω. In this project the Rsense is using three 1.2Ω
resistors in parallel to obtain 0.4Ω resistance.
About ILD4035
The ILD4035 is a hysteretic buck LED controller IC capable to drive high current, high brightness LEDs up to
350mA. The IC incorporates a wide input voltage range, an internal power switch and the output current level
can be adjusted with an external sense resistor. The IC is a step down converter tailored to drive the 1W LEDs.
According to the multifunctional control pin the IC can be switched on and off by an external signal, which is also
suitable to regulate brightness of the LEDs by PWM or analog dimming.
The precise internal bandgap stabilizes the circuit and provides stable current conditions over temperature
Furthermore, over voltage protection and temperature shut down mechanism enforce the IC to protect attached
For the application required to drive higher current than 350mA, should consider using the ILD4001 or ILD4120.
ILD4120 can drive the output current up to 1.2A and ILD4001 is also a step down converter, with the power
MOSFET driver stage as an external part. The OptiMOS BSR302N or BSS306N are recommended for the
external driver stage for ILD4001.
About BAS3020B
In this RGB wall washer application, four BAS3020B is use for the reverse polarity protection. In the case when
the input voltage polarity is mistaken, the RGB wall washer can still function normally. BAS3020B is a schottky
diode with a very low forward voltage, 0.53V @ 2A; low leakage current, 40uA @ 30V and low capacitance,
Other than using as a reverse polarity protection, this schottky diode is also suitable for high efficiency DC/DC
conversion, fast switching, rectification and clamping as well.
Application Note AN216, 1.0
Application Note AN216
RGB Wall Washer Using ILD4035
PCB Artwork
PCB artwork of the RGB Wall Washer driver circuit as shown below:
Figure 2
PCB Art work of the top and bottom view of the RGB wall washer
Application Note AN216, 1.0
Application Note AN216
RGB Wall Washer Using ILD4035
High Power LED
The high power LEDs are LR W5SM, LB W5SM and LT W5SM from OSRAM. Warning: Do not look directly in
the high brightness LED and it could damage your eyes.
15 LEDs (5 LEDs per channel) are biased at 350mA current in order to have a 15W output. The PWM signal
from the touch wheel output control the duty cycle of the drivers hence the mixture of the RGB could produce
16millions of colors.
Application Note AN216, 1.0
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