Industrial and Multimarket
Data Sheet
Revision 2.0, 2011-08-17
ILD4035
350 mA Step Down LED Driver
LED Drivers for High Power LEDs
Edition 2011-08-17
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2011 Infineon Technologies AG
All Rights Reserved.
Legal Disclaimer
The information given in this document shall in no event be regarded as a guarantee of conditions or
characteristics. With respect to any examples or hints given herein, any typical values stated herein and/or any
information regarding the application of the device, Infineon Technologies hereby disclaims any and all warranties
and liabilities of any kind, including without limitation, warranties of non-infringement of intellectual property rights
of any third party.
Information
For further information on technology, delivery terms and conditions and prices, please contact the nearest
Infineon Technologies Office (www.infineon.com).
Warnings
Due to technical requirements, components may contain dangerous substances. For information on the types in
question, please contact the nearest Infineon Technologies Office.
Infineon Technologies components may be used in life-support devices or systems only with the express written
approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure
of that life-support device or system or to affect the safety or effectiveness of that device or system. Life support
devices or systems are intended to be implanted in the human body or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may
be endangered.
ILD4035
350 mA Step Down LED Driver
Data Sheet 3 Revision 2.0, 2011-08-17
Trademarks of Infineon Technologies AG
AURIX™, BlueMoon™, C166™, CanPAK™, CIPOS™, CIPURSE™, COMNEON™, EconoPACK™, CoolMOS™,
CoolSET™, CORECONTROL™, CROSSAVE™, DAVE™, EasyPIM™, EconoBRIDGE™, EconoDUAL™,
EconoPIM™, EiceDRIVER™, eupec™, FCOS™, HITFET™, HybridPACK™, I²RF™, ISOFACE™, IsoPACK™,
MIPAQ™, ModSTACK™, my-d™, NovalithIC™, OmniTune™, OptiMOS™, ORIGA™, PRIMARION™,
PrimePACK™, PrimeSTACK™, PRO-SIL™, PROFET™, RASIC™, ReverSave™, SatRIC™, SIEGET™,
SINDRION™, SIPMOS™, SMARTi™, SmartLEWIS™, SOLID FLASH™, TEMPFET™, thinQ!™,
TRENCHSTOP™, TriCore™, X-GOLD™, X-PMU™, XMM™, XPOSYS™.
Other Trademarks
Advance Design System™ (ADS) of Agilent Technologies, AMBA™, ARM™, MULTI-ICE™, KEIL™,
PRIMECELL™, REALVIEW™, THUMB™, µVision™ of ARM Limited, UK. AUTOSAR™ is licensed by AUTOSAR
development partnership. Bluetooth™ of Bluetooth SIG Inc. CAT-iq™ of DECT Forum. COLOSSUS™,
FirstGPS™ of Trimble Navigation Ltd. EMV™ of EMVCo, LLC (Visa Holdings Inc.). EPCOS™ of Epcos AG.
FLEXGO™ of Microsoft Corporation. FlexRay™ is licensed by FlexRay Consortium. HYPERTERMINAL™ of
Hilgraeve Incorporated. IEC™ of Commission Electrotechnique Internationale. IrDA™ of Infrared Data
Association Corporation. ISO™ of INTERNATIONAL ORGANIZATION FOR STANDARDIZATION. MATLAB™ of
MathWorks, Inc. MAXIM™ of Maxim Integrated Products, Inc. MICROTEC™, NUCLEUS™ of Mentor Graphics
Corporation. Mifare™ of NXP. MIPI™ of MIPI Alliance, Inc. MIPS™ of MIPS Technologies, Inc., USA. muRata™
of MURATA MANUFACTURING CO., MICROWAVE OFFICE™ (MWO) of Applied Wave Research Inc.,
OmniVision™ of OmniVision Technologies, Inc. Openwave™ Openwave Systems Inc. RED HAT™ Red Hat, Inc.
RFMD™ RF Micro Devices, Inc. SIRIUS™ of Sirius Satellite Radio Inc. SOLARIS™ of Sun Microsystems, Inc.
SPANSION™ of Spansion LLC Ltd. Symbian™ of Symbian Software Limited. TAIYO YUDEN™ of Taiyo Yuden
Co. TEAKLITE™ of CEVA, Inc. TEKTRONIX™ of Tektronix Inc. TOKO™ of TOKO KABUSHIKI KAISHA TA.
UNIX™ of X/Open Company Limited. VERILOG™, PALLADIUM™ of Cadence Design Systems, Inc. VLYNQ™
of Texas Instruments Incorporated. VXWORKS™, WIND RIVER™ of WIND RIVER SYSTEMS, INC. ZETEX™ of
Diodes Zetex Limited.
Last Trademarks Update 2010-10-26
Revision History
Page or Item Subjects (major changes since previous revision)
Revision 2.0, 2011-08-17
Table 2 Maximum peak current specified for hysteretic peak condition
Table 2 Maximum junction temperature increased to 150 °C
Figure 3 Safe operating area increased
Table 4 Maximum supply voltage reduced to 40 V
Table 4 Overall current consumption and standby current reduced
Table 4 Over temperature protection improved from flicker to sloped behaviour
Table 5 Application setup changed
Table 6 Voltage range of digital control signals changed
Chapter 6.3 Over temperature protection improved from flicker to sloped behaviour
Chapter 6.4 Figures of switching parameters changed
Revision 1.0, 2010-11-11
ILD4035
350 mA Step Down LED Driver
Table of Contents
Data Sheet 4 Revision 2.0, 2011-08-17
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2Product Brief . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2 Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3 Digital Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Basic Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1 Setting the average LED current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2 Dimming of the LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.3 Temperature Protection Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.4 Switching Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7 Application Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8 Evaluation Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
9 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table of Contents
ILD4035
350 mA Step Down LED Driver
List of Figures
Data Sheet 5 Revision 2.0, 2011-08-17
Figure 1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 2 Total Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 3 Safe Operating Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 4 PWM Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 5 Application Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 6 ILD4035 on Evaluation Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 7 Package Outline SC74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 8 Recommended PCB Footprint for Reflow Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 9 Tape Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
List of Figures
ILD4035
350 mA Step Down LED Driver
List of Tables
Data Sheet 6 Revision 2.0, 2011-08-17
Table 1 Pin Definition and Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 2 Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 3 Maximum Thermal Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 4 DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 5 Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 6 Digital Control Parameter at Pin EN/PWM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
List of Tables
ILD4035
350 mA Step Down LED Driver
List of Tables
Data Sheet 7 Revision 2.0, 2011-08-17
SC74-3D
Product Name Package Pin Configuration Marking
ILD4035 SC74-6-4 1 = VS2 = GND 3 = EN 4 = Vswitch 5 = GND 6 = Vsense 35
350 mA Step Down LED Driver with Internal Switch
ILD4035
Data Sheet 8 Revision 2.0, 2011-08-17
1 Features
• Wide input voltage range: 4.5 V ... 40 V
• Internal switch for up to 400 mA average LED current
• Up to 95 % efficiency
• Over current protection
• Over voltage protection
• Temperature protection mechanism
• Inherent open-circuit LED protection
• Soft-start capability
• Low shut down current
• Analog and PWM dimming possible
• Typical 3 % output current accuracy
• Minimum external components required
• Small package: SC74
Applications
• LED driver for general lighting applications
• Retail, office and residential luminaires and downlights
• LED replacement lamps
• Architectural lighting
ILD4035
350 mA Step Down LED Driver
Product Brief
Data Sheet 9 Revision 2.0, 2011-08-17
2 Product Brief
The ILD4035 is a hysteretic step down LED driver IC for general lighting applications, which is capable to drive
high power LEDs with average currents up to 400 mA.
The IC incorporates a wide input voltage range and an internal power switch. The output current level can be
adjusted with an external sense resistor.
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 voltage dimming.
Depending on the value of the switching inductor the switching frequency and the voltage ripple can be set.
The precise internal bandgap stabilizes the circuit and provides stable current conditions over temperature range.
To ensure a long lifetime of the LED system, the ILD4035 incorporates an overvoltage and an overcurrent
protection.
In addition, the integrated thermal protection will reduce the output current to protect the LEDs and the IC against
thermal stress.
Figure 1 Block Diagram
ILD4035_ Block diagram.vsd
6
5
43
2
1V
S
GND
EN /
PWM
V
sense
GND
V
switch
ILD4035
Buck LED Converter
I / V
Vref
Vstab Vstab
Vstab
Vstab Vstab
Over Cur r ent Protecti on
TPC
Over Voltage Pr otection
ILD4035
350 mA Step Down LED Driver
Product Brief
Data Sheet 10 Revision 2.0, 2011-08-17
Pin Definition
Table 1 Pin Definition and Function
Pin No. Name Pin
Type
Buffer
Type
Function
1VsInput – Supply voltage
2 GND GND – IC ground
3 EN / PWM Input – Multifunctional pin:
• Chip enable signal
• Analog dimming signal
• PWM dimming signal
4Vswitch Output – Power switch output
5 GND GND – IC ground
6Vsense Input – LED current sense input
ILD4035
350 mA Step Down LED Driver
Maximum Ratings
Data Sheet 11 Revision 2.0, 2011-08-17
3 Maximum Ratings
Attention: Stresses above the max. values listed here may cause permanent damage to the device.
Exposure to absolute maximum rating conditions for extended periods may affect device
reliability. Maximum ratings are absolute ratings; exceeding only one of these values may
cause irreversible damage to the integrated circuit.
Table 2 Maximum Ratings
Parameter Symbol Values Unit Note /
Test Condition
Min. Typ. Max.
Supply voltage VS––45V–
Peak output current ISwitch – – 550 mA Hysteretic peak
current
Total power dissipation, Ts ≤ 85°C Ptot ––1000mW–
Junction temperature TJ––150°C–
Storage temperature range TSTG -65 – 150 °C –
ESD capability
at all pins
VESD HBM
––4
kV HBM acc. to
JESD22-A114
ILD4035
350 mA Step Down LED Driver
Thermal Characteristics
Data Sheet 12 Revision 2.0, 2011-08-17
4 Thermal Characteristics
Figure 2 Total Power Dissipation
Equation (1) is gives an estimation for the power dissipation of ILD4035.
(1)
Table 3 Maximum Thermal Resistance
Parameter Symbol Values Unit Note /
Test Condition
Min. Typ. Max.
Junction - soldering point1)
1) For calculation of RthJA please refer to application note AN077 (Thermal Resistance Calculation)
RthJS ––65K/W–
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160
Ptot [W]
TS [°C]
mA
I
µWfcycledutyIVP
LED
SwitchLEDtot
350
11.1 ⋅⋅+⋅⋅=
ILD4035
350 mA Step Down LED Driver
Thermal Characteristics
Data Sheet 13 Revision 2.0, 2011-08-17
Figure 3 Safe Operating Area
Figure 3 shows the safe operating area for the respective inductance values. The safe operating area consists of
the minimum and maximum allowed average LED current and the resulting voltage overhead. The voltage
overhead Voverhead is the difference between the supply voltage VS and the sum of the LED forward voltages VΣfLED.
Example calculation 1
3 LEDs in series, VfLED= 3V, ILED = 350 mA, VS = 12 V
Voverhead = VS - VΣfLED = 12 V - 9 V = 3 V
→ any of the above coil values can be used
Example calculation 2
6 LEDs in series, VfLED= 3V, ILED = 250 mA, VS = 24 V
Voverhead = VS - VΣfLED = 24 V - 18 V = 6 V
→ the coil values needs to be at least 68 µH
Outside the safe operating area the switching frequency, hysteretic peak current and associated power dissipation
Ptot of ILD4035 will increase beyond the maximum ratings.
0
5
10
15
20
25
30
35
40
45
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
VS - VΣfLED [V]
Average LED current ILED [A]
47 μH
68 μH
100 μH
150 μH
220 μH
330 μH
ILD4035
350 mA Step Down LED Driver
Electrical Characteristics
Data Sheet 14 Revision 2.0, 2011-08-17
5 Electrical Characteristics
5.1 DC Characteristics
All parameters at TA = 25 °C, unless otherwise specified.
VS = 12 V, 3 LEDs, Rsense = 303 mΩ (ILED = 375 mA), L = 100 μH, VEN = 3 V, VfLED = 3 V
Table 4 DC Characteristics
Parameter Symbol Values Unit Note / Test Condition
Min. Typ. Max.
Supply voltage VS4.5 – 40 V
Overall current consumption open
load
IS open load 1.4 2.3 3.1 mA VS=4.5V
ILED =0mA
Overall current consumption open
load
IS open load 1.5 2.4 3.2 mA VS=12V
ILED =0mA
Overall current consumption open
load
IS open load 1.8 3.0 3.9 mA VS=40V
ILED =0mA
Overall standby current consumption IS standby ––1µAVEN =0V; VS=12V
Overall standby current consumption IS standby ––5μAVEN =0V; VS=40V
Enable voltage for standby mode VEN -0.3 – 0.4 V
Enable voltage for analog dimming VEN 1 – 2 V linear dimming range
Input current of multifunctional control
pin
IEN – 50 140 μAVEN =3V
VS=4.5..40V
Current of sense input Isense –20–μA at any LED current
Over temperature protection TS,TSD –113–°CTS for 10 % ILED
reduction, defined by TJ
ILD4035
350 mA Step Down LED Driver
Electrical Characteristics
Data Sheet 15 Revision 2.0, 2011-08-17
5.2 Switching Characteristics
All parameters at TA = 25 °C, unless otherwise specified.
VS = 12 V, 3 LEDs, Rsense = 303 mΩ (ILED = 375 mA), L = 100 μH, VEN = 3 V, VfLED = 3 V
5.3 Digital Signals
All parameters at TA = 25 °C, unless otherwise specified.
Table 5 Switching Characteristics
Parameter Symbol Values Unit Note / Test Condition
Min. Typ. Max.
Switching frequency fSwitch –120–kHz
Maximum switching frequency fSwitch max – – 500 kHz for any coil value
Mean current sense threshold voltage Vsense –114–mV
Sense threshold hysteresis Vsensehys –±7.5 – %
Residual voltage at collector of power
transistor
Vswitch on – 1.1 – V output switch turned on
Output current accuracy Ioutacc –±3– %
Table 6 Digital Control Parameter at Pin EN/PWM
Parameter Symbol Values Unit Note / Test Condition
Min. Typ. Max.
Input voltage for power on VOn 2.5 3 40 V full LED current
Input voltage for power off VOff -0.3 – 0.4 V
Min. power on puls duration tOn 10 – µs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 16 Revision 2.0, 2011-08-17
6 Basic Application Information
This section covers the basic information required for calculating the parameters for a certain LED application.
For detailed application information please check the Application Note AN215 (Driving 1 W LEDs with ILD4035)
or visit our web site http://www.infineon.com/led.appnotes
6.1 Setting the average LED current
The average output current for the LEDs is set by the external sense resistor Rsense. To calculate the value of this
resistor a first approximation can be calculated using Equation (2).
Vsense is dependent on the supply voltage VS and the number of LEDs in series.
(2)
Example calculation 1
VS = 12 V, 100 µH, VfLED = 3 V, 3 LEDs in series
→ Vsense = 114 mV
ILED = 375 mA
→ Rsense = 303 mΩ
Example calculation 2
VS = 24 V, 100 µH, VfLED = 3 V, 6 LEDs in series
→ Vsense = 106 mV
ILED = 350 mA
→ Rsense = 303 mΩ
An easy way to achieve these resistor values is to connect standard resistors in parallel
6.2 Dimming of the LEDs
Analog voltage dimming
The voltage level of the EN/PWM pin can be used for analog dimming of the LED current. To achieve a linear
change in LED current versus control voltage the recommended voltage range at the EN/PWM pin is 1 V to 2 V.
The maximum achievable LED current is defined by resistor Rsense. The maximum LED current will be achieved for
VEN ≥ 2.5 V. Below 0.4 V the ILD4035 is set to standby mode and the output is switched off. The typical dimming
performance is shown in below figures.
LED
sense
sense
I
V
R=
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 17 Revision 2.0, 2011-08-17
PWM Dimming
Besides the analog dimming functionality the EN/PWM pin acts as input for a pulse width modulated (PWM) signal
to control the dimming of the LED string. For PWM dimming the signal's logic high level should be at least 2.5 V
and the PWM frequency should be lower than 5 kHz. For the ILD4035/4001 demo board a dimming frequency less
than 330 Hz is recommended to maintain a maximum contrast ratio of 100:1. The achieveable contrast ratio is
shown on Figure 4 based on the measured average LED current deviating 3 dB from the linear reference. The
maximum contrast ratio depends mainly on the rise time of the inductor current and is thus dependent on supply
voltage, inductor size and LED string forward voltage.
ILED versus VEN, TA=25 °C ILED (relative) versus VEN, TA=25 °C
ILED versus VEN, 333 mΩ, 100 µH
0
0.1
0.2
0.3
0.4
1 1.5 2 2.5 3
ILED [A]
VEN [V]
303 mΩ, 100 μH
333 mΩ, 100 μH
600 mΩ, 100 μH
1200 mΩ, 220 μH
0
10
20
30
40
50
60
70
80
90
100
110
1 1.5 2 2.5 3
ILED [%]
VEN [V]
303 mΩ, 100 μH
333 mΩ, 100 μH
600 mΩ, 100 μH
1200 mΩ, 220 μH
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
1 1.5 2 2.5 3
ILED [A]
VEN [V]
-40 °C
25 °C
85 °C
105 °C
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 18 Revision 2.0, 2011-08-17
Figure 4 PWM Dimming
1
10
100
1000
100 1000 10000
Contrast Ratio
PWM Dimming Frequency [Hz]
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 19 Revision 2.0, 2011-08-17
6.3 Temperature Protection Circuit
ILD4035 incorporates a temperature protection circuit referring to the junction temperature of ILD4035. The higher
the junction temperature of ILD4035 the lower the current of the LEDs. This feature helps to reduce the power
dissipation of ILD4035 and the LEDs. Yet still the product specific maximum ratings for junction temperature need
to be observed to avoid a permanent damage of the devices.
ILD4035 has been characterized on ILD4035/4001 application board heated from the backside without additional
air flow on the circuit board surface besides natural convection. Design and layout of the circuit board as well as
the air flow influence the thermal resistance junction to ambient RthJA of ILD4035 and thus its junction temperature.
Below figures show the LED current versus soldering point temperature TS.
6.4 Switching Parameters
For all shown parameters ILD4035 has been measured on evaluation board ILD4035/4001 at TA = 25 °C. Used
LEDs have a typical forward voltage VfLED of 3 V. For details see application note AN215 (Driving 1W LEDs with
ILD4035) or visit our web site http://www.infineon.com/lowcostleddrivers.
LED current versus TS, VS = 12 V LED current (relative) versus TS, VS = 12 V
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
40 50 60 70 80 90 100 110 120 130
ILED [A]
TS [°C]
303 mΩ, 100 μH
333 mΩ, 100 μH
600 mΩ, 100 μH
1200 mΩ, 220 μH
70
80
90
100
110
40 50 60 70 80 90 100 110 120 130
ILED [%]
TS [°C]
303 mΩ, 100 μH
333 mΩ, 100 μH
600 mΩ, 100 μH
1200 mΩ, 220 μH
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 20 Revision 2.0, 2011-08-17
Rsense = 303 mΩ, L= 47 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.25
0.3
0.35
0.4
0.45
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 21 Revision 2.0, 2011-08-17
Rsense = 303 mΩ, L= 68 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.25
0.3
0.35
0.4
0.45
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 22 Revision 2.0, 2011-08-17
Rsense = 303 mΩ, L= 100 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.25
0.3
0.35
0.4
0.45
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 23 Revision 2.0, 2011-08-17
Rsense = 303 mΩ, L= 220 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.25
0.3
0.35
0.4
0.45
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 24 Revision 2.0, 2011-08-17
Rsense = 367 mΩ, L= 47 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.2
0.25
0.3
0.35
0.4
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 25 Revision 2.0, 2011-08-17
Rsense = 367 mΩ, L= 68 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.2
0.25
0.3
0.35
0.4
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 26 Revision 2.0, 2011-08-17
Rsense = 367 mΩ, L= 100 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.2
0.25
0.3
0.35
0.4
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Basic Application Information
Data Sheet 27 Revision 2.0, 2011-08-17
Rsense = 367 mΩ, L= 220 µH
ILED versus VS and Number of LEDs fSwitch versus VS and Number of LEDs
Efficiency versus VS and Number of LEDs Duty Cycle versus VS and Number of LEDs
0.2
0.25
0.3
0.35
0.4
0 5 10 15 20 25 30 35 40 45
ILED [A]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40 45
fSwitch [kHz]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30 35 40 45
Efficiency [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Duty Cycle [%]
VS [V]
1 LED
2 LEDs
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
9 LEDs
10 LEDs
ILD4035
350 mA Step Down LED Driver
Application Circuit
Data Sheet 28 Revision 2.0, 2011-08-17
7 Application Circuit
Figure 5 Application Circuit
8 Evaluation Board
Figure 6 ILD4035 on Evaluation Board
ILD4035
350 mA Step Down LED Driver
Package Information
Data Sheet 29 Revision 2.0, 2011-08-17
9 Package Information
Figure 7 Package Outline SC74
Figure 8 Recommended PCB Footprint for Reflow Soldering
Figure 9 Tape Loading
SC74-PO V0
4
546
321
1.1 MAX.
(0.35)
(2.25)
±0.2
2.9 B
0.2
+0.1
-0.05
0.35
Pin 1
marking
M
B6x
0.95
1.9
0.15
-0.06
+0.1
1.6
A
±0.1
2.5
0.25
±0.1
±0.1
A0.2
M
0.1 MAX.
0.5
0.95
1.9
2.9
SC74-FPR
V0
4
SC74-T
P
2.7
4
3.15
Pin 1
marking
8
0.2
1.15
Published by Infineon Technologies AG
www.infineon.com