© 2009 Semiconductor Component Industries, LLC. Publication Order Number:
October-2017, Rev.2 FAN5341/D
FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
FAN5341
Series Boost LED Driver with Integrated Schottky Diode and
Single-Wire Digital Interface
Features
Asynchronous Boost Converter
Internal Schottky Diode
Up to 500mW Output Power
Drives 3 to 5 LEDs in Series
2.7V to 5.5V Input Voltage Range
Single-Wire Digital Control Interface to Set LED
Brightness Levels
32 Linear Steps
1.2MHz Fixed Switching Frequency
Soft-Start Capability
Input Under-Voltage Lockout (UVLO)
Output Over-Voltage Protection (OVP)
Short-Circuit Detection
Thermal Shutdown (TSD) Protection
Low Profile 6-lead 2.0 x 2.0 x 0.55mm UMLP Package
Applications
Cellular Mobile Handsets
Mobile Internet Devices
Portable Media Players
PDA, DSC, MP3 Players
Description
The FAN5341 is an asynchronous constant-current LED
driver capable of efficiently delivering up to 500mW to a
string of up to five LEDs in series. Optimized for small form-
factor applications, the 1.2MHz fixed switching frequency
allows the use of small chip inductors and capacitors.
The FAN5341 uses a simple single-wire digital control
interface to program the brightness levels of the LEDs in 32
linear steps by applying digital pulses.
For safety, the device features integrated over-voltage, over-
current, short-circuit detection, and thermal-shutdown
protection. In addition, input under-voltage lockout protection
is triggered if the battery voltage is too low.
The FAN5341 is available in a very low profile, small form-
factor 2mm x 2mm x 0.55mm 6-lead UMLP package that is
green and RoHS compliant.
Ordering Information
Part Number
Temperature Range
Package
Packing
FAN5341UMPX
-40 to 85°C
6-lead, 2.0 x 2.0mm UMLP
Tape and Reel
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Typical Application Diagram
6
3
L1
VIN
2.7V to 5.5V 5
1
4
VOUT
FB
GND
SW
EN
2
FAN5341
L = 10µH
CIN = 10µF
COUT = 1µF
RSET = 12.7 @ ILED =20mA
3 – 5 LEDs
RSET = 10.0 @ ILED =25mA
Figure 1. Typical Application
Block Diagram
2
6
5
1
D1
BOOST
CONTROL
GATE
DRIVE
34
OVP/
SCD
Digital I/F
VIN
GND
EN
SW
VOUT
FB
Figure 2. Functional Block Diagram
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Pin Configuration
Figure 3. UMLP6 Package, ^Top View
Pin Definitions
Pin #
Name
Description
1
VOUT
Boost Output Voltage. Output of the boost regulator. Connect the LEDs to this pin. Connect COUT
(Output Capacitor) to GND.
2
VIN
Input Voltage. Connect to power source and decouple with CIN to GND.
3
EN
Enable Brightness Control. Program dimming levels by driving pin with digital pulses.
4
FB
Voltage Feedback. The boost regulator regulates this pin to 0.253V to control the LED string current.
Tie this pin to a current setting resistor (RSET) between GND and the cathode of the LED string.
5
SW
Switching node. Tie inductor L1 from VIN to SW pin.
6
GND
Ground. Tie directly to a GND plane.
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above
the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended
exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings
are stress ratings only.
Symbol
Parameter
Min.
Max.
Units
VIN
VIN
-0.3
6.0
V
VFB, VEN
FB, EN Pins
-0.3
VIN + 0.3
V
VSW
SW Pin
-0.3
22.0
V
VOUT
VOUT Pin
–0.3
22.0
V
ESD
Electrostatic Discharge Protection
Level
Human Body Model per JESD22-A114
3.3
kV
Charged Device Model per JESD22-C101
2.0
TJ
Junction Temperature
-40
+150
°C
TSTG
Storage Temperature
-65
+150
°C
TL
Lead Soldering Temperature, 10 Seconds
+260
°C
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating
conditions are specified to ensure optimal performance to the datasheet specifications. ON Semiconductor does not recommend
exceeding them or designing to absolute maximum ratings.
Symbol
Parameter
Comments
Min.
Max.
Units
VIN
VIN Supply Voltage
2.7
5.5
V
VOUT
VOUT Voltage(1)
6.2
17.5
V
IOUT
VOUT Load Current
500mW Maximum Output Power
5
25
mA
TA
Ambient Temperature
-40
+85
°C
TJ
Junction Temperature
-40
+125
°C
Note:
1. Application should guarantee that minimum and maximum duty-cycle should fall between 20-85% to meet the specified
range
Thermal Properties
Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured w ith four-layer 2s2p
boards in accordance to JEDEC standard JESD51. Special attention must be paid not to exceed junction temperature TJ(max) at a
given ambient temperature TA.
Symbol
Parameter
Typical
Units
JA
Junction-to-Ambient Thermal Resistance, UMLP6 Package
70
°C/W
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Electrical Specifications
VIN = 2.7V to 5.5V and TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = 25°C and VIN = 3.6V.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
Power Supplies
ISD
Shutdown Supply Current
EN = GND, VIN = 3.6V
0.30
0.75
A
VUVLO
Under-Voltage Lockout
Threshold
VIN Rising
2.10
2.35
2.60
V
VIN Falling
1.90
2.15
2.40
VUVHYST
Under-Voltage Lockout
Hysteresis
250
mV
EN: Enable Pin
VIH
HIGH-Level Input Voltage
1.2
V
VIL
LOW-Level Input Voltage
0.4
V
REN
EN Pull-Down Resistance
200
300
400
k
TLO
EN Low Time for Dimming
VIN = 3.6V; See Figure 14
0.5
300
µs
THI
Time Delay Between Steps
VIN = 3.6V; See Figure 14
0.5
µs
TSD
EN Low, Shutdown Pulse Width
VIN = 3.6V; from Falling Edge of EN
1
ms
Feedback and Reference
VFB
Feedback Voltage
ILED = 20mA from -40°C to +85°C,
2.7V ≤ VIN ≤ 5.5V
240
253
266
mV
IFB
Feedback Input Current
VFB = 253mV
0.1
1.0
A
Power Outputs
RDS(ON)_Q1
Boost Switch On-Resistance
VIN = 3.6V, ISW = 100mA
600
m
VIN = 2.7V, ISW = 100mA
650
ISW(OFF)
SW Node Leakage(1)
EN = 0, VIN = VSW = VOUT = 5.5V,
VLED = 0
0.1
2.0
A
ILIM-PK
Boost Switch Peak Current Limit
VIN = 3.6V
750
mA
Oscillator
fSW
Boost Regulator Switching
Frequency
1.0
1.2
1.4
MHz
Output and Protection
VOVP
Boost Output Over-Voltage
Protection
18.0
18.9
21.0
V
OVP Hysteresis
0.8
VTLSC
VOUT Short Circuit Detection
Threshold
VOUT Falling
VIN – 1.4
V
VTHSC
VOUT Short Circuit Detection
Threshold
VOUT Rising
VIN – 1.2
V
DMAX
Maximum Boost Duty Cycle(2,3)
85
%
DMIN
Minimum Boost Duty Cycle(2,3)
20
TTSD
Thermal Shutdown
150
°C
THYS
Thermal Shutdown Hysteresis
35
°C
Notes:
1. SW leakage current includes the leakage current of 2 internal switches; SW to GND and SW to VOUT.
2. Not tested in production and guaranteed by design.
3. Application should guarantee that minimum and maximum duty cycle should fall between 20-85% to meet the specified
range.
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Electrical Specifications
Figure 4. 5 LEDs: Efficiency vs. LED Current
vs. Input Voltage
Figure 5. 5 LEDs: Efficiency vs. LED Current
vs. Input Voltage
Figure 6. 4 LEDs: Efficiency vs. LED Current
vs. Input Voltage
Figure 7. Delta of VFB Over Input Voltage and
Temperature for 4 LEDs with L=10µH and
COUT=1.0µF at ILED=25mA
Figure 8. 3 LEDs: Efficiency vs. LED Current
vs. Input Voltage
Figure 9. Over-Voltage Protection vs. Input Voltage
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
2.7 3 3.3 3.6 3.9 4.2
Input Voltage (V)
Delta Feedback Voltage (mV)
-40°C
+25°C
+85°C
5 LEDs
L = 10µH
COUT = 1.0µF
ILED = 25mA
5 LEDs
L = 4.7µH
COUT = 1.0µF
ILED = 25mA
4 LEDs
L = 10µH
COUT = 1.0µF
ILED = 25mA
3 LEDs
L = 10µH
COUT = 1.0µF
ILED = 25mA
4 LEDs
L = 10µH
COUT = 1.0µF
ILED = 25mA
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Electrical Specifications
Figure 10. Line Transient Response for 4 LEDs at
VIN=3.6V 0.6V with L=10µH, COUT=1.0µF and
ILED=25mA
Figure 11. FAN5341 Dimming Operation at VIN=3.6V for 4
LEDs with L=10µH, COUT=1.0µF and ILED=25mA
Figure 12. Startup Waveform for Switch Voltage, Inductor
Current, VFB and EN for 4 LEDs at VIN=3.6V
0.6V with L=10µH, COUT=1.0µF and ILED=25mA
Figure 13. Steady-State Waveform for VOUT, Switch Voltage
and Inductor Current for 4 LEDs at VIN=3.6V
0.6V with L=10µH, COUT=1.0µF and ILED=25mA
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Circuit Description
Overview
The FAN5341 is an inductive current-mode boost serial
LED driver that achieves LED current regulation by
maintaining 0.253V across the RSET resistor. The current
through the LED string (ILED) is therefore given by:
SET
LED R
I253.0
(1)
The voltage VOUT is determined by the sum of the forward
voltages across each LED, plus the voltage across RSET,
which is always 253mV.
Driving Five LEDs in Series
FAN5341 can drive five LEDs in series but, the forward
voltage (VF) of the LED MUST be less than 3.5V such that it
remains under the over-voltage specification of 18.9V.
UVLO and Soft-Start
If EN has been low for more than 1ms, the IC may initiate a
“cold start” soft-start cycle when EN rises, provided VIN is
above the UVLO threshold.
Digital Interface
The FAN5341 implements a single-wire digital interface to
program the LED brightness to one of thirty-two (32) levels
spaced in linear steps. With this single-wire solution, the
FAN5341 does not require the system processor to
constantly supply a signal to it to drive the LEDs.
Digital Dimming Control
The FAN5341 starts driving the LEDs at the maximum
brightness level. After startup, the control logic is ready to
accept programming pulses to decrease the brightness
level by the number of positive edges applied to the EN pin.
Figure 14 shows the digital pulse dimming control.
Over-Current and Short-Circuit Detection
The boost regulator employs a cycle-by-cycle peak inductor
current limit of ~750mA.
Over-Voltage / Open-Circuit Protection
If the LED string is an open circuit, FB remains at 0V and
the output voltag continues to increase in the absence of an
over-voltage protection (OVP) circuit. The FAN5341’s OVP
circuit disables the boost regulator when VOUT exceeds
18.9V and continues to keep the regulator off until VOUT
drops below 18.1V.
Thermal Shutdown
When the die temperature exceeds 150°C, a reset occurs
and remains in effect until the die cools to 125°C, at w hich
time, the circuit is allowed to begin the soft-start sequence.
EN 1 2 3 4 313029
28
IWLED
Shutdown
0 1
Level 32: 100% Level 31 Level 30
Level 28
Level 1
Level 2
Level 3
Level 4
Level 5
Level 32: 100% Level 31
tHI tLO tSD
Level 29
Shutdown
0
Figure 14. Digital Pulse-Dimming Control Diagram
Application Information
Inductor & Output Capacitor Selection
# of LEDs
Inductor (L)
Part Number
Manufacturer
Min COUT
Part Number
Manufacturer
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
3, 4, 5
10.0µH
LQH43MN100K03
Murata
1.00µF
CV105X5R105K25AT
AVX/Kyocera
NLCV32T-100K-PFR
TDK
VLF3010AT-100MR49-1
TDK
4.7µH
LQH43MN4R7K03
Murata
1.00µF
CV105X5R105K25AT
AVX/Kyocera
NLCV32T-4R7M-PFR
TDK
LPF2010T-4R7M
ABCO
Table 1. Recommended External Components
Component Placement and PCB Recomendations
Figure 15. Recommended Component Placement
Input Capacitance
In a typical application, the input and output capacitors
should be placed as close to the IC as possible; no
additional capacitance is needed to ensure proper
functionality. However, in a testing environment, where the
FAN5341 is typically powered by a power supply with
relatively long cables, an additional input capacitor (10µF)
may be needed to ensure stable functioning. This capacitor
should be placed close to where the power supply cables
attach to the FAN5341 evaluation board.
PCB Recommendations
The inductor can be connected to VIN with vias through
another layer if needed.
The feedback pin should be connected back to the IC on
a sub-layer.
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
Physical Dimensions
Figure 16. 6-Lead Molded Leadless Package (UMLP)
Package drawings are provided as a service to customers considering ON Semiconductor components. Drawings may change in any manner without notice.
Please note the revision and/or date on the drawing and contact ON Semiconductor representative to verify or obtain the most recent revision. Package
specifications do not expand the terms of ON Semiconductor’s worldwide terms and conditions, specifically the warranty therein, which cov ers ON Semiconductor products.
SIDE VIEW
NOTES:
A. PACKAGE CONFORMS TO JEDEC MO-229
EXCEPT WHERE NOTED.
B. DIMENSIONS ARE IN MILLIMETERS.
C. DIMENSIONS AND TOLERANCES PER
ASME Y14.5M, 1994.
D. LANDPATTERN RECOMMENDATION IS BASED
ON FSC DESIGN ONLY.
E. DRAWING FILENAME: MKT-UMLP06Erev2.
BOTTOM VIEW
TOP VIEW
RECOMMENDED LAND PATTERN
13
64
2X
2X
0.05
0.00
0.55 MAX
0.10 C
0.08 C
(0.15)
C
SEATING
PLANE
2.0
2.0
0.70
0.80
1.35
1.45
PIN1
IDENT
0.10 C A B
0.05 C6X
6X
0.10 C
0.10 C
PIN1
IDENT
A
B
0.35
0.25
0.35
0.25
0.65
1.45
0.80
0.50
0.35 0.65
6X
6X
1.80
A
(0.25)
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FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface
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