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FAN5617 — High-Efficiency, Constant-Current LED Driver with TinyWire
TM
Brightness Control
April 2007
FAN5617
High-Efficiency, Constant-Current LED Driver with
TinyWire™ Brightness Control
Features
Three-Channel Parallel LED Driver for a Large Range
of Forward Voltages
TinyWire™ Single-Wire Digital Brightness Control
32 Static Brightness Levels with 5-Bit Internal DAC
Adaptive V
OUT
Adjustment to the Highest Diode
Forward Voltage
Matched LED Currents; Matched or Unmatched LEDs
Built-in Charge Pump with Three Modes of Operation:
1x (linear), 1.5x, and 2x
Up to 90% Efficiency
Low EMI, Low Ripple
Up to 90mA Total Output Current
Drives up to Three LEDs at 30mA Each
External Resistor Sets Maximum (100%) LED Current
2.7V to 5.5V Input Voltage Range
1MHz Operating Frequency
Shutdown Isolates Output from Input, Typically <1µA
Protections: Short-Circuit; Soft-Start Limits Inrush
Current
Minimal External Components Required
3x3mm 16-Lead MLP Package
Description
The FAN5617 is a low-ripple, low-EMI, high-efficiency,
constant-current LED driver that drives three LEDs in
parallel. The LED brightness control is programmable
through Fairchild’s proprietary single-wire digital
interface, TinyWire™. The charge pump DC/DC
converter operates in three modes: 1X, 1.5X, and 2X
over the entire input voltage range of 2.7V to 5.5V. The
adaptive nature of the built-in charge pump eliminates
the need for LED pre-selection (matching) and delivers
high output efficiency. FAN5617 is capable of driving up
to 90mA total output current, 30mA per channel. The
driver’s built-in, proprietary auto-sense circuit ensures
the same efficiency regardless of the number of LEDs
connected. When the input voltage is insufficient to
sustain the LEDs programmable current level, the
FAN5617 reconfigures itself to operate as a linear
regulator and the charge pump circuit turns off.
The FAN5617 features Fairchild’s TinyWire™ single-
wire digital interface for LED brightness control. The
built-in 5-bit DAC provides selection of 32 dimming
levels, where each level is a percentage of the
maximum LED current set by the external resistor, R
SET
.
The FAN5617 includes shutdown, short-circuit, and
thermal protection circuitry.
Minimal external components are required: two bucket
capacitors (2µF and 1µF), a 4.7µF input capacitor, and a
1µF output capacitor are needed for proper operation.
The FAN5617 is available in a 3x3mm, 16-lead, molded
leadless package (MLP).
Applications
Portable Handheld Backlight
PDAs, DVD players, Pagers, Camcorder Backlights
Portable Medical Diagnostic Equipments Display
MP3 Player Displays
Digital Still Camera Backlight
Ordering Information
Part Number
FAN5617MPX
Pb-Free
Yes
Operating Temperature Range
0°C to 85°C
Package
MLP-16 3x3mm
Packing Method
Tape and Reel
TinyWire™ is a trademark of Fairchild Semiconductor Corporation.
© 2006 Fairchild Semiconductor Corporation
FAN5617 Rev. 1.0.2
www.fairchildsemi.com
FAN5617 — High-Efficiency, Constant-Current LED Driver with TinyWire
TM
Brightness Control
Application Diagram
EN
DATA
R
SET
16 15 14 13
1
2
3
4
5
6
7
8
C
OUT
VOUT
P1 = GND
12
11
10
9
CAP1 CAP2
C
IN
VIN
C
IN
CAP1, CAP2
C
OUT
R
SET
4.7μF
0.1μF
1μF
15K
Figure 1. Typical Application
Pin Configuration
DATA
GND
14
16
15
RSET
N/C
N/C
LED–
1
2
VIN
13
12
11
EN
CAP2–
CAP1–
CAP1+
CAP2+
P1 = GND
3
4
10
9
5
6
7
8
LED–
LED–
Figure 2. Top View 3x3mm MLP Package
Pin Definitions
Pin
1
2,3
4-6
7
8
9
10
11
12
13
14
15
16
Name
RSET
N/C
LED–
P1, PGND
VOUT
CAP2+
CAP1+
CAP1–
CAP2–
VIN
GND
EN
DATA
Description
Current set resistor.
A resistor from this pin to GND sets the maximum LED current.
No internal connection.
LED cathode
drive.
Power Ground
for the IC. Solder to PCB ground plane.
Regulated Output Voltage.
Connect to output capacitor and anodes of all LEDs.
Bucket Capacitor 2.
Connect this pin to the positive terminal of the bucket capacitor
Bucket Capacitor 1.
Connect this pin to the positive terminal of the bucket capacitor
Bucket Capacitor 1.
Connect this pin to the negative terminal of the bucket capacitor
Bucket Capacitor 2.
Connect this pin to the negative terminal of the bucket capacitor
Supply Input Voltage.
Ground.
All signals are referenced to this point. Solder to PCB ground plane.
Enable.
Enables the IC when high and disables at HIGH-to-LOW transition. The TinyWire control overrides
the state of the EN pin if a command is received.
DATA input
for TinyWire brightness control. This pin has a 33kΩ internal pull-up resistor to V
IN
.
© 2006 Fairchild Semiconductor Corporation
FAN5617 Rev. 1.0.2
PGND
VOUT
www.fairchildsemi.com
2
FAN5617 — High-Efficiency, Constant-Current LED Driver with TinyWire
TM
Brightness Control
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.
Parameter
V
IN
, V
OUT
, EN, DATA, GND
Voltage on All Other Pins
CAP+, CAP- to GND
Thermal Resistance – Junction to Tab (θ
JC
)
Lead Soldering Temperature (10 seconds)
Junction Temperature
Storage Temperature
Electrostatic Discharge (ESD) Protection Level
(2)
HBM
CDM
(1)
Min.
-0.3
-0.3
-0.3
Max.
6
V
IN
+0.3
V
IN
+0.3
8
260
150
Units
V
V
V
°C/W
°C
°C
°C
kV
kV
-65
4.0
2.0
150
Notes:
1. Junction-to-ambient thermal resistance,
θ
JA
, is a strong function of PCB material, board thickness, copper
thickness and number of vias used, diameter of via used, available copper surface, and attached heat sink
characteristics. A reasonable estimated value for
θ
JA
for zero air flow at 0.5W is 60ºC/W.
2.
Using Mil Std. 883E, method 3015.7 (Human Body Model) and EIA/JESD22C101-A (Charged Device Model).
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. Fairchild does not
recommend exceeding them or designing to absolute maximum ratings.
Parameter
Supply Voltage Range
LED Forward Voltage
Current Through Each LED
Operating Ambient Temperature
Operating Junction Temperature
Min.
2.5
Max.
5.5
4
Units
V
V
mA
°C
°C
2
-40
-40
30
+85
+125
© 2006 Fairchild Semiconductor Corporation
FAN5617 Rev. 1.0.2
www.fairchildsemi.com
3
FAN5617 — High-Efficiency, Constant-Current LED Driver with TinyWire
TM
Brightness Control
Electrical Specifications
Unless otherwise noted, V
IN
= 2.7V to 5.5V, I
LED
= 2mA to 20mA, EN = HIGH, N
BR
= 31, T
A
= -40°C to +85°C. Typical
values are at 25°C.
Parameter
Power Supplies
Input Under-Voltage Lockout
Current Matching with Unmatched LEDs
I
LED
/I
SET
Ratio
Reference Voltage for Current Set
Start-up Time
(4)
(3)
Conditions
V
IN
Falling
V
IN
Rising
2mA
≤
I
LED
≤
15mA,
2.8V
≤
LED V
F
<4V
V
IN
= 3.6V, I
OUT
= 15mA
I
LED
= 2 to 20mA
C
OUT
= 1µF, V
IN
= 3.6V, I
LED
= 15mA
I
LED
= 15mA
V
IN
= 5.5V, I
OUT
= 5mA
EN=0V, DATAIN = V
IN
V
IN
= 5.5V, V
OUT
= 0V
LED V
f
= 3.5V, I
LED
= 3 x 20mA
LED V
f
= 3.5V, I
LED
= 3 x 20mA
V
IN
= 3.75V, LED V
f
= 3.4V,
I
LED
= 18mA
(5)
Min.
Typ.
Max.
1.6
Units
V
V
2.3
0.6
245
230
588
200
260
260
600
270
170
250
0.1
65
3.9
2.9
90
0.8
1
150
15
1.2
1
80
6
+3
275
280
612
500
250
%
mV
µS
mV
µA
µA
mA
V
V
V
%
MHz
ºC
ºC
Minimum Cathode Voltage
Quiescent Current
Shutdown Supply Current
Output Short-Circuit Current
V
OUT
Over-Voltage Protection
V
IN
at Mode Transition from 1x to 1.5x
V
IN
at Mode Transition from 1.5x to 2x
Peak Efficiency
(6)
Oscillator Frequency
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
Logic Input Thresholds (EN and DATA)
Input Low Voltage
Input High Voltage
DATA Input Low Current
V
IN
= 3.6V
1.25
110
0.4
V
V
µA
Notes:
3. Current Matching refers to the absolute value of the difference in the current between the two LED branches:
Current Matching (%)
≡
(
I
LEDi
(
I
−
I
LEDj
x 100
+
I
LEDj
)
LEDi
)
where i, j = 1, 2, or 3.
4.
5.
6.
Start-up time is defined as the period from when the driver is turned on to the time when I
LED
is within 10% of its
programmed value.
When DATA remains low, the TinyWire interface is biased on and consumes up to 30μA of current.
Efficiency is expressed as a ratio between the electrical power into the LEDs and the total power consumed from the
input power supply, expressed as:
Efficiency
≡
∑
V
i
=
1
3
LEDi
x I
LEDi
V
IN
x I
IN
Some vendors calculate the efficiency as a function of V
OUT
instead of LED VF. That method does not account
for the power lost due to the cathode voltage not being equal to zero, which overstates efficiency by up to 5%.
© 2006 Fairchild Semiconductor Corporation
FAN5617 Rev. 1.0.2
www.fairchildsemi.com
4
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