AIC1647
White LED Step-Up Converter in SOT23
FEATURES
1.2MHz Fixed Frequency Current-Mode PWM
Operation.
Efficiency Up to 84% at V
IN
=4.2V, 3LEDs,
I
LED
=20mA
Drives Up to 6LEDs in series
Low Supply Current: 70µA
Matches LED Current
Require Tiny Inductors and Capacitors
Tiny SOT23-5 Package
DESCRIPTION
AIC1647 is a fixed frequency step-up DC/DC
converter designed to drive white LEDs with a
constant current to provide backlight in hand-
held devices. Series connection of the LEDs
provides identical LED currents resulting in
uniform brightness. This configuration eliminates
the need for ballast resistors. Low 95mV
feedback voltage minimizes power loss in the
current setting resistor for better efficiency.
AIC1647 is a step-up PWM converter, which
APPLICATIONS
Cellular Phones
PDAs
Digital Still Cameras
Handheld Devices
White LED Display Backlighting
includes an internal N-channel MOSFET switch
for high efficiency. The high switching frequency,
1.2MHz,
allows
the
use
of
tiny
external
components, saves the layout space and cost.
AIC1647 is available in a space-saving, 5-lead
SOT-23-5 package.
TYPICAL APPLICATION CIRCUIT
3.3~4.2V
C1
1µF
L
6.8µH
VIN
SHDN
GND
FB
SW
D1
C2
1µF
BZV55-B12
11.8V~12.2V
90
V
IN
=4.2V
85
Efficiency (%)
80
75
70
D2
R1
1K
R
FB
4.7Ω
20mA
V
IN
=3.0V
V
IN
=3.6V
AIC1647
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
C1: JMK107BJ105KA, TAIYO YUDEN
C2: EMK212BJ105KA, TAIYO YUDEN
3 LEDs, 6.8µH
65
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
60
0
5
LED Current (mA)
10
15
20
Fig. 1 Li-Ion Powered Driver with Over Voltage Protection for Three White LEDs
Analog Integrations Corporation
Si-Soft Research Center
3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C.
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
DS-1647P-03 010405
1
AIC1647
ORDERING INFORMATION
AIC1647XXXX
PACKING TYPE
TR: TAPE & REEL
BG: BAG
PACKAGE TYPE
V: SOT-23-5
C: Commercial
P: Lead Free Commercial
Example:
AIC1647CVTR
in SOT-23-5 Package & Tape &
Reel Packing Type
1
2
3
ORDER NUMBER
AIC1647CV&PV
(SOT-23-5)
PIN CONFIGURATION
FRONT VIEW
VIN
5
SHDN
4
SW GND FB
MARKING
Part No.
AIC1647
CV
1647
PV
1647P
ABSOLUTE MAXIMUM RATINGS
Input Voltage (VIN)
SW Voltage
FB Voltage
SHDN
Voltage
6V
33V
6V
6V
–40°C to 85°C
125°C
–65°C to 150°C
260°C
Operating Temperature Range
Maximum Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering, 10 sec)
Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
TEST CIRCUIT
L1
V
IN
C1
1µF
10µH
VIN
SHDN
GND
FB
AIC1647
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
C1: JMK107BJ105KA, TAIYO YUDEN
C2: EMK212BJ224KG, TAIYO YUDEN
D1
C2
SW
D2
BZV55-B12
11.8V~12.2V
0.22µF
ILED
R1
1K
RFB
4.7Ω
2
AIC1647
ELECTRICAL CHARACTERISTICS
(V
SHDN
=3V, V
IN
=3V, T
A
=25°C, unless otherwise specified.) (Note 1)
PARAMETER
Minimum Operating Voltage
Maximum Operating Voltage
SYMBOL
V
IN
V
IN
Switching
Supply Current
I
IN
Non switching
V
SHDN
= 0V
ERROR AMPLIFIER
Feedback Voltage
FB Input Bias Current
OSCILLATOR
Switching Frequency
Maximum Duty Cycle
POWER SWITCH
SW ON Resistance
Switch Leakage Current
CONTROL INPUT
SHDN
Voltage High
SHDN
Voltage Low
TEST CONDITIONS
MIN
2.5
TYP
MAX
UNIT
V
5.5
1
70
0.1
5
100
1.0
V
mA
µA
V
FB
I
FB
V
FB
=95mV
85
95
1
105
mV
nA
f
OSC
DC
0.8
85
1.2
90
1.6
MHz
%
R
DS(ON)
I
SW(OFF)
V
SW
=33V
1.4
0.1
5
1
Ω
µA
V
IH
V
IL
ON
OFF
1.5
0.3
V
V
Note 1: Specifications are production tested at T
A
=25°C. Specifications over the -40°C to 85°C operating
temperature range are assured by design, characterization and correlation with Statistical Quality
Controls (SQC).
3
AIC1647
TYPICAL PERFORMANCE CHARACTERISTICS
1.6
Switching Frequency (MHz)
0
50
100
150
95.0
Feedback Voltage (mV)
94.5
94.0
93.5
93.0
92.5
92.0
-50
1.4
1.2
1.0
0.8
0.6
Temperature (°C)
Fig. 2 Feedback Voltage vs. Temperature
0.4
-50
Fig. 3
Temperature (°C)
Switching Frequency vs. Temperature
0
50
100
150
70
1.6
FB=GND
60
FB=V
IN
50
Supply Current (mA)
Non-Switching
Supply Current (µA)
1.4
1.2
1.0
40
0.8
0.6
6
Switching
2
3
4
5
6
30
2
Supply Voltage (V)
Fig. 4 Supply Current vs. Supply Voltage
3
4
5
Fig. 5
Supply Voltage (V)
Supply Current vs. Supply Voltage
1.4
100
1.3
I
LED_DUTY
/ I
LEDMAX
(%)
80
V
IN
=3.6V; L=10µH
C
IN
=1µF, C
OUT
=0.22µF
3LEDs
R
DSON
(
Ω
)
1.2
60
1.1
100Hz
& 200Hz
40
1.0
500Hz
20
0.9
1KHz
2KHz
0
20
40
3KHz
60
80
100
0.8
2.5
3.0
Supply Voltage (V)
Fig. 6 R
DS-ON
vs. Supply Voltage
3.5
4.0
4.5
5.0
5.5
6.0
0
SHDN
PIN PWM Duty (%)
Fig. 7
Dimming Control by Shutdown PIN
4
AIC1647
TYPICAL PERFORMANCE CHARACTERISTICS
90
90
(Continued)
85
V
IN
=4.2V
V
IN
=3.0V
V
IN
=4.2V
85
Efficiency (%)
Efficiency (%)
80
80
V
IN
=3.6V
75
75
V
IN
=3.6V
V
IN
=3.0V
4 LEDs, 10µH
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
0
5
10
15
20
70
65
3 LEDs, 10µH
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
70
65
60
0
60
LED Current (mA)
Fig. 8 3 LEDs Efficiency vs. LED Current
5
10
15
20
Fig. 9
LED Current (mA)
4 LEDs Efficiency vs. LED Current
85
80
V
IN
=4.2V
80
75
V
IN
=4.2V
Efficiency (%)
Efficiency (%)
75
V
IN
=3.6V
V
IN
=3.0V
V
IN
=3.6V
70
70
5 LEDs, 10µH
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
0
5
10
15
20
V
IN
=3.0V
6 LEDs, 10µH
65
65
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
60
60
LED Current (mA)
Fig. 10 5 LEDs Efficiency vs. LED Current
0
Fig. 11
LED Current (mA)
6 LEDs Efficiency vs. LED Current
5
10
15
90
80
V
IN
=4.2V
85
75
6 LEDs, 6.8µH
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
V
IN
=4.2V
Efficiency (%)
80
75
70
65
60
Efficiency (%)
V
IN
=3.0V
V
IN
=3.6V
70
V
IN
=3.6V
3 LEDs, 6.8µH
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
0
65
V
IN
=3.0V
LED Current (mA)
Fig. 12 3 LEDs Efficiency vs. LED Current
5
10
15
20
60
0
Fig. 13
LED Current (mA)
6 LEDs Efficiency vs. LED Current
5
10
15
5
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