AIC1648
Built-in OVP White LED Step-Up Converter
Analog Integrations Corporation
Si-Soft Research Center
DS-1648P-03 010405
3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C.
FEATURES
Built-In Open Circuit Protection
Over Voltage Protection
Efficiency Up to 84% at V
IN
=4.2V, 3LEDs,
I
LED
=20mA
1.2MHz Fixed Switching Frequency
Drives Up to 5LEDs in series
Low Supply Current: 70
A
Matches LED Current
Requires Tiny Inductor and Capacitors
Tiny SOT-23-6 Package
APPLICATIONS
Cellular Phones
PDAs
DSCs
Handheld Devices
White LED Display Backlighting
DESCRIPTION
AIC1648 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 LEDs
provides identical LED currents resulting in
uniform brightness. This configuration eliminates
the need of ballast resistors. The built-in open
load protection prevents the damage resulting
from an open circuit condition. Low 95mV
feedback voltage minimizes power loss in the
current setting resistor for better efficiency.
AIC1648 is a step-up PWM converter, which
includes an internal N-channel MOSFET switch
for high efficiency. The high switching frequency,
1.2MHz, allows the use of tiny external
components.
AIC1648 is available in a space-saving, 6-lead
SOT-23-6 package.
TYPICAL APPLICATION CIRCUIT
L
6.8
H
D1
SW
VIN
OVP
SHDN
FB
GND
AIC1648
3.3~4.2V
R
FB
4.7
C1
1
F
C2
1
F
20mA
L1: 976AS-6R8M/D321F, TOKO
D1: RB521S-30, ROHM
C1: JMK107BJ105KA, TAIYO YUDEN
C2: EMK212BJ105KA, TAIYO YUDEN
LED Current (mA)
Ef
fi
ci
e
n
cy (
%
)
0
5
10
15
20
60
65
70
75
80
85
90
V
IN
=3.6V
V
IN
=4.2V
V
IN
=3.0V
3 LEDs, 6.8
H
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
Fig. 1 Li-Ion Powered Driver for Three White LEDs
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
1
AIC1648
ORDERING INFORMATION
ORDER NUMBER
PIN CONFIGURATION
Example: AIC1648CGTR
in SOT-23-6 Package & Tape & Reel Packing Type
PACKING TYPE
TR: TAPE & REEL
BG: BAG
PACKAGE TYPE
G: SOT-23-6
C: COMMERCIAL
P: LEAD FREE COMMERCIAL
AIC1648XXXX
GND
SW
3
2
1
4
VIN
6
FB
SHDN
OVP
5
AIC1648CG&PG
(SOT-23-6)
FRONT VIEW
MARKING
Part No.
CG
PG
AIC1648 1648 1648P
ABSOLUTE MAXIMUM RATINGS
Input Voltage (VIN)
6V
SW Voltage
33V
FB Voltage
6V
SHDN Voltage
6V
OVP Voltage
34V
Operating Temperature Range
40
C to 85C
Maximum Junction Temperature
125
C
Storage Temperature Range
65
C to 150C
Lead Temperature (Soldering, 10 sec)
260
C
Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
TEST CIRCUIT
L1
10
H
D1
SW
VIN
OVP
SHDN
FB
GND
AIC1648
V
IN
RFB
4.7
C1
1
F
C2
0.22
F
I
LED
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
C1: JMK107BJ105KA, TAIYO YUDEN
C2: EMK212BJ224KG, TAIYO YUDEN
2
AIC1648
ELECTRICAL CHARACTERISTICS
(V
SHDN
=3V, V
IN
=3V, T
A
=25
C, unless otherwise specified.) (Note 1)
PARAMETER SYMBOL
TEST
CONDITIONS
MIN
TYP
MAX
UNIT
Minimum Operating Voltage
V
IN
2.5
V
Maximum Operating Voltage
V
IN
5.5 V
Switching
1
5
mA
Non switching
70
100
Supply Current
I
IN
V
SHDN
= 0V
0.1
1.0
A
ERROR AMPLIFIER
Feedback Voltage
V
FB
85
95
105
mV
FB Input Bias Current
I
FB
V
FB
=95mV
1 nA
OSCILLATOR
Switching Frequency
f
OSC
0.8 1.2 1.6 MHz
Maximum Duty Cycle
DC
85
90
%
POWER SWITCH
SW ON Resistance
R
DS(ON)
1.4
5
Switch Leakage Current
I
SW(OFF)
V
SW
=33V
0.1
1
A
CONTROL INPUT
SHDN
Voltage High
V
IH
ON
1.5
V
SHDN
Voltage Low
V
IL
OFF
0.3 V
OVER VOLTAGE PROTECTION
OVP Input Resistance
R
OVP
0.6 1.2 1.8
M
OVP Threshold
V
OVP
1V Hysteresis typical
22
27
32
V
Note 1: Specifications are production tested at T
A
=25
C. Specifications over the -40C to 85C operating
temperature range are assured by design, characterization and correlation with Statistical Quality
Controls (SQC).
3
AIC1648
TYPICAL PERFORMANCE CHARACTERISTICS
-50
0
50
100
150
92.0
92.5
93.0
93.5
94.0
94.5
95.0
Temperature (
C)
Fig. 2 Feedback Voltage vs. Temperature
F
e
edbac
k
V
o
lt
age (mV)
-50
0
50
100
150
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Sw
it
c
h
ing Fr
equenc
y (
M
Hz
)
Temperature (
C)
Fig. 3 Switching Frequency vs. Temperature
Supply Voltage (V)
Fig. 4 Supply Current vs. Supply Voltage
Supply C
u
rr
ent (
A)
2
3
4
5
6
30
40
50
60
70
FB=V
IN
Non-Switching
Supp
ly
Curre
n
t (m
A)
Supply Voltage (V)
Fig. 5 Supply Current vs. Supply Voltage
2
3
4
5
6
0.6
0.8
1.0
1.2
1.4
1.6
FB=GND
Switching
Supply Voltage (V)
Fig. 6 R
DS-ON
vs. Supply Voltage
R
DS
O
N
(
)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0.8
0.9
1.0
1.1
1.2
1.3
1.4
I
L
E
D_DUT
Y
/ I
LED
M
AX
(%
)
SHDN
PIN PWM Duty (%)
0
20
40
60
80
100
0
20
40
60
80
100
100Hz
& 200Hz
500Hz
1KHz
3KHz
2KHz
V
IN
=3.6V; L=10
H
C
IN
=1
F, C
OUT
=0.22
F
3LEDs
Fig. 7 Dimming Control by Shutdown PIN
4
AIC1648
TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
LED Current (mA)
Fig. 8 3 LEDs Efficiency vs. LED Current
Ef
f
i
cienc
y (
%
)
0
5
10
15
20
60
65
70
75
80
85
90
3 LEDs, 10H
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
V
IN
=3.6V
V
IN
=4.2V
V
IN
=3.0V
Ef
f
i
cienc
y (
%
)
LED Current (mA)
Fig. 9 4 LEDs Efficiency vs. LED Current
0
5
10
15
20
60
65
70
75
80
85
90
V
IN
=3.6V
V
IN
=4.2V
V
IN
=3.0V
4 LEDs, 10H
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
LED Current (mA)
Fig. 10 5 LEDs Efficiency vs. LED Current
Ef
f
i
cienc
y (
%
)
0 5
10
15
20
60
65
70
75
80
85
V
IN
=3.6V
V
IN
=4.2V
V
IN
=3.0V
5 LEDs, 10H
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
LED Current (mA)
Fig. 11 3 LEDs Efficiency vs. LED Current
Ef
f
i
cienc
y (
%
)
0
5
10
15
20
60
65
70
75
80
85
90
V
IN
=3.6V
V
IN
=4.2V
V
IN
=3.0V
3 LEDs, 6.8H
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
Test circuit refer to Fig.1
Fig. 12 Start-Up from Shutdown
V
IN
=3.6V; 3 LEDs; L1=10
F; C
OUT
=0.22
F; I
LED
=20mA
V
SHDN
, 2V/div
I
INDUCTOR
, 100mA/div
V
OUT
, 2V/div
Fig. 13 Operation Wave Form
V
IN
=3.6V; 3 LEDs; L1=10
F; C
OUT
=0.22
F; I
LED
=10mA
V
OUT
, 100mV/div
I
INDUCTOR
, 100mA/div
V
SW
, 10V/div
5
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