AIC1642
3-Pin One-Cell Step-Up DC/DC Converter
Analog Integrations Corporation 4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan DS-1642-01 012102
TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1
■ FEATURES
l A Guaranteed Start-Up from less than 0.9 V.
l High Efficiency.
l Low Quiescent Current.
l Less Number of External Components needed.
l Low Ripple and Low Noise.
l Fixed Output Voltage: 2.7V, 3.0V, 3.3V, and 5V.
l Space Saving Packages: SOT-89 and TO-92
■ APPLICATIONS
l Pagers.
l Cameras.
l Wireless Microphones.
l Pocket Organizers.
l Battery Backup Suppliers.
l Portable Instruments.
■ DESCRIPTION
The AIC1642 is a high efficiency step-up
DC/DC converter for applications using 1 to 4
battery cells. Only three external components
are required to deliver a fixed output voltage of
2.7V, 3.0V, 3.3V, or 5V. The AIC1642 starts up
from less than 0.9V input with 1mA load. Pulse
Frequency Modulation scheme brings optimized
performance for applications with light output
loading and low input voltages. The output rip-
ple and noise are lower compared with the cir-
cuits operating in PSM mode.
The PFM control circuit operating in 100KHz
(max.) switching rate results in smaller passive
components. The space saving SOT-89 and
TO-92 packages make the AIC1642 is an ideal
choice of DC/DC converter for space conscious
applications, like pagers, electronic cameras,
and wireless microphones.
■ TYPICAL APPLICATION CIRCUIT
D1
GS SS12
VOUT
SW
GND
AIC1642-27
AIC1642-30
AIC1642-33
AIC1642-50
C2
22µF+
V
OUT
L1
100µH
V
IN
+C1
47µF
One Cell Step-Up DC/DC Converter
AIC1642
2
■ ORDERING INFORMATION
TO-92
TOP VIEW
1: GND
2: VOUT
3: SW
1
2
3
1 2 3
SOT-89
TOP VIEW
1: GND
2: VOUT
3: SW
PACKING TYPE
TR: TAPE & REEL
TB: TUBE
BG: BAG
PACKAGE TYPE
X: SOT-89
Z: TO-92
OUTPUT VOLTAGE
27: 2.7V
30: 3.0V
33: 3.3V
50: 5.0V
AIC16
42-XXCXXX
Example: AIC1642-27COTR
à 2.7V Version, in MSOP8 Package
& Tape & Reel Packing Type
PIN CONFIGURATION
■ ABSOLUATE MAXIMUM RATINGS
Supply Voltage ……………………………………………………………………………….12V
SW pin Voltage ……………………………………………………………………………….12V
SW pin Switch Current ………………………………………………………………………0.6A
Operating Temperature Range ………………………………..…………….….--40°C to 85°C
Storage Temperature Range ………………………………………………… -65°C to 150 °C
Lead Temperature (Soldering 10 Sec.) …………………………………………………260°C
■ TEST CIRCUIT
FOUT
AIC1642
2.5V VOUT SW
GND
100
Oscillator Test Circuit
AIC1642
3
n
ELECTRICAL CHARACTERISTICS (TA=25°C, IOUT=10mA, Unless otherwise
specified)
PARAMETER TEST CONDITIONS SYMBOL
MIN.
TYP. MAX.
UNIT
Output Voltage
VIN=1.8V, AIC1642-27
VIN=1.8V, AIC1642-30
VIN=2.0V, AIC1642-33
VIN=3.0V, AIC1642-50
VOUT
2.633
2.925
3.218
4.875
2.700
3.000
3.300
5.000
2.767
3.075
3.382
5.125
V
Input Voltage VIN 8 V
Start-Up Voltage IOUT=1mA, VIN:0→2V VSTART
0.8 0.9 V
Hold-on Voltage IOUT=1mA, VIN:2→0V VHOLD
0.7 V
No-Load Input Current IOUT=0mA IIN 15 µA
Supply Current
AIC1642-27
AIC1642-30
AIC1642-33
AIC1642-50
VIN=VOUT x 0.95
Measurement of the IC input
current (VOUT pin)
IDD1
42
50
60
90
µA
Supply Current VIN=VOUT + 0.5V
Measurement of the IC input
current (VOUT pin) IDD2 8 µA
SW Leakage Current VSW=10V, VIN=VOUT + 0.5V 0.5 µA
SW Switch-On Resis-
tance
AIC1642-27
AIC1642-30
AIC1642-33
AIC1642-50
VIN=VSW x 0.95, VSW=0.4V
RON
2.2
2.1
2.0
1.9
Ω
Oscillator Duty Cycle VIN=VOUT x 0.95
Measurement of the SW Pin
Waveform DUTY 65 75 85 %
Max. Oscillator Freq. VIN=VOUT x 0.95
Measurement of the SW Pin
Waveform FOSC 80 105 130 KHz
Efficiency η 80 %
AIC1642
4
n
TYPICAL PERFORMANCE CHARACTERISTICS
Capacitor (C1) : 47 µ F (Tantalum Type)
Diode (D1) : 1N5819 Schottky Type
Fig. 1 AIC1642-27 Load Regulation (L=100µH CD54)
020 40 60 80 100 120 140 160 180
2.2
2.3
2.4
2.5
2.6
2.7
2.8
VIN=2.0V
VIN=1.8V
VIN=1.5V
VIN=1.2V
VIN=0.9V
Output voltage (V)
Output Current (mA) Fig. 2 AIC1642-27 Efficiency (L=100µH CD54)
020 40 60 80 100 120 140 160 180
55
60
65
70
75
80
85
VIN=2.0V
VIN=1.8V
VIN=1.5V
VIN=1.2V
VIN=0.9V
Efficiency (%)
Output current (mA)
Fig. 3 AIC1642-27 Start-up & Hold-on Voltage (L=100µH)
0
2
4
6
8
10
12
14
16
18
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Start up
Hold on
Input Voltage (V)
Output Current (mA) -40 -20 0 20 40 60 80 100
2.62
2.64
2.66
2.68
2.70
2.72
2.74
2.76
2.78
Fig. 4 AIC1642-27 Output Voltage vs. Temperature
No Load
Output Voltage VOUT (V)
Temperature (°C)
-
40
-20
0
20
40
60
80
100
20
40
60
80
100
120
140
160
Fig. 5 AIC1642-27 Switching Frequency vs. Temperature
Switching Frequency (kHz)
Temperature (°C)
-40
-20
0
20
40
60
80
100
66
68
70
72
74
76
78
80
82
Fig. 6 AIC1642-27 Maximum Duty Cycle vs. Temperature
Maximum Duty Cycle (%)
Temperature (°C)
AIC1642
5
n
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
-40
-20
0
20
40
60
80
100
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
Fig. 7 AIC1642-27 SW On Resistance vs. Temperature
SW Turn On Resistance (Ω)
Temperature (°C)
-40
-20
0
20
40
60
80
100
20
24
28
32
36
40
44
48
52
Fig. 8 AIC1642-27 Supply Current IDD1 vs. Temperature
Supply Current IDD1 (
µ
A)
Temperature (°C)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
3.1
VIN=2.0V
VIN=.8V
VIN=1.5V
V
IN
=1.2V
VIN=0.9
Fig. 9 AIC1642-30 Load Regulation (L=100µH CD54)
Output voltage VOUT(V)
Output Current (mA) 0 20 40 60 80 100 120 140 160 180
50
55
60
65
70
75
80
85
V
IN
=2.0V
V
IN
=1.8V
V
IN
=1.5V
V
IN
=1.2V
V
IN
=0.9V
Fig. 10 AIC1642-30 Efficiency (L=100µH CD54)
Efficiency (%)
Output Current (mA)
0
2
4
6
8
10
12
14
16
18
20
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Fig. 11 AIC1642-30 Start-up & Hold-on Voltage (L=100µH)
Start up
Hold on
Input Voltage (V)
Output Current (mA)
-40
-20
0
20
40
60
80
100
2.90
2.92
2.94
2.96
2.98
3.00
3.02
3.04
3.06
Fig. 12 AIC1642-30 Output Voltage vs. Temperature
No Load
Output Voltage
Vout (V)
Temperature (°C)
AIC1642
6
n
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
-40 -20 0 20 40 60 80 100
0
20
40
60
80
100
120
140
160
Fig. 13 AIC1642-30 Switching Frequency vs. Temperature
Switching Frequency (kHz)
Temperature (
°
C)
-40
-20
0
20
40
60
80
100
66
68
70
72
74
76
78
80
82
Fig. 14 AIC1642-30 Maximum Duty Cycle vs. Temperature
Maximum Duty Cycle (%)
Temperature (°C)
-40
-20
0
20
40
60
80
100
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
Fig. 15 AIC1642-30 SW On Resistance vs. Temperature
SW Turn On Resistance (Ω)
Temperature (°C)
-40
-20
0
20
40
60
80
100
20
24
28
32
36
40
44
48
52
Fig. 16 AIC1642-30 Supply Current vs. Temperature
Supply Current IDD1 (
µ
A)
Temperature (°C)
0
25
50
75
100
125
150
175
200
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
Fig. 17 AIC1642-33 Load Regulation (L=100µH CD54)
Output Voltage (V)
Output Current (mA)
VIN=2.0V
VIN=1.8
VIN=1.5V
VIN=1.2
VIN=0.9
0
25
50
75
100
125
150
175
200
50
55
60
65
70
75
80
85
90
Fig. 18 AIC1642-33 Efficiency (L=100µH CD54)
Efficiency (%)
Output Current (mA)
VIN=2.0V
VIN=1.8V
VIN=1.5V
VIN=1.2V
VIN=0.9V
AIC1642
7
n
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
0
2
4
6
8
10
12
14
16
18
20
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Fig. 19 AIC1642-33 Start-up & Hold-on Voltage (L=100µH)
Start up
Hold on
Input Voltage (V)
Output Current (mA)
-
40
-
20
0
20
40
60
80
100
3.00
3.05
3.10
3.15
3.20
3.25
3.30
3.35
3.40
3.45
3.50
No Load
Fig. 20 AIC1642-33 Output Voltage vs. Temperature
Output Voltage VOUT (V)
Temperature (°C)
-40
-20
0
20
40
60
80
100
50
60
70
80
90
100
110
120
130
140
150
Fig. 21 AIC1642-33 Switching Frequency vs. Temperature
Switching Frequency (KHz)
Temperature (°C)
-40
-20
0
20
40
60
80
100
66
68
70
72
74
76
78
80
82
Fig. 22 AIC1642-33 Maximum Duty Cycle vs. Temperature
Maximum Duty Cycle (%)
Temperature (°C)
-40
-20
0
20
40
60
80
100
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
Fig. 23 AIC1642-33 SW On Resistance vs. Temperature
SW Turn On Resistance (Ω)
Temperature (°C)
-40
-20
0
20
40
60
80
100
24
28
32
36
40
44
48
52
56
60
Fig. 24 AIC1642-33 Supply Current vs. Temperature
Supply Current IDD1 (
µ
A)
Temperature (°C)
AIC1642
8
n
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
0
50
100
150
200
250
300
350
400
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Fig. 25 AIC1642-50 Load Regulation ( L=100µH CD54)
Output Voltage (V)
Output Current (mA)
VIN=3.0V
VIN=2.0V
VIN=1.5V
VIN=1.2V
VIN=0.9
0
50
100
150
200
250
300
350
400
45
50
55
60
65
70
75
80
85
90
Fig. 26 AIC1642-50 Efficiency (L=100µH, CD54)
Efficiency (%)
Output Current (mA)
VIN=3.0V
VIN=2.0V
VIN=1.5V
VIN=1.2
VIN=0.9V
0
2
4
6
8
10
12
14
16
18
20
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Fig. 27 AIC1642-50 Start-up & Hold-on Voltage (L=100µH)
Start up
Hold on
Input Voltage (V)
Output Current (mA)
-40
-20
0
20
40
60
80
100
4.4
4.5
4.6
4.7
4.8
4.9
5.0
5.1
5.2
5.3
No Load
Fig. 28 AIC1642-50 Output Voltage vs. Temperature
Output Voltage
Vout (V)
Temperature (°C)
-40
-20
0
20
40
60
80
100
60
70
80
90
100
110
120
130
140
150
Fig. 29 AIC1642-50 Switching Frequency vs. Temperature
Switching Frequency (KHz)
Temperature (°C)
-40
-20
0
20
40
60
80
100
64
66
68
70
72
74
76
78
80
82
Fig. 30 AIC1642-50 Maximum Duty Cycle vs. Temperature
Maximum Duty Cycle (%)
Temperature (°C)
AIC1642
9
n
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
-40
-20
0
20
40
60
80
100
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
Fig. 31 AIC1642-50 SW On Resistance vs.
Temperature
SW Turn On Resistance (Ω)
Temperature (°C)
-40
-20
0
20
40
60
80
100
10
20
30
40
50
60
70
80
90
100
Fig. 34 AIC1642-50 Supply Current vs. Temperature
Supply Current IDD1 (
µ
A)
Temperature (°C)
■ BLOCK DIAGRAM
+
GND
VOUT SW
1.25V REF.
1M
Enable
-
OSC, 100KHz
■ PIN DESCRIPTIONS
PIN1 : GND - Ground. Must be low imped-
ance; sorer directly to ground
plane.
PIN2 : VOUT - IC supply pin. Connect VOUT
to the regulator output.
PIN3 : SW – Internal drain of N-MOSFET
switch.
AIC1642
10
■ APPLICATION INFORMATION
GENERAL DESCRIPTION
AIC1642 PFM (pulse frequency modulation) control-
ler ICs combine a switch mode regulator, N-channel
power MOSFET, precision voltage reference, and
voltage detector in a single monolithic device. They
offer extreme low quiescient current, high efficiency,
and very low gate threshold voltage to ensure start-
up with low battery voltage (0.8V typ.). Designed to
maximize battery life in portable products, and
minimize switching losses by only switching as
needed service the load.
PFM controllers transfer a discrete amount of en-
ergy per cycle and regulate the output voltage by
modulating switching frequency with the constant
turn-on time. Switching frequency depends on load,
input voltage, and inductor value, and it can range
up to 100KHz. The SW on-resistance is typically 1.9
to 2.2Ω to minimize switch losses.
When the output voltage drops, the error compara-
tor enables 100kHz oscillator that turns on the
MOSFET around 7.5us and 2.5us off time. Turning
on the MOSFET allows inductor current to ramp up,
storing energy in a magnetic field. When MOSFET
turns off that force inductor current through diode to
the output capacitor and load. As the stored energy
is depleted, the current ramp down until the diode
turns off. At this point, inductor may ring due to re-
sidual energy and stray capacitance. The output ca-
pacitor stores charge when current flowing through
the diode is high, and release it when current is low,
thereby maintaining a steady voltage across the
load.
As the load increases, the output capacitor dis-
charges faster and the error comparator initiates cy-
cles sooner, increasing the switching frequency.
The maximum duty cycle ensure adequate time for
energy transfer to output during the second half
each cycle. Depending on circuit, PFM controller
can operate in either discontinuous mode or con-
tinuous conduction mode. Continuous conduction
mode means that the inductor current does not
ramp to zero during each cycle.
+
VIN
SW
VOUT
EXT
IDIOUT
Isw Ico
IIN
IPK
IIN
VEXT
ISW
IOUT
TDIS
Charge Co.
VSW Discharge Co.
ID
t
Discontinuous Conduction Mode
AIC1642
11
IPK
IIN
VEXT
ISW
IOUT
VSW
ID
t
Continuous Conduction Mode
Continuous Conduction Mode
At the boundary between continuous and dis-
continuous mode, output current (IOB) is deter-
mined by
)x1(*T*
L
V
*
2
1
*
V
V
ION
IN
OUT
IN
OB −
=
where Vd is the diode drop,
L
T
*)RR(xON
SON +=
RON= Switch turn on resistance, RS= Inductor
DC resistance
TON = Switch ON time
In the discontinuous mode, the switching fre-
quency (Fsw) is
Fsw = )x(1
TV)(I*)VV(V*(L)*22
ON
2
IN
OUTINDOUT +
×−+
In the continuous mode, the switching fre-
quency is
(
)
−+ −+
≅
−+−
+
−+ −+
=
SWDOUT
INDOUT
ON
SWDOUT
SWIN
SWDOUT
INDOUT
ON
SW
VVV VVV
T1
)]
VVV VV
(
2
x
[1*
)VV(V VVV
T1
f
where Vsw = switch drop and proportion to out-
put current.
Inductor Selection
To operate as an efficient energy transfer ele-
ment, the inductor must fulfill three require-
ments. First, the inductance must be low
enough for the inductor to store adequate en-
ergy under the worst case condition of minimum
input voltage and switch ON time. Second, the
inductance must also be high enough so maxi-
mum current rating of AIC1642 and inductor are
not exceed at the other worst case condition of
maximum input voltage and ON time. Lastly, the
inductor must have sufficiently low DC resis-
tance so excessive power is not lost as heat in
the windings. But unfortunately this is inversely
related to physical size.
Minimum and maximum input voltage, output
voltage and output current must be established
in advance and then inductor can be selected.
In discontinuous mode operation, at the end of
the switch ON time, peak current and energy in
the inductor build according to
+
−−
+
=)T*
LRsRON
exp(1*
RsRV
ION
ON
IN
PK
( )
−
≅2
x
1*T*
L
VON
IN
ON
IN T
L
V
≅ (simple loss equation),
where L
T
*)RR(xON
SON +=
AIC1642
12
EL =2
IpkL
2
1×
Power required from the inductor per cycle must
be equal or greater than
)
fsw
1
(*)(I*)VV(V/fPOUTINDOUTSWL−+=
In order for the converter to regulate the output.
When loading is over IOB, PFM controller oper-
ates in continuous mode. Inductor peak current
can be derived from
−
−
+
−
−−+
=2
x
1 * T *
2L
VV
I *
2
x
VV VVV
ION
SWIN
OUT
SWIN
SWDOUT
PK
Valley current (Iv) is
−
−
−
−
−−+
=2
x
1*T*
2L
VSWV
I*
2
x
VSWVVVV
ION
IN
OUT
IN
SWDOUT
V
Table 1 Indicates resistance and height for each coil.
Power Inductor Type Inductance
( µH ) Resistance ( Ω )
Rated Current
(A)
Height
(mm)
22 0.10 0.7
47 0.18 0.5
DS1608
100 0.38 0.3 2.9
22 0.08 2.7
Coilcraft SMT Type
(www.coilcraft.com) DO3316 47 0.14 1.8 5.2
47 0.25 0.7
Sumida SMT Type CD54 100 0.50 0.5 4.5
47 0.25 0.7
Hold SMT Type PM54 100 0.50 0.5 4.5
Hold SMT Type PM75 33 0.11 1.2 5.0
Capacitor Selection
A poor choice for an output capacitor can result in
poor efficiency and high output ripple. Ordinary
aluminum electrolytic, while inexpensive may
have unacceptably poor ESR and ESL. There are
low ESR aluminum capacitors for switch mode
DC-DC converters which work much well than
general unit. Tantalum capacitors provide still bet-
ter performance at more expensive. OS-CON ca-
pacitors have extremely low ESR in a small size.
If capacitance is reduced, output ripple will in-
crease.
Most of the input supply is supplied by the input
bypass capacitor, the capacitor voltage rating
should be at least 1.25 times greater than a
maximum input voltage.
Diode Selection
Speed, forward drop, and leakage current are the
three main considerations in selecting a rectifier
diode. Best performance is obtained with Schot-
tky rectifier diode such 1N5819. Motorola makes
MBR0530 in surface mount. For lower output
power a 1N4148 can be used although efficiency
and start-up voltage will suffer substantially.
AIC1642
13
Component Power Dissipation
Operating in discontinuous mode, power loss in
the winding resistance of inductor can be ap-
proximate equal to
( ) ( )
OUT
OUT
FOUT
D
ON
LP*
VVV
*R*
L
T
3
2
PD
+
=
where POUT=VOUT * IOUT; RS=Inductor DC R;
VD = Diode drop.
The power dissipated in a switch loss is
( ) ( )
OUT
OUT
INDOUT
ON
ON
SW P*
VVVV
*R*
L
T
3
2
PD
−+
=
The power dissipated in rectifier diode is
( )
OUT
OUT
DP*
VV
PDd
=
■ PHYSICAL DIMENSIONS
l SOT-89 (unit: mm)
SYMBOL MIN MAX
A 1.40 1.60
B 0.36 0.48
C 0.35 0.44
D 4.40 4.60
D1 1.62 1.83
E 2.29 2.60
e 1.50 (TYP.)
e1 3.00 (TYP.)
H 3.94 4.25
B
e
H
e1
D
D1
A
C
L
E
L 0.89 1.20
l SOT-89 MARKING
Part No. Marking
AIC1642-27 AM27
AIC1642-30 AM30
AIC1642-33 AM33
AIC1642-50 AM50
AIC1642
14
l TO-92 (unit: mm)
SYMBOL MIN MAX
A 4.32 5.33
C 0.38 (TYP.)
D 4.40 5.20
E 3.17 4.20
AL
e1
D
C
E
e1 1.27 (TYP.)
