AIC1628
3-Cell, High-Efficiency, Step-Up DC/DC Converter
Analog Integrations Corporation
4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC
www.analog.com.tw
DS-1628-00
TEL: 886-3-5772500
FAX: 886-3-5772510
1
FEATURES
4V to 24V Input Voltage Operation.
Adjustable Output Voltage.
Low Quiescent Current at 100
A.
Pulse-Skipping and Pulse-Frequency Modulation
Maintain High Efficiency (max. 95%).
90KHz to 250KHz Oscillator Frequency.
Power-Saving Shutdown Mode (8
A Typical).
Push-Pull Driver Output.
APPLICATIONS
Flash Memory Programming Power Supply.
Positive LCD Contrast Bias for Notebook &
Palmtop Computers.
Step-Up DC/DC Converter Module.
Telecom Power Supply.
DESCRIPTION
The AIC1628 is a high performance step-up
DC/DC converter, designed to drive an external
power switch to generate programmable posi-
tive voltages. In the particularly suitable LCD
contrast bias and flash memory programming
power supply applications, typical full-load effi-
ciencies are 85% to 95%. 4V to 24V input op-
eration range allows the AIC1628 to be powered
directly by the battery pack in the most battery-
operated applications for greater efficiency.
Output voltage can be scaled to 40V or greater
by two external resistors. A Pulse-Frequency
Modulation scheme is employed to maintain
high efficiency conversion under wide input
voltage range. Quiescent current is about
100
A and can be reduced to 8A in shutdown
mode. Switching frequency being around 90KHz
to 250KHz range, small size switching compo-
nents are ideal for battery powered portable
equipments, like notebook and palmtop com-
puters.
TYPICAL APPLICATION CIRCUIT
AIC1628
CL
DHI
DLOW
FB
GND
SHDN
VIN
VREF
+36V
>50mA
V
OUT
1N5819
C5
+
C6
V
IN
+5V ~ 24V
C1
120
F
+
5V
*Buss Fuse MCR-2A
**Sumida CDR105
*Fuse
60m
68
H
0.047
F
C2
R1
470K
R2
16.5K 0.033F
C3
220
F
0.1
F
D1
2SK940
0.01
F
C4
**L1
Q1
Load Current (mA)
Ef
f
i
ci
e
n
c
y
(
%
)
V
IN
=13V
0
50
100
150
200
80
85
90
95
V
IN
=18V
V
IN
=9V
V
IN
=5V
V
OUT
=36V
Color LCD Contrast Bias Supply
Efficiency vs. Output Current
AIC1628
2
ORDERING INFORMATION
AIC1628 XX
PACKAGE TYPE
N: PLASTIC DIP
S: SMALL OUTLINE
TEMPERATURE RANGE
C=0
C~+70C
ORDER NUMBER
AIC1628CN
(PLASTIC DIP
)
PIN CONFIGURATION
AIC1628CS
(PLASTIC SO)
TOP VIEW
DLOW
1
3
4
2
8
6
5
7
CL
VREF
SHDN
FB
DHI
GND
VIN
ABSOLUTE MAXIMUM RATINGS
VIN Supply Voltage (V
IN
Pin)
........................................................................................
24V
SHDN Pin Voltage
........................................................................................................
15V
Operating Temperature Range
............................................................................
0
C~70C
Storage Temperature Range
........................................................................
-65
C~ 150C
TEST CIRCUIT
Refer to Typical Application Circuit
ELECTRICAL CHARACTERISTICS
(V
IN
= 13V, Ta=25
C, unless otherwise
specified.)
PARAMETERS
TEST CONDITIONS
MIN.
TYP.
MAX.
UNIT
Input Voltage
4
24
V
Quiescent Current
V
FB
= 1.5V
100
200
A
Shutdown Mode Current
V
SHDN
= 0V
8
20
A
V
REF
Voltage
I
SOURCE
= 250
A
1.16
1.22
1.28
V
V
REF
Source Current
250
A
DLOW "ON Resistance"
15
DHI "ON Resistance"
10
CL Threshold
V
IN
- V
CL
45
60
75
mV
Shutdown Threshold
0.8
1.5
2.4
V
Shutdown Input Leakage
Current
V
SHDN
< 15V
1
A
AIC1628
3
TYPICAL PERFORMANCE CHARACTERISTICS
Frequency vs V
IN
Voltage
V
IN
(V)
4
9
14
19
24
80
130
180
230
280
Ta= 0
C
Ta= 25
C
Ta= 70
C
Fr
equenc
y
(
K
Hz)
Duty Cycle vs V
IN
Voltage
100
V
IN
(V)
30
40
50
60
70
80
90
4
9
14
19
24
Ta= 70
C
Ta= 25
C
Duty
Cy
cle (
%
)
Ta= 0
C
Quiescent Current vs V
IN
Voltage
60
70
80
90
100
110
4
9
14
19
24
Ta= 0
C
Ta= 25
C
Ta= 70
C
V
IN
(V)
Q
u
i
e
s
c
ent
Cur
r
ent
(
A)
Current Limit Threshold vs Temperature
Temperature (
C)
C
L
T
h
r
e
s
hol
d
(
m
V)
0
20
40
60
80
50
55
60
65
70
75
V
IN
= 5V
V
IN
= 20V
V
IN
= 13V
Reference Voltage vs Temperature
0
20
40
60
80
1.1
1.15
1.2
1.25
1.3
Temperature (
C)
Re
f
e
rence V
o
l
t
ag
e
(V
)
V
IN
= 5V
AIC1628
4
BLOCK DIAGRAM
+
-
+
-
ERROR COMPARATOR
LATCH
CURRENT LIMIT
COMPARATOR
1.22V
REFERENCE
VOLTAGE
PFM
OSCILLATOR
VREF
VIN
SHDN
4
3
2
1
FB
OUTPUT DRIVER
V
IN
VIN
60mV
DHI
DLOW
CL
8
7
6
5
GND
PIN DESCRIPTIONS
PIN 1: VIN
- 4V to 24V input supply voltage.
PIN 2: VREF - 1.22V reference output. Bypass
with a 0.047
F capacitor to GND.
Sourcing capability is guaran-
teed to be greater than 250
A.
PIN 3:
SHDN
- Logical input to shutdown the
chip.
>1.5V = normal operation,
GND = Shutdown,
Can not be floating or forced
greater than 15V. In shutdown
mode DLOW and DHI pins are
at low level.
PIN 4: FB-
Feedback signal input to sense
VREF. Connecting a resistance
R1 to V
OUT
and a resistance R2
to GND yields the output voltage:
V
OUT
= (R1+R2)/R2 x VREF
(Refer to typical application cir-
cuit)
PIN 5: GND - Power ground.
PIN 6: DLOW -Driver sinking output. Connected to
gate of the external N-channel MOS-
FET or base of the NPN bipolar tran-
sistor.
PIN 7: DHI
- Driver sourcing output. Connected to
DLOW when using an external N-
channel MOSFET. When using an
external NPN bipolar transistor, con-
nect a base resistance RB from this
pin to DLOW. RB value depends on
V
IN
, inductor and NPN current gain.
PIN 8: CL
- Current-limit input. Threshold voltage
is 60mV from V
IN
. This pin clamps
the switch peak current to prevent
over-current damage to the external
switch, under abnormal conditions.
AIC1628
5
APPLICATION EXAMPLES
*
Buss Fuse MCR-2A
**
Sumida RCH108
AIC1628
CL
DHI
DLOW
FB
SHDN
VIN
VREF
2SK940
Q1
+12V
>150mA
V
OUT
D1 1N5819
300
F
C3
+
V
IN
+5V ~ 11V
C1
120
F
+
*Fuse
60m
**L1
47
H
GND
R1
100K
R2
11.3K
C2
0.
047
F
Load Current (mA)
E
f
fi
ci
ency (
%
)
0
50
100
150
200
250
300
350
85
90
95
100
V
IN
=11V
V
IN
=9V
V
IN
=7V
V
IN
=5V
Efficiency vs Load Current
Fig. 1 Flash memory programming supply
Battery
Powered
180
F
*L1
47
H
+2V~ 5V
+
C1
150
F
>50mA
+12V
D1 1N5819
V
OUT
*Sumida RCH108
+
C4
AIC1628
CL
DHI
DLOW
FB
GND
SHDN
VIN
VREF
+
C2
5V
0.047
F
C3
33
F
2SK940
Q1
R2
20K
R1
470K
Load Current (mA)
E
ffi
c
i
e
n
c
y
(
%
)
0
50
100
150
75
80
85
90
V
IN
=2V
Efficiency vs Load Current
V
IN
=3V
V
IN
=4V
Fig. 2 2-cells to +12V Flash memory programmer
C4
C6
0.033
F
C5
0.1
F
RB
910
R2
17.5K
500K
C3
220
F
+
V
IN
+
C2
0.047
F
0.1
F
*L1
150
H
+4V~ 6V
C1
150
F
+30V
D1 1N5819
V
OUT
*Sumida CD54
AIC1628
CL
DHI
DLOW
FB
GND
SHDN
VIN
VREF
2SC4672
Q1
R1
75
80
95
90
0
10
20
30
40
50
Load Current (mA)
E
ffi
c
i
e
n
c
y
(
%
)
V
IN
=4V
Efficiency vs Load Current
V
IN
=5V
V
IN
=6V
Fig. 3 4-cells to +30V power supply
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