AIC1741
LOW DROPOUT ADJUSTABLE REGULATOR
SPEC NO: DS-1741-00
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
1
FEATURES
1% Accuracy 1.235V Voltage Reference.
Fast Transient Response.
Low Ground Current at 55
A.
Wide Output Current Range, 10
A~80mA.
Output Programmable from 1.235V~11V.
Low Temperature Coefficiency.
Error Flag Warns of Output Dropout.
APPLICATIONS
Voltage Regulator for Pentium
CPUs.
Wireless Communication System.
5V to 3.3V Regulator for VGA Cards.
Battery Powered Systems.
DESCRIPTION
The AIC1741 is a low power precision adjustable
regulator with 80mA output capability. The device
can be used as a secondary regular to provide
feedback in a switching power supply.
The AIC1741 circuitry includes an internal wide
band amplifier, a precision bandgap reference,
and a PMOS output transistor. The feedback
input can be connected to an external resistor
divider to program the sensed output voltage.
The VOUT pin provides loop frequency
compensation when used as a part of a larger
servo system.
Although the device works as a stand-alone
regulator, it can also drive an NPN power
transistor to construct a high current low dropout
regulator, with only very minor current loss to
ground.
TYPICAL APPLICATION CIRCUIT
C2
33
F
+
C1
10
F
+
C3
R1
390
R2
1.2K
R3
2K
Q1
TIP31C
NC
NC
6
5
4
2
3
AIC1741
8
7
1
FB
FLAG
GND
NC
VIN
VOUT
V
IN
5V
V
OUT
3.3V/3 A
10
F
+
5V to 3.3V Regulator for VGA Cards.
ORDERING INFORMATION
AIC1741 XX
ORDER NUMBER
AIC1741CN
(PLASTIC DIP)
AIC1741CS
(PLASTIC SO)
PIN CONFIGURATION
TOP VIEW
FLAG
1
3
4
2
8
6
5
7
VIN
NC
GND
NC
FB
NC
VOUT
PACKAGE TYPE
N: PLASTIC DIP
S: SMALL OUTLINE
TEMPERATURE RANGE
C: 0
C~+70
C
Pentium
is a registered trademark of Intel Corporation
AIC1741
LOW DROPOUT ADJUSTABLE REGULATOR
SPEC NO: DS-1741-00
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
2
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage
..................................................................................... -
0.3~12V
Feedback Input Voltage
.................................................................................. -
0.3~12V
Shutdown Input Voltage
................................................................................. -
0.3~12V
Error Comparator Output
................................................................................ -
0.3~12V
Operating Junction Temperature Range ................................................... -40
C~125
C
Storage Temperature Range .................................................................... -65
C~150
C
TEST CIRCUIT
NC
C
OUT
10
F
1mA
AIC1741
VOUT
NC
GND
NC
FLAG
FB
VIN
V
IN
V
OUT
3.3V
+
C
IN
1
F
R1
2K
R2
1.2K
4
2
3
6
5
8
7
1
ELECTRICAL CHARACTERISTICS
(Ta=25
C, C
IN
=1
F, C
OUT
=
10
F, unless otherwise
specified. Test conditions are referred to TEST CIRCUIT.)
PARAMETER
TEST CONDITIONS
MIN.
TYP.
MAX.
UNIT
Output Voltage
V
IN
=3.6~12V, No Load, V
OUT
=3.3V
3.267
3.3
3.333
V
Output Voltage Temperature
Coefficiency
(Note 1)
50
150
PPM/
C
Line Regulation
V
IN
=3.6~12V, I
L
=1mA, V
OUT
=3.3V
3
10
mV
Load Regulation
(Note 2)
V
IN
=7V, I
L
=0.1~80mA, V
OUT
=3.3V
4
10
mV
Dropout Voltage
(Note 3)
I
L
=0.1mA
I
L
=80mA, V
OUT
=3.3V
0.2
200
10
300
mV
Ground Current
V
IN
=4~12V, I
O
=0.1mA~I
MAX
55
80
A
Flag Pin Off Leakage Current
V
IN
=7V
1
A
Flag Pin Pull Low Voltage
I
OL
=1mA, V
IN
=2.9V
100
300
mV
Flag Pin Upper Threshold
Voltage
40
60
mV
Flag Pin Lower Threshold
Voltage
68
88
mV
Note 1:
Guaranteed by design.
Note 2:
Regulation is measured at constant junction temperature, using pulse testing with a low ON time.
Note 3:
Dropout voltage is defined as the input to output differential at which the output voltage drops 100mV
below the value measured with a 1V differential.
AIC1741
LOW DROPOUT ADJUSTABLE REGULATOR
SPEC NO: DS-1741-00
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
3
TYPICAL PERFORMANCE CHARACTERISTICS
Reference Voltage vs. Temperature
R
e
f
e
r
enc
e V
o
lt
ag
e (
V
)
Temperature (
C)
0
25
50
75
100
125
-25
-50
V
REF
=1.244V
1.18
1.2
1.22
1.24
1.26
1.28
V
REF
=1.225V
V
REF
=1.225V
Ground Current vs. Input Voltage
G
r
o
u
nd C
u
r
r
en
t
(
A)
Input Voltage (V)
0
10
20
30
40
50
60
0
2
4
6
8
10
12
Ground Current vs. Temperature
G
r
o
u
nd C
u
r
r
en
t
(
A)
Temperature(
C)
0
25
50
75
100
125
-25
-50
50
52
54
56
58
60
I
L
=80mA
I
L
=0.1mA
Dropout Voltage vs. Load Current
D
r
o
p
ou
t
V
o
lt
ag
e
(
m
V
)
Load Current (mA)
0
20
40
60
80
100
0
50
100
150
200
V
OUT
=3.3V
Temperature(
C)
Dropout Voltage vs Temperature
D
r
o
p
ou
t
V
o
lt
ag
e(
mV
)
0
25
50
75
100
125
-25
-50
0
50
100
150
200
250
300
I
L
=80mA
V
OUT
=3.3V
I
L
=0.1mA
Bias Current vs. Temperature
Bi
a
s
C
u
rr
e
n
t
(n
A)
Temperature (
C)
0
25
50
75
100
125
-25
-50
10
20
30
40
AIC1741
LOW DROPOUT ADJUSTABLE REGULATOR
SPEC NO: DS-1741-00
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
4
TYPICAL PERFORMANCE CHARACTERISTICS
(CONTINUED)
Minimum Operating Voltage vs Temperature
Mi
ni
mu
m O
p
er
a
t
in
g V
o
lt
ag
e (
V
)
Temperature (
C)
0
25
50
75
100
125
-25
-50
2.2
2.3
2.4
2.5
2.6
2.7
2.8
BLOCK DIAGRAM
-
+
VIN
VOUT
GND
FLAG
FB
66mV
1.235V, Reference
8
1
6
3
7
-
+
PIN DESCRIPTIONS
PIN 1: VOUT - Output pin.
PIN 2: NC
-
PIN 3: GND
- Power GND.
PIN 4: NC
-
PIN 5: NC
-
PIN 6: FLAG - Open drain output of error flag
warns.
PIN 7: FB
- Error amplifier positive feedback
(see Block Diagram)
PIN 8: VIN
- Power supply input.
AIC1741
LOW DROPOUT ADJUSTABLE REGULATOR
SPEC NO: DS-1741-00
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
5
APPLICATION INFORMATIONS
The AIC1741 has two major applications, one as a
low dropout linear regulator and another an error
amplifier for a switching power supply to provide
precision feedback control.
Use as a Linear Regulator
When AIC1741 is connected as a low dropout linear
regulator, two external divider resistors are needed to
set the output voltage (see Test Circuit). The output
voltage can be calculated from the following formula:
V
OUT
=V
REF
(1+R1/R2)+I
FB
R1
where V
REF
is the nominal 1.235V reference voltage
and I
FB
is the feedback pin bias current, nominally
-20nA. For better accuracy, the recommended
maximum value of R2 is 100K
.
A 1
F (or greater) capacitor is required between the
AIC1741 output and ground for stability. Without this
capacitor the part will oscillate. Even though most
types of capacitor may work, if Aluminum electrolytic
type is used, the equivalent series resistance (ESR)
should be held to 5
. or less. Many Aluminum
electrolytics have electrolytes that freeze at about
-30
C, so solid tantalums are recommended for
operation below -25
C. The value of this capacitor
may be increased without limit.
The output capacitance required for stability varies
with output voltage (smaller for higher output voltage)
and output current (smaller for lower output currents).
At the worst-case situation of a 80mA load at 1.235V
output (output shorted to FB pin) a 3.3
F or greater
capacitor should be used.
A 0.1
F capacitor should be placed from the
AIC1741 input to ground if the lead inductance
between the input and power source exceeds 500nH
(approximately 10 inches of trace). Noise injection
into the feedback terminal of the AIC1741 from
nearby noise sources can also upset the output. This
may especially be a problem when using high value
external resistors to set the output voltage. Adding a
100pF capacitor between output and feedback and
increasing the output capacitor to at least 3.3
F will
cure this problem.
The AIC1741 can drive low cost NPN bipolar
transistor to deliver more output current. Typical
application circuit is an example of 5V to 3.3V linear
regulator for VGA cards power supply. A 390
resistor and 1
F capacitor are needed between
VOUT pin and ground for stability. The minimum
dropout voltage between input to output is V
BEQ1
+V
DS
of AIC1741 output PMOSFET, typical 1V @ 3A
output current.
Use as an Error Amplifier
Fig. 1 shows a popular application for the AIC1741 in
switching power supply. The output voltage is sensed
between FB pin and GND pin of the AIC1741 through
the divider resistor. The VIN pin servos to control the
duty cycle of the pulse width modulator to stabilize
the output voltage at the set voltage. The FB pin and
VIN pin are in same phase while the FB pin and
VOUT pin are in opposite phases. Connecting a
capacitor from VOUT pin to FB pin provides
frequency compensation for the control loop. The
AIC1741 provides output voltage remote sensing to
improve precision and regulation specifications of the
output of the switching power supply.
AIC1741
LOW DROPOUT ADJUSTABLE REGULATOR
SPEC NO: DS-1741-00
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
6
APPLICATION EXAMPLES
+
+
V
IN
5V
V
OUT
: 2.5V~3.5V/10A
12V
BYV
1
1
8
AIC1741
VOUT
GND
FB
VIN
1000
F/6.3Vx2
C6
M
T
D
20N
03D
H
Q1
2N
2907
A
Q2
BST
SE
AIC1562
SC
C1
47
F
+
P5
MICROPROCESSOR
CPU
1000
F/6.3V
x5
C11
0.1
F
x2
1000
F
+
FB
GND
R8
10K
C2
220pF
R2
VCC
TC
0.022
F
C4
R1
1K
C3
0.1
F
D3
D1
L1
7.5
F
R7
470
C5
0.1
F
R10
1K
R3
1K
R2*
D2
1N4148
1N4148
ZD1
5.1V
C10
0.1
F
x2
C4
C13
C11, C12: Ceramic Capacitor
L1: Iron Powder Core
V
OUT
= (1+R10/1K)x1.235V
24K
Fig. 1 CPU Power Supply for P5 Mother Board
PHYSICAL DIMENSIONS
8 LEAD PLASTIC DIP
8 LEAD PLASTIC SO
0.5
0.1
2.54
0.10
3.2
0.3
3.3
0.1
0.6
0.3
10
max
8.5
1.0
8.0
0.5
2.5
0.1
6.2
0.2
9.3
0.3
4.80
0.20
6.0
0.2
0.015X45
1.27
0.10
1.5
0.2
0.45
0.10
8
max.
0.2
0.
1
0.2
5
0.
10
3.8
0.2
UNIT: mm
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