Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
.
Page 1 of 16 V 1.0
AAT1203
Details are subject to change without notice
250-mA MULTI-INPUT LOW-DROPOUT REGULATOR
WITH V
AUX
SWITCH
Features
Complete Power Management
Automatic Input Voltage Selection
Input Voltage Source Detector With
Hysteresis
250-mA Load Current Capability With
VCC50 or VSB50 or AUX33 Input Source
Integrated Low
( )
on
DS
r
Switch
Regulated Output 3.3V (fixed)
Output Short Circuit Protection
Pin Configuration
Description
The AAT1203 is a multi-input low-dropout
regulator designed for LAN cards. It provides
constant output supply 3.3V at an output capable
of driving a 250-mA load.
The AAT1203 is equipped with regulated power
output for systems that have multiple input
sources and require constant voltage source with a
low-dropout voltage. This is an intelligent power
source selection device with a low-dropout
regulator for either VCC50 or VSB50 inputs, and
a low-resistance bypass switch for the AUX33
input.
The AAT1203 allows transitions to progress
smoothly from one input supply to another
without generating a glitch outside of the specified
range of the 3.3-V output. The device has an
incorporated reverse-blocking scheme to prevent
excess leakage from the input terminals in the
event that the output voltage is greater than the
input voltage.
The input voltage is prioritized in the following
order: VCC50, VSB50, AUX33.
VSB50
VCC50
OUT33
AUX33
GND
GND
GND
GND
1
2
3
4
8
7
6
5
( 8-PIN SOP )
TOP VIEW
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
.
Page 2 of 16 V 1.
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AAT1203
Function Table
INPUT VOLTAGE STATUS
(V)
INPUT SELECTED
OUTPUT
V
OUTPUT
ImA
VCC50 VSB50 AUX33 VCC50/VSB50/AUX33 OUT33
Iout33
0 0 0
None
0
0
0 0 3.3
AUX33
3.3 250
0 5 0
VSB50
3.3 250
0 5 3.3
VSB50
3.3 250
5 0 0
VCC50
3.3 250
5 0 3.3
VCC50
3.3 250
5 5 0
VCC50
3.3 250
5 5 3.3
VCC50
3.3 250
Pin Description
TERMINAL
NAME
TERMINAL NO.
I/O
DESCRIPTION
VSB50
1 I
5V Standby Supply Input
VCC50
2 I
5V Main Supply Input
OUT33
3 O
3.3V Regulated Output
AUX33
4 I
3.3V Auxiliary Supply Input
GND
5 I
Ground
GND
6 I
Ground
GND
7 I
Ground
GND
8 I
Ground
Absolute Maximum Ratings
Main Supply Voltage,
(
)
50
VCC
V
...........................................................
5
.
0
-
V~7V
Standby Supply Voltage,
(
)
50
VSB
V
.........................................................
5
.
0
-
V~7V
Auxiliary Supply Voltage,
(
)
33
AUX
V
.......................................................
5
.
0
-
V~7V
Output Current Limit,
(
)
LIMIT
I
..............................................................1.5A
Continuous Power Dissipation,
d
P see Note 1......................................1.1W
Electrostatic Discharge Susceptibility, Human Body Mode.............................2kV
Operating Ambient Temperature Range,
C
T ..............................................0 to +70
Storage Temperature Range,
storage
T
..................................................
45
-
to +125
Operating Junction Temperature Range,
J
T .............................................
5
-
to +130
Lead Temperature Soldering for 10 seconds,
(
)
LEAD
T
............................260
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Advanced Analog Technology, Inc
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Page 3 of 16 V 1.
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AAT1203
Note 1The device deteriorates with increase in ambient temperature,
C
T . See Thermal Information section.
Recommended Operating Conditions
Parameter Min
Typ
Max
Unit
5V Main Supply Input, VCC50
4.5
-
5.5
V
5V Standby Supply Input, VSB50
4.5
-
5.5
V
3.3V Auxiliary Supply Input, AUX33
3.0
-
3.6
V
Load Capacitance,
L
C
4.23 4.70 5.17 F
Load Current,
L
I
0 -
250 mA
Ambient Temperature,
C
T
0 - 70
Electrical Characteristics Over Recommended Operating Free-Air
Temperature,
C
T
= 0 to 70 ,
L
C
= 4.7F (Unless Otherwise Specified)
Parameter Symbol
Test
Condition
Min Typ
Max Unit
5V Inputs
VCC50
VSB50
4.5
5.0
5.5
V
3.3V Output
OUT33
33
out
I
= 250mA
3.135 3.300
3.465
V
Line Regulation Voltage
(
)
VI
O
V
VSB50 or VCC50 = 4.5V to 5.5V
-
2
-
mV
Load Regulation Voltage
(
)
IO
O
V
20 mA
L
I 250 mA
- 40
-
mV
Quiescent Supply Current
50
I
From VCC50 VSB50 terminals,
L
I = 0mA to 250mA
- 1.0
3.0
mA
AUX
I
AUX
I
From
AUX33
terminal,
L
I = 0A
- 1.0
3.0
mA
Out33 Load Current
33
L
I
0.25
-
-
Output Current Limit
LIMIT
I
Out33 Output short to 0V
-
-
1.5
A
Thermal Shutdown
(Note 2)
TSD
T
150 -
180
Thermal Hysteresis
(Note 2)
hys
T
- 15
-
Load Capacitance
L
C
Minimal ESR to insure stability of regulated
output
- 4.7
-
F
Reverse Leakage Output
Current
(
)
REV
Ikg
I
Tested for grounded input
AUX33, VSB50 or VCC50 = GND,
Out33 = 3.3V
- -
50
A
Threshold Voltage, Low
LO
V
VSB50 or VCC50
3.85 4.05
4.25
V
Threshold Voltage, High
HI
V
VSB50 or VCC50
4.1 4.3
4.5
V
Auxiliary Switch
Resistance
)
SWITCH
(
R
VSB50 = VCC50 = 0V,
AUX33 = 3.3V,
L
I = 150mA
- -
0.4
JA
R
Without copper for heat spreading
-
100
-
Thermal Impedance,
Junction-to-Ambient
(Note 3)
With copper for heat spreading
-
70
-
/W
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Advanced Analog Technology, Inc
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Page 4 of 16 V 1.
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AAT1203
Note 2
Design targets only. Not tested in production.
Note 3Please refer to "Thermal Information"
Block Diagram
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Advanced Analog Technology, Inc
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Page 5 of 16 V 1.
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AAT1203
AUX33
VCC50
Detector
VCC50
3.3V
GND
Over
Temperature
Protection
GND
VSB50
Detector
Control
OUT33
VSB50
3.3V
Low on Resistance
-
-
+
+
GND
GND
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