Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
. V 1.0
AAT1204
400-mA MULTI-INPUT LOW-DROPOUT REGULATOR
WITH V
AUX
SWITCH
Features
Complete Power Management
Automatic Input Voltage Selection
Input Voltage Source Detector With
Hysteresis
400-mA Load Current Capability With
VCC50 or VSB50 or AUX33 Input Source
Integrated Low r
DS (on)
Switch
Regulated Output 3.3V (fixed)
Output Short Circuit Protection
Pin Configuration
Description
The AAT1204 is a multi-input low-dropout
regulator that provides constant output supply
3.3V at the output capable of driving a 400-mA
load.
The AAT1204 provides regulated power output
for systems that have multiple input sources and
require constant voltage source with a
low-dropout voltage. This is a 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.
Transitions may occur from one input supply to
another without generating a glitch outside of the
specification range on 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 SOIC )
TOP VIEW
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
. V 1.0
AAT1204
Functions 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
3.3 400
0 5 0
VSB50
3.3 400
0 5 3.3
VSB50
3.3 400
5 0 0
VCC50
3.3 400
5 0 3.3
VCC50
3.3 400
5 5 0
VCC50
3.3 400
5 5 3.3
VCC50
3.3 400
PIN Description
TERMINAL
NAME NO.
I/O Description
VSB50 1
I
5-V standby supply input
VCC50 2
I
5-V main supply input
OUT33 3
O
3.3-V regulated output
AUX33 4
I
3.3-V 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, V
VCC50
.............................................................. -0.5V~7V
Standby Supply voltage, V
VSB50
.......................................................... -0.5V~7V
Auxiliary Supply voltage, V
AUX33
.......................................................... -0.5V~7V
Output current limit, I
LIMIT
....................................................................... 1.5A
Continuous power dissipation, P
D
see Note 1.............................................. 1.1W
Electrostatic discharge susceptibility, human body model.......................................2kV
Operating ambient temperature range, T
A
................................................0 to 70
Storage temperature range, Tstg.......................................................-55 to 150
Operating junction temperature range, T
J
...............................................-5 to 135
Lead temperature soldering, 10 second,T
LEAD
..........................................260
NOTE 1The device deteriorate with increase in ambient temperature, TA. See Thermal Information section.
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
. V 1.0
AAT1204
Recommended operating conditions
Min
Typ
Max
Unit
5-V main supply input, VCC50
4.5
5.5
V
5-V standby supply input, VSB50
4.5
5.5
V
3.3V auxiliary supply input, AUX33
3
3.6
V
Load capacitance, C
L
4.23
4.7
5.17
F
Load current, I
L
0 400 mA
Ambient temperature, T
A
0
70
Electrical Characteristics over recommended operating free-air temperature, TA = 0 to 70
,CL = 4.7F (unless otherwise noted)
Parameter Test
Condition
Min
Typ
Max Unit
VCC50
5-V inputs
VSB50
4.5
5
5.5
V
OUT33 3.3-V output
Iout33 = 400mA
3.135
3.3
3.465
V
V
O
VI
Line regulation voltage
VSB50 or VCC50 = 4.5V to 5.5V
2
mV
V
O
IO
Load regulation voltage
20 mAI
L
400 mA
40
mV
I
50
Quiescent supply current
From VCC50 VSB50 terminals,
I
L
= 0 to 400mA
1.0 3.0
mA
I
AUX
From AUX33 terminal, IL = 0A
1.0
3.0
mA
I
L33
Out33 load current
0.4
I
LIMIT
Output current limit
Out33 output short to 0v
1.5
A
T
TSD
Thermal shutdown
NOTE 2
150
180
T
hys
Thermal hysteresis
NOTE2
15
C
L
Load capacitance
Minimal ESR to insure stability of
regulated output
4.7
F
I
Ikg
REV
Reverse leakage output current Tested for input that is grounded.
AUX33, VSB50 or VCC50 = GND,
Out33 = 3.3v
50
A
V
LO
Threshold voltage, low
VSB50 or VCC50
4.0
4.2 4.4
V
V
HI
Threshold voltage, high
VSB50 or VCC50
4.25
4.45 4.65
V
R
SWITCH
Auxiliary switch resistance VSB50 = VCC50 = 0V,
AUX33 = 3.3V, I
L
= 150mA
0.4
Without copper for heat spreading
100
R
JA
Thermal impedance,
Junction-to-ambientNOTE3 With copper for heat spreading
70
/W
NOTE 2
Design targets only. Not tested in production.
NOTE 3Please refer to "Thermal Information"
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
. V 1.0
AAT1204
AUX33
VCC50
Detector
VCC50
3.3V
GND
OVER
TEMPERATURE
PROTECTION
GND
VSB50
Detector
Control
OUT33
VSB50
3.3V
Low on Resistance
-
-
+
+
GND
GND
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
. V 1.0
AAT1204
TYPICAL CHARACTERISTICS
Figure 1. 3.3V VCC50 Cold Start
Figure 2. 3.3V AUX33 Cold Start
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