quency current mode PWM step-down converter. It is
ideal for portable equipment requiring very high current
up to 2A from single-cell Lithium-ion batteries while still
achieving over 90% efficiency during peak load condi-
tions. The AAT1153 also can run at 100% duty cycle for
low dropout operation, extending battery life in portable
systems while light load operation provides very low
output ripple for noise sensitive applications.
The AAT1153 can supply up to 2A output load current
from a 2.5V to 5.5V input voltage and the output voltage
can be regulated as low as 0.6V. The high switching fre-
quency minimizes the size of external components while
keeping switching losses low. The internal slope compen-
sation setting allows the device to operate with smaller
inductor values to optimize size and provide efficient
operation.
The AAT1153 is available in adjustable (0.6V to V
IN
) and
fixed (1.8V) output voltage versions. The device is avail-
able in a Pb-free, 3mm x 3mm 10-lead TDFN package and
is rated over the -40°C to +85°C temperature range.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Input Voltage Range: 2.5V to 5.5V
Output Voltages from 0.6V to V
IN
2A Output Current
High Efficiency: Up to 95%
1.2MHz Constant Switching Frequency
Low R
DS(ON)
Internal Switches: 0.15Ω
Allows Use of Ceramic Capacitors
Current Mode Operation for Excellent Line and Load
Transient Response
Short-Circuit and Thermal Fault Protection
Soft Start
Low Dropout Operation: 100% Duty Cycle
Low Shutdown Current: I
SHUTDOWN
< 1μA
TDFN33-10 Package
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
•
Cellular Phones
Digital Cameras
DSP Core Supplies
PDAs
Portable Instruments
Smart Phones
Typical Application
V
IN
2.5V-5.5V
L1
2.2μH
V
OUT
1.8V, 2A
1
2
EN
IN
AIN
LX
8
7
5
10
9
C1
22μF
3
AAT1153-1.8
LX
OUT
C2
22μF
6 AGND
4 AGND
PGND
PGND
1153.2008.02.1.2
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1
PRODUCT DATASHEET
AAT1
153
2A Step-Down Converter
Pin Descriptions
Pin #
1
2
3
4, 6
5
7, 8
9, 10
Symbol
EN
IN
AIN
AGND
FB/OUT
LX
PGND
EP
Function
Enable pin. Active high. In shutdown, all functions are disabled drawing <1μA supply current. Do not leave
EN
fl
oating.
Power supply input pin. Must be closely decoupled to AGND with a 2.2μF or greater ceramic capacitor.
Analog supply input pin. Provides bias for internal circuitry.
Analog ground pin
FB pin (AAT1153IDE-0.6): Adjustable version feedback input. Connect FB to the center point of the
external resistor divider. The feedback threshold voltage is 0.6V.
OUT pin (AAT1153IDE-1.8): Fixed version feedback input. Connect OUT to the output voltage, VOUT.
Switching node pin. Connect the output inductor to this pin.
Power ground pin
Power ground exposed pad. Must be connected to bare copper ground plane.
Pin Configuration
TDFN-10
(Top View)
EN
IN
AIN
AGND
FB/OUT
1
2
3
4
5
10
9
8
7
6
PGND
PGND
LX
LX
AGND
1. FB pin for the adjustable voltage version (AAT1153IDE-0.6), OUT pin for the fixed voltage version (AAT1153IDE-1.8).
2
www.analogictech.com
1153.2008.02.1.2
PRODUCT DATASHEET
AAT1
153
2A Step-Down Converter
Absolute Maximum Ratings
1
Symbol
IN, AIN
V
FB
, V
LX
V
EN
PGND, AGND
T
A
T
STORAGE
T
LEAD
Description
Input Supply Voltages
FB, LX Voltages
EN Voltage
Ground Voltages
Operating Temperature Range
Storage Temperature
Lead Temperature (Soldering, 10s)
Value
-0.3 to 6.0
-0.3 to V
IN
+ 0.3
-0.3 to V
IN
+ 0.3
-0.3 to 6.0
-40 to +85
-65 to 150
300
Units
V
V
V
V
°C
°C
°C
Thermal Information
2
Symbol
θ
JA
P
D
Description
Thermal Resistance
3
Maximum Thermal Dissipation at T
A
= 25°C
Value
45
2.2
Units
°C/W
W
1. Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
2. T
J
is calculated from the ambient temperature T
A
and power dissipation P
D
according to the following formula: T
J
= T
A
+ P
D
x
θ
JA
.
3. Thermal Resistance is specified with approximately 1 square inch of 1 oz. copper.
1153.2008.02.1.2
www.analogictech.com
3
PRODUCT DATASHEET
AAT1
153
2A Step-Down Converter
Electrical Characteristics
1
V
IN
= 3.6V, T
A
= -40°C to +85°C unless otherwise noted; typical values are T
A
= 25°C.
Symbol
V
IN
V
OUT
I
Q
I
FB
V
FB
ΔV
LINEREG
/
ΔV
IN
ΔV
LOADREG
/
ΔI
OUT
V
FB
F
OSC
T
S
T
SD
T
HYS
I
LIM
R
DS(ON)
V
EN(L)
V
EN(H)
I
EN
Description
Input Voltage Range
2
Output Voltage Range
Input DC Supply Current
Feedback Input Bias Current
Regulated Feedback Voltage
3
Line Regulation
Load Regulation
Output Voltage Accuracy
Oscillator Frequency
Startup Time
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Peak Switch Current
P-CH MOSFET
N-CH MOSFET
Enable Threshold Low
Enable Threshold High
Input Low Current
Conditions
Min
2.5
0.6
Typ
Max
5.5
V
IN
500
1
30
0.6120
0.6135
0.6150
0.20
Units
V
V
μA
μA
nA
V
%/V
%/A
Active Mode: V
FB
= 0.5V
Shutdown Mode: V
EN
= 0V, V
AIN
= 5.5V
V
FB
= 0.65V
T
A
= 25°C
0°C
≤
T
A
≤
85°C
-40°C
≤
T
A
≤
85°C
V
IN
= 2.5V to 5.5V, I
OUT
= 10mA
I
OUT
= 10mA to 2000mA
V
IN
= 2.5 to 5.5V, I
OUT
= 10 to 2000mA
V
FB
= 0.6V
From Enable to Output Regulation
300
0.1
0.5880
0.5865
0.5850
0.6000
0.6000
0.6000
0.10
0.20
-3
0.96
1.2
1.3
170
10
3.5
135
95
+3
1.44
% V
OUT
MHz
ms
°C
°C
A
mΩ
V
V
μA
2.5
V
IN
= 3.6V
V
IN
= 3.6V
1.5
-1.0
200
150
0.3
1.0
V
IN
= V
EN
= 5.5V
1. The AAT1153 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-
tion with statistical process controls.
2. V
IN
should be not less than V
OUT
+ V
DROPOUT
, where V
DROPOUT
= I
OUT
x (R
DS(ON)PMOS
+ ESR
INDUCTOR
), typically V
DROPOUT
= 0.3V.
3. The regulated feedback voltage is tested in an internal test mode that connects V
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