AAT2500M
400mA Step-Down Converter and 300mA LDO
General Description
The AAT2500M is a high efficiency 400mA step-
down converter and 300mA low dropout (LDO) lin-
ear regulator for applications where power efficien-
cy and solution size are critical. The typical input
power source can be a single-cell Lithium-ion/poly-
mer battery or a 5V or 3.3V power bus.
The step-down converter is capable of delivering up
to 400mA output current, uses a typical switching
frequency of 1.8MHz to greatly reduce the size of
external components, offers high speed turn-on and
maintains a low 25µA no load quiescent current.
The LDO is capable of delivering up to 300mA out-
put current.
The AAT2500M is available in the Pb-free, space-
saving 12-pin TSOPJW package and is rated over
the -40°C to +85°C operating temperature range.
Features
•
•
SystemPower
™
•
•
•
•
•
•
•
•
•
•
V
IN
Range: 2.7V to 5.5V
Output Current:
— Step-Down Converter: 400mA
— LDO: 300mA
Low Quiescent Current
— 130µA Combined for Both Step-Down
Converter plus LDO
90% Efficient Step-down Converter (at 100mA)
Integrated Power Switches
100% Duty Cycle
1.8MHz Switching Frequency
Current Limit Protection
Automatic Soft-Start
Over Temperature Protection
TSOPJW-12 Package
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
•
•
•
Cellular Phones
Digital Cameras
Handheld Instruments
Micro Hard Disc Drives
Microprocessor / DSP Core / IO Power
Optical Storage Devices
PDAs and Handheld Computers
Portable Media Players
Typical Application
AAT2500M
Input Supply
2.7V to 5.5V
4.7µF
IN_BUCK
LX
FB_BUCK
V
OUT_BUCK
2.2µH
R1
R2
IN_LDO
1µF
OUT_LDO
V
OUT(LDO)
C2
4.7µF
Enable Buck
Enable LDO
EN_BUCK
EN_LDO
AGND PGND
C1
2.2µF
2500M.2007.06.1.0
1
AAT2500M
400mA Step-Down Converter and 300mA LDO
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8, 9, 10, 11
12
Symbol
LX
PGND
EN_BUCK
EN_LDO
FB_BUCK
OUT_LDO
IN_LDO
AGND
IN_BUCK
Function
Step-down converter switching node.
Power ground for step-down converter.
Enable pin for step-down converter.
Enable pin for LDO.
Feedback input pin for step-down converter. Regulated at 0.6V for adjustable version.
LDO power output.
Input supply voltage for LDO.
Analog signal ground.
Input supply voltage for step-down converter.
Pin Configuration
TSOPJW-12
(Top View)
LX
PGND
EN_BUCK
EN_LDO
FB_BUCK
OUT_LDO
IN_BUCK
AGND
AGND
AGND
AGND
IN_LDO
1
2
3
4
5
6
12
11
10
9
8
7
2
2500M.2007.06.1.0
AAT2500M
400mA Step-Down Converter and 300mA LDO
Absolute Maximum Ratings
1
Symbol
V
P
AGND, PGND
V
EN
, V
FB
I
OUT
T
J
T
S
T
LEAD
Description
Input Voltage
Ground Pins
Enable and Feedback Pins
Maximum DC Output Current (continuous)
Operating Temperature Range
Storage Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
-0.3 to 6.0
-0.3 to +0.3
V
IN
+ 0.3
1000
-40 to 150
-65 to 150
300
Units
V
V
V
mA
°C
°C
°C
Thermal Information
Symbol
θ
JA
P
D
Description
Thermal Resistance
2
Maximum Power Dissipation
Value
110
909
Units
°C/W
mW
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at condi-
tions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 board.
2500M.2007.06.1.0
3
AAT2500M
400mA Step-Down Converter and 300mA LDO
Electrical Characteristics
1
V
IN_BUCK
= V
IN_LDO
= 5.0V. T
A
= -40°C to +85°C unless noted otherwise. Typical values are at T
A
= +25°C.
Symbol
Description
Conditions
Min
Typ
Max
Units
Power Supply
V
INBUCK
,
Input Voltage
V
INLDO
V
UVLO
I
Q
Under-Voltage Lockout
V
IN
Rising
V
IN
Falling
V
EN
= V
IN
, No Load
V
EN
= GND
No Load, T
A
= 25°C
I
OUT
= 0 to 400mA; V
IN
= 2.7 to 5.5V
V
IN
= 5.5V, V
LX
= 0 to V
IN
, V
EN
= GND
V
FB
= 1.0 V
2.7
5.5
2.7
2.35
130
1.0
V
V
V
µA
µA
V
%
µA
µA
A
Ω
Ω
%
%
MHz
µs
V
%
V
mA
A
mV
%
%
µs
V
V
µA
°C
°C
Quiescent Current
I
SHDN
Shutdown Current
Step-Down Converter
Feedback Voltage Tolerance
`
I
LXLEAK
LX Reverse Leakage Current
I
FB
Feedback Leakage
I
LIM
P-Channel Current Limit
R
DS(ON)H
High Side Switch On Resistance
R
DS(ON)L
Low Side Switch On Resistance
∆V
OUT
/V
OUT
Load Regulation
∆V
OUT
/V
OUT
Line Regulation
F
OSC
Oscillator Frequency
T
S
Start-Up Time
LDO (V
OUT
= 3.3V)
V
OUT
Output Voltage Tolerance
V
OUT
Output Voltage Range
V
IN
Input Voltage
V
FB
0.591
-3
-1.0
1.2
0.4
0.25
0.25
0.3
1.8
120
3.24
-3
V
OUT
+
V
DO
2
300
3.30
0.609
+3
1.0
0.2
I
LOAD
= 0 to 400mA
V
IN
= 2.7V to 5.5V
From Enable to Output Regulation
No Load, 25°C
I
OUT
= 0 to 300mA
3.36
3
5.5
I
OUT
Output Current
I
LIM
Current Limit
V
DO
Dropout Voltage
3
∆V
OUT
/V
OUT
Load Regulation
∆V
OUT
/V
OUT
Line Regulation
T
S
Start-Up Time
Logic Signals
V
EN(L)
Enable Threshold Low
V
EN(H)
Enable Threshold High
I
EN(H)
Enable Current Consumption
Over-Temperature Shutdown
T
SD
Threshold
Over-Temperature Shutdown
T
HYS
Hysteresis
I
OUT
= 300mA
I
LOAD
= 0 to 300mA
V
IN
= 3.7V to 5.5V
From Enable to Output Regulation
1
160
1.2
0.6
100
240
0.6
1.5
-1.0
150
15
1.0
1. Specification over the -40°C to +85°C operating temperature ranges is assured by design, characterization and correlation with sta-
tistical process controls.
2. To calculate the minimum LDO input voltage, use the following equation: V
IN(MIN)
= V
OUT(MAX)
+ V
DO(MAX)
.
3. V
DO
is defined as V
IN
- V
OUT
when V
OUT
is 98% of nominal.
4
2500M.2007.06.1.0
AAT2500M
400mA Step-Down Converter and 300mA LDO
Typical Characteristics
LDO Dropout Voltage vs. Temperature
210
3.5
LDO Dropout Characteristics
(V
OUT
= 3.3V)
I
OUT
= 50mA
Dropout Voltage (mV)
Output Voltage (V)
180
150
120
90
60
30
0
-40
I
L
= 300mA
I
L
= 200mA
I
L
= 100mA
I
L
= 50mA
-20
0
20
40
60
80
100
3.4
3.3
3.2
3.1
3.0
2.9
2.8
3.0
I
OUT
= 10mA
I
OUT
= 0.1mA
I
OUT
= 300mA
I
OUT
= 200mA
I
OUT
= 100mA
3.1
3.2
3.3
3.4
3.5
3.6
3.7
Temperature (°C)
Input Voltage (V)
LDO Dropout Voltage vs. Output Current
250
No Load Quiescent Current vs. Input Voltage
(EN_BUCK = EN_LDO = V
IN
)
150
Dropout Voltage (mV)
Input Current (µA)
200
150
100
50
0
0
50
100
85°C
25°C
130
110
90
70
50
30
2.5
85°C
25°C
-40°C
-40°C
150
200
250
300
350
3
3.5
4
4.5
5
5.5
6
Output Current (mA)
Input Voltage (V)
LDO Turn-Off Response Time
(V
IN
= 5V; V
OUT
= 3.3V; I
OUT
= 300mA)
6
6
LDO Turn-On Time From Enable
(V
IN
= 5V; V
OUT
= 3.3V; I
OUT
= 300mA)
Output Voltage (bottom)(V)
Output Voltage (bottom)(V)
Enable Voltage (top) (V)
4
2
0
3
2
1
0
-1
Enable Voltage (top) (V)
4
2
0
3.0
2.0
1.0
0.0
-1.0
Time (50ns/div)
Time (40µs/div)
2500M.2007.06.1.0
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