600mA, 1MHz Step-Down Converter
General Description
The AAT1126 SwitchReg™ is a member of
AnalogicTech's Total Power Management IC™
(TPMIC™) product family. It is a 1MHz step-down
converter with an input voltage range of 2.7V to
5.5V and output as low as 0.6V. Its low supply cur-
rent, small size, and high switching frequency
make the AAT1126 the ideal choice for portable
applications.
The AAT1126 is available in either a fixed version
with internal feedback or a programmable version
with external feedback resistors. It can deliver up
to 600mA of load current while maintaining a low
25µA no load quiescent current. The 1MHz switch-
ing frequency minimizes the size of external com-
ponents while keeping switching losses low. The
AAT1126 feedback and control delivers excellent
load regulation and transient response with a small
output inductor and capacitor.
The AAT1126 is designed to maintain high efficien-
cy throughout the operating range and provides
fast turn-on time.
The AAT1126 is available in a Pb-free, space-sav-
ing SOT23-5 package and is rated over the -40°C
to +85°C temperature range.
AAT1126
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
SwitchReg
™
V
IN
Range: 2.7V to 5.5V
V
OUT
Adjustable Down to 0.6V
— Fixed or Adjustable Version
Fast Turn-On Time (100µs Typical)
25µA No Load Quiescent Current
Up to 97% Efficiency
Output Current Up to 600mA
1MHz Switching Frequency
Soft Start
Over-Temperature Protection
Current Limit Protection
100% Duty Cycle Low-Dropout Operation
0.1µA Shutdown Current
SOT23-5 Package
Temperature Range: -40°C to +85°C
Applications
•
•
•
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Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor / DSP Core / IO Power
PDAs and Handheld Computers
USB Devices
Typical Application (Fixed Output Voltage)
V
IN
5
V
O
U1
AAT1126
VIN
EN
GND
OUT
4
3
L1
4.7µH
LX
C2
4.7µF
2
1
C1
10µF
1126.2006.05.1.1
1
600mA, 1MHz Step-Down Converter
Pin Descriptions
Pin #
1
2
3
4
5
AAT1126
Symbol
GND
EN
LX
OUT
VIN
Function
Ground pin.
Enable pin.
Switching node. Connect the inductor to this pin. It is internally connected to
the drain of both high- and low-side MOSFETs.
Feedback input pin. This pin is connected either directly to the converter
output or to an external resistive divider for an adjustable output.
Input supply voltage for the converter.
Pin Configuration
SOT23-5
(Top View)
GND
EN
LX
1
5
VIN
2
3
4
OUT
2
1126.2006.05.1.1
600mA, 1MHz Step-Down Converter
Absolute Maximum Ratings
1
Symbol
V
IN
V
LX
V
OUT
V
EN
T
J
T
LEAD
AAT1126
Description
Input Voltage GND
L
X
to GND
OUT to GND
EN to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
6.0
-0.3 to V
IN
+ 0.3
-0.3 to V
IN
+ 0.3
-0.3 to 6.0
-40 to 150
300
Units
V
V
V
V
°C
°C
Thermal Information
Symbol
P
D
θ
JA
Description
Maximum Power Dissipation (SOT23-5)
Thermal Resistance
2
( SOT23-5)
Value
667
150
Units
mW
°C/W
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.
1126.2006.05.1.1
3
600mA, 1MHz Step-Down Converter
Electrical Characteristics
1
T
A
= -40°C to +85°C, unless otherwise noted. Typical values are T
A
= 25°C, V
IN
= 3.6V.
Symbol
Description
Conditions
Min
2.7
V
IN
Rising
Hysteresis
V
IN
Falling
I
OUT
= 0 to 600mA,
V
IN
= 2.7V to 5.5V
No Load, 0.6V Adjustable
Version
EN = AGND = PGND
600
0.45
0.40
V
IN
= 5.5V, V
LX
= 0 to V
IN
,
EN = GND
V
IN
= 2.7V to 5.5V
0.6V Output, No Load
T
A
= 25°C
0.6V Output
>0.6V Output
From Enable to Output
Regulation
T
A
= 25°C
1
0.5
591
250
100
0.7
1.0
140
15
1.5
600
609
0.2
100
1.8
-3.5
0.6
25
+3.5
V
IN
50
1.0
AAT1126
Typ
Max
5.5
2.6
Units
V
V
mV
V
%
V
µA
µA
mA
Ω
Ω
µA
%/V
mV
µA
kΩ
µs
MHz
°C
°C
V
V
µA
Step-Down Converter
V
IN
Input Voltage
V
UVLO
V
OUT
V
OUT
I
Q
I
SHDN
I
OUT_X
R
DS(ON)H
R
DS(ON)L
I
LXLEAK
ΔV
Linereg
V
OUT
I
OUT
R
OUT
T
S
F
OSC
T
SD
T
HYS
EN
V
EN(L)
V
EN(H)
I
EN
Enable Threshold Low
Enable Threshold High
Input Low Current
UVLO Threshold
Output Voltage Tolerance
Output Voltage Range
Quiescent Current
Shutdown Current
Maximum Load Current
High Side Switch On Resistance
Low Side Switch On Resistance
LX Leakage Current
Line Regulation
Out Threshold Voltage Accuracy
Out Leakage Current
Out Impedance
Start-Up Time
Oscillator Frequency
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
0.6
V
IN
= V
FB
= 5.5V
1.4
-1.0
1.0
1. The AAT1126 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured
by design, characterization, and correlation with statistical process controls.
4
1126.2006.05.1.1
Power technology
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