verter with an input voltage range of 2.7V to 5.5V and
output voltage as low as 0.6V. It is optimized to react
quickly to a load variation.
The AAT1146 is available in fixed voltage versions with
internal feedback and a programmable version with
external feedback resistors. It can deliver 400mA of load
current while maintaining a low 27μA no load quiescent
current. The 1.4MHz switching frequency minimizes the
size of external components while keeping switching
losses low.
The AAT1146 is designed to maintain high efficiency
throughout the operating range, which is critical for por-
table applications.
The AAT1146 is available in the Pb-free, space-saving
2.0x2.1mm SC70JW-8 and SOT23-5 packages and is
rated over the -40°C to +85°C temperature range.
Fast Transient 400mA Step-Down Converter
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
V
IN
Range: 2.7V to 5.5V
V
OUT
Fixed or Adjustable from 0.6V to V
IN
27μA No Load Quiescent Current
Up to 98% Efficiency
400mA Max Output Current
1.4MHz Switching Frequency
120μs Soft Start
Fast Load Transient
Over-Temperature Protection
Current Limit Protection
100% Duty Cycle Low-Dropout Operation
<1μA Shutdown Current
SC70JW-8 and SOT23-5 Packages
Temperature Range: -40°C to +85°C
Applications
•
•
•
•
•
•
Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor / DSP Core / IO Power
PDAs and Handheld Computers
USB Devices
Typical Application (Fixed Output Voltage)
U1
AAT1146
V
IN
C2
4.7µF
L1
LX
OUT
PGND
PGND
4.7µH
V
O
C1
4.7µF
VIN
EN
AGND
PGND
1146.2008.06.1.6
www.analogictech.com
1
PRODUCT DATASHEET
AAT1146
SwitchReg
TM
Pin Descriptions
Pin #
SC70JW-8
1
2
3
4
5
6, 7, 8
SOT23-5
2
4
5
3
1
Fast Transient 400mA Step-Down Converter
Symbol
EN
OUT
VIN
LX
AGND
PGND
Function
Enable pin.
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.
Switching node. Connect the inductor to this pin. It is internally connected to the drain of
both high- and low-side MOSFETs.
Non-power signal ground pin.
Main power ground return pins. Connect to the output and input capacitor return.
Pin Configuration
SC70JW-8
(Top View)
SOT23-5
(Top View)
EN
OUT
VIN
LX
1
8
PGND
PGND
PGND
AGND
GND
EN
LX
1
5
VIN
2
7
3
6
2
4
5
3
4
OUT
2
www.analogictech.com
1146.2008.06.1.6
PRODUCT DATASHEET
AAT1146
SwitchReg
TM
Absolute Maximum Ratings
1
Symbol
V
IN
V
LX
V
OUT
V
EN
T
J
T
LEAD
Fast Transient 400mA Step-Down Converter
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 V
IN
+ 0.3
-40 to 150
300
Units
V
V
V
V
°C
°C
Thermal Information
Symbol
P
D
θ
JA
Description
Maximum Power Dissipation
2, 3
Thermal Resistance
2
SC70JW-8
SOT23-5
SC70JW-8
SOT23-5
Value
625
667
160
150
Units
mW
°C/W
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions 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.
3. SC70JW-8: Derate 6.25mW/°C above 25°C.
SOT23-5: Derate 6.67mW/°C above 25°C.
1146.2008.06.1.6
www.analogictech.com
3
PRODUCT DATASHEET
AAT1146
SwitchReg
TM
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 400mA, 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
>1.0V Output
2
From Enable to Output Regulation
T
A
= 25°C
1
591
250
1.0
150
1.4
140
15
2.0
0.1
600
609
0.2
100
1.8
-3.0
0.6
27
+3.0
V
IN
70
1.0
Fast Transient 400mA Step-Down Converter
Typ
Max
5.5
2.7
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
LIM
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
UVLO Threshold
Output Voltage Tolerance
Output Voltage Range
Quiescent Current
Shutdown Current
P-Channel Current Limit
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
Enable Threshold Low
Enable Threshold High
Input Low Current
0.6
V
IN
= V
OUT
= 5.5V
1.4
-1.0
1.0
1. The AAT1146 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. The AAT1146 fixed output versions have the output set to different voltages.
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