Fast Transient 800mA Step-Down Converter
General Description
The AAT1110 SwitchReg™ is a member of
AnalogicTech's Total Power Management IC™
(TPMIC™) product family. It is a 1.4MHz step-
down converter with an input voltage range of 2.7V
to 5.5V and output as low as 0.6V. Its low supply
current, small size, and high switching frequency
make the AAT1110 the ideal choice for portable
applications.
The AAT1110 is available in either a fixed version
with internal feedback or a programmable version
with external feedback resistors. It can deliver up
to 800mA 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 AAT1110 feedback and control delivers excel-
lent load regulation and transient response with a
small output inductor and capacitor.
The AAT1110 is designed to maintain high efficien-
cy throughout the operating range and provides
fast turn-on time.
The AAT1110 is available in a space-saving
2.0x2.1mm SC70JW-8 package and is rated over
the -40°C to +85°C temperature range.
AAT1110
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
SwitchReg
™
V
IN
Range: 2.7V to 5.5V
V
OUT
Fixed or Adjustable from 0.6V to V
IN
27µA No Load Quiescent Current
Output Current Up to 800mA
1.4MHz Switching Frequency
120µs Soft Start
Fast Load Transient
Over-Temperature Protection
Current Limit Protection
100% Duty Cycle Low-Dropout Operation
<1µA of Shutdown Current
SC70JW-8 Package
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)
V
IN
3
1
V
O
U1
AAT1110
VIN
EN
AGND
PGND
LX
OUT
PGND
PGND
4
2
7
6
L1
4.7μH
C1
22μF
C2
4.7μF
5
8
1110.2006.04.1.0
1
Fast Transient 800mA Step-Down Converter
Pin Descriptions
Pin #
1
2
3
4
5
6, 7, 8
AAT1110
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 pin. Connect to the output and input capacitor
return.
Pin Configuration
SC70JW-8
(Top View)
EN
OUT
VIN
LX
1
2
3
4
8
7
6
5
PGND
PGND
PGND
AGND
2
1110.2006.04.1.0
Fast Transient 800mA Step-Down Converter
Absolute Maximum Ratings
1
Symbol
V
IN
V
LX
V
OUT
V
EN
T
J
T
LEAD
AAT1110
Description
Input Voltage to GND
LX 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 (SC70JW-8)
Thermal Resistance
2
(SC70JW-8)
Value
625
160
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.
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Fast Transient 800mA 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 800mA,
V
IN
= 2.7V to 5.5V
No Load, 0.6V Adjustable
Version
EN = AGND = PGND
800
100
1.8
-3.5
0.6
27
1200
0.45
0.40
0.1
600
609
0.2
250
150
1.0
1.4
140
15
2.0
+3.5
V
IN
70
1.0
AAT1110
Typ
Max
5.5
2.7
Units
V
V
mV
V
%
V
µA
µA
mA
Ω
Ω
%/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
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
P-Channel Current Limit
High Side Switch On Resistance
Low Side Switch On Resistance
Line Regulation
Out Threshold Voltage Accuracy
Out Leakage Current
Out Impedance
Start-Up Time
Oscillator Frequency
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
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
591
0.6
V
IN
= V
OUT
= 5.5V
1.4
-1.0
1.0
1. The AAT1110 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
1110.2006.04.1.0
Fast Transient 800mA Step-Down Converter
Typical Characteristics
Efficiency vs. Load
(V
OUT
= 1.8V; L = 4.7µH)
100
1.0
AAT1110
DC Regulation
(V
OUT
= 1.8V)
V
IN
= 2.7V
Output Error (%)
90
V
IN
= 4.2V
0.5
Efficiency (%)
80
70
60
50
0.1
1
V
IN
= 3.6V
0.0
V
IN
= 3.6V
V
IN
= 4.2V
-0.5
V
IN
= 2.7V
-1.0
10
100
1000
0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Efficiency vs. Load
(V
OUT
= 2.5V; L = 6.8µH)
100
2.0
DC Regulation
(V
OUT
= 2.5V)
1.5
V
IN
= 3.0V
Output Error (%)
90
V
IN
= 5.0V
V
IN
= 4.2V
Efficiency (%)
1.0
0.5
0.0
-0.5
-1.0
-1.5
80
70
60
50
0.1
1
V
IN
= 4.2V V
IN
= 5.0V
V
IN
= 3.6V
V
IN
= 3.6V
V
IN
= 3.0V
-2.0
10
100
1000
0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Efficiency vs. Load
(V
OUT
= 3.3V; L = 6.8µH)
100
1.0
DC Regulation
(V
OUT
= 3.3V; L = 6.8µH)
V
IN
= 3.6V
Output Error (%)
90
Efficiency (%)
0.5
80
V
IN
= 5.0V
V
IN
= 4.2V
V
IN
= 4.2V
0.0
70
60
50
0.1
1
10
100
1000
-0.5
V
IN
= 5.0V
-1.0
0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
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