SwitchReg
TM
AAT1150
1MHz 1A Step-Down DC/DC Converter
1150.2005.03.1.2
1
General Description
The AAT1150 SwitchRegTM is a member of
AnalogicTech's Total Power Management ICTM
(TPMICTM) product family. The step-down switch-
ing converter is ideal for applications where high
efficiency, small size, and low ripple are critical.
Able to deliver 1A with internal power MOSFETs,
the current-mode controlled IC provides high effi-
ciency using synchronous rectification. Fully inter-
nally compensated, the AAT1150 simplifies system
design and lowers external parts count.
The AAT1150 is available in an MSOP-8 package
and is rated over the -40C to +85C temperature
range.
Features
V
IN
Range: 2.7V to 5.5V
Up to 95% Efficiency
110m
R
DS(ON)
MOSFET Switch
<1.0A of Shutdown Current
1MHz Switching Frequency
Fixed or Adjustable V
OUT
: 1.0V to 4.2V
High Initial Accuracy: 1%
1.0A Peak Current
Integrated Power Switches
Synchronous Rectification
Internally Compensated Current Mode Control
Constant PWM Mode for Low Output Ripple
Internal Soft Start
Current Limit Protection
Over-Temperature Protection
MSOP-8 package
-40C to +85C Temperature Range
Applications
Cable/DSL Modems
Computer Peripherals
High Efficiency Conversion From 5V or 3.3V
Supply
Network Cards
Set-Top Boxes
Typical Application
OUTPUT
4.1
H
2x 22
F
10
F
0.1
F
100
LX
VP
INPUT
FB
SGND
AAT1150
ENABLE
VCC
PGND
AAT1150
1MHz 1A Step-Down DC/DC Converter
2
1150.2005.03.1.2
Pin Descriptions
Pin Configuration
MSOP-8
(Top View)
1
2
LX
PGND
LX
VP
FB
SGND
EN
VCC
1
2
3
4
8
7
6
5
Pin #
Symbol
Function
1
FB
Feedback input pin. This pin must be connected to the converter's output. It is
used to set the output of the converter to regulate to the desired value.
2
SGND
Signal ground.
3
EN
Enable input pin. When connected high, the AAT1150 is in normal operation.
When connected low, it is powered down. This pin should not be left floating.
4
VCC
Power supply. It supplies power for the internal circuitry.
5
VP
Input supply voltage for converter power stage.
6, 7
LX
Inductor connection pins. These pins should be connected to the output
inductor. Internally, Pins 6 and 7 are connected to the drains of the P-chan-
nel switch and N-channel synchronous rectifier.
8
PGND
Power ground return for the output stage.
AAT1150
1MHz 1A Step-Down DC/DC Converter
1150.2005.03.1.2
3
Absolute Maximum Ratings
1
T
A
= 25C, unless otherwise noted.
Thermal Characteristics
Recommended Operating Conditions
Symbol
Description
Rating
Units
T
Ambient Temperature Range
-40 to +85
C
Symbol
Description
Value
Units
JA
Maximum Thermal Resistance (MSOP-8)
3
150
C/W
P
D
Maximum Power Dissipation (MSOP-8, T
A
= 25C)
3, 4
667
mW
Symbol
Description
Value
Units
V
CC
, V
P
V
CC
, V
P
to GND
6
V
V
LX
LX to GND
-0.3 to V
P
+0.3
V
V
FB
FB to GND
-0.3 to V
CC
+0.3
V
V
EN
EN to GND
-0.3 to 6
V
T
J
Operating Junction Temperature Range
-40 to 150
C
V
ESD
ESD Rating
2
- HBM
3000
V
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. Human body model is a 100pF capacitor discharged through a 1.5K
resistor into each pin.
3. Mounted on a demo board.
4. Derate 6.7mW/C above 25C.
AAT1150
1MHz 1A Step-Down DC/DC Converter
4
1150.2005.03.1.2
Electrical Characteristics
V
IN
= V
CC
= V
P
= 5V, T
A
= -40C to +85C, unless otherwise noted. Typical values are at T
A
= 25C.
Symbol
Description
Conditions
Min
Typ
Max
Units
V
IN
Input Voltage Range
2.7
5.5
V
V
OUT
Output Voltage Tolerance
V
IN
= V
OUT
+ 0.3 to 5.5V,
-4.0
4.0
%
I
OUT
= 0 to 1A
V
OUT
(V
OUT
*
V
IN
) Load Regulation
V
IN
= 4.2V, I
LOAD
= 0 - 1A
3.0
%
V
OUT
/V
OUT
Line Regulation
V
IN
= 2.7 to 5.5V
0.2
%/V
V
UVLO
Under-Voltage Lockout
V
IN
Rising
2.5
V
V
IN
Falling
1.2
V
UVLO(HYS)
Under-Voltage Lockout Hysteresis
250
mV
I
Q
Quiescent Supply Current
No Load, V
FB
= 0
160
300
A
I
SHDN
Shutdown Current
V
EN
= 0V, V
IN
= 5.5V
1.0
A
I
LIM
Current Limit
T
A
= 25C
1.2
A
R
DS(ON)H
High Side Switch On Resistance
T
A
= 25C
110
150
m
R
DS(ON)L
Low Side Switch On Resistance
T
A
= 25C
100
150
m
Efficiency
V
IN
= 5V, V
OUT
= 3.3V,
93
%
I
OUT
= 600mA
V
EN(L)
Enable Low Voltage
V
IN
= 2.7 to 5.5V
0.6
V
V
EN(H)
Enable High Voltage
V
IN
= 2.7 to 5.5V
1.4
V
I
EN
Enable Pin Leakage Current
V
EN
= 5.5V
1.0
A
F
OSC
Oscillator Frequency
T
A
= 25C
700
1000
1200
kHz
T
SD
Over-Temperature Shutdown
140
C
Threshold
T
HYS
Over-Temperature Shutdown
15
C
Hysteresis
Typical Characteristics
Oscillator Frequency Variation vs. Temperature
(V
IN
= 3.6V)
-10
-6
-2
2
6
10
-20
0
20
40
60
80
100
Temperature (
C)
Variation (%)
Oscillator Frequency Variation vs.
Supply Voltage
-1.5
-0.5
0.5
1.5
2.5
3.5
2.5
3
3.5
4
4.5
5
5.5
Supply Voltage (V)
Variation (%)
Enable Threshold vs. Input Voltage
0.7
0.8
0.9
1
1.1
1.2
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Enable Threshold (V)
V
EN
(H)
V
EN
(L)
R
DS(ON)
vs. Input Voltage
80
90
100
110
120
130
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
R
DS(ON)
(m
)
High Side
Low Side
Low Side R
DS(ON)
vs. Temperature
70
90
110
130
150
170
-20
0
20
40
60
80
100
120
Temperature (
C)
R
DS(ON)
(m
)
2.7V
3.6V
4.2V
5.5V
High Side R
DS(ON)
vs. Temperature
70
90
110
130
150
170
-20
0
20
40
60
80
100
120
Temperature (
C)
R
DS(ON)
(m
)
2.7V
3.6V
4.2V
5.5V
AAT1150
1MHz 1A Step-Down DC/DC Converter
1150.2005.03.1.2
5
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