1MHz 3A Step-Down DC/DC Converter
General Description
The AAT1154 SwitchReg is a step-down switching
converter ideal for applications where high efficien-
cy, small size, and low ripple are critical. Able to
deliver 3A with an internal power MOSFET, the cur-
rent-mode controlled IC provides high efficiency.
Fully internally compensated, the AAT1154 simpli-
fies system design and lowers external parts count.
The AAT1154 is available in a Pb-free SOP-8 pack-
age and is rated over the -40°C to +85°C tempera-
ture range.
AAT1154
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
SwitchReg
™
V
IN
Range: 2.7V to 5.5V
Fixed or Adjustable V
OUT
: 1.0V to 4.2V
3A Output Current
Up to 95% Efficiency
Integrated Low On Resistance Power Switch
Internally Compensated Current Mode Control
1MHz Switching Frequency
Constant Pulse Width Modulation (PWM)
Mode
Low Output Ripple With Light Load
Internal Soft Start
Current Limit Protection
Over-Temperature Protection
SOP-8 Package
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
Cable/DSL Modems
Computer Peripherals
High Efficiency Conversion from 5V or 3.3V
Supply
Network Cards
Set-Top Boxes
Typical Application
INPUT
VP
FB
10μF
100Ω
AAT1154
VCC
LX
1.5μH
EN
0.1μF
GND
120μF
OUTPUT
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1
1MHz 3A Step-Down DC/DC Converter
Pin Descriptions
Pin #
1
AAT1154
Symbol
FB
Function
Feedback input pin. This pin must be connected to the converter
output. It is used to set the converter output to regulate to the
desired value.
Ground connection.
Enable input pin. When connected high, the AAT1154 is in normal
operation; when connected low, it is powered down. This pin
should not be left floating.
Power supply: supplies power for the internal circuitry.
Input supply voltage for converter power stage.
Inductor connection pins. These pins should be connected to the
output inductor. Internally, Pins 6 and 7 are connected to the drain
of the P-channel switch.
2
3
GND
EN
4
5, 8
6, 7
VCC
VP
LX
Pin Configuration
SOP-8
FB
GND
EN
VCC
1
8
VP
LX
LX
VP
1
2
2
7
3
6
4
5
2
1154.2006.09.1.6
1MHz 3A Step-Down DC/DC Converter
Absolute Maximum Ratings
1
T
A
= 25°C, unless otherwise noted.
Symbol
V
CC
, V
P
V
LX
V
FB
V
EN
T
J
V
ESD
AAT1154
Description
VCC, VP to GND
LX to GND
FB to GND
EN to GND
Operating Junction Temperature Range
ESD Rating
2
- HBM
Value
6
-0.3 to V
P
+ 0.3
-0.3 to V
CC
+ 0.3
-0.3 to V
CC
+ 0.3
-40 to 150
3000
Units
V
V
V
V
°C
V
Thermal Characteristics
3
Symbol
Θ
JA
P
D
Description
Thermal Resistance
Maximum Power Dissipation (T
A
= 25°C)
4
Value
110
909
Units
°C/W
mW
Recommended Operating Conditions
Symbol
T
Description
Ambient Temperature Range
Rating
-40 to +85
Units
°C
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 1.5kΩ resistor into each pin.
3. Mounted on a demo board (FR4, in still air).
4. Derate 9.1mW/°C above 25°C.
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1MHz 3A Step-Down DC/DC Converter
Electrical Characteristics
V
IN
= V
CC
= V
P
= 5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= 25°C.
Symbol
V
IN
V
OUT
V
UVLO
V
UVLO(HYS)
I
Q
I
SHDN
I
LIM
R
DS(ON)H
η
ΔV
OUT
(V
OUT
*ΔV
IN
)
ΔV
OUT
/V
OUT
F
OSC
V
EN(L)
V
EN(H)
T
SD
T
HYS
AAT1154
Description
Input Voltage Range
Output Voltage Tolerance
Under-Voltage Lockout
Under-Voltage Lockout Hysteresis
Quiescent Supply Current
Shutdown Current
Current Limit
High Side Switch On Resistance
Efficiency
Load Regulation
Line Regulation
Oscillator Frequency
Enable Threshold Low
Enable Threshold High
Over-Temperature Shutdown
Threshold
Over-Temperature Shutdown
Hysteresis
Conditions
V
IN
= V
OUT
+ 0.2V to 5.5V,
I
OUT
= 0A to 3A
V
IN
Rising
V
IN
Falling
No Load, V
FB
= 0V
V
EN
= 0V, V
IN
= 5.5V
T
A
= 25°C
T
A
= 25°C
I
OUT
= 1A
I
LOAD
= 0A to 3A
V
IN
= 2.7V to 5.5V
T
A
= 25°C
Min
2.7
-5.0
1.2
Typ Max Units
5.5
5.0
2.5
250
630
V
%
V
mV
µA
µA
A
mΩ
%
%
%/V
MHz
V
V
°C
°C
1000
1.0
4.4
60
92
±2.6
0.75
1
0.6
1.4
140
15
4
1154.2006.09.1.6
1MHz 3A Step-Down DC/DC Converter
Typical Characteristics
Efficiency vs. Load Current
(V
IN
= 5V; V
OUT
= 3.3V)
100
95
AAT1154
R
DS(ON)
vs. Temperature
90
80
Efficiency (%)
90
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
R
DS(ON)
(mΩ)
85
80
75
70
65
60
0.01
0.1
1
10
70
60
50
40
-20
0
20
40
60
80
100
120
V
IN
= 5.5V
V
IN
= 5V
Output Current (A)
Temperature (°C)
Oscillator Frequency Variation vs.
Supply Voltage
0.5
70
65
R
DS(ON)
vs. V
IN
(I
DS
= 1A)
R
DS(ON)
(mΩ)
Ω
Variation (%)
0.25
60
55
50
45
40
0
-0.25
-0.5
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Input Voltage (V)
Oscillator Frequency Variation vs. Temperature
(V
IN
= 5V)
Enable Threshold (V)
1
0
1.2
1.1
1
0.9
0.8
0.7
0.6
-20
0
20
40
60
80
100
Enable Threshold vs. Input Voltage
EN(H)
Variation (%)
-1
-2
-3
-4
EN(L)
2.5
3
3.5
4
4.5
5
5.5
Temperature (°C)
Input Voltage (V)
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