AAT2511
Dual 600mA, 1MHz Step-Down DC/DC Converter
2511.2006.02.1.2
1
SystemPower
TM
General Description
The AAT2511 is a member of AnalogicTech's Total
Power Management ICTM (TPMICTM) product fam-
ily. It is comprised of two 1MHz step-down con-
verters designed to minimize external component
size and cost. The input voltage ranges from 2.7V
to 5.5V. The output voltage ranges from 0.6V to the
maximum applied input voltage and is externally
adjustable.
Peak current mode control with internal compensa-
tion provides a stable converter with low ESR ceram-
ic output capacitors for extremely low output ripple.
Each channel has a low 25A quiescent operating
current, which is critical for maintaining high effi-
ciency at light load.
For maximum battery life, each converter's high-
side P-channel MOSFET conducts continuously
when the input voltage approaches dropout (100%
duty cycle operation).
Both regulators have independent input and
enable inputs.
The AAT2511 is available in a Pb-free, thermally-
enhanced 12-pin TDFN33 package, and is rated
over the -40C to +85C temperature range.
Features
Up to 97% Efficiency
25A Quiescent Current Per Channel
V
IN
Range: 2.7V to 5.5V
V
OUT
Range: 0.6V to V
IN
Output Current: 600mA
Low R
DS(ON)
0.4
Integrated Power Switches
Low Drop Out 100% Duty Cycle
1.0MHz Switching Frequency
Shutdown Current <1A
Current Mode Operation
Internal Reference Soft Start
Short-Circuit Protection
Fast Turn-On (100s Typical)
Over-Temperature Protection
3mm x 3mm, < 1mm high
TDFN33-12 Package
-40C to +85C Temperature Range
Applications
Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
Portable Media Players
Typical Application
AAT2511 Efficiency
(V
IN
= 3.3V)
Load Current (mA)
Efficiency (%)
60
65
70
75
80
85
90
95
100
0.1
1
10
100
1000
2.5V
1.8V
4.7
H
L1
10
F
C1
1.8V
118k
R1
59.0k
R2
10
H
L2
10
F
C2
2.5V
59.0k
R4
10
F
C3
V
IN
187k
R3
FB1
2
EN1
1
LX1
11
GND2
7
LX2
8
GND1
10
SGND1
3
VIN1
12
VIN2
9
SGND2
6
FB2
5
EN2
4
AAT2511
U1
0.1
F
C8
Pin Descriptions
Pin Configuration
TDFN33-12
(Top View)
EN1
FB1
SGND1
1
EN2
FB2
SGND2
VIN1
LX1
GND1
VIN2
LX2
GND2
2
3
4
5
6
12
11
10
9
8
7
Pin #
Symbol
Function
1, 4
EN1, EN2
Converter enable input. A logic high enables the converter channel. A logic low
forces the channel into shutdown mode, reducing the channel supply current to less
than 1A. This pin should not be left floating. When not actively controlled, this pin
can be tied directly to the source voltage (VIN1, VIN2).
2, 5
FB1, FB2
Feedback input pin. An external resistive divider ties to this point and programs the
output voltage to the desired value.
3, 6
SGND1, SGND2
Signal ground. Return the feedback resistive divider to this ground. See section on
PCB layout guidelines and evaluation board layout diagram.
7, 10
GND2, GND1
Main power ground return. Connect to the input and output capacitor return. See sec-
tion on PCB layout guidelines and evaluation board layout diagram.
8, 11
LX2, LX1
Output switching node that connects to the respective output inductor.
9, 12
VIN2, VIN1
Input supply voltage. Must be closely decoupled to the respective power gnd.
EP
Exposed paddle (bottom). Use properly sized vias for thermal coupling to the ground
plane. See section on PCB layout guidelines.
AAT2511
Dual 600mA, 1MHz Step-Down DC/DC Converter
2
2511.2006.02.1.2
Absolute Maximum Ratings
1
Thermal Information
Symbol
Description
Value
Units
P
D
Maximum Power Dissipation
2
W
JA
Thermal Resistance
2
50
C/W
Symbol
Description
Value
Units
V
IN
VIN1, VIN2 to SGND1, SGND2, GND1, and GND2
6.0
V
V
LX
LX1, LX2 to GND1, GND2
-0.3 to V
P
+ 0.3
V
V
FB
FB1 and FB2 to SGND1, SGND2, GND1, and GND2
-0.3 to V
P
+ 0.3
V
V
EN
EN1 and EN2 to SGND1, SGND2, GND1, and GND2
-0.3 to 6.0
V
T
J
Operating Junction Temperature Range
-40 to 150
C
T
LEAD
Maximum Soldering Temperature (at leads, 10 sec)
300
C
AAT2511
Dual 600mA, 1MHz Step-Down DC/DC Converter
2511.2006.02.1.2
3
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 with exposed paddle connected to ground plane.
Electrical Characteristics
1
T
A
= -40C to 85C, unless otherwise noted. Typical values are T
A
= 25C, V
IN
= 3.6V.
Symbol
Description
Conditions
Min
Typ
Max
Units
Step-Down Converter Channels
V
IN
Input Voltage
2.7
5.5
V
V
IN
Rising
2.6
V
V
UVLO
UVLO Threshold
Hysteresis
100
mV
V
IN
Falling
1.8
V
V
OUT
Output Voltage Tolerance
I
OUT
= 0 to 400mA, V
IN
= 2.7 - 5.5V
-3.0
+3.0
%
V
OUT
Output Voltage Range
0.6
4.0
V
I
Q
Quiescent Current
No Load, 0.6V Adjustable Version,
25
50
A
Per Channel
I
SHDN
Shutdown Current
EN = SGND = GND
1.0
A
I
LIM
P-Channel Current Limit
600
mA
R
DS(ON)H
High Side Switch On Resistance
0.45
R
DS(ON)L
Low Side Switch On Resistance
0.4
I
LXLK
LX Leakage Current
V
IN
= 5.5V, V
LX
= 0 to V
IN
,
1
A
EN = SGND = GND
V
Linereg
Line Regulation
V
IN
= 2.7V to 5.5V
0.2
%/V
V
FB
FB Threshold Voltage Accuracy
0.6V Output, No Load, T
A
= 25C
597
600
615
mV
T
S
Start-Up Time
From Enable to Output Regulation
100
s
F
OSC
Oscillator Frequency
T
A
= 25C
0.7
1.0
1.5
MHz
T
SD
Over-Temperature Shutdown
140
C
Threshold
T
HYS
Over-Temperature Shutdown
15
C
Hysteresis
EN
V
EN(L)
Enable Threshold Low
0.6
V
V
EN(H)
Enable Threshold High
1.4
V
I
EN
Input Low Current
V
IN
= V
FB
= 5.5V
-1.0
1.0
A
AAT2511
Dual 600mA, 1MHz Step-Down DC/DC Converter
4
2511.2006.02.1.2
1. The AAT2511 is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is assured
by design, characterization, and correlation with statistical process controls.
2. For adjustable version with higher than 2.5V output, please consult your AnalogicTech representative.
Typical Channel Characteristics
DC Regulation
(V
OUT
= 1.5V; L = 4.7
H)
Output Current (mA)
Output Error (%)
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
0.1
1
10
100
1000
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 2.7V
Efficiency vs. Load
(V
OUT
= 1.5V; L = 4.7
H)
Output Current (mA)
Efficiency (%)
50
60
70
80
90
100
0.1
1
10
100
1000
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 2.7V
DC Regulation
(V
OUT
= 2.5V; L = 10
H)
Output Current (mA)
Output Error (%)
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
0.1
1
10
100
1000
V
IN
= 3.6V
V
IN
= 3.3V
V
IN
= 3.0V
Efficiency vs. Load
(V
OUT
= 2.5V; L = 10
H)
Output Current (mA)
Efficiency (%)
60
70
80
90
100
0.1
1
10
100
1000
V
IN
= 3.0V
V
IN
= 3.6V
V
IN
= 3.3V
DC Regulation
(V
OUT
= 3.3V; L = 10
H)
Output Current (mA)
Output Error (%)
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
0.1
1
10
100
1000
V
IN
= 4.2V
V
IN
= 3.9V
Efficiency vs. Load
(V
OUT
= 3.3V; L = 10
H)
Output Current (mA)
Efficiency (%)
60
70
80
90
100
0.1
1
10
100
1000
V
IN
= 3.9V
V
IN
= 4.2V
AAT2511
Dual 600mA, 1MHz Step-Down DC/DC Converter
2511.2006.02.1.2
5
PDF 
ZIP