AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
1
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
General Description
The AAT2500 is a member of Skyworks' Total Power
Management IC™ (TPMIC™) product family. It is a low
dropout (LDO) linear regulator and a step-down con-
verter with an input voltage range of 2.7V to 5.5V, mak-
ing it ideal for applications with single lithium-ion/poly-
mer batteries.
The LDO has an independent input and is capable of
delivering up to 300mA. The linear regulator has been
designed for high-speed turn-on and turn-off perfor-
mance, fast transient response, and good power supply
rejection ratio (PSRR). Other features include low quies-
cent current and a low dropout voltage.
The 400mA step-down converter is designed to minimize
external component size and cost while maintaining a
low 25μA no load quiescent current.
Peak current mode control with internal compensation
provides a stable converter with a low equivalent series
resistance (ESR) ceramic output capacitor for extremely
low output ripple.
For maximum battery life, the step-down converter
increases to 100% duty cycle and has a typical 180mV
dropout voltage at 400mA. The output voltage is either
fixed or adjustable with an integrated P- and N-channel
MOSFET power stage and 1MHz switching frequency.
The AAT2500 is available in a 12-pin TDFN33 package,
and is rated over a temperature range of -40°C to
+85°C.
Features
▪ V
IN Range: 2.7V to 5.5V
▪ 300mA LDO Current Output
▪ 400mV LDO Dropout Voltage at 300mA
▪ High Output Accuracy: ±1.5%
▪ Fast LDO Line / Load Transient Response
▪ 400mA, 96% Efficiency Step-Down Converter
▪ 25μA No Load Quiescent Current for Step-Down
Converter
▪ Shutdown Current <1μA
▪ Low RDS(ON) 0.4 Integrated Power Switches
▪ Low Dropout 100% Duty Cycle
▪ 1MHz Switching Frequency
▪ Internal Soft Start
▪ Over-Temperature Protection
▪ Current Limit Protection
▪ Available in TDFN33-12 Package
▪ -40°C to +85°C Temperature Range
Applications
▪ Cellular Phones
▪ Digital Cameras
▪ Handheld Instruments
▪ Microprocessor/DSP Core/IO Power
▪ PDAs and Handheld Computers
▪ Portable Media Players
Typical Application
4.7μH
L1
4.7μF
C1
2.2μF
C4
10μF
C3
10nF
C5
PGND 1
LX 2
VP
3VCC 4
ENLDO
9
EN 10
FB 11
SGND 12
VLDO
5
OUT
6
GND
8
BYP
7
AAT2500
U1
L1 Sumida CDRH3D16-4R7 C1 Murata GRM219R61A475KE19
C3 Murata GR M21BR60J106KE19
VIN = 2.7V to 5.5V
3.3V at 300mA
2.5V at 400mA
AAT2500 Step-Down Converter Efficiency
Load Current (mA)
Efficiency (%)
60
65
70
75
80
85
90
95
100
0.1 1 10 100 1000
VIN = 3.3V
1.8V
2.5V
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
2Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Pin Descriptions
Pin # Symbol Function
1 PGND Step-down converter power ground return pin. Connect to the output and input capacitor return. See sec-
tion on PCB layout guidelines and evaluation board layout diagram.
2 LX Power switching node. Output switching node that connects to the output inductor.
3 VP Step-down converter power stage supply voltage. Must be closely decoupled to PGND.
4 VCC Step-down converter bias supply. Connect to VP.
5 VLDO LDO input voltage; should be decoupled with 1μF or greater capacitor.
6 OUT 300mA LDO output pin. A 2.2μF or greater output low-ESR ceramic capacitor is required for stability.
7 BYP Bypass capacitor for the LDO. To improve AC ripple rejection, connect a 10nF capacitor to GND. This will
also provide a soft-start function.
8 GND LDO ground connection pin.
9 ENLDO Enable pin for LDO. When connected low, LDO is disabled and consumes less than 1μA of current.
10 EN Step-down converter enable. When connected low, LDO is disabled and consumes less than 1μA.
11 FB
Step-down converter feedback input pin. For fi xed output voltage versions, this pin is connected to the
converter output, forcing the converter to regulate to the specifi c voltage. For adjustable output versions,
an external resistive divider ties to this point and programs the output voltage to the desired value.
12 SGND
Step-down converter signal ground. For external feedback, return the feedback resistive divider to this
ground. For internal fi xed version, tie to the point of load return. See section on PCB layout guidelines
and evaluation board layout diagram.
EP Exposed paddle (bottom). Use properly sized vias for thermal coupling to the ground plane. See section
on PCB layout guidelines.
Pin Configuration
TDFN33-12
(Top View)
PGND
LX
VP
1
VCC
VLDO
OUT
SGND
FB
EN
ENLDO
GND
BYP
2
3
4
5
6
12
11
10
9
8
7
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
3
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
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 with exposed paddle connected to ground plane.
Absolute Maximum Ratings1
Symbol Description Value Units
VP
, VLDO Input Voltages to GND 6.0 V
VLX LX to GND -0.3 to VP + 0.3 V
VFB FB to GND -0.3 to VP + 0.3 V
VEN EN to GND -0.3 to 6.0 V
TJOperating Junction Temperature Range -40 to 150 °C
TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C
Thermal Information
Symbol Description Value Units
PD Maximum Power Dissipation 2 W
JA Thermal Resistance250 °C/W
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
4Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
1. The AAT2500 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. To calculate the minimum LDO input voltage, use the following equation: VIN(MIN) = VOUT(MAX) + VDO(MAX), as long as VIN ≥ 2.5V.
3. For VOUT <2.1V, VDO = 2.5 - VOUT
.
4. VDO is defined as VIN - VOUT when VOUT is 98% of nominal.
Electrical Characteristics1
VIN = VLDO = VOUT(NOM) + 1V for VOUT options greater than 1.5V. VIN = VLDO = 2.5V for VOUT ≤ 1.5V. IOUT = 1mA, COUT =
2.2μF, C IN = 1μF, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol Description Conditions Min Typ Max Units
LDO
VOUT Output Voltage Tolerance IOUT = 1mA
to 300mA
TA = 25°C -1.5 1.5
%
TA = -40°C
to 85°C -2.5 2.5
VIN Input Voltage VOUT +
VDO25.5 V
VDO Dropout Voltage3, 4 IOUT = 300mA 400 600 mV
VOUT/
VOUT*VIN
Line Regulation VIN = VOUT + 1V to 5V 0.09 %/V
VOUT(Line) Dynamic Line Regulation IOUT = 300mA, VIN = VOUT + 1V to
VOUT + 2V, TR/TF = 2μs2.5 mV
VOUT(Load) Dynamic Load Regulation IOUT = 1mA to 300mA, TR <5μs60mV
IOUT Output Current VOUT > 1.3V 300 mA
ISC Short-Circuit Current VOUT < 0.4V 600 mA
IQLDO LDO Quiescent Current VIN = 5V, No Load, ENLDO = VIN 70 125 μA
ISHDN Shutdown Current VIN = 5V; ENLDO = GND,
EN = SGND = PGND 1.0 μA
PSRR Power Supply Rejection Ratio IOUT = 10mA,
CBYP = 10nF
1kHz 67
dB10kHz 47
1MHz 45
TSD Over-Temperature Shutdown Threshold 145 °C
THYS Over-Temperature Shutdown Hysteresis 12 °C
eNOutput Noise eNBW = 300Hz to 50kHz 50 μVRMS
TCOutput Voltage Temperature Coeffi cient 22 ppm/°C
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
5
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
1. The AAT2500 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. For adjustable version with higher than 2.5V output, please consult your Skyworks representative.
Electrical Characteristics1
Typical values are TA = 25°C, VIN = VCC = Vp = 3.6V.
Symbol Description Conditions Min Typ Max Units
Buck Converter
VIN Input Voltage 2.7 5.5 V
VUVLO UVLO Threshold
VIN Rising 2.6 V
Hysteresis 100 mV
VIN Falling 1.8 V
VOUT Output Voltage Tolerance IOUT = 0 to 400mA, VIN = 2.7V to 5.5V -3.0 +3.0 %
VOUT Output Voltage Range Fixed Output Version 0.6 4.0 V
Adjustable Output Version20.6 2.5
IQBUCK Step-Down Converter Quiescent Current ENLDO = GND, No Load, 0.6V Adjustable Model 25 50 μA
ISHDN Shutdown Current EN = SGND = PGND, ENLDO = GND 1.0 μA
ILIM P-Channel Current Limit 600 mA
RDS(ON)H High Side Switch On Resistance 0.45
RDS(ON)L Low Side Switch On Resistance 0.4
ILXLK LX Leakage Current VIN = 5.5V, VLX = 0 - VIN, EN = SGND = PGND 1.0 μA
VLinereg Line Regulation VIN = 2.7V to 5.5V 0.2 %/V
VFB FB Threshold Voltage Accuracy 0.6V Output, No Load, TA = 25°C 597 600 615 mV
IFB FB Leakage Current 0.6V Output 0.2 μA
RFB FB Impedance >0.6V Output 250 k
FOSC Oscillator Frequency TA = 25°C 0.7 1.0 1.5 MHz
TSD Over-Temperature Shutdown Threshold 140 °C
THYS Over-Temperature Shutdown Hysteresis 15 °C
Logic Signals
VEN(L) Enable Threshold Low 0.6 V
VEN(H) Enable Threshold High 1.5 V
IEN(H) Leakage Current 1.0 1.0 μA
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
6Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
LDO Dropout Voltage vs. Temperature
(EN = GND; ENLDO = VIN)
0
60
120
180
240
300
360
420
480
540
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Temperature (
°
C)
Dropout Voltage (mV)
IL = 300mA
IL = 150mA IL = 100mA
IL = 50mA
LDO Dropout Characteristics
(EN = GND; ENLDO = VIN)
2.00
2.20
2.40
2.60
2.80
3.00
3.20
2.70 2.80 2.90 3.00 3.10 3.20 3.30
Input Voltage (V)
Output Voltage (V)
IOUT = 300mA
IOUT = 150mA
IOUT = 100mA
IOUT = 50mA
IOUT = 10mA
IOUT = 0mA
LDO Dropout Voltage vs. Output Current
(EN = GND; ENLDO = VIN)
0
50
100
150
200
250
300
350
400
450
500
0 50 100 150 200 250 300
Output Current (mA)
Dropout Voltage (mV)
85°C
25°C
-40°C
LDO Ground Current vs. Input Voltage
(EN = GND; ENLDO = VIN)
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
2 2.5 3 3.5 4.545
Input Voltage (V)
Ground Current (
µ
A)
IOUT=0mA
IOUT=10mA
IOUT=50mA
IOUT=150mA
IOUT=300mA
LDO Output Voltage vs. Temperature
(EN = GND; ENLDO = VIN)
1.196
1.197
1.198
1.199
1.200
1.201
1.202
1.203
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100
Temperature (
°
C)
Output Voltage (V)
LDO Initial Power-Up Response Time
(CBYP = 10nF; EN = GND; ENLDO = VIN)
Time (400µs/div)
VENLDO (5V/div)
VOUT (1V/div)
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
7
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C, VIN = VLDO = VCC = VP
.
LDO Turn-Off Response Time
(CBYP = 10nF; EN = GND; ENLDO = VIN)
Time (50µs/div)
VENLDO (5V/div)
VOUT (1V/div)
LDO Turn-On Time From Enable (VIN present)
(CBYP = 10nF; EN = GND; ENLDO = VIN)
Time (5µs/div)
VIN = 4V
VOUT = 1V/div
VENLDO = 5V/div
LDO Line Transient Response
(CBYP = 10nF; EN = GND; ENLDO = VIN)
2.98
2.99
3.00
3.01
3.02
3.03
3.04
Time (100µs/div)
Input Voltage (V)
0
1
2
3
4
5
6
Output Voltage (V)
VIN
VOUT
LDO Load Transient Response
(CBYP = 10nF; EN = GND; ENLDO = VIN)
2.60
2.65
2.70
2.75
2.80
2.85
2.90
Time (100µs/div)
Output Voltage (V)
-100
0
100
200
300
400
500
Output Current (mA)
VOUT
IOUT
LDO Load Transient Response 300mA
(CBYP = 10nF; EN = GND; ENLDO = VIN)
2.10
2.20
2.30
2.40
2.50
2.60
2.70
2.80
2.90
3.00
Time (10µs/div)
Output Voltage (V)
-100
0
100
200
300
400
500
600
700
800
Output Current (mA)
VOUT
IOUT
LDO Self Noise
(EN = GND; ENLDO = VIN)
0.001
0.01
0.1
1
10
0.01 0.1 1 10 100 1000 10000
Frequency (kHz)
Noise Amplitude (
μ
V/rtHz)
Band Power:
300Hz to 50kHz = 44.6μVrms
100Hz to 100kHz = 56.3μVrms
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
8Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Over-Current Protection
(EN = GND; ENLDO = VIN)
Time (50ms/div)
Output Current (mA)
-200
0
200
400
600
800
1000
1200
LDO ENLDO vs. VIN
1.050
1.075
1.100
1.125
1.150
1.175
1.200
1.225
1.250
2.5 3.0 3.5 4.0 4.5 5.0 5.5
Input Voltage (V)
VIH
VIL
Step-Down Converter Efficiency vs. Load
(VOUT = 2.5V; EN = VIN; ENLDO = GND)
Output Current (mA)
Efficiency (%)
60
70
80
90
100
0.1 1.0 10 100 1000
VIN = 3.3V
VIN = 3.6V
VIN = 3.0V
Step-Down Converter Load Regulation
(VOUT = 2.5V; EN = VIN; ENLDO = GND)
Output Current (mA)
Output Error (%)
-2.0
-1.0
0.0
1.0
2.0
0.1 1.0 10 100 1000
VIN = 3.0V
VIN = 3.3V
VIN = 3.6V
Step-Down Converter Efficiency vs. Load
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
Output Current (mA)
Efficiency (%)
50
60
70
80
90
100
0.1 1.0 10 100 1000
VIN = 2.7V VIN = 3.6V
VIN = 4.2V
Step-Down Converter DC Regulation
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
Output Current (mA)
Output Error (%)
-2.0
-1.0
0.0
1.0
2.0
0.1 1.0 10 100 1000
VIN = 2.7V
VIN = 3.6V
VIN = 4.2V
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
9
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Step-Down Converter
Frequency vs. Input Voltage
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
Input Voltage (V)
Frequency Variation (%)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Step-Down Converter
Output Voltage Error vs. Temperature
(VIN = 3.6V; VO = 1.5V; EN = VIN; ENLDO = GND)
Tem
p
erature
(
°
°
C
)
Output Error (%)
-2.0
-1.0
0.0
1.0
2.0
-40 -20 0 20 40 60 80 100
Step-Down Converter
Switching Frequency vs. Temperature
(VIN = 3.6V; VO = 1.5V; EN = VIN; ENLDO = GND)
Temperature (°
°
C)
Frequency Variation (%)
-0.20
-0.10
0.00
0.10
0.20
-40 -20 0 20 40 60 80 100
Step-Down Converter
Input Current vs. Input Voltage
(VO = 1.8V; EN = VIN; ENLDO = GND)
Input Voltage (V)
Input Current (μ
μ
A)
85°C
25°C
-40°C
15
20
25
30
35
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Step-Down Converter
P-Channel RDS(ON) vs. Input Voltage
(EN = VIN; ENLDO = GND)
Input Voltage (V)
RDS(ON) (mΩ
Ω
)
300
350
400
450
500
550
600
650
700
750
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
25°C
120°C100°C
85°C
Step-Down Converter
N-Channel RDS(ON) vs. Input Voltage
(EN = VIN; ENLDO = GND)
Input Voltage (V)
RDS(ON) (mΩ
Ω
)
300
350
400
450
500
550
600
650
700
750
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
25°C
120°C100°C
85°C
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Step-Down Converter Load Transient Response
(30mA - 300mA; VIN = 3.6V; VOUT = 1.8V;
C1 = 10μ
μ
F; EN = VIN; ENLDO = GND)
Output Voltage
(top) (V)
Load and Inductor Current
(200mA/div) (bottom)
Time (25
μ
s/div)
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0 1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
300mA
30mA
Step-Down Converter Load Transient Response
(30mA - 300mA; VIN = 3.6V; VOUT = 1.8V; C1 = 10μ
μ
F;
C4 = 100pF; EN = VIN; ENLDO = GND)
Output Voltage (AC Coupled)
(top) (V)
Load and Inductor Current
(200mA/div) (bottom)
Time (25
μ
s/div)
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.1
0.0 1.2
1.4
0.8
0.6
1.0
0.2
0.4
-0.2
0.0
300mA
30mA
Step-Down Converter Load Transient Response
(30mA - 300mA; VIN = 3.6V; VOUT = 1.8V;
C1 = 4.7µF; EN = VIN; ENLDO = GND)
Output Voltage
(top) (V)
Load and Inductor Current
(200mA/div) (bottom)
Time (25µs/div)
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0 1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
300mA
30mA
Step-Down Converter Line Transient
(VOUT = 1.8V @ 400mA; EN = VIN; ENLDO = GND)
Output Voltage
(top) (V)
Input Voltage
(bottom) (V)
Time (25µs/div)
1.50
1.55
1.60
1.65
1.70
1.75
1.80
1.85
1.90
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
Step-Down Converter Line Regulation
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
Input Voltage (V)
Accuracy (%)
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
IOUT = 400mA
IOUT = 100mA
IOUT = 10mA
Step-Down Converter Soft Start
(VIN = 3.6V; VOUT = 1.8V; 400mA;
EN = VIN; ENLDO = GND)
Enable and Output Voltage
(top) (V)
Inductor Current
(bottom) (A)
Time (250µs/div)
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
11
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Step-Down Converter Output Ripple
(VIN = 3.6V; VOUT = 1.8V; 400mA;
EN = VIN; ENLDO = GND)
Output Voltage (AC Coupled)
(top) (mV)
Inductor Current
(bottom) (A)
Time (250ns/div)
-120
-100
-80
-60
-40
-20
0
20
40
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Functional Block Diagram
EN
LX
Error
Amp.
Logic
DH
DL
PGND
VP
FB
GND
Voltage
Reference
Voltage
Reference
Error
Amp.
OUT
Control
Logic
VLDO
Fast Start
Control
ENLDO
BYP
SGND
VCC
See
Note
Over-Current
Protection
Note: Internal resistor divider included for ≥1.2V versions. For low voltage versions, the feedback pin is tied directly to the error amplifier input.
Functional Description
The AAT2500 is a high performance power management
IC comprised of a buck converter and a linear regulator.
The buck converter is a high efficiency converter capable
of delivering up to 400mA. Designed to operate at
1.0MHz, the converter requires only three external com-
ponents (CIN, COUT
, and LX) and is stable with a ceramic
output capacitor. The linear regulator delivers 300mA
and is also stable with ceramic capacitors.
Linear Regulator
The advanced circuit design of the linear regulator has
been specifically optimized for very fast start-up and
shutdown timing. This proprietary CMOS LDO has also
been tailored for superior transient response character-
istics. These traits are particularly important for applica-
tions that require fast power supply timing.
The high-speed turn-on capability is enabled through
implementation of a fast-start control circuit, which
accelerates the power-up behavior of fundamental con-
trol and feedback circuits within the LDO regulator. Fast
turn-off time response is achieved by an active output
pull-down circuit, which is enabled when the LDO regula-
tor is placed in shutdown mode. This active fast shut-
down circuit has no adverse effect on normal device
operation. The LDO regulator output has been specifi-
cally optimized to function with low-cost, low-ESR
ceramic capacitors; however, the design will allow for
operation over a wide range of capacitor types.
A bypass pin has been provided to allow the addition of
an optional voltage reference bypass capacitor to reduce
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
13
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
output self noise and increase power supply ripple rejec-
tion. Device self noise and PSRR will be improved by the
addition of a small ceramic capacitor in this pin. However,
increased values of CBYPASS may slow down the LDO regu-
lator turn-on time. The regulator comes with complete
short-circuit and thermal protection. The combination of
these two internal protection circuits gives a comprehen-
sive safety system to guard against extreme adverse
operating conditions.
The regulator features an enable/disable function. This
pin (ENLDO) is active high and is compatible with CMOS
logic. To assure the LDO regulator will switch on, the
ENLDO turn-on control level must be greater than 1.5V.
The LDO regulator will go into the disable shutdown
mode when the voltage on the EN pin falls below 0.6V. If
the enable function is not needed in a specific applica-
tion, it may be tied to VIN to keep the LDO regulator in a
continuously on state.
When the regulator is in shutdown mode, an internal
1.5k resistor is connected between OUT and GND. This
is intended to discharge COUT when the LDO regulator is
disabled. The internal 1.5K resistor has no adverse
impact on device turn-on time.
Step-Down Converter
The AAT2500 buck is a constant frequency peak current
mode PWM converter with internal compensation. It is
designed to operate with an input voltage range of 2.7V
to 5.5V. The output voltage ranges from 0.6V to the input
voltage for the internally fixed version, and up to 2.5V for
the externally adjustable version. The 0.6V fixed model
shown in Figure 1 is also the adjustable version and is
externally programmable with a resistive divider, as
shown in Figure 2. The converter MOSFET power stage is
sized for 400mA load capability with up to 96% efficiency.
Light load efficiency exceeds 80% at a 500μA load.
Soft Start
The AAT2500 soft-start control prevents output voltage
overshoot and limits inrush current when either the input
power or the enable input is applied. When pulled low, the
enable input forces the converter into a low-power, non-
switching state with a bias current of less than 1μA.
Low Dropout Operation
For conditions where the input voltage drops to the out-
put voltage level, the converter duty cycle increases to
100%. As 100% duty cycle is approached, the minimum
off-time initially forces the high side on-time to exceed
the 1MHz clock cycle and reduce the effective switching
frequency. Once the input drops below the level where
the output can be regulated, the high side P-channel
MOSFET is turned on continuously for 100% duty cycle.
At 100% duty cycle, the output voltage tracks the input
voltage minus the IR drop of the high side P-channel
MOSFET RDS(ON).
Low Supply
The under-voltage lockout (UVLO) guarantees sufficient
VIN bias and proper operation of all internal circuitry prior
to activation.
Fault Protection
For overload conditions, the peak inductor current is lim-
ited. Thermal protection disables switching when the
internal dissipation or ambient temperature becomes
excessive. The junction over-temperature threshold is
140°C with 15°C of hysteresis.
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Applications Information
Linear Regulator
Input and Output Capacitors
An input capacitor is not required for basic operation of
the linear regulator. However, if the AAT2500 is physically
located more than three centimeters from an input power
source, a CIN capacitor will be needed for stable operation.
Typically, a 1μF or larger capacitor is recommended for CIN
in most applications. CIN should be located as closely to
the device VIN pin as practically possible.
An input capacitor greater than 1μF will offer superior
input line transient response and maximize power supply
ripple rejection. Ceramic, tantalum, or aluminum elec-
trolytic capacitors may be selected for CIN. There is no
specific capacitor ESR requirement for CIN. However, for
300mA LDO regulator output operation, ceramic capaci-
tors are recommended for CIN due to their inherent capa-
bility over tantalum capacitors to withstand input current
surges from low impedance sources such as batteries in
portable devices.
For proper load voltage regulation and operational stabil-
ity, a capacitor is required between OUT and GND. The
COUT capacitor connection to the LDO regulator ground
pin should be made as directly as practically possible for
maximum device performance. Since the regulator has
been designed to function with very low ESR capacitors,
ceramic capacitors in the 1.0μF to 10μF range are rec-
ommended for best performance. Applications utilizing
the exceptionally low output noise and optimum power
supply ripple rejection should use 2.2μF or greater for
COUT
. In low output current applications, where output
load is less than 10mA, the minimum value for COUT can
be as low as 0.47μF.
Equivalent Series Resistance
ESR is a very important characteristic to consider when
selecting a capacitor. ESR is the internal series resistance
associated with a capacitor that includes lead resistance,
internal connections, size and area, material composi-
tion, and ambient temperature. Typically, capacitor ESR
is measured in milliohms for ceramic capacitors and can
range to more than several ohms for tantalum or alumi-
num electrolytic capacitors.
Bypass Capacitor and
Low Noise Applications
A bypass capacitor pin is provided to enhance the low
noise characteristics of the LDO. The bypass capacitor is
not necessary for operation; however, for best device
performance, a small ceramic capacitor in the range of
470pF to 10nF should be placed between the bypass pin
(BYP) and the device ground pin (GND). To practically
realize the highest power supply ripple rejection and low-
est output noise performance, it is critical that the capac-
itor connection between the BYP pin and GND pin be
direct and PCB traces should be as short as possible.
DC leakage on this pin can affect the LDO regulator out-
put noise and voltage regulation performance. For this
reason, the use of a low leakage, high quality ceramic
(NPO or C0G type) or film capacitor is highly recom-
mended.
L1
4.7μF
C1
VOUTBUCK
VIN
4.7μF
C4
10μF
C3
10nF
C5
VOUTLDO
PGND 1
LX 2
VP
3VCC 4
ENLDO
9
EN 10
FB 11
SGND 12
VLDO
5
OUT
6
GND
8
BYP
7
AAT2500
U1
L1
4.7μF
C1
VIN
R1
59k
R2
4.7μF
C4
10μF
C3
10nF
C5
VOUTLDO
VOUTBUCK
100pF
C8
PGND 1
LX 2
VP
3VCC 4
ENLDO
9
EN 10
FB 11
SGND 12
VLDO
5
OUT
6
GND
8
BYP
7
AAT2500
U1
Figure 1: AAT2500 Fixed Output. Figure 2: AAT2500 with Adjustable Step-Down
Output and Enhanced Transient Response.
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
15
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Step-Down Converter
Inductor Selection
The step-down converter uses peak current mode control
with slope compensation to maintain stability for duty
cycles greater than 50%. The output inductor value must
be selected so the inductor current down slope meets the
internal slope compensation requirements. The internal
slope compensation for the adjustable and low-voltage
fixed versions of the AAT2500 is 0.24A/μs. This equates
to a slope compensation that is 75% of the inductor cur-
rent down slope for a 1.5V output and 4.7μH inductor.
0.75 · V
O
m = = = 0.24
L
0.75 · 1.5V
4.7μH
A
μs
This is the internal slope compensation for the adjust-
able (0.6V) version or low-voltage fixed versions. When
externally programming the 0.6V version to 1.5V, the
calculated inductance is 7.5μH.
0.75 · V
O
L = = ≈ 3 · V
O
= 3 · 1.5V = 4.5μH
m
0.75
·
V
O
0.24A
μs
A
μs
A
A
μs
In this case, a standard 4.7μH value is selected.
Manufacturer’s specifications list both the inductor DC
current rating, which is a thermal limitation, and the
peak current rating, which is determined by the satura-
tion characteristics. The inductor should not show any
appreciable saturation under normal load conditions.
Some inductors may meet the peak and average current
ratings yet result in excessive losses due to a high DCR.
Always consider the losses associated with the DCR and
its effect on the total converter efficiency when selecting
an inductor.
The 4.7μH CDRH3D16 series inductor selected from
Sumida has a 105m DCR and a 900mA DC current rat-
ing. At full load, the inductor DC loss is 17mW which gives
a 2.8% loss in efficiency for a 400mA, 1.5V output.
Input Capacitor
Select a 4.7μF to 10μF X7R or X5R ceramic capacitor for
the input. To estimate the required input capacitor size,
determine the acceptable input ripple level (VPP) and solve
for C. The calculated value varies with input voltage and
is a maximum when VIN is double the output voltage.
⎛⎞
· 1 -
⎝⎠
VOBUCK
VIN
CIN =
VOBUCK
VIN
⎛⎞
- ESR · FS
⎝⎠
VPP
IOBUCK
⎛⎞
· 1 - = for VIN = 2 · VOBUC
K
⎝⎠
VOBUCK
VIN
VOBUCK
VIN
1
4
CIN(MIN) = 1
⎛⎞
- ESR · 4 · FS
⎝⎠
VPP
IOBUCK
Always examine the ceramic capacitor DC voltage coef-
ficient characteristics when selecting the proper value.
For example, the capacitance of a 10μF, 6.3V, X5R
ceramic capacitor with 5.0V DC applied is actually about
6μF.
The maximum input capacitor RMS current is:
⎛⎞
IRMS = IOBUCK · · 1 -
⎝⎠
VOBUCK
VIN
VOBUCK
VIN
The input capacitor RMS ripple current varies with the
input and output voltage and will always be less than or
equal to half of the total DC load current.
⎛⎞
· 1 - = D · (1 - D) = 0.52 =
⎝⎠
VOBUCK
VIN
VOBUCK
VIN
1
2
for VIN = 2 x VOBUCK
IOBUCK
RMS(MAX)
I2
=
The term
⎛⎞
· 1 -
⎝⎠
VOBUCK
VIN
VOBUCK
VIN appears in both the input volt-
age ripple and input capacitor RMS current equations
and is a maximum when VOBUCK is twice VIN. This is why
the input voltage ripple and the input capacitor RMS cur-
rent ripple are a maximum at 50% duty cycle.
The input capacitor provides a low impedance loop for
the edges of pulsed current drawn by the AAT2500. Low
ESR/ESL X7R and X5R ceramic capacitors are ideal for
this function. To minimize stray inductance, the capaci-
tor should be placed as closely as possible to the IC. This
keeps the high frequency content of the input current
localized, minimizing EMI and input voltage ripple.
The proper placement of the input capacitor (C2) can be
seen in the evaluation board layout in Figure 3.
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
16 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
A laboratory test set-up typically consists of two long
wires running from the bench power supply to the evalu-
ation board input voltage pins. The inductance of these
wires, along with the low-ESR ceramic input capacitor,
can create a high Q network that may affect converter
performance. This problem often becomes apparent in
the form of excessive ringing in the output voltage dur-
ing load transients. Errors in the loop phase and gain
measurements can also result.
Since the inductance of a short PCB trace feeding the
input voltage is significantly lower than the power leads
from the bench power supply, most applications do not
exhibit this problem.
In applications where the input power source lead induc-
tance cannot be reduced to a level that does not affect
the converter performance, a high ESR tantalum or alu-
minum electrolytic should be placed in parallel with the
low ESR, ESL bypass ceramic. This dampens the high Q
network and stabilizes the system.
Output Capacitor
The output capacitor limits the output ripple and pro-
vides holdup during large load transitions. A 4.7μF to
10μF X5R or X7R ceramic capacitor typically provides
sufficient bulk capacitance to stabilize the output during
large load transitions and has the ESR and ESL charac-
teristics necessary for low output ripple.
The output voltage droop due to a load transient is dom-
inated by the capacitance of the ceramic output capacitor.
During a step increase in load current, the ceramic output
capacitor alone supplies the load current until the loop
responds. Within two or three switching cycles, the loop
responds and the inductor current increases to match the
load current demand. The relationship of the output volt-
age droop during the three switching cycles to the output
capacitance can be estimated by:
COUT =
3 · ΔILOAD
VDROOP · FS
Once the average inductor current increases to the DC
load level, the output voltage recovers. The above equa-
tion establishes a limit on the minimum value for the
output capacitor with respect to load transients.
The internal voltage loop compensation also limits the
minimum output capacitor value to 4.7μF. This is due to
its effect on the loop crossover frequency (bandwidth),
phase margin, and gain margin. Increased output capac-
itance will reduce the crossover frequency with greater
phase margin.
The maximum output capacitor RMS ripple current is
given by:
1
23
VOUT · (VIN(MAX) - VOUT)
RMS(MAX)
IL · F · VIN(MAX)
=·
·
Dissipation due to the RMS current in the ceramic output
capacitor ESR is typically minimal, resulting in less than
a few degrees rise in hot-spot temperature.
Figure 3: AAT2500 Evaluation Board Top Side. Figure 4: AAT2500 Evaluation Board
Bottom Side.
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
17
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
1. For step-down converter, enhanced transient configuration C8 = 100pF and C1 = 10uF.
Adjustable Output Resistor Selection
For applications requiring an adjustable output voltage,
the 0.6V version can be externally programmed.
Resistors R1 and R2 of Figure 5 program the output to
regulate at a voltage higher than 0.6V. To limit the bias
current required for the external feedback resistor string
while maintaining good noise immunity, the minimum
suggested value for R2 is 59k. Although a larger value
will further reduce quiescent current, it will also increase
the impedance of the feedback node, making it more
sensitive to external noise and interference. Table 1
summarizes the resistor values for various output volt-
ages with R2 set to either 59k for good noise immu-
nity or 221k for reduced no load input current.
⎛⎞
⎝⎠
R1 = -1 · R2 = - 1 · 59kΩ = 88.5kΩ
VOUT
VREF
⎛⎞
⎝⎠
1.5V
0.6V
The adjustable version of the AAT2500, combined with
an external feedforward capacitor (C8 in Figures 2 and
5), delivers enhanced transient response for extreme
pulsed load applications. The addition of the feedforward
capacitor typically requires a larger output capacitor C1
for stability.
VOUT (V)
R2 = 59kΩ
R1 (kΩ)
R2 = 221kΩ
R1 (kΩ)
0.8 19.6 75
0.9 29.4 113
1.0 39.2 150
1.1 49.9 187
1.2 59.0 221
1.3 68.1 261
1.4 78.7 301
1.5 88.7 332
1.8 118 442
1.85 124 464
2.0 137 523
2.5 187 715
Table 1: Adjustable Resistor Values For Use With
0.6V Step-Down Converter.
Table 3
L1
4.7μF1
C1
10μF
C2
GND
VIN1
1
2
3
Buck Enable
LX1
GND
Table 3
R1
59k
R2
PGND
1
LX
2
VP
3
VCC
4ENLDO 9
EN 10
FB 11
SGND 12
IN
5
OUT
6
GND 8
BYP 7
AAT2500
U1
4.7μF
C4
10μF
C3
10nF
C5 1
2
3
LDO Enable
VOUTLDO
VOUTBUCK
1
2
3
LDO Input
0.01μF
C7
C81
n/a
C9
Figure 5: AAT2500 Evaluation Board Schematic.
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
18 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Thermal Calculations
There are three types of losses associated with the
AAT2500 step-down converter: switching losses, con-
duction losses, and quiescent current losses. Conduction
losses are associated with the RDS(ON) characteristics of
the power output switching devices. Switching losses are
dominated by the gate charge of the power output
switching devices. At full load, assuming continuous con-
duction mode (CCM), a simplified form of the step-down
converter and LDO losses is given by:
PTOTAL
IOBUCK
2 · (RDSON(HS) · VOBUCK + RDSON(LS) · [VIN - VOBUCK])
VIN
=
+ (tsw · F · IOBUCK + IQBUCK + IQLDO) · VIN + IOLDO · (VIN - VOLDO)
IQBUCK is the step-down converter quiescent current and
IQLDO is the LDO quiescent current. The term tsw is used
to estimate the full load step-down converter switching
losses.
For the condition where the buck converter is in dropout
at 100% duty cycle, the total device dissipation reduces
to:
PTOTAL = IOBUCK
2 · RDSON(HS) + IOLDO · (VIN - VOLDO)
+ (IQBUCK + IQLDO) · VIN
Since RDS(ON), quiescent current, and switching losses all
vary with input voltage, the total losses should be inves-
tigated over the complete input voltage range.
Given the total losses, the maximum junction tempera-
ture can be derived from the JA for the TDFN33-12 pack-
age which is 50°C/W.
TJ(MAX) = PTOTAL · ΘJA + TAMB
PCB Layout
The following guidelines should be used to ensure a
proper layout.
1. The input capacitor C2 should connect as closely as
possible to VP and PGND, as shown in Figure 4.
2. The output capacitor and inductor should be con-
nected as closely as possible. The connection of the
inductor to the LX pin should also be as short as pos-
sible.
3. The feedback trace should be separate from any
power trace and connect as closely as possible to the
load point. Sensing along a high-current load trace
will degrade DC load regulation. If external feedback
resistors are used, they should be placed as closely as
possible to the FB pin. This prevents noise from being
coupled into the high impedance feedback node.
4. The resistance of the trace from the load return to
GND should be kept to a minimum. This will help to
minimize any error in DC regulation due to differ-
ences in the potential of the internal signal ground
and the power ground.
5. For good thermal coupling, PCB vias are required
from the pad for the TDFN paddle to the ground
plane. The via diameter should be 0.3mm to 0.33mm
and positioned on a 1.2mm grid.
6. The LDO bypass capacitor (C5) should be connected
directly between Pins 7 (BYP) and 8 (GND).
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
19
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Step-Down Converter Design Example
Specifications
VOBUCK = 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load ILOAD = 300mA
VOLDO = 3.3V @ 300mA
VIN = 2.7V to 4.2V (3.6V nominal)
FS = 1.0MHz
TAMB = 85°C
1.8V Buck Output Inductor
L1 = 3 · V
O2
= 3 · 1.8V = 5.4μH
μs
A
μs
A
(see Table 1)
For Sumida inductor CDRH3D16, 4.7μH, DCR = 105m.
V
OBUCK
V
OBUCK
1.8
V
1.8V
ΔI
L1
=
⋅ 1 - = ⋅ 1 - = 218mA
L1 ⋅ F
V
IN
4.7μH ⋅ 1.0MHz
4.2V
I
PKL1
= I
OBUCK
+ ΔI
L1
= 0.4A + 0.11A = 0.51A
2
P
L1
= I
OBUCK2
⋅ DCR = 0.4A
2
⋅ 105mΩ = 17mW
⎛
⎝⎞
⎠
⎛
⎝⎞
⎠
1.8V Output Capacitor
VDROOP = 0.2V
1
23
1 1.8V · (4.2V - 1.8V)
4.7μH · 1.0MHz · 4.2V
23
RMS
IL1 · F · VIN(MAX)
= ·
·
3 · ΔILOAD
VDROOP · FS
3 · 0.3A
0.2V · 1MHz
COUT = = = 4.5μF
· = 63mArms
·
(VOBUCK) · (VIN(MAX) - VOBUCK)=
Pesr = esr · IRMS2 = 5mΩ · (63mA)2 = 20μW
Input Capacitor
Input Ripple VPP = 25mV
CIN = = = 4.75μF
1
⎛⎞
- ESR · 4 · FS
⎝⎠
VPP
IOBUCK
1
⎛⎞
- 5mΩ · 4 · 1MHz
⎝⎠
25mV
0.4A
IOBUCK
RMS
I
P = esr · I
RMS
2 = 5mΩ ·
(
0.2A
)
2 = 0.2mW
2
= = 0.2Arms
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
20 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
AAT2500 Losses
PTOTAL
+ (tsw · F · IOBUCK + IQBUCK + IQLDO) · VIN + (VIN - VLDO) · ILDO
IOBUCK
2 · (RDSON(HS) · VOBUCK + RDSON(LS) · [VIN - VOBUCK])
VIN
=
=
+ (5ns · 1.0MHz · 0.4A + 50μA +125μA) · 4.2V + (4.2V - 3.3V) · 0.3A = 392mW
0.42 · (0.725Ω · 1.8V + 0.7Ω · [4.2V - 1.8V])
4.2V
TJ(MAX) = TAMB + ΘJA • PLOSS = 85°C + (50°C/W) • 392mW = 105°
C
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
21
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
1. For reduced quiescent current R2 = 221k.
VOUT (V)
Adjustable Version
(0.6V device)
R1 (kΩ)
R2 = 59kΩ
R1 (kΩ)
R2 = 221kΩ1L1 (μH)
0.8 19.6 75.0 4.7
0.9 29.4 113 4.7
1.0 39.2 150 4.7
1.1 49.9 187 4.7
1.2 59.0 221 4.7
1.3 68.1 261 4.7
1.4 78.7 301 4.7
1.5 88.7 332 4.7
1.8 118 442 4.7
1.85 124 464 4.7
2.0 137 523 4.7 or 6.8
2.5 187 715 10
VOUT (V)
Fixed Version
R1 (kΩ)
R2 Not Used L1 (μH)
0.6-3.3V 0 4.7
Table 3: Evaluation Board Component Values.
Manufacturer Part Number
Inductance
(μH)
Max DC
Current (A)
DCR
(Ω)
Size (mm)
LxWxH Type
Sumida CDRH3D16-4R7 4.7 0.90 0.11 3.8x3.8x1.8 Shielded
Sumida CDRH3D16-100 10 0.55 0.21 3.8x3.8x1.8 Shielded
Murata LQH32CN4R7M23 4.7 0.45 0.20 2.5x3.2x2.0 Non-Shielded
Murata LQH32CN4R7M33 4.7 0.65 0.15 2.5x3.2x2.0 Non-Shielded
Murata LQH32CN4R7M53 4.7 0.65 0.15 2.5x3.2x1.55 Non-Shielded
Coilcraft LPO6610-472 4.7 1.10 0.20 5.5x6.6x1.0 1mm
Coilcraft LPO3310-472 4.7 0.80 0.27 3.3x3.3x1.0 1mm
Coiltronics SDRC10-4R7 4.7 1.53 0.117 4.5x3.6x1.0 1mm Shielded
Coiltronics SDR10-4R7 4.7 1.30 0.122 5.7x4.4x1.0 1mm Shielded
Coiltronics SD3118-4R7 4.7 0.98 0.122 3.1x3.1x1.85 Shielded
Coiltronics SD18-4R7 4.7 1.77 0.082 5.2x5.2x1.8 Shielded
Table 4: Typical Surface Mount Inductors.
Manufacturer Part Number Value Voltage Temp. Co. Case
Murata GRM21BR61A475KA73L 4.7μF 10V X5R 0805
Murata GRM18BR60J475KE19D 4.7μF 6.3V X5R 0603
Murata GRM21BR60J106KE19 10μF 6.3V X5R 0805
Murata GRM21BR60J226ME39 22μF 6.3V X5R 0805
Table 5: Surface Mount Capacitors.
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
22 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3. Contact Sales for availability.
4. Product not available for U.S. market.
Ordering Information
Package
Voltage
Marking1Part Number (Tape and Reel)2
Buck Converter LDO
TDFN33-12 Adj - 0.6V 3.3V NZXYY AAT2500IWP-AW-T14
TDFN33-12 Adj - 0.6V 3.0V NYXYY AAT2500IWP-AT-T14
TDFN33-12 Adj - 0.6V 2.8V OAXYY AAT2500IWP-AQ-T14
TDFN33-12 Adj - 0.6V 1.8V ONXYY AAT2500IWP-AI-T14
TDFN33-12 1.8V 3.3V SHXYY AAT2500IWP-IW T14
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Legend
Voltage Code
Adjustable (0.6V) A
0.9 B
1.2 E
1.5 G
1.8 I
1.9 Y
2.5 N
2.6 O
2.7 P
2.8 Q
2.85 R
2.9 S
3.0 T
3.3 W
4.2 C
AAT2500
1MHz Step-Down Converter/LDO Regulator
DATA SHEET
23
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202014A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a
service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Sky-
works may change its documentation, products, services, specifi cations or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
responsibility whatsoever for confl icts, incompatibilities, or other diffi culties arising from any future changes.
No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided here-
under, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale.
THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES
NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, IN-
CLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM
THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or en-
vironmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper
use or sale.
Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifi cations as a result of design defects, errors, or operation of products outside of pub-
lished parameters or design specifi cations. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifi cations or parameters.
Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
identifi cation purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.
1. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing
process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
Package Information1
TDFN33-12
Top View Bottom View
Detail "A"
Side View
3.00
±
0.05
Index Area Detail "A"
1.70
±
0.05
3.00
±
0.05
0.05
±
0.05
0.23
±
0.05
0.75
±
0.05
2.40
±
0.05
Pin 1 Indicator
(optional)
0.40
±
0.05
0.45
±
0.050.23
±
0.05
0.1 REF
C0.3
All dimensions in millimeters.
