Analogic AAT2500IFP-AQ-T1 1mhz step-down converter/ldo regulator Datasheet

AAT2500
1MHz Step-Down Converter/LDO Regulator
General Description
Features
The AAT2500 is a member of AnalogicTech's Total
Power Management IC™ (TPMIC™) product family. It is a low dropout (LDO) linear regulator and a
step-down converter with an input voltage range of
2.7V to 5.5V, making it ideal for applications with
single lithium-ion/polymer batteries.
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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
performance, fast transient response, and good
power supply rejection ratio (PSRR). Other features include low quiescent 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 or
STDFN33 package, and is rated over a temperature range of -40°C to +85°C.
SystemPower™
VIN 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 StepDown Converter
Shutdown Current <1µA
Low RDS(ON) 0.4Ω Integrated Power Switches
Low Dropout 100% Duty Cycle
1MHz Switching Frequency
Internal Soft Start
Over-Temperature Protection
Current Limit Protection
Available in TDFN33-12 or STDFN33-12
Package
-40°C to +85°C Temperature Range
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Applications
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Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
Portable Media Players
Typical Application
VIN = 2.7V to 5.5V
3
5
3.3V at 300mA
9
6
7
C4
2.2μF
8
C5
10nF
AAT2500 Step-Down Converter Efficiency
VP
VCC
VLDO
EN
ENLDO
LX
OUT
FB
BYP
SGND
GND
PGND
100
4
L1
2
11
4.7μH
12
1
U1
AAT2500
C1
4.7μF
90
2500.2006.05.1.16
1.8V
85
80
75
70
65
60
0.1
L1 Sumida CDRH3D16-4R7 C1 Murata GRM219R61A475KE19
C3 Murata GRM21BR60J106KE19
2.5V
95
2.5V at 400mA
10
Efficiency (%)
C3
10μF
VIN = 3.3V
1
10
100
1000
Load Current (mA)
1
AAT2500
1MHz Step-Down Converter/LDO Regulator
Pin Descriptions
Pin #
Symbol
1
PGND
2
3
4
5
6
LX
VP
VCC
VLDO
OUT
7
BYP
8
9
GND
ENLDO
10
EN
11
FB
12
SGND
EP
Pin Configuration
Function
Step-down converter power ground return pin. Connect to the output and input capacitor return. See section on PCB layout guidelines and evaluation board layout diagram.
Power switching node. Output switching node that connects to the output inductor.
Step-down converter power stage supply voltage. Must be closely decoupled to PGND.
Step-down converter bias supply. Connect to VP.
LDO input voltage; should be decoupled with 1µF or greater capacitor.
300mA LDO output pin. A 2.2µF or greater output low-ESR ceramic capacitor is
required for stability.
Bypass capacitor for the LDO. To improve AC ripple rejection, connect a 10nF capacitor to GND. This will also provide a soft-start function.
LDO ground connection pin.
Enable pin for LDO. When connected low, LDO is disabled and consumes less than
1µA of current.
Step-down converter enable. When connected low, LDO is disabled and consumes
less than 1µA.
Step-down converter feedback input pin. For fixed output voltage versions, this pin is
connected to the converter output, forcing the converter to regulate to the specific voltage. For adjustable output versions, an external resistive divider ties to this point and
programs the output voltage to the desired value.
Step-down converter signal ground. For external feedback, return the feedback resistive divider to this ground. For internal fixed version, tie to the point of load return. See
section on PCB layout guidelines and evaluation board layout diagram.
Exposed paddle (bottom). Use properly sized vias for thermal coupling to the ground
plane. See section on PCB layout guidelines.
TDFN/STDFN33-12
(TopView)
PGND
LX
VP
VCC
VLDO
OUT
2
1
12
2
11
3
10
4
9
5
8
6
7
SGND
FB
EN
ENLDO
GND
BYP
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Absolute Maximum Ratings1
Symbol
Description
VP, VLDO
VLX
VFB
VEN
TJ
TLEAD
Input Voltages to GND
LX to GND
FB to GND
EN to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
6.0
-0.3 to VP + 0.3
-0.3 to VP + 0.3
-0.3 to 6.0
-40 to 150
300
V
V
V
V
°C
°C
Value
Units
2
50
W
°C/W
Thermal Information
Symbol
PD
θJA
Description
Maximum Power Dissipation
Thermal Resistance2
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.
2500.2006.05.1.16
3
AAT2500
1MHz Step-Down Converter/LDO Regulator
Electrical Characteristics1
Symbol
LDO
VOUT
VIN
VDO
ΔVOUT/
VOUT*ΔVIN
Description
Line Regulation
Dynamic Line Regulation
ΔVOUT(Load)
IOUT
ISC
IQLDO
Dynamic Load Regulation
Output Current
Short-Circuit Current
LDO Quiescent Current
ISHDN
Shutdown Current
PSRR
Power Supply Rejection Ratio
THYS
eN
TC
Min
Typ Max
Units
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, CIN = 1µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
TA = 25°C
-1.5
1.5
Output Voltage Tolerance
IOUT = 1mA to 300mA TA = -40°C
%
-2.5
2.5
to 85°C
Input Voltage
VOUT+VDO2
5.5
V
3, 4
Dropout Voltage
IOUT = 300mA
400 600
mV
ΔVOUT(Line)
TSD
Conditions
Over-Temperature Shutdown
Threshold
Over-Temperature Shutdown
Hysteresis
Output Noise
Output Voltage Temperature
Coefficient
VIN = VOUT + 1V to 5V
IOUT = 300mA, VIN = VOUT + 1V to
VOUT + 2V, TR/TF = 2µS
IOUT = 1mA to 300mA, TR <5µS
VOUT > 1.3V
VOUT < 0.4V
VIN = 5V, No Load, ENLDO = VIN
VIN = 5V; ENLDO = GND,
EN = SGND = PGND
1kHz
IOUT = 10mA, CBYP = 10nF 10kHz
1MHz
eNBW = 300Hz to 50kHz
0.09
%/V
2.5
mV
60
125
mV
mA
mA
µA
1.0
µA
300
600
70
67
47
45
dB
145
°C
12
°C
50
µVRMS
22
ppm/°C
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 correlation 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.
4
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Electrical Characteristics1
Symbol
Description
Conditions
Buck Converter Typical values are TA = 25°C, VIN = VCC = Vp = 3.6V.
VIN
Input Voltage
VIN Rising
VUVLO
UVLO Threshold
Hysteresis
VIN Falling
IOUT = 0 to 400mA,
VOUT
Output Voltage Tolerance
VIN = 2.7V to 5.5V
Fixed Output Version
VOUT
Output Voltage Range
Adjustable Output Version2
Step-Down Converter
ENLDO = GND, No Load,
IQBUCK
Quiescent Current
0.6V Adjustable Model
ISHDN
Shutdown Current
EN = SGND = PGND, ENLDO = GND
ILIM
P-Channel Current Limit
High Side Switch On
RDS(ON)H
Resistance
Low Side Switch On
RDS(ON)L
Resistance
VIN = 5.5V, VLX = 0 - VIN
ILXLK
LX Leakage Current
EN = SGND = PGND
VLinereg
Line Regulation
VIN = 2.7V to 5.5V
FB Threshold Voltage
VFB
0.6V Output, No Load, TA = 25°C
Accuracy
IFB
FB Leakage Current
0.6V Output
RFB
FB Impedance
>0.6V Output
FOSC
Oscillator Frequency
TA = 25°C
Over-Temperature Shutdown
TSD
Threshold
Over-Temperature Shutdown
THYS
Hysteresis
Logic Signals
VEN(L)
Enable Threshold Low
VEN(H)
Enable Threshold High
IEN(H)
Leakage Current
Min
Typ
Max
Units
5.5
2.6
V
V
mV
V
-3.0
+3.0
%
0.6
0.6
4.0
2.5
V
50
µA
1.0
µA
mA
2.7
100
1.8
25
600
597
250
0.7
0.45
Ω
0.4
Ω
600
1.0
1.0
µA
0.2
%/V
615
mV
0.2
µA
kΩ
MHz
1.5
140
°C
15
°C
0.6
1.5
1.0
1.0
V
V
µA
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 correlation with statistical process controls.
2. For adjustable version with higher than 2.5V output, please consult your AnalogicTech representative.
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5
AAT2500
1MHz Step-Down Converter/LDO Regulator
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
LDO Dropout Voltage vs. Temperature
LDO Dropout Characteristics
(EN = GND; ENLDO = VIN)
(EN = GND; ENLDO = VIN)
3.20
IL = 300mA
480
420
Output Voltage (V)
Dropout Voltage (mV)
540
360
300
IL = 100mA
IL = 150mA
240
180
120
60
-40 -30 -20 -10 0
2.80
IOUT = 300mA
IOUT = 150mA
2.60
2.40
2.20
IL = 50mA
0
IOUT = 0mA
3.00
IOUT = 10mA
2.00
2.70
10 20 30 40 50 60 70 80 90 100 110 120
2.80
IOUT = 100mA
IOUT = 50mA
2.90
Temperature (°C)
3.10
3.20
3.30
LDO Ground Current vs. Input Voltage
LDO Dropout Voltage vs. Output Current
(EN = GND; ENLDO = VIN)
(EN = GND; ENLDO = VIN)
90.00
500
Ground Current (μA)
450
Dropout Voltage (mV)
3.00
Input Voltage (V)
400
350
300
85°C
250
200
25°C
150
-40°C
100
80.00
70.00
60.00
IOUT=300mA
50.00
IOUT=150mA
IOUT=50mA
40.00
IOUT=0mA
30.00
IOUT=10mA
20.00
10.00
50
0
0
50
100
150
200
250
300
0.00
2
2.5
3
3.5
4
4.5
5
Input Voltage (V)
Output Current (mA)
LDO Output Voltage vs. Temperature
LDO Initial Power-Up Response Time
(EN = GND; ENLDO = VIN)
(CBYP = 10nF; EN = GND; ENLDO = VIN)
1.203
VENLDO (5V/div)
Output Voltage (V)
1.202
1.201
1.200
1.199
1.198
1.197
1.196
-40 -30 -20 -10
0
10 20
30
40
50 60
Temperature (°C)
6
70 80
90 100
VOUT (1V/div)
μs/div
400μ
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C, VIN = VLDO = VCC = VP.
LDO Turn-Off Response Time
LDO Turn-On Time From Enable (VIN present)
(CBYP = 10nF; EN = GND; ENLDO = VIN)
(CBYP = 10nF; EN = GND; ENLDO = VIN)
VENLDO = 5V/div
VENLDO (5V/div)
VOUT (1V/div)
VIN = 4V
VOUT = 1V/div
50μs/div
μs/div
5μ
LDO Line Transient Response
LDO Load Transient Response
(CBYP = 10nF; EN = GND; ENLDO = VIN)
(CBYP = 10nF; EN = GND; ENLDO = VIN)
Input Voltage (V)
3.03
2.85
4
3.02
3
3.01
2
3.00
1
VOUT
2.99
0
400
VOUT
2.80
300
2.75
200
2.70
100
2.65
2.60
2.98
500
0
IOUT
-100
100μS/div
LDO Self Noise
(CBYP = 10nF; EN = GND; ENLDO = VIN)
(EN = GND; ENLDO = VIN)
3.00
800
2.90
700
2.80
600
VOUT
500
2.60
400
2.50
300
2.40
2.30
200
IOUT
100
2.20
0
2.10
-100
10μ
μs/div
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Noise Amplitude (μV/rtHz)
LDO Load Transient Response 300mA
Output Current (mA)
Output Voltage (V)
100μs/div
2.70
Output Current (mA)
VIN
Output Voltage (V)
5
3.04
Output Voltage (V)
6
2.90
10
1
0.1
0.01
Band Power:
300Hz to 50kHz = 44.6μVrms
100Hz to 100kHz = 56.3μVrms
0.001
0.01
0.1
1
10
100
1000
10000
Frequency (kHz)
7
AAT2500
1MHz Step-Down Converter/LDO Regulator
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Over-Current Protection
LDO ENLDO vs. VIN
(EN = GND; ENLDO = VIN)
Output Current (mA)
1200
1.250
1000
1.225
800
1.200
VIH
1.175
600
1.150
400
1.125
200
1.100
0
1.075
VIL
1.050
2.5
-200
Time (50ms/div)
3.5
4.0
4.5
5.0
5.5
Input Voltage (V)
Step-Down Converter Efficiency vs. Load
Step-Down Converter Load Regulation
(VOUT = 2.5V; EN = VIN; ENLDO = GND)
(VOUT = 2.5V; EN = VIN; ENLDO = GND)
100
2.0
VIN = 3.3V
Output Error (%)
VIN = 3.0V
Efficiency (%)
3.0
90
VIN = 3.6V
80
70
1.0
VIN = 3.0V
0.0
VIN = 3.3V
-1.0
VIN = 3.6V
60
0.1
1.0
10
100
-2.0
1000
0.1
1.0
Output Current (mA)
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
100
2.0
Output Error (%)
VIN = 3.6V
VIN = 2.7V
90
Efficiency (%)
1000
Step-Down Converter DC Regulation
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
80
VIN = 4.2V
70
60
0.1
1.0
10
Output Current (mA)
8
100
Output Current (mA)
Step-Down Converter Efficiency vs. Load
50
10
100
1000
1.0
VIN = 4.2V
0.0
VIN = 2.7V
-1.0
VIN = 3.6V
-2.0
0.1
1.0
10
100
1000
Output Current (mA)
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Step-Down Converter
Frequency vs. Input Voltage
Step-Down Converter
Output Voltage Error vs. Temperature
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
(VIN = 3.6V; VO = 1.5V; EN = VIN; ENLDO = GND)
2.0
0.5
Output Error (%)
Frequency Variation (%)
1.0
0.0
-0.5
-1.0
-1.5
-2.0
1.0
0.0
-1.0
-2.0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40
-20
0
Input Voltage (V)
60
80
100
(VO = 1.8V; EN = VIN; ENLDO = GND)
(VIN = 3.6V; VO = 1.5V; EN = VIN; ENLDO = GND)
35
Input Current (μ
μA)
0.20
Frequency Variation (%)
40
Step-Down Converter
Input Current vs. Input Voltage
Step-Down Converter
Switching Frequency vs. Temperature
0.10
0.00
-0.10
-0.20
-40
85°C
30
25°C
25
20
-40°C
15
-20
0
20
40
60
80
2.5
100
3.0
3.5
4.0
4.5
5.0
5.5
Temperature (°°C)
Input Voltage (V)
Step-Down Converter
P-Channel RDS(ON) vs. Input Voltage
Step-Down Converter
N-Channel RDS(ON) vs. Input Voltage
(EN = VIN; ENLDO = GND)
6.0
(EN = VIN; ENLDO = GND)
750
750
700
700
650
120°C
650
100°C
RDS(ON) (mΩ
Ω)
RDS(ON) (mΩ
Ω)
20
Temperature (°°C)
600
550
85°C
500
450
25°C
400
120°C
600
550
500
85°C
450
400
350
25°C
350
300
100°C
300
2.5
3.0
3.5
4.0
4.5
Input Voltage (V)
2500.2006.05.1.16
5.0
5.5
6.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
9
AAT2500
1MHz Step-Down Converter/LDO Regulator
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
(30mA - 300mA; VIN = 3.6V; VOUT = 1.8V; C1 = 10μ
μF;
C4 = 100pF; EN = VIN; ENLDO = GND)
1.9
1.2
1.0
1.8
300mA
1.7
1.6
0.8
0.6
30mA
1.5
0.4
1.4
0.2
1.3
0.0
1.2
-0.2
1.4
0.1
0.0
1.2
300mA
-0.1
-0.2
1.0
0.8
30mA
-0.3
0.6
-0.4
0.4
-0.5
0.2
-0.6
0.0
-0.7
-0.2
Time (25μs/div)
Time (25μs/div)
(VOUT = 1.8V @ 400mA; EN = VIN; ENLDO = GND)
1.2
1.8
1.0
300mA
0.8
1.6
0.6
30mA
1.5
0.4
1.4
0.2
1.3
0.0
1.2
-0.2
1.90
7.0
1.85
6.5
1.80
6.0
1.75
5.5
1.70
5.0
1.65
4.5
1.60
4.0
1.55
3.5
1.50
Step-Down Converter Line Regulation
Step-Down Converter Soft Start
(VOUT = 1.8V; EN = VIN; ENLDO = GND)
(VIN = 3.6V; VOUT = 1.8V; 400mA;
EN = VIN; ENLDO = GND)
0
-0.05
IOUT = 10mA
-0.1
-0.15
-0.2
IOUT = 400mA
-0.25
-0.3
2.5
3.0
3.5
4.0
4.5
Input Voltage (V)
10
5.0
5.5
6.0
4.0
3.5
3.0
3.0
2.0
2.5
1.0
2.0
0.0
1.5
-1.0
1.0
-2.0
0.5
-3.0
0.0
-4.0
-0.5
Inductor Current
(bottom) (A)
Accuracy (%)
IOUT = 100mA
Enable and Output Voltage
(top) (V)
0.1
-0.35
3.0
Time (25μ
μs/div)
Time (25μs/div)
0.05
Input Voltage
(bottom) (V)
1.4
1.9
Load and Inductor Current
(200mA/div) (bottom)
2.0
Output Voltage
(top) (V)
Step-Down Converter Line Transient
(30mA - 300mA; VIN = 3.6V; VOUT = 1.8V;
μF; EN = VIN; ENLDO = GND)
C1 = 4.7μ
Output Voltage
(top) (V)
Step-Down Converter Load Transient Response
1.7
Load and Inductor Current
(200mA/div) (bottom)
1.4
Load and Inductor Current
(200mA/div) (bottom)
2.0
Output Voltage (AC Coupled)
(top) (V)
Step-Down Converter Load Transient Response
(30mA - 300mA; VIN = 3.6V; VOUT = 1.8V;
μF; EN = VIN; ENLDO = GND)
C1 = 10μ
Output Voltage
(top) (V)
Step-Down Converter Load Transient Response
250μ
μs/div
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Step-Down Converter Output Ripple
40
0.9
20
0.8
0
0.7
-20
0.6
-40
0.5
-60
0.4
-80
0.3
-100
0.2
-120
0.1
Inductor Current
(bottom) (A)
Output Voltage (AC Coupled)
(top) (mV)
(VIN = 3.6V; VOUT = 1.8V; 400mA;
EN = VIN; ENLDO = GND)
Time (250ns/div)
2500.2006.05.1.16
11
AAT2500
1MHz Step-Down Converter/LDO Regulator
Functional Block Diagram
VP
VCC
FB
Error
Amp.
DH
See
Note
LX
Logic
Voltage
Reference
Control
Logic
EN
DL
PGND
SGND
OUT
VLDO
Over-Current
Protection
Error
Amp.
Voltage
Reference
BYP
ENLDO
Fast Start
Control
GND
Note: Internal resistor divider included for ≥1.2V versions. For low voltage versions, the feedback pin is tied directly to the error
amplifier input.
12
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
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 components
(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 startup and shutdown timing. This proprietary CMOS
LDO has also been tailored for superior transient
response characteristics. These traits are particularly important for applications 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 control 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 regulator is
placed in shutdown mode. This active fast shutdown circuit has no adverse effect on normal
device operation. The LDO regulator output has
been specifically optimized to function with lowcost, 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 output self noise and increase power
supply ripple rejection. 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 regulator turn-on time. The regulator comes with complete short-circuit and thermal protection. The com-
2500.2006.05.1.16
bination of these two internal protection circuits
gives a comprehensive 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 application, 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 1.5kΩ resistor is connected between OUT and
GND. This is intended to discharge COUT when the
LDO regulator is disabled. The internal 1.5KΩ
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.
13
AAT2500
1MHz Step-Down Converter/LDO Regulator
VIN
VIN
C3
10μF
3
5
9
VOUTLDO
6
7
8
C4
4.7μF
VP
VCC
VLDO
EN
ENLDO
LX
OUT
FB
BYP
SGND
GND
PGND
C5
10nF
4
10
2
L1
VOUTBUCK
3
5
9
11
VOUTLDO
6
12
7
1
C1
4.7μF
U1
AAT2500
Figure 1: AAT2500 Fixed Output.
Low Dropout Operation
For conditions where the input voltage drops to the
output 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
limited. 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.
14
C3
10μF
8
C4
4.7μF
C5
10nF
VP
VCC
VLDO
EN
ENLDO
LX
OUT
FB
BYP
SGND
GND
PGND
U1
AAT2500
4
10
2
VOUTBUCK
L1
R1
11
12
1
C8
100pF
R2
59k
C1
4.7μF
Figure 2: AAT2500 with Adjustable Step-Down
Output and Enhanced Transient Response.
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 electrolytic capacitors may be selected for CIN. There is no specific capacitor ESR
requirement for CIN. However, for 300mA LDO regulator output operation, ceramic capacitors are recommended for CIN due to their inherent capability
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
stability, 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 recommended for best performance. Applications utilizing
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
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 composition, and ambient temperature. Typically, capacitor
ESR is measured in milliohms for ceramic capacitors and can range to more than several ohms for
tantalum or aluminum electrolytic capacitors.
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/µsec. This equates to a slope
compensation that is 75% of the inductor current
down slope for a 1.5V output and 4.7µH inductor.
0.75 ⋅ VO 0.75 ⋅ 1.5V
A
=
= 0.24
L
4.7μH
μsec
m=
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 lowest
output noise performance, it is critical that the
capacitor 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 output 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 recommended.
This is the internal slope compensation for the
adjustable (0.6V) version or low-voltage fixed versions. When externally programming the 0.6V version to 2.5V, the calculated inductance is 7.5µH.
L=
0.75 ⋅ VO
=
m
=3
μsec
0.75 ⋅ VO
≈ 3 A ⋅ VO
A
0.24A μsec
μsec
⋅ 2.5V = 7.5μH
A
In this case, a standard 10µH value is selected.
For high-voltage fixed versions (2.5V and above),
m = 0.48A/µsec. Table 1 displays inductor values
for the AAT2500 fixed and adjustable options.
Configuration
Output Voltage
Inductor
Slope Compensation
0.6V Adjustable With
External Resistive Divider
0.6V to 2.0V
4.7µH
0.24A/µsec
2.5V
10µH
0.24A/µsec
0.6V to 2.0V
4.7µH
0.24A/µsec
2.5V to 3.3V
4.7µH
0.48A/µsec
Fixed Output
Table 1: Inductor Values.
2500.2006.05.1.16
15
AAT2500
1MHz Step-Down Converter/LDO Regulator
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
saturation 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 105mΩ DCR and a 900mA DC
current rating. 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.
CIN =
VOBUCK ⎛ VOBUCK⎞
· 1⎝
VIN
VIN ⎠
⎛ VPP
⎞
- ESR · FS
⎝ IOBUCK
⎠
⎞ 1
VOBUCK ⎛
V
· 1 - OBUCK = for VIN = 2 × VOBUCK
⎝
VIN
VIN ⎠ 4
CIN(MIN) =
1
⎛ VPP
⎞
- ESR · 4 · FS
⎝ IOBUCK
⎠
Always examine the ceramic capacitor DC voltage
coefficient 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 ·
16
⎞
VOBUCK ⎛
V
· 1 - OBUCK
⎝
VIN
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.
VOBUCK ⎛ VOBUCK⎞
· 1=
⎝
VIN
VIN ⎠
D · (1 - D) =
0.52 =
1
2
for VIN = 2 x VOBUCK
IRMS(MAX) =
IOBUCK
2
VOBUCK
⎛
VOBUCK⎞
· 1The term
appears in both the
⎝
VIN
VIN ⎠
input voltage 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 current 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 capacitor 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.
A laboratory test set-up typically consists of two
long wires running from the bench power supply to
the evaluation 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 during 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.
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Figure 3: AAT2500 Evaluation Board Top Side.
Figure 4: AAT2500 Evaluation Board
Bottom Side.
In applications where the input power source lead
inductance cannot be reduced to a level that does
not affect the converter performance, a high ESR
tantalum or aluminum electrolytic should be placed
in parallel with the low ESR, ESL bypass ceramic.
This dampens the high Q network and stabilizes
the system.
Once the average inductor current increases to the
DC load level, the output voltage recovers. The
above equation establishes a limit on the minimum
value for the output capacitor with respect to load
transients.
Output Capacitor
The output capacitor limits the output ripple and
provides 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 characteristics necessary for low
output ripple.
The output voltage droop due to a load transient is
dominated 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 voltage droop during the three switching cycles to the
output capacitance can be estimated by:
COUT =
2500.2006.05.1.16
3 · ΔILOAD
VDROOP · FS
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 capacitance will reduce the
crossover frequency with greater phase margin.
The maximum output capacitor RMS ripple current
is given by:
IRMS(MAX) =
1
2· 3
·
VOUT · (VIN(MAX) - VOUT)
L · 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.
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
17
AAT2500
1MHz Step-Down Converter/LDO Regulator
R2 is 59kΩ. 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 2
summarizes the resistor values for various output
voltages with R2 set to either 59kΩ for good noise
immunity or 221kΩ for reduced no load input current.
Ω
R2 = 59kΩ
Ω
R2 = 221kΩ
VOUT (V)
Ω)
R1 (kΩ
Ω)
R1 (kΩ
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.8
1.85
2.0
2.5
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
124
137
187
75
113
150
187
221
261
301
332
442
464
523
715
⎛ VOUT ⎞
⎛ 1.5V ⎞
R1 = V
-1 · R2 = 0.6V - 1 · 59kΩ = 88.5kΩ
⎝ REF ⎠
⎝
⎠
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.
Table 2: Adjustable Resistor Values For Use
With 0.6V Step-Down Converter.
LX1
VOUTBUCK
C7
0.01μF
C1
4.7μF1
C2
10μF
L1
Table 3
VIN1
U1
1
2
3
4
3
2
1
5
6
LDO Input
C3
10μF
C9
n/a
AAT2500
PGND
SGND
LX
FB
VP
EN
VCC
ENLDO
IN
GND
OUT
BYP
C4
4.7μF
12
11
R1
Table 3
R2
59k
10
9
8
7
C5
10nF
GND
C81
3
2
1
Buck Enable
3
2
1
LDO Enable
GND
VOUTLDO
Figure 5: AAT2500 Evaluation Board Schematic.
1. For step-down converter, enhanced transient configuration C8 = 100pF and C1 = 10uF.
18
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Thermal Calculations
There are three types of losses associated with the
AAT2500 step-down converter: switching losses,
conduction 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 conduction mode
(CCM), a simplified form of the step-down converter and LDO losses is given by:
PTOTAL =
IOBUCK2 · (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 = IOBUCK2 · 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 investigated over the complete input
voltage range.
2500.2006.05.1.16
Given the total losses, the maximum junction temperature can be derived from the θJA for the
TDFN/STDFN33-12 package 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
connected as closely as possible. The connection of the inductor to the LX pin should also be
as short as possible.
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 differences 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/STDFN paddle to the ground plane. The via diameter should
be 0.3mm to 0.33mm and positioned on a
1.2mm grid.
6. LDO bypass capacitor (C5) should be connected
directly between pins 7 (BYP) and 8 (GND)
19
AAT2500
1MHz Step-Down Converter/LDO Regulator
Step-Down Converter Design Example
Specifications
VOBUCK = 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load ΔILOAD = 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
μsec
μsec
⋅ VO2 = 3
⋅ 1.8V = 5.4μH
A
A
(see Table 1)
For Sumida inductor CDRH3D16, 4.7µH, DCR = 105mΩ.
ΔIL1 =
⎛ 1.8V ⎞
VOBUCK ⎛ VOBUCK⎞
1.8V
⋅ 1=
⋅ 1= 218mA
VIN ⎠ 4.7μH ⋅ 1.0MHz ⎝ 4.2V⎠
L1 ⋅ F ⎝
IPKL1 = IOBUCK +
ΔIL1
= 0.4A + 0.11A = 0.51A
2
PL1 = IOBUCK2 ⋅ DCR = 0.4A2 ⋅ 105mΩ = 17mW
1.8V Output Capacitor
VDROOP = 0.2V
COUT =
3 · ΔILOAD
3 · 0.3A
=
= 4.5μF
0.2V · 1MHz
VDROOP · FS
IRMS =
(VOBUCK) · (VIN(MAX) - VOBUCK)
1
1.8V · (4.2V - 1.8V)
·
= 63mArms
=
L1 · F · VIN(MAX)
2 · 3 4.7μH · 1.0MHz · 4.2V
2· 3
1
·
Pesr = esr · IRMS2 = 5mΩ · (63mA)2 = 20μW
20
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Input Capacitor
Input Ripple VPP = 25mV
CIN =
IRMS =
1
⎛ VPP
⎞
- ESR · 4 · FS
⎝ IOBUCK
⎠
=
1
= 4.75μF
⎛ 25mV
⎞
- 5mΩ · 4 · 1MHz
⎝ 0.4A
⎠
IOBUCK
= 0.2Arms
2
P = esr · IRMS2 = 5mΩ · (0.2A)2 = 0.2mW
AAT2500 Losses
PTOTAL =
IOBUCK2 · (RDSON(HS) · VOBUCK + RDSON(LS) · [VIN - VOBUCK])
VIN
+ (tsw · F · IOBUCK + IQBUCK + IQLDO) · VIN + (VIN - VLDO) · ILDO
=
0.42 · (0.725Ω · 1.8V + 0.7Ω · [4.2V - 1.8V])
4.2V
+ (5ns · 1.0MHz · 0.4A + 50μA +125μA) · 4.2V + (4.2V - 3.3V) · 0.3A = 392mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 392mW = 105°C
2500.2006.05.1.16
21
AAT2500
1MHz Step-Down Converter/LDO Regulator
VOUT (V)
Ω)
R1 (kΩ
Ω)
R1 (kΩ
Adjustable Version
(0.6V device)
Ω
R2 = 59kΩ
Ω1
R2 = 221kΩ
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.8
1.85
2.0
2.5
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
124
137
187
75.0
113
150
187
221
261
301
332
442
464
523
715
VOUT (V)
Ω)
R1 (kΩ
Fixed Version
R2 Not Used
0.6-3.3V
0
L1 (µH)
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7 or 6.8
10
L1 (µH)
4.7
Table 3: Evaluation Board Component Values.
Manufacturer
Sumida
Sumida
MuRata
MuRata
MuRata
Coilcraft
Coilcraft
Coiltronics
Coiltronics
Coiltronics
Coiltronics
Part Number
Inductance
(µH)
Max DC
Current (A)
DCR
Ω)
(Ω
Size (mm)
LxWxH
Type
CDRH3D16-4R7
CDRH3D16-100
LQH32CN4R7M23
LQH32CN4R7M33
LQH32CN4R7M53
LPO6610-472
LPO3310-472
SDRC10-4R7
SDR10-4R7
SD3118-4R7
SD18-4R7
4.7
10
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
0.90
0.55
0.45
0.65
0.65
1.10
0.80
1.53
1.30
0.98
1.77
0.11
0.21
0.20
0.15
0.15
0.20
0.27
0.117
0.122
0.122
0.082
3.8x3.8x1.8
3.8x3.8x1.8
2.5x3.2x2.0
2.5x3.2x2.0
2.5x3.2x1.55
5.5x6.6x1.0
3.3x3.3x1.0
4.5x3.6x1.0
5.7x4.4x1.0
3.1x3.1x1.85
5.2x5.2x1.8
Shielded
Shielded
Non-Shielded
Non-Shielded
Non-Shielded
1mm
1mm
1mm Shielded
1mm Shielded
Shielded
Shielded
Table 4: Typical Surface Mount Inductors.
1. For reduced quiescent current R2 = 221kΩ.
22
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Manufacturer
MuRata
MuRata
MuRata
MuRata
Part Number
Value
Voltage
Temp. Co.
Case
GRM21BR61A475KA73L
GRM18BR60J475KE19D
GRM21BR60J106KE19
GRM21BR60J226ME39
4.7µF
4.7µF
10µF
22µF
10V
6.3V
6.3V
6.3V
X5R
X5R
X5R
X5R
0805
0603
0805
0805
Table 5: Surface Mount Capacitors.
2500.2006.05.1.16
23
AAT2500
1MHz Step-Down Converter/LDO Regulator
Ordering Information
Voltage
Package
Buck Converter
LDO
Marking1
Part Number (Tape and Reel)2
STDFN33-123
TDFN33-12
TDFN33-12
TDFN33-12
TDFN33-12
TDFN33-12
TDFN33-12
TDFN33-12
TDFN33-12
TDFN33-12
TDFN33-12
Adj - 0.6V
Adj - 0.6V
Adj - 0.6V
Adj - 0.6V
Adj - 0.6V
Adj - 0.6V
Adj - 0.6V
Adj - 0.6V
1.2V
1.8V
1.8V
2.8V
3.3V
3.0V
2.8V
2.7V
2.5V
1.8V
1.5V
3.0V
2.7V
3.3V
OAXYY
NZXYY
NYXYY
OAXYY
ORXYY
OOXYY
ONXYY
OMXYY
OWXYY
PFXYY
SHXYY
AAT2500IFP-AQ-T1
AAT2500IWP-AW-T1
AAT2500IWP-AT-T1
AAT2500IWP-AQ-T1
AAT2500IWP-AP-T1
AAT2500IWP-AN-T1
AAT2500IWP-AI-T1
AAT2500IWP-AG-T1
AAT2500IWP-ET-T1
AAT2500IWP-IP-T1
AAT2500IWP-IW T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
Legend
Voltage
Adjustable
(0.6V)
0.9
1.2
1.5
1.8
1.9
2.5
2.6
2.7
2.8
2.85
2.9
3.0
3.3
4.2
Code
A
B
E
G
I
Y
N
O
P
Q
R
S
T
W
C
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3. Contact Sales for availability.
24
2500.2006.05.1.16
AAT2500
1MHz Step-Down Converter/LDO Regulator
Package Information
TDFN33-12
2.40 ± 0.05
Detail "B"
3.00 ± 0.05
Index Area
(D/2 x E/2)
0.3 ± 0.10 0.16 0.375 ± 0.125
0.075 ± 0.075
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
Pin 1 Indicator
(optional)
0.23 ± 0.05
Detail "A"
0.45 ± 0.05
0.1 REF
0.05 ± 0.05
Side View
0.229 ± 0.051
+ 0.05
0.8 -0.20
7.5° ± 7.5°
Option A:
C0.30 (4x) max
Chamfered corner
Option B:
R0.30 (4x) max
Round corner
Detail "B"
Detail "A"
All dimensions in millimeters.
2500.2006.05.1.16
25
AAT2500
1MHz Step-Down Converter/LDO Regulator
STDFN33-12
Detail "B"
2.40 ± 0.05
3.00 ± 0.05
Index Area
(D/2 × E2)
0.35 ± 0.10
0.16 MIN
Detail "A"
3.00 ± 0.05
0.075 ± 0.075
1.70 ± 0.05
Top View
Bottom View
0.45 ± 0.05
Pin 1 Indicator
(Optional)
0.21 ± 0.05
0.1 REF
(Optional)
0.152
0.60 MAX
7.5° ± 7.5°
0.05 ± 0.05
C0.30 (4x) Max
Chamfered Corner
(Optional)
Side View
Detail "B"
Detail "A"
All dimensions in millimeters.
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights,
or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice.
Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech
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26
2500.2006.05.1.16