AAT2113A [ANALOGICTECH]
3MHz, Fast Transient 1.5A Step-Down Converter in 2mm x 2mm Package; 3MHz的，快速瞬态1.5A降压转换器，采用2mm x 2mm封装
| 型号： | AAT2113A |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | 3MHz, Fast Transient 1.5A Step-Down Converter in 2mm x 2mm Package |
| 文件： | 总19页 (文件大小：2997K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
General Description
Features
• 5mm x 5mm Total Solution Size
The AAT2113A SwitchReg™ is a 1.5A step-down con-
verter with a typical input voltage of 3.3V and a fixed
output voltage of 1.2V or an adjustable output. The
3MHz switching frequency enables the use of small
external components. The ultra-small 2mm x 2mm foot-
print and high efficiency make the AAT2113A an ideal
choice for portable applications.
•
•
•
•
1.5A Maximum Output Current
Tiny 0.47ꢀH Chip Inductor
Excellent Transient Response
Input Voltage: 2.7V to 5.5V
• Ultra-small, Low Profile 8-pin 2mm x 2mm FTDFN
Package
•
Fixed or Adjustable Output Voltage Options:
The AAT2113A delivers 1.5A maximum output current
while consuming only 55μA no-load quiescent current.
Low RDS(ON) integrated MOSFETs and 100% duty cycle
operation make the AAT2113A the ideal choice for high
output voltage, high current applications which require a
low dropout threshold.
Fixed Output Voltage: 1.2V
Adjustable Output Voltage: 1.0V to 1.8V
High Efficiency, Low Noise Architecture
3MHz Switching Frequency
▪
▪
•
•
•
•
•
•
•
•
No External Compensation Required
55μA No Load Quiescent Current
100% Duty Cycle Low-Dropout Operation
Internal Soft Start
Over-Temperature and Current Limit Protection
<1μA Shutdown Current
The AAT2113A provides excellent transient response and
output accuracy across the operating range. No external
compensation is required.
The AAT2113A maintains high efficiency throughout the
load range. The unique low-noise architecture reduces
ripple and spectral noise. The AAT2113A automatically
optimizes efficiency during Light Load mode (LL) and
maintains constant frequency and low output ripple dur-
ing PWM mode.
• -40°C to 85°C Temperature Range
Applications
• Cellular Phones
• Digital Cameras
Over-temperature and short circuit protection safeguard
the AAT2113A and system components from damage.
• Hard Disk Drives
• MP3 Players
• PDAs and Handheld Computers
• Portable Media Players
• USB Devices
The AAT2113A is available in a Pb-free, ultra-small, low
profile, 8-pin 2mm x 2mm FTDFN package. The product
is rated over a temperature range of -40°C to 85°C.
• Wireless Network Cards
Typical Application
Load Transient Response
VIN
VOUT
(VIN = 5V; VOUT = 1.2V; IOUT = 10% to 100%;
COUT = 10µF, 6.3V, 0603)
U1
L1
1.2V/1.5A
2.7V to 5.5V
VP
EN
LX
LX
1.3V
0.47µH
1.25V
1.2V
100mV
C3
C1
AAT2113A
1.15V
1.1V
10µF
4.7µF
C3
1.0µF
6.3V
VCC
FB
6.3V
0603
1.5A
6.3V
0603
AGND
PGND
0402
150mA
FTDFN22-8
Time (20µs/div)
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2113A.2009.06.1.1
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PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Pin Descriptions
Pin #
Symbol Function
1
2
3
PGND
VP
VCC
Main power ground return pin. Connect to the output and input capacitor return.
Input power supply tied to the source of the high side P-channel MOSFET.
Power supply; supplies power for the internal circuitry.
Feedback input pin. This pin is connected directly to the converter output for the 1.2V fixed output version,
or connected to an external resistor divider for the adjustable output version.
Analog Ground. This pin is internally connected to the analog ground of the control circuitry.
Enable pin. A logic low disables the converter and it consumes less than 1μA of current. When connected
4
5
6
FB
AGND
EN
high, it resumes normal operation.
Switching node. Connect the inductor to this pin. It is internally connected to the drain of both high and
low side MOSFETs.
7, 8
LX
Pin Configuration
FTDFN22-8
(Top View)
1
2
3
4
8
7
6
5
PGND
VP
LX
LX
VCC
FB
EN
AGND
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2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Absolute Maximum Ratings1
TA = 25°C unless otherwise noted.
Symbol
Description
Value
Units
VCC, VP
VLX
VFB
EN
TJ
VP, VCC to GND
LX to GND
FB to GND
EN to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec.)
6.0
V
V
V
V
°C
°C
-0.3 to VP + 0.3
-0.3 to VP + 0.3
-0.3 to VCC + 0.3
-40 to 150
TLEAD
300
Thermal Characteristics
Symbol
Description
Value
Units
ΘJA
PD
Maximum Thermal Resistance
Maximum Power Dissipation2, 3
70
1.4
°C/W
W
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.
3. Derate 14mW/°C above 25°C.
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PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Electrical Characteristics1
VIN = 3.3V, TA = -40°C to 85°C unless otherwise noted. Typical values are at TA = 25°C.
Symbol Description
Conditions
Min
Typ Max Units
VIN
VOUT
Input Voltage
Output Voltage Range
2.7
1
3.3
1.2
5.5
1.8
2.4
V
V
V
mV
V
VIN rising
Hysteresis
VIN falling
VUVLO
UVLO Threshold
180
1.6
IOUT = 0A to 1.5A, VIN = 3.3V, VOUT = 1.2V
fixed
VOUT
Output Voltage Tolerance
-3.0
+3.0
%
IQ
ISHDN
ILIM
Quiescent Current
Shutdown Current
Current Limit
No Load
EN = GND
55
90
1.0
μA
μA
A
2
3
RDS(ON)H
RDS(ON)L
ΔVLOADREG Load Regulation
ΔVLINEREG
ΔVIN
High Side Switch On-Resistance
Low Side Switch On-Resistance
140
100
0.5
mΩ
mΩ
%
ILOAD = 0A to 1.5A
VIN = 3.3V to 4.0V
/
Line Regulation
0.3
%/V
V
Feedback Threshold Voltage Accuracy
(Adjustable Version)
VFB
No load, TA = 25°C
0.0591 0.60 0.609
ILXLEAK,R
IFBLEAK
FOSC
TS
LX Reverse Leakage Current
FB Leakage Current
Internal Oscillator Frequency
Start-up Time
VIN unconnected, VLX = 5.5V, EN = GND
VOUT = 1.2V
1.0
0.2
3.4
μA
μA
MHz
μs
2.6
3
60
Enable to Output Regulation
TSD
THYS
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
140
25
°C
°C
EN Logic
VIL
EN Threshold Low
EN Threshold High
EN Leakage Current
0.4
1.0
V
V
μA
VIH
ILEAK
1.4
-1.0
VEN = 5.5V
1. The AAT2113A is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and cor-
relation with statistical process controls.
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2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Typical Characteristics
Efficiency vs. Output Current
(VOUT = 1.2V; L = 0.47µH)
Efficiency vs. Output Current
(VOUT = 1.8V; L = 0.47µH)
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
VIN = 5.5V
IN = 5.0V
VIN = 5.5V
IN = 5.0V
VIN = 4.2V
VIN = 3.6V
VIN = 3.0V
VIN = 2.7V
V
V
VIN = 4.2V
VIN = 3.6V
IN = 3.0V
V
VIN = 2.7V
0.1
1
10
100
1000
10000
0.1
1
10
100
1000
10000
Output Current (mA)
Output Current (mA)
Load Regulation
Load Regulation
(VOUT = 1.2V; L = 0.47µH)
(VOUT = 1.8V; L = 0.47µH)
1.0
1.0
0.8
VIN = 5.5V
VIN = 5.0V
VIN = 4.2V
VIN = 3.6V
VIN = 3.0V
VIN = 2.7V
VIN = 5.5V
VIN = 5.0V
0.8
0.6
V
IN = 4.2V
0.6
VIN = 3.6V
VIN = 3.0V
VIN = 2.7V
0.4
0.4
0.2
0.2
0.0
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-0.2
-0.4
-0.6
-0.8
-1.0
0.1
1
10
100
1000
10000
0.1
1
10
100
1000
10000
Output Current (mA)
Output Current (mA)
Line Regulation
Line Regulation
(VOUT = 1.2V; L = 0.47µF)
(VOUT = 1.8V; L = 0.47µF)
1.0
1.0
IOUT = 1500mA
OUT = 1000mA
IOUT = 500mA
OUT = 1mA
IOUT = 1500mA
OUT = 1000mA
IOUT = 500mA
OUT = 1mA
0.8
0.6
0.8
0.6
I
I
0.4
0.4
I
I
0.2
0.2
0.0
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-0.2
-0.4
-0.6
-0.8
-1.0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
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PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Typical Characteristics
Output Voltage vs. Input Voltage
Output Voltage vs. Input Voltage
(VOUT = 1.2V; IOUT = 1A)
(VOUT = 1.8V; IOUT = 1A)
1.25
1.24
1.23
1.22
1.21
1.20
1.19
1.18
1.85
1.84
1.83
1.82
1.81
1.80
1.79
1.78
1.77
1.76
1.75
T = 85°C
T = 25°C
T = -40°C
T = 85°C
T = 25°C
T = -40°C
1.17
1.16
1.15
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
Output Voltage Error vs. Temperature
Output Voltage Error vs. Temperature
(VOUT = 1.2V; VIN = 3.3V; IOUT = 1A)
(VOUT = 1.8V; VIN = 3.3V; IOUT = 1A)
1.0
1.5
1.0
0.5
0.5
0.0
0.0
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
-40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90
-40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90
Temperature (°C)
Temperature (°C)
Switching Frequency vs. Temperature
Quiescent Current vs. Input Voltage
(VOUT = 1.2V; IOUT = 1A)
(No Load)
3.04
3.02
3.00
2.98
2.96
2.94
2.92
2.90
2.88
2.86
2.84
80
70
60
50
40
30
20
10
0
T = 85°C
T = 25°C
T = -40°C
-40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Temperature (°C)
Input Voltage (V)
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2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Typical Characteristics
Load Transient
Load Transient
(VOUT = 1.2V; VIN = 3.3V; IOUT = 0A to 1.5A; COUT = 10µF)
(VOUT = 1.8V; VIN = 3.3V; IOUT = 0A to 1.5A; COUT = 10µF)
1.30
1.25
1.20
1.15
1.90
1.85
1.80
1.75
1.10
1.5
1.0
0.5
0.0
1.70
1.5
1.0
0.5
0.0
-0.5
Time (20µs/div)
Time (20µs/div)
Load Transient
Load Transient
(VOUT = 1.2V; VIN = 3.3V; IOUT = 75mA to 1350mA; COUT = 10µF)
(VOUT = 1.8V; VIN = 3.3V; IOUT = 75mA to 1350mA; COUT = 10µF)
1.30
1.25
1.20
1.15
1.90
1.85
1.80
1.75
1.10
1.5
1.0
0.5
0.0
-0.5
1.70
1.5
1.0
0.5
0.0
Time (20µs/div)
Time (20µs/div)
Line Transient
Line Transient
(VOUT = 1.2V; VIN = 3.3V to 3.6V; IOUT = 1A)
(VOUT = 1.8V; VIN = 3.3V to 3.6V; IOUT = 1A)
4.0
3.5
3.0
4.0
3.5
3.0
1.210
1.205
1.200
1.195
1.190
1.815
1.810
1.805
1.800
1.795
Time (50µs/div)
Time (20µs/div)
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2113A.2009.06.1.1
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PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Typical Characteristics
Soft Start
Soft Start
(VOUT = 1.2V; VIN = 3.3V; IOUT = 1A)
(VOUT = 1.8V; VIN = 3.3V; IOUT = 1A)
4
3
2
1
0
4
3
2
1
0
2
2
1
1
0
0
-1
-1
Time (100µs/div)
Time (2ms/div)
Output Voltage Ripple
Output Voltage Ripple
(VOUT = 1.2V; VIN = 3.3V; IOUT = 1mA)
(VOUT = 1.8V; VIN = 3.3V; IOUT = 1mA)
1.21
1.20
1.19
1.81
1.80
1.79
0.3
0.2
0.1
0
0.3
0.2
0.1
0
-0.1
-0.2
-0.1
-0.2
Time (10µs/div)
Time (10µs/div)
Output Voltage Ripple
Output Voltage Ripple
(VOUT = 1.2V; VIN = 3.3V; IOUT = 1.5A)
(VOUT = 1.8V; VIN = 3.3V; IOUT = 1.5A)
1.22
1.20
1.18
1.82
1.80
1.78
2.0
1.5
1.0
0.5
2.0
1.5
1.0
Time (200ns/div)
Time (200ns/div)
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2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Functional Block Diagram
FB
VCC
VP
AAT2113A-1.2V Only
Err
Amp
DH
DL
VREF
=
LX
Logic
0.6V
Comp
Input
PGND
AGND
EN
In battery-powered applications, as VIN decreases, the
converter dynamically adjusts the operating frequency
prior to dropout to maintain the required duty cycle and
provide accurate output regulation. Output regulation is
maintained until the dropout voltage, or minimum input
voltage, is reached. At 1.5A output load, dropout voltage
headroom is approximately 200mV.
Functional Description
The AAT2113A SwitchReg is a 1.5A step-down converter
with a typical input voltage of 3.3V and a fixed output
voltage of 1.2V. The 3MHz switching frequency enables
the use of small external components. The ultra-small,
2mm x 2mm footprint and high efficiency make the
AAT2113A an ideal choice for portable applications.
Typically, a 0.47μH inductor and a 10μF ceramic capaci-
tor are recommended for a 1.2V output (see Figure 2 for
recommended values).
The AAT2113A typically achieves better than ±0.5%
output regulation across the input voltage and output
load range. A current limit of 3.0A (typical) protects the
IC and system components from short-circuit damage.
Typical no load quiescent current is 55ꢀA.
At dropout, the converter duty cycle increases to 100%
and the output voltage tracks the input voltage minus
the RDS(ON) drop of the P-channel high-side MOSFET (plus
the DC drop of the external inductor). The device inte-
grates extremely low RDS(ON) MOSFETs to achieve low
dropout voltage during 100% duty cycle operation.
Thermal protection completely disables switching when
the maximum junction temperature is detected. The
junction over-temperature threshold is 140°C with 15°C
of hysteresis. Once an over-temperature or over-current
fault condition is removed, the output voltage automati-
cally recovers.
The integrated low-loss MOSFET switches can provide
excellent efficiency at heavy loads. Light load operation
maintains high efficiency, low ripple and low spectral
noise even at lower currents (typically <150mA). PWM
mode operation maintains constant frequency and low
output ripple at output loads greater than 200mA.
Peak current mode control and optimized internal com-
pensation provide high loop bandwidth and excellent
response to input voltage and fast load transient events.
Soft start eliminates output voltage overshoot when the
enable or the input voltage is applied. Under-voltage
lockout prevents spurious start-up events.
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2113A.2009.06.1.1
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PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
teresis. Once an over-temperature or over-current fault
condition is removed, the output voltage automatically
recovers.
Control Loop
The AAT2113A is a peak current mode step-down con-
verter. The current through the P-channel MOSFET (high
side) is sensed for current loop control, as well as short-
circuit and overload protection. A fixed slope compensa-
tion signal is added to the sensed current to maintain
stability for duty cycles greater than 50%. The peak cur-
rent mode loop appears as a voltage-programmed cur-
rent source in parallel with the output capacitor.
Under-Voltage Lockout
Internal bias of all circuits is controlled via the VCC
input. Under-voltage lockout (UVLO) guarantees suffi-
cient VIN bias and proper operation of all internal cir-
cuitry prior to activation.
The output of the voltage error amplifier programs the
current mode loop for the necessary peak switch current
to force a constant output voltage for all load and line
conditions. Internal loop compensation terminates the
transconductance voltage error amplifier output. The
reference voltage is internally set to program the con-
verter output voltage greater than or equal to 0.6V.
Component Selection
Inductor Selection
The step-down converter uses peak current mode con-
trol 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.
Soft Start/Enable
For applications where the duty cycle is less than 50%,
the inductor values can be chosen freely.
Soft start limits the current surge seen at the input and
eliminates output voltage overshoot. The enable input,
when pulled low, forces the AAT2113A into a low-power,
non-switching state. The total input current during shut-
down is less than 1ꢀA.
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.
Current Limit and
Over-Temperature Protection
Some inductors may meet the peak and average current
ratings yet result in excessive losses due to a high DCR.
For overload conditions, the peak input current is limit-
ed. To minimize power dissipation and stresses under
current limit and short-circuit conditions, switching is
terminated after entering current limit for a series of
pulses. Switching is terminated for seven consecutive
clock cycles after a current limit has been sensed for a
series of four consecutive clock cycles.
Always consider the losses associated with the DCR and
its effect on the total converter efficiency when selecting
an inductor.
For low cost application and a sufficiently small footprint
in a 5x5mm area, the LQM2HPNR47MG0 shielded chip
inductor, which has 40mΩ DCR and 1.8A DC current rat-
ing, is selected for 1.2V output.
Thermal protection completely disables switching when
internal dissipation becomes excessive. The junction
over-temperature threshold is 140°C with 15°C of hys-
The inductors listed in Table 1 have been used with the
AAT2113A.
Manufacturer
Part Number
Value (μH)
DC Resistance (Ω)
Size (mm)
Murata
LQM2HPNR47MG0
EPL2010-421ML
EPL2010-681ML
0.47 ± 20%
0.42 ± 20%
0.68 ± 20%
0.04 ± 25%
0.04 ± 25%
0.058 ± 25%
2.5x2.0x1.0
2.0x2.0x1.0
2.0x2.0x1.0
Coilcraft
Table 1: AAT2113A List of Inductors.
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2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
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.
Input Capacitor
Select a 4.7ꢀF to 10ꢀF 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 volt-
age and is a maximum when VIN is double the output
voltage.
VO
VIN
VO
VIN
1
2
· 1 -
=
D · (1 - D) = 0.52 =
for VIN = 2 · VO
VO
⎛
VO ⎞
· 1 -
⎝
IO
2
VIN
VIN
⎠
IRMS(MAX)
=
CIN =
⎛ VPP
⎝ IO
⎞
- ESR ·FS
⎠
VO
⎛
⎝
VO
⎞
⎠
·
1 -
VIN
VIN
VO
⎛
VO ⎞
VIN ⎠
1
The term
appears in both the input voltage
· 1 -
⎝
=
for VIN = 2 · VO
VIN
4
ripple and input capacitor RMS current equations and is
a maximum when VO 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 AAT2113A. 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 (C1) can be seen in the
evaluation board layout in the Layout section of this
datasheet (see Figure 3).
1
CIN(MIN)
=
⎛ VPP
⎝ IO
⎞
- ESR · 4 · FS
⎠
Always examine the ceramic capacitor DC voltage coef-
ficient characteristics when selecting the proper value.
For example, the capacitance of a 10ꢀF, 6.3V, X5R
ceramic capacitor with 3.5V DC applied is actually about
5ꢀF. Some examples of DC bias voltage versus capaci-
tance for different package sizes are shown in Figure 1.
12
0603 Package
0805 Package
10
8
A laboratory test set-up typically consists of two long
wires running from the bench power supply to the eval-
uation 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.
6
4
2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
DC Bias Voltage (V)
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.
Figure 1: 10μF Capacitor Value vs. DC Bias
Voltage for Different Package Sizes.
The maximum input capacitor RMS current is:
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 capacitor. This dampens
the high Q network and stabilizes the system.
VO
VIN
VO
VIN
IRMS = IO ·
· 1 -
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2113A.2009.06.1.1
11
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
The AAT2113A adjustable version, combined with an
external feed forward capacitor (C2 in Figure 5), delivers
enhanced transient response for extreme pulsed load
applications. The suggested value for C2 is in the range
of 22pF to 100pF.
Output Capacitor
The output capacitor limits the output ripple and pre-
vents the output voltage droop during large load transi-
tions. A 10ꢀF to 22ꢀF 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.
R2 = 59kΩ
R1 (kΩ)
R2 = 200kΩ
R1 (kΩ)
VOUT (V)
The output voltage droop due to a load transient is
dominated by the capacitance of the ceramic output
capacitor.
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
39.2
49.9
59
68.1
78.7
88.7
97.6
107
118
133
165
200
232
267
301
332
365
400
During a step increase in load current, the ceramic out-
put 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:
Table 2: Feedback Resistor Selection for
Adjustable Output Voltage Version.
3 · ΔILOAD
COUT
=
V
DROOP · FS
Thermal Calculations
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.
There are three types of losses associated with the
AAT2113A 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 losses is
given by:
The internal voltage loop compensation also limits the
minimum output capacitor value to 10ꢀF. 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.
IO2 · (RDS(ON)H · VO + RDS(ON)L · [VIN - VO])
PTOTAL
=
Feedback Resistor Selection
VIN
Resistors R1 and R2 of Figure 5 program the output to
regulate at a voltage higher than 0.6V for the AAT2113A
adjustable version. To limit the bias current required for
the external feedback resistor string while maintaining
good noise immunity, the suggested value for R2 is
200kΩ. Table 1 summarizes the resistor values for vari-
ous output voltages with R2 set to either 59kΩ or 200kΩ.
Alternately, the feedback resistor may be calculated
using the following equation:
+ (tsw · FS · IO + IQ) · VIN
IQ is the step-down converter quiescent current. The
term tSW is used to estimate the full load step-down con-
verter switching losses. For the condition where the
step-down converter is in dropout at 100% duty cycle,
the total device dissipation reduces to:
V
VREF
1.8V
0.6V
PTOTAL= IO2 · RDS(ON)H + IQ · VIN
R1 =
OUT -1 · R2 =
- 1 · 200kΩ = 400kΩ
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12
2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
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.
3. For the fixed version, the feedback trace or FB pin
should be separated from any power trace and con-
nected as closely as possible to the load point.
Sensing along a high-current load trace will degrade
DC load regulation. For the adjustable version, the
trace connecting the FB pin to resistors R1 and R2
should be as short as possible by placing R1 and R2
immediately next to the AAT2113A. The sense trace
connection from R1 to the output voltage should be
separate from any power trace and connect as
closely as possible to the load point. The external
feed-forward capacitor C2 should be connected as
close as possible in parallel with R1 for enhanced
transient response.
Given the total losses, the maximum junction tempera-
ture can be derived from the θJA for the FTDFN22-8
package, which is 70°C/W.
TJ(MAX) = PTOTAL · ΘJA + TAMB
PCB Layout Considerations
The suggested PCB layout for the AAT2113A is shown in
Figures 3 and 4 (fixed version) or Figures 6 and 7 (adjust-
able version). The following guidelines should be used to
help ensure a proper layout:
4. The resistance of the trace from the load return to
PGND 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.
1. The input capacitor (C1) should be connected as
close as possible to VP and PGND.
2. The output capacitor and L1 should be connected as
closely as possible. The connection of L1 to the LX
pin should be as short as possible.
5. Connect unused signal pins to ground to avoid
unwanted noise coupling.
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2113A.2009.06.1.1
13
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
VIN
2.7V to 5.5V
VOUT
1.2V/1.5A
U1
L1
8
7
4
1
2
6
3
VP
EN
LX
LX
0.47μH
EN
AAT2113A
C1
4.7μF
C2
10μF
VCC
FB
C3
1μF
5
AGND
PGND
FTDFN22-8
U1
AAT2113AIXS-1.2V-T1 AnalogicTech, 3MHz Fast Transient, 1.5A Step-Down Converter , FTDFN22-8, 2x2mm
GRM188R60J475KE19D, Murata, Cap, MLC, 4.7μF/6.3V, 0603 (HMAX = 0.9mm)
C1
L1
LQM2HPNR47MGO, Murata, 0.47μH, ISAT = 1800mA, DCR = 40mΩ, 2.5 x 2 x 0.9 mm, shielded chip inductor
GRM188R60J106ME47D, Murata, Cap, MLC, 10μF/6.3V, 0603 (HMAX = 0.9mm)
C2
C3
GRM155R60J105KE19D, Murata, Cap, MLC, 1μF/6.3V, 0402
Figure 2: AAT2113A Evaluation Board Schematic For 1.2V Fixed Output Voltage Version.
Figure 3: AAT2113A Evaluation Board
Top Side Layout for 1.2V Fixed
Output Voltage Version.
Figure 4: AAT2113A Evaluation Board
Bottom Side Layout for 1.2V Fixed
Output Voltage Version.
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14
2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
VIN
2.7V–5.5V
VOUT
1.2V/1.5A
U1
L1
8
7
4
1
2
6
VP
EN
LX
LX
0.47μH
R1
C2
22pF
EN
200k
C3
10μF
AAT2113A
C1
4.7μF
3
5
VCC
FB
C4
1μF
R2
200k
AGND
PGND
U1
AAT2113AIXS-0.6-T1 AnalogicTech, 3MHz Fast Transient, 1.5A Step-Down Converter, FTDFN22-8, 2x2mm
GRM188R60J475KE19D, Murata, Cap, MLC, 4.7μF/6.3V, 0603 (HMAX = 0.8mm)
Optional, 22pF, 0201
C1
C2
L1
LQM2HPNR47MGO, Murata, 0.47ꢀH, ISAT =1.8A, DCR = 0.04Ω, 2.5 x 2 x 1mm, shielded chip inductor
Carbon film resistor, 200kΩ, 1%, 0201
R1, R2
C3
GRM188R60J106ME47D, Murata, Cap, MLC, 10μF/6.3V, 0603 (HMAX = 0.8mm)
GRM155R60J105KE19D, Murata, Cap, MLC, 1μF/6.3V, 0402
C4
Figure 5: AAT2113A Evaluation Board Schematic For Adjustable Output Voltage Version.
Figure 6: AAT2113A Evaluation Board
Top Side Layout for Adjustable
Output Voltage Version.
Figure 7: AAT2113A Evaluation Board
Bottom Side Layout for Adjustable
Output Voltage Version.
w w w . a n a l o g i c t e c h . c o m
2113A.2009.06.1.1
15
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
AAT2113A Design Example
Specifications
VOUT = 1.2V @ 1.5A, Pulsed Load ΔILOAD = 1.5A
VIN = 3.3V
FS = 3MHz
TAMB = 85°C in 8-pin 2x2mm DFN low profile package
Output Inductor
For Murata, 0.47μH LQM2HPNNR47MG0 shielded chip inductor has a 40mΩ DCR.
VO
L1 · FS
VO
VIN
1.2
V
1.2V
3.3V
ΔI =
· 1 -
=
· 1 -
= 542mA
0.47μH · 3MHz
ΔI
2
IPK = IOUT
+
= 1.5A + 0.271A = 1.8A
PL1 = IOUT2 · DCR = 1.5A2 · 40mΩ = 90mW
Output Capacitor
For VDROOP = 0.12V (10% Output Voltage)
3 · ΔILOAD
VDROOP · FS
3 · 1.5A
0.12V · 3MHz
COUT
=
=
= 12.5μF; use 10μF
For VDROOP = 0.06V (5% Output Voltage)
3 · ΔILOAD
VDROOP · FS 0.06V · 3MHz
3 · 1.5A
COUT
=
=
= 25μF; use 22μF
VOUT · (VIN(MAX) - VOUT
)
1
1.2V · (5V - 1.2V)
1.5μH · 3MHz · 5V
1
·
= 58.5mArms
IRMS(MAX)
=
·
=
L · FS · VIN(MAX)
2· 3
2· 3
PRMS = ESR · IRMS2 = 5mΩ · (58.5mA)2 = 17μW
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16
2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Input Capacitor
For Input Ripple VPP = 30mV
1
1
CIN =
=
= 5.6μF; use 4.7μF
VPP
IO
30mV
1.5A
- ESR · 4 · FS
- 5mΩ · 4 · 3MHz
IOUT1
2
IRMS
=
= 0.75A
P = ESR · (IRMS)2 = 5mΩ · (0.75A)2 = 2.8mW
AAT2113A Losses
All values assume 85°C ambient temperature and thermal resistance of 70°C/W in the 8-pin 2x2mm DFN low profile
package.
PTOTAL = IOUT2 · RDS(ON)H + (tSW · FSW · IOUT + IQ) · VIN
= 1.5A2 · 152mΩ + (5ns · 3MHz · 1.5A + 50μA) · 3.3V
= 416mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (70°C/W) · 416mW = 114°C
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2113A.2009.06.1.1
17
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Ordering Information
Output Voltage
Package
Marking1
Part Number (Tape and Reel)2
1.2V
Adjustable (0.6V)
FTDFN22-8
FTDFN22-8
8BXYY
8AXYY
AAT2113AIXS-1.2-T1
AAT2113AIXS-0.6-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/about/quality.aspx.
Package Information
FTDFN22-83
0.400 0.050
Detail "A"
Index Area
Bottom View
2.000 0.050
Top View
0.500 0.050
+
0.100
0.000
- 0.000
Side View
Pin 1 Identification
Detail "A"
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3. 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.
w w w . a n a l o g i c t e c h . c o m
18
2113A.2009.06.1.1
PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
Advanced Analogic Technologies, Inc.
3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© 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. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
w w w . a n a l o g i c t e c h . c o m
2113A.2009.06.1.1
19
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