Analogic AAT1149A 2.2mhz fast transient 400ma step-down converter Datasheet

PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
General Description
Features
The AAT1149A SwitchReg is a 2.2MHz step-down converter with an input voltage range of 2.2V to 5.5V. It is
optimized to react quickly to load variations and operate
with a tiny 0603 inductor that is only 1mm tall.
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The AAT1149A can deliver 400mA of load current and
operates in PWM only mode for low noise operation. The
2.2MHz switching frequency minimizes the size of external components while keeping switching losses low.
The AAT1149A is optimized for low noise portable
applications.
The AAT1149A is available in a Pb-free, space-saving
5-pin wafer-level chip scale (WLCSP) package and is
rated over the -40°C to +85°C temperature range.
Ultra-Small 0603 Inductor (Height = 1mm)
VIN Range: 2.2V to 5.5V
VOUT Fixed 1.875V
400mA Max Output Current
Up to 98% Efficiency
3mA No Load Quiescent Current
2.2MHz Switching Frequency
70μs Soft Start
Fast Load Transient
Over-Temperature Protection
Current Limit Protection
100% Duty Cycle Low-Dropout Operation
<1μA Shutdown Current
0.9x1.2mm WLCSP Package
Temperature Range: -40°C to +85°C
Applications
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Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor / DSP Core / IO Power
PDAs and Handheld Computers
USB Devices
Typical Application
VIN = 3.6V
C2
4.7µF
1149A.2008.08.1.1
U1
AAT1149A
IN
LX
EN
FB
AGND
PGND
PGND
PGND
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VOUT = 1.875V
L1 2.2µH
C1
4.7µF
1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Pin Descriptions
Pin #
Symbol
1
2
4
FB
EN
AGND
PGND
IN
5
LX
3
Function
Feedback input pin. Connect this pin ito the converted output voltage node.
Enable pin.
Non-power signal ground pin.
Main power ground return pins. Connect to the output and input capacitor return.
Input supply voltage for the converter.
Switching node. Connect the inductor to this pin. It is internally connected to the drain of both high- and
low-side MOSFETs.
Pin Configuration
WLCSP-5
(Top View)
FB
AGND/PGND
IN
2
1
2
EN
5
LX
3
4
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1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Absolute Maximum Ratings1
Symbol
VIN
VLX
VFB
VEN
TJ
TLEAD
Description
Input Voltage 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 VIN + 0.3
-0.3 to VIN + 0.3
-0.3 to 6.0
-40 to 150
300
V
V
V
V
°C
°C
Value
Units
352
284
mW
°C/W
Thermal Information
Symbol
PD
θJA
Description
Maximum Power Dissipation
Thermal Resistance2
2, 3
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; use the NSMD (none-solder mask defined) pad style for tighter control on the copper etch process.
3. Derate 3.52 mW/°C above 25°C.
1149A.2008.08.1.1
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3
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Electrical Characteristics1
VIN = 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
Conditions
Step-Down Converter
Input Voltage
VIN
VOUT
Output Voltage Tolerance
Quiescent Current
IQ
ISHDN
Shutdown Current
P-Channel Current Limit
ILIM
High Side Switch On Resistance
RDS(ON)H
RDS(ON)L
Low Side Switch On Resistance
LX Leakage Current
ILXLEAK
Line Regulation
ΔVLinereg
TS
Start-Up Time
FOSC
Oscillator Frequency
TSD
Over-Temperature Shutdown Threshold
THYS
Over-Temperature Shutdown Hysteresis
EN
Enable Threshold Low
VEN(L)
VEN(H)
Enable Threshold High
IEN
Input Low Current
IOUT = 0 to 400mA, VIN = 2.7V to 5.5V
No Load
VEN = GND
Min
Typ
2.2
-3.0
3
Max
Units
5.5
3.0
6
1.0
V
%
mA
μA
mA
Ω
Ω
μA
%/V
μs
MHz
°C
°C
600
0.40
0.35
VIN = 5.5V, VLX = 0 to VIN, VEN = GND
VIN = 2.7V to 5.5V
From Enable to Output Regulation
TA = 25°C
1
0.1
70
2.2
140
15
0.6
VIN = VOUT = 5.5V
1.4
-1.0
1.0
V
V
μA
1. The AAT1149A 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.
4
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1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Typical Characteristics
Efficiency vs. Output Current
Load Regulation
(VOUT = 1.875V)
100
1.6
90
1.4
80
1.2
Output Error (%)
Efficiency (%)
(VOUT = 1.875V)
70
60
50
40
VIN = 5V
VIN = 4.2V
VIN = 3.6V
VIN = 3V
VIN = 2.7V
30
20
10
0
0.1
1
10
100
VIN = 5V
VIN = 4.2V
VIN = 3.6V
VIN = 3V
VIN = 2.2V
1
0.8
0.6
0.4
0.2
0
-0.2
1000
0.1
10
1
Output Current (A)
100
1000
Output Current (A)
No Load Quiescent Current vs. Input Voltage
Frequency Variation vs. Input Voltage
(VOUT = 1.875V)
2
Frequency Variation (%)
Supply Current (µA)
5
4.5
4
3.5
3
2.5
2
T = 85°C
T = 25°C
T = -40°C
1.5
1
2.5
3
3.5
4
4.5
5
5.5
6
1
0
-1
-2
-3
-4
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
Switching Frequency Variation vs. Temperature
Output Voltage Error vs. Temperature
(VIN = 3.6V; VO = 1.875V; IOUT = 400mA)
2.0
10
8
Output Error (%)
Variation (%)
6
4
2
0
-2
-4
-6
1.0
0.0
-1.0
-8
-10
-40
-20
0
20
40
60
80
100
120
-2.0
-40
Temperature (°°C)
1149A.2008.08.1.1
-20
0
20
40
60
80
100
Temperature (°°C)
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5
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Typical Characteristics
Line Regulation
Line Transient
(VOUT = 1.875V)
(VOUT = 1.875V; VIN = 3.6V to 4.2V)
Accuracy (%)
0.6
400mA
0.4
0mA
0.2
100mA
0
-0.2
-0.4
600mA
-0.6
-0.8
-1
2.5
3
3.5
4
4.5
5
5.5
5
4
3
2
1
0.04
0
0.02
0
-0.02
6
Input Voltage (V)
Time (200µs/div)
N-Channel RDS(ON) vs. Input Voltage
Line Transient
(WLCSP-5)
1.94
4.25
1.92
4.00
1.90
3.75
1.88
3.50
1.86
3.25
1.84
3.00
1.82
2.75
1.80
2.50
1.78
750
700
650
RDS(ON) (mΩ
Ω)
4.50
Output Voltage (bottom) (V)
Input Voltage (top) (V)
(VOUT = 1.875V; No Load)
100°C
120°C
600
550
500
450
85°C
400
350
25°C
300
250
2.5
3
3.5
4
4.5
5
5.5
P-Channel RDS(ON) vs. Input Voltage
Load Transient
(VOUT = 1.875V; VIN = 3.6V; IOUT = 1mA to 400mA)
(WLCSP-5)
RDS(ON) (mΩ
Ω)
Output Voltage (top)
(200mV/div)
700
100°C
600
550
500
85°C
450
400
350
25°C
300
250
2.5
3
3.5
4
4.5
5
5.5
0
-0.2
0.5
0
0.5
0
6
Input Voltage (V)
6
0.2
Output Current (middle)
Inductor Current (bottom)
(500mA/div)
750
120°C
6
Input Voltage (V)
Time (50µs/div)
650
Output Voltage
(bottom) (20mV/div)
Input Voltage (top) (1V/div)
1
0.8
Time (100µs/div)
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1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Soft Start
(VOUT = 1.875V)
0
-0.2
0.5
0
0.5
0
4.00
2.00
3.00
1.75
2.00
1.50
1.00
1.25
0.00
1.00
-1.00
0.75
-2.00
0.50
-3.00
0.25
-4.00
0.00
Time (50µs/div)
Time (100µs/div)
1149A.2008.08.1.1
Inductor Current
(bottom) (250mA/div)
0.2
Enable and Output Voltage
(top) (V)
Load Transient
(VOUT = 1.875V; VIN = 3.6V; IOUT = 10mA to 400mA)
Output Current (middle)
Inductor Current (bottom)
(500mA/div)
Output Voltage (top)
(200mV/div)
Typical Characteristics
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PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Functional Block Diagram
IN
FB
Err
Amp
.
DH
Voltage
Reference
EN
LX
Logic
DL
INPUT
PGND
AGND
Functional Description
The AAT1149A is a high performance 400mA 2.2MHz
monolithic step-down converter. It minimizes external
component size, enabling the use of a tiny 0603 inductor
that is only 1mm tall, and is optimized for low noise.
Apart from the small bypass input capacitor, only a small
L-C filter is required at the output. Typically, a 1.8μH
inductor and a 4.7μF ceramic capacitor are recommended (see table of values).
Only three external power components (CIN, COUT, and L)
are required. Output voltage is fixed internally.
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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.
The input voltage range is 2.2V to 5.5V. The converter
efficiency has been optimized for all load conditions,
ranging from no load to 400mA.
The internal error amplifier and compensation provides
excellent transient response, load, and line regulation.
Soft start eliminates any output voltage overshoot when
the enable or the input voltage is applied.
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1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Applications Information
Control Loop
The AAT1149A is a peak current mode step-down converter. 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 compensation signal is added to the sensed current to maintain
stability for duty cycles greater than 50%. The peak current mode loop appears as a voltage-programmed current source in parallel with the output capacitor.
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. For the
adjustable output, the error amplifier reference is fixed
at 0.6V.
Soft Start / Enable
Soft start limits the current surge seen at the input and
eliminates output voltage overshoot. When pulled low,
the enable input forces the AAT1149A into a low-power,
non-switching state. The total input current during shutdown is less than 1μA.
Current Limit and
Over-Temperature Protection
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. A
2.2μH inductor is recommended for a 1.875V output.
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 2.2μH CBC2518 series inductor selected from Taiyo
Yuden has a 130mW DCR and a 890mA saturation current rating. At full load, the inductor DC loss is 21mW
which gives a 2.8% loss in efficiency for a 400mA,
1.875V output.
Input Capacitor
For overload conditions, the peak input current is limited. 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.
Thermal protection completely disables switching when
internal dissipation becomes excessive. The junction
over-temperature threshold is 140°C with 15°C of hysteresis. Once an over-temperature or over-current fault
conditions is removed, the output voltage automatically
recovers.
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 =
V ⎞
VO ⎛
· 1- O
VIN ⎝
VIN ⎠
⎛ VPP
⎞
- ESR · FS
⎝ IO
⎠
VO ⎛
V ⎞
1
· 1 - O = for VIN = 2 · VO
VIN ⎝
VIN ⎠
4
1
CIN(MIN) =
⎛ VPP
⎞
- ESR · 4 · FS
⎝ IO
⎠
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.
1149A.2008.08.1.1
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9
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
The maximum input capacitor RMS current is:
IRMS = IO ·
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.
VO ⎛
V ⎞
· 1- O
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.
VO ⎛
V ⎞
· 1- O =
VIN ⎝
VIN ⎠
D · (1 - D) =
0.52 =
1
2
for VIN = 2 · VO
IRMS(MAX) =
VO
IO
2
⎛
V ⎞
· 1- O
The term V ⎝ V ⎠ appears in both the input voltage 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.
IN
IN
The input capacitor provides a low impedance loop for the
edges of pulsed current drawn by the AAT1149A. 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 1.
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.
In applications where the input power source lead inductance cannot be reduced to a level that does not affect
10
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 =
3 · ΔILOAD
VDROOP · FS
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.
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
VOUT · (VIN(MAX) - VOUT)
L · FS · VIN(MAX)
2· 3
·
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.
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1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Figure 1: AAT1149AIUV Evaluation Board
Top Side.
Figure 2: AAT1149AIUV Evaluation Board
Bottom Side.
VIN
U1
4
5
IN
AAT1149AIUV
EN
3
2
1
2
L1
LX
EN
FB
VOUT
C3
open
R1
0
1
R2
open
C1
4.7μF
C2
4.7μF
GND
3
WLCSP-5
Figure 3: AAT1149AIUV Evaluation Board Schematic.
Thermal Calculations
There are three types of losses associated with the
AAT1149A 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 losses is given by:
1149A.2008.08.1.1
PTOTAL =
IO2 · (RDS(ON)H · VO + RDS(ON)L · [VIN - VO])
VIN
+ (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 converter switching losses.
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PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
For the condition where the step-down converter is in
dropout at 100% duty cycle, the total device dissipation
reduces to:
PTOTAL = IO2 · RDS(ON)H + IQ · VIN
Layout
The suggested PCB layout for the AAT1149A is shown in
Figures 1 and 2. The following guidelines should be used
to help ensure a proper layout.
1.
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.
2.
Given the total losses, the maximum junction temperature can be derived from the θJA for the WLCSP-8 package which is 284°C/W.
3.
TJ(MAX) = PTOTAL · ΘJA + TAMB
4.
WLCSP Package Light Sensitivity
The electrical performance of the WLCSP package can be
adversely affected by exposing the device to certain light
sources such as direct sunlight or a halogen lamp whose
wavelengths are red and infra-reds. However, fluorescent lighting has very little effect on the electrical performance of the WLCSP package.
12
5.
The input capacitor (C2) should connect as closely as
possible to IN (Pin 4) and PGND (Pin 3).
C1 and L1 should be connected as closely as possible. The connection of L1 to the LX pin should be as
short as possible.
The feedback trace or FB pin (Pin 1) should be separate from any power trace and connect as closely as
possible to the load point. Sensing along a highcurrent load trace will degrade DC load regulation.
The resistance of the trace from the load return to
the PGND (Pin 3) 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.
The pad on the PCB for the WLCSP-5 package should
use NSMD (non-solder mask defined) configuration
due to its tighter control on the copper etch process.
A pad thickness of less than 1oz is recommended to
achieve higher stand-off.
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1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Step-Down Converter Design Example
Specifications
VO = 1.875V @ 400mA (adjustable using 0.6V version), Pulsed Load DILOAD = 300mA
VIN = 2.7V to 4.2V (3.6V nominal)
FS
= 2.2MHz
TAMB = 85°C
1.875V Output Inductor
L1 = 1
µs
µs
· VO = 1
· 1.875V = 1.875µH (use 2.2μH)
A
A
For Taiyo Yuden inductor CBC2518T2R2M, 2.2μH, DCR = 130mΩ.
ΔIL1 =
VO
V
1.875V
1.875V
· 1- O =
· 1= 214mA
L1 · FS
VIN
2.2µH · 2.2MHz
4.2V
IPKL1 = IO +
ΔIL1
= 0.4A + 0.107A = 0.507A
2
PL1 = IO2 · DCR = 0.4A2 · 130mΩ = 21mW
1.875V Output Capacitor
VDROOP = 0.1V
COUT =
3 · ΔILOAD
3 · 0.3A
=
= 4.1µF; use 4.7µF
0.1V · 2.2MHz
VDROOP · FS
IRMS =
(VO) · (VIN(MAX) - VO)
1
1.875V · (4.2V - 1.875V)
·
= 62mArms
=
L1 · FS · VIN(MAX)
2 · 3 2.2µH · 2.2MHz · 4.2V
2· 3
1
·
Pesr = esr · IRMS2 = 5mΩ · (62mA)2 = 19µW
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PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Input Capacitor
Input Ripple VPP = 10mV
CIN =
IRMS =
1
VPP
- ESR · 4 · FS
IO
=
1
10mV
- 5mΩ · 4 · 2.2MHz
0.4A
= 5.7µF; use 4.7µF
IO
= 0.2Arms
2
P = esr · IRMS2 = 5mΩ · (0.2A)2 = 0.2mW
AAT1149A Losses (WLCSP-5 Package)
PTOTAL =
IO2 · (RDS(ON)H · VO + RDS(ON)L · [VIN -VO])
VIN
+ (tsw · FS · IO + IQ) · VIN
=
0.42 · (0.725Ω · 1.875V + 0.7Ω · [4.2V - 1.875V])
4.2V
+ (5ns · 2.2MHz · 0.4A + 3mA) · 4.2V = 149mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (284°C/W) · 149mW = 127°C
14
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1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Part Number/Type
Inductance (μH)
Rated
Current (mA)
DCR (Ω)
BRL2012
2.2
550
250
0805
(HMAX = 1mm)
CBC2518
Wire Wound Chip
2.2
890
130
2.5x1.8x1.8
Sumida
CDRH2D09
Shielded
2.5
440
150
3.2x3.2x1.0
Murata
LQH2MCN4R7M02
Unshielded
2.2
425
480
2.0x1.6x0.95
Coiltronics
SD3118
Shielded
2.2
510
116
3.15x3.15x1.2
Manufacturer
Taiyo Yuden
Size (mm)
LxWxH
Table 1: Typical Surface Mount Inductors.
Manufacturer
Part Number
Value
Voltage
Temp. Co.
Case
Murata
Murata
Murata
GRM219R61A475KE19
GRM21BR60J106KE19
GRM185R60J475M
4.7μF
10μF
4.7μF
10V
6.3V
6.3V
X5R
X5R
X58
0805
0805
0603
Table 2: Surface Mount Capacitors.
1. For reduced quiescent current, R2 = 221kΩ.
1149A.2008.08.1.1
www.analogictech.com
15
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
Ordering Information
Output Voltage1
Package
Marking
Part Number (Tape and Reel)2
1.875
WLCSP-5
3UYW
AAT1149AIUV-1.875-T1
3
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
WLCSP-5
0.910 ± 0.035
0.400 BSC
0.180
+ 0.030
- 0.025
0.300
0.380
Line_1: Part Code
Line_2: Year Code + Date Code
0.300
0.070
1.235 ± 0.035
Line_2
0.4
00
BS
C
60°
0.693 BSC
Line_1
0.140
0.200 ± 0.030
Top View
Side View
+ 0.030
0.580 -0.070
Bottom View
ø 0.2 (Ref.)
Pin 1 indication
End View
All dimensions in millimeters.
1. Contact Sales for other voltage options.
3. Sample stock is generally held on part numbers listed in BOLD.
3. YW = date code (year, week) for WLCSP-5 package.
16
www.analogictech.com
1149A.2008.08.1.1
PRODUCT DATASHEET
AAT1149A
SwitchRegTM
2.2MHz Fast Transient 400mA Step-Down Converter
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.
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17