SwitchRegAAT1149B SwitchReg 2.2MHz step-down converter with input volt
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AAT1 149B
SwitchRegAAT1149B SwitchReg 2.2MHz step-down converter with input voltage range 2.2V 5.5V. optimized react quickly load variations operate with tiny 0603 inductor that only tall. AAT1149B deliver 400mA load current while maintaining load quiescent current. 2.2MHz switching frequency minimizes size external components while keeping switching losses low. AAT1149B maintains high efficiency throughout operating range, which critical portable applications. AAT1149B available Pb-free, space-saving 5-pin wafer-level chip scale (WLCSP) package rated over -40°C +85°C temperature range.
2.2MHz Fast Transient 400mA Step-Down Converter
Features
Ultra-Small 0603 Inductor (Height 1mm) Range: 2.2V 5.5V VOUT Fixed 1.8V 400mA Output Current Efficiency Load Quiescent Current 2.2MHz Switching Frequency Soft Start Fast Load Transient Over-Temperature Protection Current Limit Protection 100% Duty Cycle Low-Dropout Operation Shutdown Current 0.9x1.2mm WLCSP Package Temperature Range: -40°C +85°C
Applications
Cellular Phones Digital Cameras Handheld Instruments Microprocessor Core Power PDAs Handheld Computers Devices
Typical Application
3.6V AAT1149B VOUT 1.8V 2.2µH
4.7µF AGND PGND
PGND PGND
4.7µF
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AAT1 149B
SwitchRegDescriptions
2.2MHz Fast Transient 400mA Step-Down Converter
Symbol
AGND PGND
Function
Feedback input pin. Connect this converted output voltage node. Enable pin. Non-power signal ground pin. Main power ground return pins. Connect output input capacitor return. Input supply voltage converter. Switching node. Connect inductor this pin. internally connected drain both high- low-side MOSFETs.
Configuration
WLCSP-5 (Top View)
AGND/PGND
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SwitchRegAbsolute Maximum Ratings1
Symbol
TLEAD
2.2MHz Fast Transient 400mA Step-Down Converter
Description
Input Voltage Operating Junction Temperature Range Maximum Soldering Temperature leads, sec)
Value
-0.3 -0.3 -0.3
Units
Thermal Information
Symbol
Description
Maximum Power Dissipation Thermal Resistance2
Value
Units
°C/W
Stresses above those listed Absolute Maximum Ratings cause permanent damage device. Functional operation conditions other than operating conditions specified implied. Only Absolute Maximum Rating should applied time. Mounted board; NSMD (none-solder mask defined) style tighter control copper etch process. Derate 3.52 mW/°C above 25°C.
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AAT1 149B
SwitchRegElectrical Characteristics1
3.6V, -40°C +85°C, unless otherwise noted. Typical values 25°C. Symbol Description Conditions
-3.0 0.40 0.35 5.5V, VIN, 2.7V 5.5V From Enable Output Regulation 25°C VOUT 5.5V -1.0
2.2MHz Fast Transient 400mA Step-Down Converter
Units
Step-Down Converter Input Voltage VOUT Output Voltage Tolerance Quiescent Current ISHDN Shutdown Current P-Channel Current Limit ILIM High Side Switch Resistance RDS(ON)H RDS(ON)L Side Switch Resistance Leakage Current ILXLEAK Line Regulation VLinereg Start-Up Time FOSC Oscillator Frequency Over-Temperature Shutdown Threshold THYS Over-Temperature Shutdown Hysteresis Enable Threshold VEN(L) VEN(H) Enable Threshold High Input Current
IOUT 400mA, 2.7V 5.5V Load
AAT1149B guaranteed meet performance specifications over -40°C +85°C operating temperature range assured design, characterization, correlation with statistical process controls.
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AAT1 149B
SwitchRegTypical Characteristics
Efficiency Output Current
(VOUT 1.8V; 1.5µH)
2.2MHz Fast Transient 400mA Step-Down Converter
Load Regulation
(VOUT 1.8V; 1.5µH)
5.5V 4.2V 3.6V 2.7V 2.3V
Output Error
Efficiency
-0.5 -1.5
5.5V 4.2V 3.6V 2.7V 2.3V
1000
1000
10000
Output Current (mA)
Output Current
Load Quiescent Current Input Voltage
Frequency Variation Input Voltage
(VOUT 1.8V)
Supply Current (µA)
Frequency Variation
85°C 25°C -40°C
Input Voltage
Input Voltage
Switching Frequency Variation Temperature
Output Voltage Error Temperature
(VIN 3.6V; 1.8V; IOUT 400mA)
Output Error
Variation
-1.0
-2.0
Temperature (°C)
Temperature (°C)
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SwitchRegTypical Characteristics
Line Regulation
(VOUT 1.8V)
2.2MHz Fast Transient 400mA Step-Down Converter
Line Transient
(VOUT 1.8V; 3.6V 4.2V) Input Voltage (top) (1V/div)
0.04 0.02 -0.02
Output Voltage (bottom) (20mV/div)
Accuracy
-0.2 -0.4 -0.6 -0.8
400mA
100mA
600mA
Input Voltage
Time (200µs/div)
Line Transient
(VOUT 1.8V; Load)
4.50 1.94 1.92 1.90 1.88 1.86 1.84 1.82 1.80 1.78
N-Channel RDS(ON) Input Voltage
(WLCSP-5) Output Voltage (bottom)
Input Voltage (top)
4.25 4.00 3.75 3.50 3.25 3.00 2.75 2.50
RDS(ON)
25°C
120°C
100°C
85°C
Time (50µs/div)
Input Voltage
P-Channel RDS(ON) Input Voltage
(WLCSP-5)
120°C 100°C
Step-Down Converter Load Transient Response
(VIN 3.6V; VOUT 1.8V; IOUT 40mA 400mA; COUT 4.7µF) Output Voltage Coupled) (bottom)
400mA
Output Current (top)
RDS(ON)
25°C 85°C
40mA
Input Voltage
Time (100µs/div)
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AAT1 149B
SwitchRegTypical Characteristics
Soft Start
(VOUT 1.8V) Enable Output Voltage (top)
4.00 3.00 2.00 1.00 0.00 -1.00 -2.00 -3.00 -4.00 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 0.00
2.2MHz Fast Transient 400mA Step-Down Converter
Inductor Current (bottom) (250mA/div)
Time (50µs/div)
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SwitchRegFunctional Block Diagram
2.2MHz Fast Transient 400mA Step-Down Converter
Voltage Reference
Logic
INPUT
PGND
AGND
Functional Description
AAT1149B high performance 400mA 2.2MHz monolithic step-down converter. minimizes external component size, enabling tiny 0603 inductor that only tall, optimized noise. Apart from small bypass input capacitor, only small filter required output. Typically, 1.8H inductor 4.7F ceramic capacitor recommended (see table values). Only three external power components (CIN, COUT, required. Output voltage fixed internally.
dropout, converter duty cycle increases 100% output voltage tracks input voltage minus RDS(ON) drop P-channel high-side MOSFET. input voltage range 2.2V 5.5V. converter efficiency been optimized load conditions, ranging from load 400mA. internal error amplifier compensation provides excellent transient response, load, line regulation. Soft start eliminates output voltage overshoot when enable input voltage applied.
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SwitchRegControl Loop
AAT1149B peak current mode step-down converter. current through P-channel MOSFET (high side) sensed current loop control, well short circuit overload protection. fixed slope compensation signal added sensed current maintain stability duty cycles greater than 50%. peak current mode loop appears voltage-programmed current source parallel with output capacitor. output voltage error amplifier programs current mode loop necessary peak switch current force constant output voltage load line conditions. Internal loop compensation terminates transconductance voltage error amplifier output. adjustable output, error amplifier reference fixed 0.6V.
2.2MHz Fast Transient 400mA Step-Down Converter
Applications Information
Inductor Selection
step-down converter uses peak current mode control with slope compensation maintain stability duty cycles greater than 50%. output inductor value must selected inductor current down slope meets internal slope compensation requirements. 2.2H inductor recommended 1.875V output. Manufacturer's specifications list both inductor current rating, which thermal limitation, peak current rating, which determined saturation characteristics. inductor should show appreciable saturation under normal load conditions. Some inductors meet peak average current ratings result excessive losses high DCR. Always consider losses associated with effect total converter efficiency when selecting inductor. 2.2H CBC2518 series inductor selected from Taiyo Yuden 130mW 890mA saturation current rating. full load, inductor loss 21mW which gives 2.8% loss efficiency 400mA, 1.875V output.
Soft Start Enable
Soft start limits current surge seen input eliminates output voltage overshoot. When pulled low, enable input forces AAT1149B into low-power, non-switching state. total input current during shutdown less than
Current Limit Over-Temperature Protection
overload conditions, peak input current limited. minimize power dissipation stresses under current limit short-circuit conditions, switching terminated after entering current limit series pulses. Switching terminated seven consecutive clock cycles after current limit been sensed series four consecutive clock cycles. Thermal protection completely disables switching when internal dissipation becomes excessive. junction over-temperature threshold 140°C with 15°C hysteresis. Once over-temperature over-current fault conditions removed, output voltage automatically recovers.
Input Capacitor
Select 4.7F ceramic capacitor input. estimate required input capacitor size, determine acceptable input ripple level (VPP) solve calculated value varies with input voltage maximum when double output voltage.
CIN(MIN)
Always examine ceramic capacitor voltage coefficient characteristics when selecting proper value. example, capacitance 10F, 6.3V, ceramic capacitor with 5.0V applied actually about
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SwitchRegmaximum input capacitor current
2.2MHz Fast Transient 400mA Step-Down Converter
converter performance, high tantalum aluminum electrolytic should placed parallel with ESR, bypass ceramic. This dampens high network stabilizes system.
IRMS
input capacitor ripple current varies with input output voltage will always less than equal half total load current.
Output Capacitor
output capacitor limits output ripple provides holdup during large load transitions. 4.7F ceramic capacitor typically provides sufficient bulk capacitance stabilize output during large load transitions characteristics necessary output ripple. output voltage droop load transient dominated capacitance ceramic output capacitor. During step increase load current, ceramic output capacitor alone supplies load current until loop responds. Within three switching cycles, loop responds inductor current increases match load current demand. relationship output voltage droop during three switching cycles output capacitance estimated
0.52
IRMS(MAX)
term appears both input voltage ripple input capacitor current equations maximum when twice VIN. This input voltage ripple input capacitor current ripple maximum duty cycle.
input capacitor provides impedance loop edges pulsed current drawn AAT1149B. ESR/ESL ceramic capacitors ideal this function. minimize stray inductance, capacitor should placed closely possible This keeps high frequency content input current localized, minimizing input voltage ripple. proper placement input capacitor (C2) seen evaluation board layout Figure laboratory test set-up typically consists long wires running from bench power supply evaluation board input voltage pins. inductance these wires, along with low-ESR ceramic input capacitor, create high network that affect converter performance. This problem often becomes apparent form excessive ringing output voltage during load transients. Errors loop phase gain measurements also result. Since inductance short trace feeding input voltage significantly lower than power leads from bench power supply, most applications exhibit this problem. applications where input power source lead inductance cannot reduced level that does affect
COUT
ILOAD VDROOP
Once average inductor current increases load level, output voltage recovers. above equation establishes limit minimum value output capacitor with respect load transients. internal voltage loop compensation also limits minimum output capacitor value 4.7F. This effect loop crossover frequency (bandwidth), phase margin, gain margin. Increased output capacitance will reduce crossover frequency with greater phase margin. maximum output capacitor ripple current given
IRMS(MAX)
VOUT (VIN(MAX) VOUT) VIN(MAX)
Dissipation current ceramic output capacitor typically minimal, resulting less than degrees rise hot-spot temperature.
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1149B.2008.07.1.0
AAT1 149B
SwitchReg2.2MHz Fast Transient 400mA Step-Down Converter
Figure AAT1149BIUV Evaluation Board Side.
Figure AAT1149BIUV Evaluation Board Bottom Side.
VOUT open
AAT1149BIUV
open
4.7F
4.7F
WLCSP-5
Figure AAT1149BIUV Evaluation Board Schematic.
Thermal Calculations
There three types losses associated with AAT1149B step-down converter: switching losses, conduction losses, quiescent current losses. Conduction losses associated with RDS(ON) characteristics power output switching devices. Switching losses dominated gate charge power output switching devices. full load, assuming continuous conduction mode (CCM), simplified form losses given
PTOTAL
(RDS(ON)H RDS(ON)L [VIN VO])
(tsw
step-down converter quiescent current. term used estimate full load step-down converter switching losses.
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AAT1 149B
SwitchReg2.2MHz Fast Transient 400mA Step-Down Converter
Layout
suggested layout AAT1149B shown Figures following guidelines should used help ensure proper layout. input capacitor (C2) should connect closely possible (Pin PGND (Pin should connected closely possible. connection should short possible. feedback trace (Pin should separate from power trace connect closely possible load point. Sensing along highcurrent load trace will degrade load regulation. resistance trace from load return PGND (Pin should kept minimum. This will help minimize error regulation differences potential internal signal ground power ground. WLCSP-5 package should NSMD (non-solder mask defined) configuration tighter control copper etch process. thickness less than recommended achieve higher stand-off. condition where step-down converter dropout 100% duty cycle, total device dissipation reduces
PTOTAL RDS(ON)H
Since RDS(ON), quiescent current, switching losses vary with input voltage, total losses should investigated over complete input voltage range. Given total losses, maximum junction temperature derived from WLCSP-8 package which 284°C/W.
TJ(MAX) PTOTAL TAMB
WLCSP Package Light Sensitivity
electrical performance WLCSP package adversely affected exposing device certain light sources such direct sunlight halogen lamp whose wavelengths infra-reds. However, fluorescent lighting very little effect electrical performance WLCSP package.
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1149B.2008.07.1.0
AAT1 149B
SwitchReg2.2MHz Fast Transient 400mA Step-Down Converter
Step-Down Converter Design Example
Specifications
1.8V 400mA (adjustable using 0.6V version), Pulsed Load ILOAD 300mA 2.7V 4.2V (3.6V nominal) 2.2MHz
TAMB 85°C
1.8V Output Inductor
1.8V 1.8µH (use 2.2H)
Taiyo Yuden inductor CBC2518T2R2M, 2.2H, 130m.
1.8V 1.8V 214mA 2.2µH 2.2MHz 4.2V 0.4A 0.107A 0.507A
IPKL1
0.4A2 130m 21mW
1.8V Output Capacitor
VDROOP 0.1V
COUT IRMS
ILOAD 0.3A 4.1µF; 4.7µF 0.1V 2.2MHz VDROOP (VO) (VIN(MAX) 1.8V (4.2V 1.8V) 62mArms VIN(MAX) 2.2µH 2.2MHz 4.2V
Pesr IRMS2 (62mA)2 19µW
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AAT1 149B
SwitchRegInput Capacitor
Input Ripple 10mV
2.2MHz Fast Transient 400mA Step-Down Converter
0.2Arms
10mV 2.2MHz 0.4A
5.7µF; 4.7µF
IRMS
IRMS2 (0.2A)2 0.2mW
AAT1149B Losses (WLCSP-5 Package)
PTOTAL (RDS(ON)H RDS(ON)L [VIN -VO])
(tsw
0.42 (0.725 1.8V [4.2V 1.8V])
4.2V
(5ns 2.2MHz 0.4A 3mA) 4.2V 149mW TJ(MAX) TAMB PLOSS 85°C (284°C/W) 149mW 127°C
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AAT1 149B
SwitchRegManufacturer
Taiyo Yuden
2.2MHz Fast Transient 400mA Step-Down Converter
Part Number/Type
BRL2012 CBC2518 Wire Wound Chip CDRH2D09 Shielded LQM2MPN2R2NGOL Unshielded SD3118 Shielded
Inductance
Rated Current (mA)
1200
Size (mm) LxWxH
0805 (HMAX 1mm) 2.5x1.8x1.8 3.2x3.2x1.0 2.0x1.6x0.95 3.15x3.15x1.2
Sumida Murata Coiltronics
Table Typical Surface Mount Inductors. Manufacturer
Murata Murata Murata
Part Number
GRM219R61A475KE19 GRM21BR60J106KE19 GRM185R60J475M
Value
4.7F 4.7F
Voltage
6.3V 6.3V
Temp.
Case
0805 0805 0603
Table Surface Mount Capacitors.
reduced quiescent current, 221k.
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SwitchRegOrdering Information
Output Voltage1
1.875
2.2MHz Fast Transient 400mA Step-Down Converter
Package
WLCSP-5
Marking
ZZYW
Part Number (Tape Reel)2
AAT1149BIUV-1.8-T1
AnalogicTech products offered Pb-free packaging. term "Pb-free" means semiconductor products that compliance with current RoHS standards, including requirement that lead exceed 0.1% weight homogeneous materials. more information, please visit website
Package Information
WLCSP-5
0.910 0.035 0.400 0.030 0.025 0.380 0.300 Line_1: Part Code Line_2: Year Code Date Code
0.180
Line_1
Line_2
0.693
0.300
0.070 0.140 (Ref.) indication
0.200 0.030
Bottom View
1.235 0.035
Side View
View
View
dimensions millimeters.
Contact Sales other voltage options. Sample stock generally held part numbers listed BOLD. date code (year, week) WLCSP-5 package.
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0.030 0.580 -0.070
1149B.2008.07.1.0
AAT1 149B
SwitchReg2.2MHz Fast Transient 400mA Step-Down Converter
Advanced Analogic Technologies, Inc. 3230 Scott Boulevard, Santa Clara, 95054 Phone (408) 737-4600 (408) 737-4611
Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility circuitry other than circuitry entirely embodied AnalogicTech product. circuit patent licenses, copyrights, mask work rights, other intellectual property rights implied. AnalogicTech reserves right make changes their products specifications discontinue product service without notice. Except provided AnalogicTech's terms conditions sale, AnalogicTech assumes liability whatsoever, AnalogicTech disclaims express implied warranty relating sale and/or AnalogicTech products including liability warranties relating fitness particular purpose, merchantability, infringement patent, copyright other intellectual property right. order minimize risks associated with customer's applications, adequate design operating safeguards must provided customer minimize inherent procedural hazards. Testing other quality control techniques utilized extent AnalogicTech deems necessary support this warranty. Specific testing parameters each device necessarily performed. AnalogicTech AnalogicTech logo trademarks Advanced Analogic Technologies Incorporated. other brand product names appearing this document registered trademarks trademarks their respective holders.
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