AAT1120 SwitchReg 1.5MHz step-down converter with input voltage range

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AAT1120 SwitchReg 1.5MHz step-down converter with input voltage range

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500mA Step-Down Converter General Description
AAT1120 SwitchReg 1.5MHz step-down converter with input voltage range 2.7V 5.5V output 0.6V. supply current, small size, high switching frequency make AAT1120 ideal choice portable applications. AAT1120 delivers 500mA load current, while maintaining load quiescent current. 1.5MHz switching frequency minimizes size external components, while keeping switching losses low. AAT1120 feedback control delivers excellent load regulation transient response with small output inductor capacitor. AAT1120 available Pb-free, 8-pin, 2x2mm STDFN package rated over -40°C +85°C temperature range.
AAT1120
SwitchReg
Range: 2.7V 5.5V VOUT Range: 0.6V 500mA Output Current Efficiency Typical Quiescent Current 1.5MHz Switching Frequency Soft-Start Control Over-Temperature Current Limit Protection 100% Duty Cycle Low-Dropout Operation Shutdown Current Small External Components Ultra-Small STDFN22-8 Package Temperature Range: -40°C +85°C
Applications
Bluetooth® Headsets Cellular Phones Digital Cameras Handheld Instruments Micro Hard Disk Drive Portable Music Players Devices
Typical Application
AAT1120 4.7µF 3.0H 118k 4.7µF
1.8V
500mA
PGND
1120.2007.01.1.0
500mA Step-Down Converter Descriptions
AAT1120
Symbol
PGND
Function
Input power pin; connected source P-channel MOSFET. Connect input capacitor. Input bias voltage converter. Non-power signal ground pin. Feedback input pin. Connect this external resistive divider adjustable output. connect. Enable pin. logic high enables normal operation. logic shuts down converter. Switching node. Connect inductor this pin. connected internally drain both high- low-side MOSFETs. Input power return pin; connected source N-channel MOSFET. Connect output input capacitor return. Exposed paddle (bottom): connect ground directly beneath package.
Configuration
STDFN22-8 (Top View)
PGND
1120.2007.01.1.0
500mA Step-Down Converter Absolute Maximum Ratings1
Symbol
VOUT TLEAD
AAT1120
Description
Input Voltage Bias Power Operating Junction Temperature Range Maximum Soldering Temperature leads, sec)
Value
-0.3 -0.3 -0.3
Units
Thermal Information
Symbol
Description
Maximum Power Dissipation (STDFN22-8) Thermal Resistance2 (STDFN22-8)
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. 1120.2007.01.1.0
500mA Step-Down Converter Electrical Characteristics1
3.6V, -40°C +85°C, unless otherwise noted; typical values 25°C. Symbol
VUVLO VOUT VOUT ISHDN ILIM RDS(ON)H RDS(ON)L ILXLEAK VLinereg/VIN FOSC THYS VEN(L) VEN(H)
AAT1120
Description
Input Voltage UVLO Threshold Output Voltage Tolerance2 Output Voltage Range Quiescent Current Shutdown Current P-Channel Current Limit High-Side Switch Resistance Low-Side Switch Resistance Leakage Current Line Regulation Feedback Threshold Voltage Accuracy Leakage Current Oscillator Frequency Startup Time Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Enable Threshold Enable Threshold High Input Current
Conditions
Rising Hysteresis Falling IOUT 500mA, 2.7V 5.5V Load
Units
-3.0 0.59 0.42
5.5V, 2.7V 5.5V 3.6V VOUT 1.0V From Enable Output Regulation
0.591 0.600 -1.0 0.609
5.5V
AAT1120 guaranteed meet performance specifications over -40°C +85°C operating temperature range assured design, characterization, correlation with statistical process controls. Output voltage tolerance independent feedback resistor network accuracy.
1120.2007.01.1.0
500mA Step-Down Converter Typical Characteristics
Efficiency Load
(VOUT 3.0V; 4.7µH)
AAT1120
Load Regulation
(VOUT 3.0V; 4.7µH)
-0.2 -0.4 -0.6 -0.8 -1.0 1000
Efficiency
4.2V 5.0V
Load Regulation
3.6V
3.6V
5.0V
4.2V
1000
Output Current (mA)
Output Current (mA)
Efficiency Load
(VOUT 1.8V; 3.3µH)
Load Regulation
(VOUT 1.8V; 3.3µH)
-0.5 -1.0 -1.5 -2.0 1000
2.7V
Load Regulation
3.6V
Efficiency
2.7V
3.6V
4.2V
4.2V
1000
Output Current (mA)
Output Current (mA)
Efficiency Load
(VOUT 1.2V; 1.5µH)
-0.5 -1.5 1000
Load Regulation
(VOUT 1.2V; 1.5µH) 2.7V 3.6V 4.2V
Efficiency
2.7V 3.6V 4.2V 5.0V
Load Regulation
5.0V
1000
Output Current (mA)
Output Current (mA)
1120.2007.01.1.0
500mA Step-Down Converter Typical Characteristics
Soft Start
(VIN 3.6V; VOUT 1.8V; 500mA)
AAT1120
Line Regulation
(VOUT 1.8V)
-0.2 -0.4
0.30 0.20
Enable Output Voltage (top)
-1.0 -2.0 -3.0 -4.0 -5.0
Accuracy
IOUT 50mA IOUT 10mA IOUT 250mA IOUT 150mA
Inductor Current (bottom)
0.10 0.00 -0.10 -0.20 -0.30
IOUT
Time (100µs/div)
Input Voltage
Output Voltage Error Temperature
(VIN 3.6V; VOUT 1.8V; IOUT 500mA)
10.0 -1.0 -2.0 -3.0
Switching Frequency Variation Temperature
(VIN 3.6V; VOUT 1.8V)
Output Error
Variation
-2.0 -4.0 -6.0 -8.0 -10.0
Temperature (°C)
Temperature (°C)
Frequency Variation Input Voltage
Load Quiescent Current Input Voltage
Frequency Variation
Supply Current (µA)
-1.0 -2.0 -3.0 -4.0
VOUT 1.8V
85°C 25°C -40°C
VOUT 3.0V
Input Voltage
Input Voltage
1120.2007.01.1.0
500mA Step-Down Converter Typical Characteristics
P-Channel RDS(ON) Input Voltage
1000
AAT1120
N-Channel RDS(ON) Input Voltage
120°C
100°C
RDS(ON)H
RDS(ON)L
85°C
120°C
100°C 85°C
25°C
25°C
Input Voltage
Input Voltage
Load Transient Response
(1mA 500mA; 3.6V; VOUT 1.8V; COUT 4.7µF; 100pF)
Load Transient Response
(350mA 500mA; 3.6V; VOUT 1.8V; COUT 4.7µF; 100pF)
Load Inductor Current (bottom) (400mA/div)
Load Inductor Current (bottom) (200mA/div)
Output Voltage (top)
Output Voltage (top)
Time (25µs/div)
Time (25µs/div)
Line Response
(VOUT 1.8V 500mA)
1.90 1.85
Output Voltage (top)
1.80 1.75 1.70 1.65 1.60 1.55 1.50
Input Voltage (bottom)
Time (25µs/div)
1120.2007.01.1.0
500mA Step-Down Converter Typical Characteristics
Output Ripple
(VIN 3.6V; VOUT 1.8V; IOUT 1mA)
AAT1120
Output Ripple
(VIN 3.6V; VOUT 1.8V; IOUT 500mA)
Output Voltage Coupled) (top) (mV)
Output Voltage Coupled) (top) (mV)
0.04 0.03 0.02
-100 -120
Inductor Current (bottom)
Inductor Current (bottom)
0.01 0.00 -0.01
Time (2µs/div)
Time (200ns/div)
1120.2007.01.1.0
500mA Step-Down Converter Functional Block Diagram
AAT1120
Voltage Reference Logic
INPUT
PGND
Functional Description
AAT1120 high performance 500mA, 1.5MHz monolithic step-down converter designed operate with input voltage range 2.7V 5.5V. converter operates 1.5MHz, which minimizes size external components. Typical values 3.3H output inductor 4.7F ceramic output capacitor. device designed operate with output voltage 0.6V. Power devices sized 500mA current capability while maintaining over
efficiency full load. Light load efficiency maintained greater than down load current. dropout, converter duty cycle increases 100% output voltage tracks input voltage minus RDS(ON) drop P-channel highside MOSFET. high-DC gain error amplifier with internal compensation controls output. provides excellent transient response load/line regulation. Soft start eliminates output voltage overshoot when enable input voltage applied.
1120.2007.01.1.0
500mA Step-Down Converter
Control Loop
AAT1120 500mA 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. error amplifier reference fixed 0.6V.
AAT1120
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. internal slope compensation adjustable low-voltage fixed versions AAT1120 0.45A/sec. This equates slope compensation that inductor current down slope 1.8V output 3.0H inductor.
0.75 0.75 1.8V 0.45 3.0µH µsec
Soft Start Enable
Soft start increases inductor current limit point discrete steps when input voltage enable input applied. limits current surge seen input eliminates output voltage overshoot. When pulled low, enable input forces AAT1120 into low-power, non-switching state. total input current during shutdown less than
This internal slope compensation AAT1120. When externally programming 3.0V, calculated inductance 5.0H.
0.75
µsec 0.75 1.67 0.45A µsec
1.67
Current Limit Over-Temperature Protection
overload conditions, peak input current limited. load impedance decreases output voltage falls closer zero, more power dissipated internally, raising device temperature. Thermal protection completely disables switching when internal dissipation becomes excessive, protecting device from damage. junction over-temperature threshold 140°C with 15°C hysteresis.
µsec 3.0V 5.0µH
this case, standard 4.7H value selected. most designs, AAT1120 operates with inductor value 4.7H. Table displays inductor values AAT1120 with different output voltage options. 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.
Under-Voltage Lockout
Internal bias circuits controlled power. Under-voltage lockout (UVLO) guarantees sufficient bias proper operation internal circuits prior activation.
1120.2007.01.1.0
500mA Step-Down Converter
Output Voltage
AAT1120
input capacitor ripple current varies with input output voltage will always less than equal half total load current.
0.52
Table Inductor Values. 3.0H CDRH2D09 series inductor selected from Sumida 150m 470mA current rating. full load, inductor loss 9.375mW which gives 2.08% loss efficiency 250mA, 1.8V output.
IRMS(MAX)
Input Capacitor
Select 4.7F ceramic capacitor input. estimate required input capacitor size, determine acceptable input ripple level (VPP) solve CIN. calculated value varies with input voltage maximum when double output voltage.
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 AAT1120. 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 (C1) 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.
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 maximum input capacitor current
IRMS
1120.2007.01.1.0
500mA Step-Down Converter
applications where input power source lead inductance cannot reduced level that does affect converter performance, high tantalum aluminum electrolytic should placed parallel with ESR, bypass ceramic. This dampens high network stabilizes system. maximum output capacitor ripple current given
VOUT (VIN(MAX) VOUT) VIN(MAX)
AAT1120
IRMS(MAX)
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. enhanced transient response temperature operation application, (X5R, X7R) ceramic capacitor recommended stabilize extreme pulsed load conditions. 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
ILOAD VDROOP
Dissipation current ceramic output capacitor typically minimal, resulting less than degrees rise hot-spot temperature.
Adjustable Output Resistor Selection
Resistors Figure program output regulate voltage higher than 0.6V. limit bias current required external feedback resistor string while maintaining good noise immunity, suggested value 59k. Decreased resistor values necessary maintain noise immunity pin, resulting increased quiescent current. Table summarizes resistor values various output voltages.
VOUT 3.3V 0.6V 267k
With enhanced transient response extreme pulsed load application, external feed-forward capacitor, Figure added. VOUT
1.85
COUT
221k
1000
19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7
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.
Table Adjustable Resistor Values Step-Down Converter.
1120.2007.01.1.0
500mA Step-Down Converter
Thermal Calculations
There three types losses associated with AAT1120 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
AAT1120
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 STDFN22-8 package which 50°C/W.
TJ(MAX) PTOTAL TAMB
PTOTAL
(RDS(ON)H RDS(ON)L [VIN VO])
(tsw
step-down converter quiescent current. term used estimate full load stepdown converter switching losses.
PGND
+VOUT Adj. (optional) 100pF
4.7F
AAT1120
4.7F
Figure AAT1120 Schematic.
1120.2007.01.1.0
500mA Step-Down Converter
Layout
suggested layout AAT1120 STDFN22-8 package shown Figures following guidelines should used help ensure proper layout. input capacitor (C1) should connect closely possible (Pin PGND (Pin (Pin should connected closely possible. connection (Pin should short possible. make node small using narrow trace. trace should kept wide, direct short. feedback (Pin should separate from power trace connect closely possible load point. Sensing along high-current load trace will degrade load regulation. Feedback resistors should placed closely possible (Pin minimize length high impedance feedback trace. possible, they should also placed away from (switching node) inductor improve noise immunity. resistance trace from load return PGND (Pin (Pin should kept minimum. This will help minimize error regulation differences potential internal signal ground power ground. high density, small footprint layout achieved using inexpensive, miniature, nonshielded, high inductor.
AAT1120
Figure AAT1120 Evaluation Board Side Layout.
Figure Exploded View AAT1120 Evaluation Board Side Layout.
Figure AAT1120 Evaluation Board Bottom Side Layout.
1120.2007.01.1.0
500mA Step-Down Converter Step-Down Converter Design Example
Specifications
TAMB 1.8V 250mA, Pulsed Load ILOAD 200mA 2.7V 4.2V (3.6V nominal) 1.5MHz 85°C
AAT1120
1.8V Output Inductor
1.67 µsec µsec 1.67 1.8V
(use 3.0H; Table
Sumida inductor CDRH2D09-3R0, 3.0H, 150m.
1.8V 1.8V 228mA 3.0µH 1.5MHz 4.2V
IPKL1
250mA 114mA 364mA
250mA2 150m 9.375mW
1.8V Output Capacitor
VDROOP 0.1V
ILOAD 0.2A (use 4.7µF) 0.1V 1.5MHz VDROOP (VO) (VIN(MAX) 1.8V (4.2V 1.8V) 66mArms 3.0µH 1.5MHz 4.2V VIN(MAX)
COUT IRMS
Pesr IRMS2 (66mA)2 21.8µW
1120.2007.01.1.0
500mA Step-Down Converter
Input Capacitor
Input Ripple 25mV
AAT1120
1.38µF (use 4.7µF) 25mV 1.5MHz 0.2A
IRMS
0.1Arms
IRMS2 (0.1A)2 0.05mW
AAT1120 Losses
PTOTAL (RDS(ON)H RDS(ON)L [VIN -VO])
(tsw
0.22 (0.59 1.8V 0.42 [4.2V 1.8V])
4.2V
(5ns 1.5MHz 0.2A 30µA) 4.2V 26.14mW
TJ(MAX) TAMB PLOSS 85°C (50°C/W) 26.14mW 86.3°C
1120.2007.01.1.0
500mA Step-Down Converter
Output Voltage VOUT
1.85
AAT1120
19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7
221k1
1000
3.0/3.3 3.0/3.3 3.0/3.3 3.9/4.2
Table Evaluation Board Component Values.
Manufacturer
Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Taiyo Yuden Taiyo Yuden Taiyo Yuden Taiyo Yuden
Part Number
CDRH2D09-1R5 CDRH2D09-2R2 CDRH2D09-2R5 CDRH2D09-3R0 CDRH2D09-3R9 CDRH2D09-4R7 CDRH2D09-5R6 CDRH2D11-1R5 CDRH2D11-2R2 CDRH2D11-3R3 CDRH2D11-4R7 NR3010 NR3010 NR3010 NR3010 MIPWT3226D-1R5 MIPWT3226D-2R2 MIPWT3226D-3R0 MIPWT3226D-4R2
Inductance
Current (mA)
1200 1100 1200 1100 1000
Size (mm) LxWxH
3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.2x3.2x1.2 3.2x3.2x1.2 3.2x3.2x1.2 3.2x3.2x1.2 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.2x2.6x0.8 3.2x2.6x0.8 3.2x2.6x0.8 3.2x2.6x0.8
Type
Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Chip shielded Chip shielded Chip shielded Chip shielded
Table Suggested Inductors Suppliers.
reduced quiescent current, 221k. opened, shorted. 1120.2007.01.1.0
500mA Step-Down Converter
Value
AAT1120
Manufacturer
Murata Murata
Part Number
GRM118R60J475KE19B GRM188R60J106ME47D
Voltage Rating
Temp.
Case Size
0603 0603
Table Surface Mount Capacitors.
1120.2007.01.1.0
500mA Step-Down Converter Ordering Information
Output Voltage
0.6V
AAT1120
Package
STDFN22-8
Marking1
VQXYY
Part Number (Tape Reel)2
AAT1120IES-0.6-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 Information3
STDFN22-8
Index Area (D/2 E/2) Detail
2.00 0.05
0.80 0.05
2.00 0.05
View
Bottom View
0.35 0.05
0.55 0.05
0.15 0.025
1.45 0.05
0.05 0.05
Side View
Indicator (optional)
0.23 0.05
Detail
dimensions millimeters. assembly date code. Sample stock generally held part numbers listed BOLD. leadless package family, which includes QFN, TQFN, DFN, TDFN STDFN, exposed copper (unplated) lead terminals manufacturing process. solder fillet exposed copper edge cannot guaranteed required ensure proper bottom solder connection. 1120.2007.01.1.0
0.45 0.05
500mA Step-Down Converter
AAT1120
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. Customers advised obtain latest version relevant information verify, before placing orders, that information being relied current complete. products sold subject terms conditions sale supplied time order acknowledgement, including those pertaining warranty, patent infringement, limitation liability. AnalogicTech warrants performance semiconductor products specifications applicable time sale accordance with AnalogicTech's standard warranty. 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.
Advanced Analogic Technologies, Inc.
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1120.2007.01.1.0

AAT1120 SwitchReg 1.5MHz step-down converter with input voltage range

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