SwitchRegAAT1184 single output step-down (Buck) output regulator with

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SwitchRegAAT1184 single output step-down (Buck) output regulator with

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AAT1
SwitchRegAAT1184 single output step-down (Buck) output regulator with integrated high side MOSFET. input range making ideal power solution consumer communications equipment operating from cost AC/DC adapter with output. step-down regulator provides 1.2A output current small package. 490kHz fixed switching frequency allows small filtering components. Voltage mode control allows optimum performance across entire output voltage load range. controller includes programmable over-current, integrated soft-start over-temperature protection. AAT1184 available Pb-free, profile 12-pin TSOPJW package. rated operating temperature range -40°C 85°C.
High Voltage Step-Down Regulator
Features
24.0V VOUT Adjustable from 1.5V 5.5V IOUT 1.2A Small Solution Size Low-Cost Non-Synchronous Solution Shutdown Current <35A High Switching Frequency Voltage Mode Control Fixed Frequency Lowest Noise Programmable Over-Current Protection Over-Temperature Protection Internal Soft Start Profile 3x3mm TSOPJW-12 Package -40°C 85°C Temperature Range
Applications
Cable Modems Notebook Computers Satellite Wireless Systems
Typical Application
TSOPJW 0.1µF BAS16 25µF B340A 2.32K 68nF 330pF 44.2k 22µF 4.7µH VOUT 5V/1.2A
AAT1184
2.2µF 24.3K COMP
220pF 56pF
6.04k
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SwitchRegDescriptions
High Voltage Step-Down Regulator
Symbol
COMP
Function
Output current sense pin. Connect small signal resistor from this switching node (LX) enable over-current sense step-down converter. Enable input pin. Active high. Boost drive input pin. Connect cathode fast rectifier from this connect 100nF capacitor from this switching node (LX) internal hi-side MOSFET gate drive. Step-down converter switching pin. Connect output inductor this pin. Connect pins together. Input supply voltage step-down regulator. Connect both pins together. Connect input capacitor close this best noise performance. Internal linear regulator. Connect 2.2F/6.3V capacitor from this pin. Ground step-down converter. Connect input output capacitors return terminals close this best noise performance. Feedback input step-down converter. Connect external resistor divider this program output voltage desired value. Compensation step-down regulator. Connect series resistor, capacitor network compensate voltage mode control loop. Output voltage sense pin. Connect output capacitor enable over-current sense stepdown converter.
Configuration
TSOPJW-12 (Top View)
COMP
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SwitchRegAbsolute Maximum Ratings1
Symbol
VIN(HI) VIN(LO) VBST1-LX VCONTROL IIN(PULSED) TLEAD
High Voltage Step-Down Regulator
Description
COMP, Operating Junction Temperature Range Maximum Soldering Temperature leads, sec)
Value
-0.3 30.0 -0.3 -0.3 -0.3 VIN(LO) -0.3 12.0
Units
Thermal Information
Symbol
Description
Thermal Resistance Maximum Power Dissipation2
Value
Units
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. Derate 7mW/°C above 25°C ambient temperature.
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SwitchRegElectrical Characteristics1
12V; -40°C 85°C, unless noted otherwise. Typical values 25°C. Symbol
VUVLO VOUT VLINEREG/ VLOADREG/ ISHDN VOCP DMAX TON(MIN) RDSON(H) FOSC FFOLDBACK VEN(L) VEN(H)
High Voltage Step-Down Regulator
Description
Input Voltage UVLO Threshold Output Voltage Range Output Voltage Accuracy Feedback Voltage Line Regulation Load Regulation Quiescent Current Shutdown Current Over-Current Offset Voltage Leakage Current Maximum Duty Cycle Minimum On-Time Side On-Resistance Oscillator Frequency Short Circuit Foldback Frequency Soft-Start Time Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Enable Threshold Enable Threshold High Input Current
Conditions
Rising Hysteresis Falling IOUT 1.2A 24V, VOUT 3.3V, IOUT 1.2A 24V, VOUT 5.0V, IOUT 1.2A 12V, VOUT 3.3V, IOUT 1.2A 12V, VOUT IOUT 1.2A High, load Low, High, 6.0V 24.0V, 25°C 24.0V, 24.0V 4.5V
24.0
Units
-2.5 0.591 0.609
0.600 0.02
-1.0
35.0
Current Limit Triggered From Enable Output Regulation
-1.0
AAT1184 guaranteed meet performance specifications over -40°C +85°C operating temperature range assured design, characterization correlation with statistical process controls.
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SwitchRegTypical Characteristics
Step-Down Converter Efficiency Load
(VOUT 3.3V; 4.7µH)
High Voltage Step-Down Regulator
Step-Down Converter Efficiency Load
(VOUT 4.7µH)
Efficiency
Efficiency
1000 10000
1000 10000
Output Current (mA)
Output Current (mA)
Step-Down Converter Regulation
(VOUT 3.3V; 4.7µH)
-0.5 -1.0 -1.5 -2.0 -2.5 -3.0
Step-Down Converter Regulation
(VOUT 4.7µH)
Output Error
-0.5 -1.0 -1.5 -2.0
Output Error
1000 10000
1000 10000
Output Current (mA)
Output Current (mA)
Step-Down Converter Line Regulation
(VOUT 3.3V; 4.7µH)
-0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0
Step-Down Converter Line Regulation
(VOUT 4.7µH)
Accuracy
-0.5 -1.0 -1.5
Accuracy
IOUT 0.1mA IOUT 10mA IOUT 100mA IOUT 600mA IOUT 1200mA
IOUT 0.1mA IOUT 10mA IOUT 100mA IOUT 600mA IOUT 1200mA
Input Voltage
Input Voltage
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SwitchRegTypical Characteristics
Step-Down Converter Output Ripple
(VIN 12V; VOUT 3.3V; IOUT 1mA) Output Voltage Coupled) (bottom) Output Voltage Coupled) (bottom) Voltage (top) Inductor Current (middle)
High Voltage Step-Down Regulator
Step-Down Converter Output Ripple
(VIN 12V; VOUT IOUT 1mA) Voltage (top) Inductor Current (middle)
3.31 3.30 3.29
5.02 5.00 4.98
Time (2µs/div)
Time (2µs/div)
Step-Down Converter Output Ripple
(VIN 12V; VOUT 3.3V; IOUT 1.2A) Output Voltage Coupled) (bottom) Output Voltage Coupled) (bottom) Voltage (top) Inductor Current (middle)
Step-Down Converter Output Ripple
(VIN 12V; VOUT IOUT 1.2mA) Voltage (top) Inductor Current (middle)
5.02 5.00 4.98
3.31 3.30 3.29
Time (1µs/div)
Time (1µs/div)
Step-Down Converter Load Transient Response
(IOUT 0.12A 1.2A; 12V; VOUT 3.3V; COUT 2x22µF) Output Voltage Coupled) (bottom)
Step-Down Converter Load Transient Response
(IOUT 0.12A 1.2A; 12V; VOUT COUT 2x22µF)
Output Voltage Coupled) (bottom)
Output Current (top)
Output Current (top)
1.2A 0.12A
1.2A 0.12A
Time (100µs/div)
Time (100µs/div)
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SwitchRegTypical Characteristics
Step-Down Converter Load Transient Response
(IOUT 0.6A 1.2A; 12V; VOUT 3.3V; COUT 2x22µF) Output Voltage Coupled) (bottom)
High Voltage Step-Down Regulator
Step-Down Converter Load Transient Response
(IOUT 0.6A 1.2A; 12V; VOUT COUT 2x22µF) Output Voltage Coupled) (bottom)
Output Current (top)
Output Current (top)
1.2A 0.6A
1.2A 0.6A
Time (100µs/div)
Time (100µs/div)
Step-Down Converter Load Transient Response
(IOUT 0.6A 1.2A; 12V; VOUT 3.3V; COUT 2x22µF) Output Voltage Coupled) (bottom)
Step-Down Converter Load Transient Response
(IOUT 0.9A 1.2A; 12V; VOUT COUT 2x22µF) Output Voltage Coupled) (bottom)
Output Current (top)
Output Current (top)
1.2A 0.9A
1.2A 0.9A
-0.5
Time (100µs/div)
Time (100µs/div)
Step-Down Converter Line Transient Response
(VIN 10V; VOUT 3.3V; IOUT 1.2A) Output Voltage Coupled) (bottom) Input Voltage (top)
3.35 3.30 3.25
Step-Down Converter Line Transient Response
(VIN 10V; VOUT IOUT 1.2A) Output Voltage Coupled) (bottom) Input Voltage (top)
Time (100ms/div)
Time (100ms/div)
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SwitchRegTypical Characteristics
Step-Down Converter Soft Start
(VIN 12V; 10V; VOUT 3.3V; IOUT 1.2A) Enable Voltage (top) Output Voltage (middle) Enable Voltage (top) Output Voltage (middle)
High Voltage Step-Down Regulator
Step-Down Converter Soft Start
(VIN 12V; 10V; VOUT IOUT 1.2A)
Inductor Current (bottom)
Inductor Current (bottom)
Time (500µs/div)
Time (500µs/div)
Step-Down Converter Switching Frequency Input Voltage
(VIN 24V; VOUT 3.3V; IOUT 1.2A) Frequency Variation Output Voltage Error
-0.5 -1.0 -1.5 -2.0 -0.5 -1.0 -1.5
Step-Down Converter Output Voltage Error Temperature
(VIN 12V; VOUT 3.3V)
IOUT 0.1mA IOUT 10mA IOUT 100mA IOUT 600mA IOUT 1200mA
Input Voltage
Temperature (°C)
Step-Down Converter Output Voltage Error Temperature
(VIN 12V; VOUT Output Voltage Error
-0.2 -0.4 -0.6 -0.8 -1.0
Load Step-Down Converter Input Current Input Voltage
(VEN VIN)
Input Current (µA)
IOUT 0.1mA IOUT 10mA IOUT 100mA IOUT 600mA IOUT 1200mA
85°C 25°C -40°C
Temperature (°C)
Input Voltage
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SwitchRegTypical Characteristics
Input Voltage
1.35 1.30
High Voltage Step-Down Regulator
1.25 1.20 1.15 1.10
1.05 1.00
Input Voltage
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SwitchRegFunctional Block Diagram
High Voltage Step-Down Regulator
VINT
Reg.
Error
Comp. Comp.
COMP
Logic
Control Logic Voltage
Comp
VOCP 0.1V
Functional Description
AAT1184 high voltage step-down (Buck) regulator with input voltage range from 6.0V 24.0V, providing high output current small package. output voltage user-programmable from 1.5V 5.5V. device optimized low-cost adapter inputs. device utilizes voltage mode control configured optimum performance across entire output voltage load range.
controller includes integrated over-current, softstart over-temperature protection. Over-current sensed through output inductor winding resistance (DCR). external resistor capacitor network adjusts current limit according inductor desired output current limit. Frequency reduction limits over-current stress during overload short-circuit events. operating frequency returns nominal setting when over-current conditions removed. AAT1184 available Pb-free 12-pin TSOPJW package with rated operating temperature range -40°C 85°C.
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SwitchRegApplications Information
high voltage DC/DC step-down converter provides output voltage from 1.5V 5.5V. integrated high-side n-channel MOSFET device provides 1.2A output current1. Input voltage range 6.0V 24.0V. step-down converter utilizes constant frequency (PWM-mode) voltage mode control achieve high operating efficiency while maintaining extremely output noise across operating range. High 490kHz (nominal) switching frequency allows small external filtering components, achieving minimum cost solution size. External compensation allows designer optimize transient response while achieving stability across operating range.
High Voltage Step-Down Regulator
capacitors maintain minimum capacitance drop with bias.
Output Inductor Selection
step-down converter utilizes constant frequency (PWM-mode) voltage mode control. 4.7H inductor value selected maintain desired output current ripple minimize converter's response time load transients. peak switch current should exceed inductor saturation current, MOSFET external Schottky rectifier peak current ratings.
Rectifier Selection
When high-side switch input voltage will applied cathode Schottky diode. rectifier's rated reverse breakdown voltage must chosen least equal maximum input voltage stepdown regulator. When high-side switch off, current will flow from power ground output through Schottky diode inductor. power dissipation Schottky diode during time-off determined following equation:
Output Voltage Current
output voltage using external resistor divider shown Table Minimum output voltage 1.5V maximum output voltage 5.5V. Typical maximum duty cycle 85%. VOUT
1.85
6.04k
9.09 12.1 12.4 14.0 19.1 24.3 27.4 44.2
IOUT
VOUT
Where voltage drop across Schottky diode.
Input Capacitor Selection
cost applications, 100F/25V electrolytic capacitor selected control voltage overshoot across high side MOSFET. small ceramic capacitor with voltage rating least 1.05 times greater than maximum input voltage connected close possible input (Pin high frequency decoupling.
Table Feedback Resistor Values. Alternatively, feedback resistor calculated using following equation:
(VOUT 0.6)
rounded nearest resistor value.
Feedback Compensation Networks
transfer function Error Amplifier dominated Gain COUT output filter regulator. This output filter equivalent series resistor (ESR) create double pole zero FESR following equations:
Buck Regulator Output Capacitor Selection
ceramic output capacitor required filter inductor current ripple supply load transient current IOUT 1.2A. 1206 package with minimum voltage rating recommended output
COUT
Output current capability vary dependent package selection, maximum ambient temperature, airflow heatsinking.
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SwitchRegFESR
High Voltage Step-Down Regulator
COUT
feedback compensation networks provide closed loop transfer function with highest crossing frequency adequate phase margin system stability. Equations relate compensation network's poles zeros components
Components feedback, feed forward, compensation, current limit networks need adjusted maintain system stability different input output voltage applications shown Table
VOUT
COMP
Figure AAT1184 Feedback Compensation Networks Type Voltage-Mode Control Loop.
Network
Feedback Feed-forward Compensation
Components
VOUT 3.3V
27.4k 6.02k 330pF 470pF 56pF 24.3k 68nF 2.32k Open Open
VOUT 5.0V
44.2k 6.02k 330pF 220pF 56pF 24.3k 68nF 2.32k Open Open
Current Limit
Table AAT1184 Feedback Compensation Network Components VOUT 3.3V VOUT 5.0V.
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SwitchRegThermal Protection
AAT1184 internal thermal protection circuit which will turn when device temperature exceeds 135°C. internal thermal protection circuit will actively turn high side regulator output device prevent possibility over temperature damage. Buck regulator output will remain shutdown state until internal temperature falls back below 135°C trip point. combination interaction between short circuit thermal protection systems allows Buck regulator withstand indefinite short-circuit conditions without sustaining permanent damage.
High Voltage Step-Down Regulator
step-down converter current. term used estimate full load step-down converter switching losses. asynchronous Step-Down converter, power dissipation only internal high side MOSFET during time. When switch off, power dissipates external Schottky diode. Total package losses AAT1184 reduce following equation:
PTOTAL IOUT2 RDS(ON)H (tSW IOUT
where VOUT duty cycle.
Thermal Calculations
There types losses associated with AAT1184 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 synchronous step-down converter losses given
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 TSOPJW-12 package, which 140°C/W.
TJ(MAX) PTOTAL TAMB
PTOTAL
IOUT2 (RDS(ON)H VOUT RDS(ON)L [VIN VOUT])
(tSW IOUT
VOUT 5V/1.2A 4.7µH 2.32k
4.7µH 2.32k 68nF
5.0V/1.2A
68nF
Figure Resistor Network Adjust Current Limit Less than Pre-Set Over-Current Threshold (Add R7).
Figure Resistor Network Adjust Current Limit Greater than Pre-Set Over-Current Level (Add R8).
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SwitchRegOver-Current Protection
controller provides true-load output current sensing which protects load limits component stresses. output current sensed through resistance output inductor (DCR). controller reduces operating frequency when over-current condition detected; limiting stresses preventing inductor saturation. This allows smallest possible inductor given output load. small resistor divider necessary adjust over-current threshold compensate variation inductor DCR. preset current limit threshold triggered when differential voltage from exceeds 100mV (nominal).
High Voltage Step-Down Regulator
should placed close possible minimize parasitic inductance switched current path which generates large voltage spike during switching interval. connection inductor switching node should short possible. feedback trace should separated from power trace connected close possible load point. Sensing along highcurrent load trace will degrade load regulation. resistance trace from load returns PGND should kept minimum. This will help minimize error regulation differences potential internal signal ground power ground. Connect unused signal pins ground avoid unwanted noise coupling. critical small signal components include feedback components, compensation components should placed close COMP pins. feedback resistors should located close possible with ground tied directly signal ground plane which separated from power ground plane. should connected close pins, while should connected directly output inductor. best current limit performance, should placed bottom layer avoid noise coupling from inductor.
Layout Considerations
suggested layout AAT1184 shown Figures following guidelines should used help ensure proper layout. power input capacitors C12) should connected close possible high voltage input (IN) power ground.
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SwitchReg
High Voltage Step-Down Regulator
VOUT 5V/1.2A
0.1µF
4.7µH B340A 68nF open
2.32k
330pF 44.2k
BAS16
22µF
open
open
2.2µF
1184
open
22µF open
COMP
6.04k 24.3K 220pF
TSOPJW-12
56pF
C4,C5,C6,C7 R1-R6
AAT1189 Analogic Technologies, Hi-Voltage Buck, TSOPJW-12 Cap, MLC, 100µF/25V, Electrolytic Cap, MLC, 0.1µF/6.3V, 0603 Cap, MLC, 2.2µF/6.3V, 0602 Cap, MLC, misc, 0603 Cap, MLC, 22µF/6.3V, 1206 Cap, MLC, 1µF/25V, 1206 BAS16, Generic, Rectifier, 0.2A/85V, Ultrafast, SOT-23 B340A, Generic, Schottky Rectifier, 3A/40V, SLF7045T-4R7M2R0-PF, TDK, 4.7µH, ISAT Carbon film resistor, 0402
Figure AAT1184ITP Evaluation Board Schematic.
Figure AAT1184ITP Evaluation Board Layer.
Figure AAT1184ITP Evaluation Board Bottom Layer.
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SwitchRegAAT1184 Design Example
Specifications
VOUT 5.0V 1.2A, Pulsed Load ILOAD 1.2A 490kHz TAMB 85°C TSOPJW-12 Package
High Voltage Step-Down Regulator
Output Inductor
inductor SLF7045T-4R7M2R0-PF, 4.7H, max.
VOUT VOUT 1.2A 4.7µH 490kHz 1.2A 0.6A 1.8A
IOUT
IOUT2 1.8A2 11.7m 37.9mW
Output Capacitor
VDROOP 0.33V (10% Output Voltage)
COUT
ILOAD 1.2A 22.3µF; 22µF 0.33V 490kHz VDROOP
IRMS(MAX)
VOUT (VIN(MAX) VOUT1) 5.0V (24V 5.0V) 496mARMS 4.7µH 490kHz VIN1(MAX)
PRMS IRMS2 (496mA)2 1.2mW
Input Capacitor
Input Ripple 25mV
IOUT
25mV 490kHz 1.2A
32µF
cost applications, 100F/25V electrolytic capacitor parallel with 1F/25V ceramic capacitor used reduce ESR.
IRMS
IOUT 0.6A
(IRMS)2 (0.6A)2 1.8mW
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SwitchRegCurrent Limit
Over-Current Offset Voltage: VOCP 100mV Total trace parasitic resistor inductor ILIMIT
High Voltage Step-Down Regulator
IPRESET
VOCP 100mV 3.3A
AAT1184 Losses
values assume 85°C ambient temperature thermal resistance 50°C/W TSOPJW-12 package.
PTOTAL IOUT2 RDS(ON)H (tSW IOUT
PTOTAL 1.2A (5ns 490kHz 1.2A 70µA)
PTOTAL 78mW TJ(MAX) TAMB PLOSS 85°C (140°C/W) 78mW 96°C
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SwitchRegOrdering Information
Package
TSOPJW-12
High Voltage Step-Down Regulator
Voltage
Marking1
3QXYY
Part Number (Tape Reel)2
AAT1184ITP-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 Information
TSOPJW-12
0.20 0.10 0.05
2.40 0.10
0.50 0.50 0.50 0.50 0.50
2.85 0.20
3.00 0.10
0.9625 0.0375 0.10 1.00 0.065
0.04
0.15 0.05
0.055 0.045
0.010
0.45 0.15 2.75 0.25
dimensions millimeters.
assembly date code. Sample stock generally held part numbers listed BOLD.
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SwitchRegHigh Voltage Step-Down Regulator
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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SwitchRegAAT1184 single output step-down (Buck) output regulator with

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