1MHz Step-Down DC/DC Converter General Description AAT1150 Switch

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1MHz Step-Down DC/DC Converter General Description AAT1150 Switch

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AAT1150
1MHz Step-Down DC/DC Converter General Description
AAT1150 SwitchRegis member AnalogicTech's Total Power Management IC(TPMICTM) product family. step-down switching converter ideal applications where high efficiency, small size, ripple critical. Able deliver with internal power MOSFETs, current-mode controlled provides high efficiency using synchronous rectification. Fully internally compensated, AAT1150 simplifies system design lowers external parts count. AAT1150 available MSOP-8 package rated over -40°C +85°C temperature range.
SwitchReg
Range: 2.7V 5.5V Efficiency 110m RDS(ON) MOSFET Switch <1.0µA Shutdown Current 1MHz Switching Frequency Fixed Adjustable VOUT: 1.0V 4.2V High Initial Accuracy: 1.0A Peak Current Integrated Power Switches Synchronous Rectification Internally Compensated Current Mode Control Constant Mode Output Ripple Internal Soft Start Current Limit Protection Over-Temperature Protection MSOP-8 package -40°C +85°C Temperature Range
Applications
Cable/DSL Modems Computer Peripherals High Efficiency Conversion From 3.3V Supply Network Cards Set-Top Boxes
Typical Application
INPUT
10µF
AAT1150
4.1µH ENABLE OUTPUT SGND 0.1µF PGND 22µF
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Descriptions
Symbol
SGND
Function
Feedback input pin. This must connected converter's output. used output converter regulate desired value. Signal ground. Enable input pin. When connected high, AAT1150 normal operation. When connected low, powered down. This should left floating. Power supply. supplies power internal circuitry. Input supply voltage converter power stage. Inductor connection pins. These pins should connected output inductor. Internally, Pins connected drains P-channel switch N-channel synchronous rectifier. Power ground return output stage.
PGND
Configuration
MSOP-8 (Top View)
SGND
PGND
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Absolute Maximum Ratings1
25°C, unless otherwise noted. Symbol
VCC, VESD
Description
VCC, Operating Junction Temperature Range Rating2
Value
-0.3 VP+0.3 -0.3 VCC+0.3 -0.3 3000
Units
Thermal Characteristics
Symbol
Description
Maximum Thermal Resistance (MSOP-8)3 Maximum Power Dissipation (MSOP-8, 25°C)3,
Value
Units
°C/W
Recommended Operating Conditions
Symbol
Description
Ambient Temperature Range
Rating
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. Human body model 100pF capacitor discharged through 1.5K resistor into each pin. Mounted demo board. Derate 6.7mW/°C above 25°C. 1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Electrical Characteristics
-40°C +85°C, unless otherwise noted. Typical values 25°C. Symbol
VOUT
Description
Input Voltage Range Output Voltage Tolerance
Conditions
VOUT 5.5V, IOUT 4.2V, ILOAD 5.5V Rising Falling Load, 5.5V 25°C 25°C 25°C VOUT 3.3V, IOUT 600mA 5.5V 5.5V 5.5V 25°C
-4.0
Units
VOUT (VOUT*VIN) Load Regulation VOUT/VOUT Line Regulation VUVLO VUVLO(HYS) ISHDN ILIM RDS(ON)H RDS(ON)L VEN(L) VEN(H) FOSC THYS Under-Voltage Lockout Under-Voltage Lockout Hysteresis Quiescent Supply Current Shutdown Current Current Limit High Side Switch Resistance Side Switch Resistance Efficiency Enable Voltage Enable High Voltage Enable Leakage Current Oscillator Frequency Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis
1000 1200
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Typical Characteristics
High Side RDS(ON) Temperature
Side RDS(ON) Temperature
3.6V RDS(ON) 2.7V
RDS(ON)
3.6V 2.7V 5.5V 4.2V
4.2V
5.5V
Temperature (°C)
Temperature (°C)
RDS(ON) Input Voltage
Enable Threshold Input Voltage
Enable Threshold
High Side RDS(ON)
VEN(H)
Side
VEN(L)
Input Voltage
Input Voltage
Oscillator Frequency Variation Supply Voltage
Oscillator Frequency Variation Temperature
(VIN 3.6V)
Variation
-0.5 -1.5
Variation
Supply Voltage
Temperature (°C)
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Typical Characteristics
Output Voltage Temperature
(IOUT 900mA; VOUT 1.5V) Output Voltage Error
Line Regulation
(VOUT 1.5V)
0.25 0.15
2.7V
Accuracy
IOUT 1.0A
0.05 -0.05 -0.15 -0.25
-0.2
3.6V
IOUT 0.4A
-0.6
-1.0
Temperature (°C)
Input Voltage
Load Regulation
(VOUT 1.5V; 3.6V)
Load Regulation
(VOUT 3.3V; 5.0V)
VOUT Error
Error
1050
IOUT (mA)
Output Current (mA)
Efficiency Input Voltage
(VOUT 1.5V)
Loop Gain Phase Output Capacitor
(VIN 3.6V; IOUT 0.3A; 22µF)
Phase (degrees)
Efficiency
Gain (dB)
Phase
0.4A
-135 -180 -225 1000
Gain
Input Voltage
Frequency (kHz)
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Typical Characteristics
Load Input Current Temperature
(VCC
Non-Switching Temperature
VCC) Operating Current (µA)
5.5V Input Current (mA)
5.0V
5.5V 5.0V
4.2V 3.6V 2.7V
4.2V
3.6V
2.7V
Temperature (°C)
Temperature (°C)
Switching Waveform
(VIN 3.6V; VOUT 1.5V; IOUT 1.2A)
Transient Response
(VIN 3.6V; VOUT 1.5V; ILOAD 0.25 1.2A)
VOUT 50mV/div V(LX) 2V/div
500mA/div
Inductor Current 500mA/div
500nsec/div
20µs/div
Output Ripple
(VIN 3.6V; VOUT 1.5V; IOUT
Output Ripple
(VIN 3.6V; VOUT 1.5V; IOUT
VOUT 5mV/div 20MHz
VOUT 5mV/div 20MHz
2V/div
2V/div
500nsec/div
500nsec/div
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Typical Characteristics
Output Ripple
(VIN 5.0V; VOUT 3.3V; IOUT
Output Ripple
(VIN 5.0V; VOUT 3.3V; IOUT
VOUT 5mV/div 20MHz
VOUT 5mV/div 20MHz
2V/div
2V/div
500nsec/div
500nsec/div
Inrush Limit
(VIN 3.6V; VOUT 1.5V;
Enable 2V/div
VOUT 1V/div 0.5A/div
200µsec/div
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Functional Block Diagram
2.7V- 5.5V
1.0V
LOGIC
Temp. Sensing
SGND
PGND
Applications Information
Control Loop
AAT1150 peak current mode buck converter. inner wide bandwidth loop controls peak current output inductor. output inductor current sensed through P-channel MOSFET (high side) also used short-circuit overload protection. fixed slope compensation signal added sensed current maintain stability. loop appears voltageprogrammed current source parallel with output capacitor. voltage error amplifier output programs current loop necessary inductor current force constant output voltage load line conditions. feedback resistive divider inter-
nal, dividing output voltage error amplifier reference voltage 1.0V. error amplifier does have large gain typical most error amplifiers. This eliminates need external compensation components while still providing sufficient loop gain load regulation. crossover frequency phase margin output capacitor value only.
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. enable input, when pulled low, forces AAT1150 into power, non-switching state. total input current during shutdown less than 1µA.
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter
Power Signal Source
Separate small signal ground power supply pins isolate internal control circuitry from noise associated with output MOSFET switching. pass filter schematic Figures filters noise associated with power switching.
Current Limit Over-Temperature Protection
overload conditions, peak input current limited. Figure displays current limit characteristics. 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.
1.5V Efficiency IOUT
2.7V-5.5V 100k 10µF 0.1µF SGND PGND 4.1µH 22µF AAT1150-1.5
1.5V
2.7V
Efficiency
4.2V
3.6V
Murata 10µF 6.3V GRM42-6X 5R106K6.3 MuRata 22µF 6.3V GRM21BR60J226ME39L 0805 Sumida CDRH5D18-4R
1000
IOUT (mA)
Figure Lithium-Ion 1.5V Converter.
Volt Efficiency IOUT
3.5V-5.5V AAT1150-3.3 10µF 100k 0.1µF SGND PGND 3.3V
5.0V
Efficiency
4.1µH
1000
22µF
Murata 10µF 6.3V GRM42-6X 5R106K6.3 MuRata 22µF 6.3V GRM21BR60J226ME39L 0805 Sumida CDRH5D18-4R
IOUT (mA)
Figure Input 3.3V Output Converter.
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter
5.0V 3.3V Figure Schematic
VOUT
3.6V 1.5V Figure Schematic
IOUT
Figure Current Limit Characteristic.
Inductor
output inductor selected limit ripple current some predetermined value, typically full load current maximum input voltage. 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. During overload short-circuit conditions, average current inductor meet exceed ILIMIT point AAT1150 without affecting converter performance. Some inductors have sufficient peak average current ratings result excessive losses high DCR. Always consider losses associated with effect total converter efficiency when selecting inductor. 1.0A load ripple maximum input voltage, maximum peak-topeak ripple current 300mA. inductance value required 3.9µH. VOUT 1.5V 1.5V 11.0A 830kHz 4.2V
factor fraction full load selected ripple current maximum input voltage. corresponding inductor current IRMS 1.0A
peak-to-peak ripple current which fixed inductor selection above. peak-to-peak current full load current, peak current full load will 115% full load. 4.1µH inductor selected from Sumida CDRH5D18 series 1.95A current rating. full load, inductor loss 57mW which amounts 3.8% loss efficiency.
Input Capacitor
primary function input capacitor provide impedance loop edges pulsed current drawn AAT1150. ESR/ESL ceramic capacitor ideal this function. minimize stray inductance, capacitor should placed closely possible This keeps high frequency content input current localized, minimizing radiated conducted while facilitating optimum performance AAT1150. Ceramic capacitors ideal this function. size required will vary depending load, output voltage, input voltage source impedance characteristics. typical value around 10µF. input capacitor
3.9µH
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter
current varies with input voltage output voltage. equation current input capacitor
Adjustable Output
applications requiring output other than fixed outputs available, version programmed externally (see Figure Resistors force output regulate higher than should times less than internal resistance pin. Once selected, calculated. 1.25V output with 10k, 2.55k.
IRMS
1VIN
input capacitor ripple current reaches maximum when times output voltage where approximately half load current. Losses associated with input ceramic capacitor typically minimal issue. Proper placement input capacitor seen reference design layout shown Figures
0.25 10.0k 2.55k
Layout Considerations
Figures display suggested layout AAT1150. most critical aspect layout placement input capacitor proper operation, must placed closely possible AAT1150.
Output Capacitor
Since there external compensation components, output capacitor strong effect loop stability. Larger output capacitance will reduce crossover frequency with greater phase margin. 1.5V 1.0A design using 4.1µH inductor, 22µF capacitors provide stable output. addition assisting stability, output capacitor limits output ripple provides holdup during large load transitions. output capacitor ripple current given
VOUT (VIN VOUT)
Thermal Calculations
There types losses associated with AAT1150 output switching MOSFET: switching losses conduction losses. Conduction losses associated with RDS(ON) characteristics output switching device. full load, assuming continuous conduction mode (CCM), simplified form total losses
IRMS
PLOSS ceramic capacitor, dissipation current capacitor concern. Tantalum capacitors, with sufficiently meet output voltage ripple requirements, also have current rating much greater than that actually seen this application.
(RDSON(H) RDSON(L) (VIN VO))
Once total losses have been determined, junction temperature derived from MSOP-8 package.
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter
Figure AAT1150 Layout Layer.
Figure AAT1150 Layout Bottom Layer.
VIN+ 3.3V 10µF 100k 0.1µF
AAT1150-1.0
2.55k 1.25V 2.7µH
SGND PGND
22µF
Murata 10µF 6.3V GRM42-6X 5R106K6.3 MuRata 22µF 6.3V GRM21BR60J226ME39L 0805 Sumida CDRH4D28-2R7µH
Figure 3.3V 1.25V Converter (Adjustable Output).
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter
Design Example
Specifications IOUT 1.0A IRIPPLE Full Load VOUT 1.5V 2.7V 4.2V (3.6V nominal) 830kHz
Maximum Input Capacitor Ripple
IRMS 0.5ARMS,
ESRCOUT IRMS2 0.52 1.25mW
Inductor Selection
VOUT 1.5V 1.5V 3.9µH 1.0A 830kHz 4.2V
Select Sumida inductor CDRH5D18, 4.1µH, 57m, 2.0mm height.
1.5V 1.5V 280mA 4.1µH 830kHz 4.2V
IOUT
1.0A 0.14A 1.14A
57mW
Output Capacitor Dissipation
IRMS VOUT (VIN VOUT) 1.5V (4.2V 1.5V) 82mARMS 4.1µH 830kHz 4.2V
PESR ESRCOUT IRMS2 0.0822A 33µW
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter
AAT1150 Dissipation
(RDSON(H) RDSON(L) (VIN -VO)) (tsw
(0.14 1.5V 0.145 (3.6V 1.5V)) 3.6V
(20nsec 830kHz 1.0A 0.3mA) 3.6V 0.203W
TJ(MAX) TAMB PLOSS 85°C 150°C/W 0.203W 115°C
Table Surface Mount Inductors.
Manufacturer
TaiyoYuden Toko Sumida Sumida MuRata MuRata
Part Number
NPO5DB4R7M A914BYW-3R5M-D52LC CDRH5D28-4R2 CDRH5D18-4R1 LQH55DN4R7M03 LQH66SN4R7M03
Value
4.7µH 3.5µH 4.2µH 4.1µH 4.7µH 4.7µH
Current
1.4A 1.34A 2.2A 1.95A 2.7A 2.2A
0.038 0.073 0.031 0.057 0.041 0.025
Size (mm) Type Shielded Shielded Shielded Shielded Non-Shielded Shielded
Table Surface Mount Capacitors.
Manufacturer
MuRata MuRata MuRata MuRata
Part Number
GRM40 106K GRM42-6 106K GRM21BR60J226ME39L GRM21BR60J106ME39L
Value
10µF 10µF 22µF 10µF
Voltage
6.3V 6.3V 6.3V 6.3V
Temp.
Case
0805 1206 0805 0805
1150.2005.03.1.2
AAT1150
1MHz Step-Down DC/DC Converter Ordering Information
Output Voltage
1.0V (Adj VOUT 1.0V) 1.5V 1.8V 2.5V 3.3V
Package
MSOP-8 MSOP-8 MSOP-8 MSOP-8 MSOP-8
Marking
JZXYY HYXYY KAXYY KCXYY HZXYY
Part Number (Tape Reel)
AAT1150IKS-1.0-T1 AAT1150IKS-1.5-T1 AAT1150IKS-1.8-T1 AAT1150IKS-2.5-T1 AAT1150IKS-3.3-T1
Package Information
MSOP-8
1.95
3.00 0.10
4.90 0.10
0.60 0.20 0.254 0.95 3.00 0.10 0.95 0.15 0.85 0.10 0.65 0.30 0.08
0.075 0.075
dimensions millimeters.
assembly date code. Sample stock held part numbers listed bold. Contact local sales office custom options.
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, advise customers 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.
Advanced Analogic Technologies, Inc.
Arques Avenue, Sunnyvale, 94085 Phone (408) 737-4600 (408) 737-4611
1150.2005.03.1.2
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1MHz Step-Down DC/DC Converter General Description AAT1150 Switch

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