1MHz 700mA Step-Down DC-DC Converter General Description AAT1156

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1MHz 700mA Step-Down DC-DC Converter General Description AAT1156

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AAT1156
1MHz 700mA Step-Down DC-DC Converter General Description
AAT1156 SwitchRegis member AnalogicTechTM's Total Power Management IC(TPMICTM) product family. step-down switching converter ideal applications where high efficiency required over full range load conditions. 2.7V 5.5V input voltage range makes AAT1156 ideal single-cell lithium-ion/polymer battery applications. Capable more than 700mA with internal MOSFETs, current-mode controlled provides high efficiency over wide operating range. Fully integrated compensation simplifies system design lowers external parts count. AAT1156 available 16-pin 3x3mm package rated over -40°C +85°C temperature range.
SwitchReg
Range: Volts Efficiency 110m RDS(ON) Internal Switches <1µA Shutdown Current 1MHz Step-Down Switching Frequency Fixed Adjustable VOUT 0.8V Integrated Power Switches Current Mode Operation Internal Compensation Stable with Ceramic Capacitors Internal Soft Start Over-Temperature Protection Current Limit Protection 16-Pin 3x3mm Package -40°C +85°C Temperature Range
Applications
Cellular Phones Digital Cameras Players Notebook Computers PDAs Wireless Notebook Adapters
Typical Application
AAT1156 10µF SGND PGND PGND PGND 22µF 4.7µH 187k
INPUT
2.5V
(VOUT 2.5V; 4.7µH; CDRH3D16)
AAT1156 Efficiency
3.0V 4.2V 3.6V
Efficiency
1000
Murata 10µF 6.3V GRM42-6X5R106K6.3 C3-C4 MuRata 22µF 6.3V GRM21BR60J226ME39L 0805 Sumida CDRH3D16-4R7NC
Output Current (mA)
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AAT1156
1MHz 700mA Step-Down DC-DC Converter Descriptions
Symbol
PGND
Function
Main power ground return pin. Connect output input capacitor return. (See board layout rules.) Feedback input pin. This connected converter output. used output converter regulate desired value internal resistive divider. adjustable output, external resistive divider connected this model. Signal ground. Connect return small signal components this pin. (See board layout rules.) Mode selector switch. When pulled low, device enters light load mode. Enable input pin. logic high enables converter; logic forces AAT1156 into shutdown mode, reducing supply current less than 1µA. should left floating. internally connected. Bias supply. Supplies power internal circuitry. Connect input power pass filter with decoupling SGND. Input supply voltage converter power stage. Must closely decoupled PGND. Connect inductor these pins. Switching node internally connected drain both high- low-side MOSFETs. Exposed paddle (bottom); connect PGND directly beneath package.
SGND
Configuration
QFN33-16 (Top View)
PGND PGND PGND
SGND
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AAT1156
1MHz 700mA Step-Down DC-DC Converter Absolute Maximum Ratings1
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 (QFN33-16) Maximum Power Dissipation (QFN33-16)4 25°C)
Value
Units
°C/W
Recommended Operating Conditions
Symbol
Description
Ambient Temperature Range
Value
Units
Stresses above those listed Absolute Maximum Ratings cause 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 (FR4, still air). Derate 20mW/°C above 25°C. 1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Electrical Characteristics
-40°C +85°C, unless otherwise noted. Typical values 25°C. Symbol
VOUT VUVLO VUVLO(HYS) ISHDN ILIM
Description
Input Voltage Range Output Voltage Tolerance Input Voltage Input High Voltage Under-Voltage Lockout Under-Voltage Lockout Hysteresis Input Current Input High Current Quiescent Supply Current
Conditions
VOUT 5.5V, IOUT 700mA
Units
Rising, Falling, 5.5V Load, 4.2V, 25°C 5.5V 25°C 25°C 25°C 4.2V, ILOAD 700mA 5.5V 25°C ±0.9 ±0.1 1000
Shutdown Current Current Limit RDS(ON)H High Side Switch Resistance RDS(ON)L Side Switch Resistance VOUT(VOUT*VIN) Load Regulation DVOUT/VOUT Line Regulation FOSC Oscillator Frequency Over-Temperature Shutdown Threshold THYS Over-Temperature Shutdown Hysteresis
1350
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Typical Characteristics
Output Ripple
(0.8V; 10mA; 3.6V) Enable Output Voltage (top)
-0.5 -1.5
Soft Start
(0.8V; 700mA; 3.6V)
Output Voltage coupled) (top) (mV)
Inductor Current (bottom)
Inductor Current (bottom)
-0.2
-0.5
Time (2µs/div)
Time (100µs/div)
Output Ripple
(0.8V; 700mA; 3.6V)
Line Transient
(IOUT 500mA; 0.8V) Output Voltage coupled) (bottom) (mV)
Output Voltage coupled) (top) (mV)
Inductor Current (bottom)
Input Voltage (top)
-0.5
Time (250ns/div)
Time (20µsec/div)
Load Transient Response
(50mA-680mA; 3.6V; VOUT 0.8V)
0.83 0.81
Load Supply Current Input Voltage
Inductor Load Current (bottom) (500mA/div)
Supply Current (µA)
85°C
Output Voltage (top) (20mV/div)
0.79 0.77 0.75 0.73 0.71 0.69 0.67
25°C -40°C
Time (10µsec/div)
Input Voltage
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Typical Characteristics
Output Voltage Temperature
(VIN 4.2V; VOUT 0.8V; 400mA VOUT)
Regulation
(VOUT 0.6V)
Output Voltage Error
Output Error
-0.1 -0.2 -0.3 -0.4
4.2V 3.6V
-1.0
2.7V
-2.0 -3.0
0.0001
0.001
0.01
Temperature (°C)
Output Current
Frequency Temperature
(VIN 3.6V)
P-Channel RDSON Input Voltage
Frequency (MHz)
100°C
120°C
RDSON
85°C
25°C
Temperature (°C)
Input Voltage
Frequency Input Voltage
1.02 1.01
N-Channel RDSON Input Voltage
Frequency (MHz)
0.99 0.98 0.97 0.96 0.95 0.94
100°C
120°C
RDSON
85°C
25°C
Input Voltage
Input Voltage
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Functional Block Diagram
2.7V 5.5V
1.0V
LOGIC
Temp. Sensing
SGND
PGND
Operation
Control Loop
AAT1156 peak current mode step-down converter. inner, wide bandwidth loop controls inductor peak current. inductor current sensed through P-channel MOSFET (high side) also used short-circuit overload protection. fixed slope compensation signal added sensed current maintain stability duty cycles greater than 50%. loop appears voltage-programmed current source parallel with output capacitor. voltage error amplifier output programs current loop necessary inductor current force constant output voltage load line conditions. external voltage feedback resistive divider divides output voltage error amplifier reference voltage 0.6V. voltage error amplifier gain limited. This eliminates need external compensation components, while
still providing sufficient loop gain good load regulation. voltage loop crossover frequency phase margin output capacitor.
Soft Start/Enable
Soft start increases inductor current limit point discrete steps once input voltage enable input applied. limits current surge seen input eliminates output voltage overshoot. When pulled low, enable input forces AAT1156 into non-switching shutdown state. total input current during shutdown less than 1µA.
Power Signal Source
Separate small signal ground power supply pins isolate internal control circuitry from noise associated with output MOSFET switching. pass filter (shown schematic Figure filters input noise associated with power switching.
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter
Enable Vin+ 10µF 100K 100k SGND
AAT1156 PGND PGND PGND 4.7µH 200k
Vout+
22µF
Murata 10µF 6.3V GRM42-6X5R106K6.3 MuRata 22µF 6.3V GRM21BR60J226ME396 0805 Sumida CDRH3D16-4R7NC
Figure AAT1156 Evaluation Board Schematic-Lithium-Ion 2.5V Converter.
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.
VOUT 1.5V 1.5V 10.7A 1MHz 4.2V
3.44µH
factor fraction full load selected ripple current maximum input voltage. ripple current full load current, peak current will 120% full load. Selecting standard value 3.3µH gives ripple current. 3.3µH inductor selected from Sumida CDRH3D16 series 1.1A current rating. full load, inductor loss 31mW which amounts less than loss efficiency 0.7A, 1.5V output.
Inductor
output inductor selected limit ripple current 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. Some inductors meet peak average current ratings result excessive losses high DCR. Always consider losses associated with effect total converter efficiency when selecting inductor. 0.7A, 1.5V output with ripple maximum input voltage 4.2V, maximum peak-to-peak ripple current 280mA. inductance value required 3.44µH.
Input Capacitor
primary function input capacitor provide impedance loop edges pulsed current drawn AAT1156. 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 AAT1156. Ceramic capacitors ideal this function. size required will vary depending
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter
load, output voltage, input voltage source impedance characteristics. Values range from 10µF. input capacitor current varies with input voltage output voltage. equation current input capacitor 1VIN ceramic capacitor, that dissipation current capacitor concern. Tantalum capacitors with sufficiently meet output voltage ripple requirements also have current rating well beyond that actually seen this application.
IRMS
Layout
Figures display suggested layout AAT1156. following guidelines should used help ensure proper layout. input capacitor (C1) should connect closely possible (Pins PGND (Pins should connected closely possible. connection from node should short possible. feedback trace (Pin should separate from power trace connect closely possible load point. Sensing along high-current load trace will degrade load regulation. resistance trace from load return PGND (Pins should kept minimum. This will help minimize error regulation differences potential internal signal ground power ground. pass filter provide cleaner bias source AAT1156 active circuitry. should placed closely possible SGND (Pin (Pin
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 shown reference design layout Figure
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, 0.7A design using 3.3µH 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)
IRMS
Figure Evaluation Board Side.
1156.2005.11.1.2
Figure Evaluation Board Bottom Side.
AAT1156
1MHz 700mA Step-Down DC-DC Converter
Thermal Calculations
There three types losses associated with AAT1156: MOSFET switching losses, conduction losses, quiescent current losses. conduction losses RDS(ON) characteristics internal Pand N-channel MOSFET power devices. full load, assuming continuous conduction mode (CCM), simplified form total losses given
(RDSON(HS) RDSON(LS) (VIN VO)) (tsw
where AAT1156 quiescent current. Once total losses have been determined, junction temperature derived from QFN33-16 package.
TAMB
Adjustable Output
Resistors Figure force output regulate higher than 0.6V. optimum value 59k. Values higher than this cause problems with stability, while lower values degrade light load efficiency. 2.5V output with 59k, 187k.
2.5V 0.6V 187k
R4=59k
Output Voltage
Figure VOUT Adjustable Output Using AAT1156.
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Design Example
Specifications
IOUT VOUT TAMB 0.7A IRIPPLE Full Load 2.5V 2.7V 4.2V (3.6V nominal) 1MHz 85°C
Maximum Input Capacitor Ripple:
IRMS 0.34Arms,
IRMS2 0.342 0.6mW
Inductor Selection:
VOUT 2.5V 2.5V 4.82µH 0.7A 1MHz 4.2V
Select Sumida inductor CDRH3D16 CDRH4D28 4.7µH. 2.5V 2.5V 220mA 4.7µH 1MHz 4.2V
IOUT
0.7A 0.11A 0.81A
(0.7A)2 40mW
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter
Output Capacitor Ripple Current:
IRMS VOUT (VIN VOUT) 2.5V (4.2V 2.5V) 62mArms 4.7µH 1MHz 4.2V
Pesr IRMS2 mA)2 19µW
AAT1156 Dissipation:
(RDSON(HS) RDSON(LS) (VIN -VO))
PTOTAL
(tsw
(0.7A)2 (0.17 2.5V 0.16 (4.2V 1.5V))
4.2V
(20nsec 1MHz 0.7A 300µA) 4.2V 0.141W
TJ(MAX) TAMB PLOSS 85°C 50°C/W 0.141W 92°C
INPUT 10µF
AAT1156 PGND PGND PGND 2.2µH 19.6k
0.8V
(VOUT 0.8V; 2.2µH; CDRH3D16)
AAT1156 Efficiency
Efficiency
2.7V 4.2V 3.6V
22µF
SGND
Murata 10µF 6.3V GRM42-6X5R106K6.3 MuRata 22µF 6.3V GRM21BR60J226ME39L 0805 Sumida CDRH3D16-2R2NC
1000
Output Current (mA)
Figure 0.8V Solution.
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Surface Mount Inductors
Manufacturer
TaiyoYuden Toko Sumida Sumida Sumida Sumida Sumida Sumida MuRata MuRata
Part Number
NPO5DB4R7M A914BYW-3R5M-D52LC CDRH4D28-4R7 CDRH3D16-2R2 CDRH3D16-3R3 CDRH3D16-4R7 CDRH5D28-4R2 CDRH5D18-4R1 LQH55DN4R7M03 LQH66SN4R7M03
Value
4.7µH 3.5µH 4.7µH 2.2µH 3.3µH 4.7µH 4.2µH 4.1µH 4.7µH 4.7µH
Current
1.4A 1.34A 1.32A 1.2A 1.1A 2.2A 1.95A 2.7A 2.2A
0.038 0.073 0.072 0.050 0.063 0.080 0.031 0.057 0.041 0.025
Size (mm) LxWxH
5.9x6.1x2.8 5.0x5.0x2.0 4.7x4.7x3.0 3.8x3.8x1.8 3.8x3.8x1.8 3.8x3.8x1.8 5.7x5.7x3.0 5.7x5.7x2.0 5.0x5.0x4.7 6.3x6.3x4.7
Type
Shielded Shielded Shielded Shielded Shielded Shielded Shielded Sielded Non-Shielded Shielded
Surface Mount Capacitors
Manufacturer
MuRata MuRata MuRata
Part Number
GRM40 106K GRM42-6 106K GRM21BR60J226ME39L
Value
10µF 10µF 22µF
Voltage
6.3V 6.3V 6.3V
Temp.
Case
0805 1206 0805
1156.2005.11.1.2
AAT1156
1MHz 700mA Step-Down DC-DC Converter Ordering Information
Output Voltage
0.6V (Adj VOUT 0.8V)
Package
QFN33-16
Marking1
LUXYY
Part Number (Tape Reel)2
AAT1156IVN-T1
Package Information
Identification
0.230 0.05
3.000 0.05
Marking
0.400 0.05
3.000 0.05
0.500 0.05
View
Bottom View
1.55 0.15 0.025 0.025 0.203 0.0254
Side View
assembly date code. Sample stock generally held part numbers listed BOLD.
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.
Advanced Analogic Technologies, Inc.
Arques Avenue, Sunnyvale, 94085 Phone (408) 737-4600 (408) 737-4611
1156.2005.11.1.2
0.850 0.05

1MHz 700mA Step-Down DC-DC Converter General Description AAT1156

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