AAT1142 SwitchReg dynamically programmable 2.2MHz step-down converter
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800mA Voltage-Scaling Step-Down Converter General Description
AAT1142 SwitchReg dynamically programmable 2.2MHz step-down converter with input voltage range 2.7V 5.5V output from 0.6V 2.0V. supply current, high level integration, small footprint make AAT1142 ideal choice microprocessor core power systems such smartphones. 2.2MHz switching frequency allows small external inductor capacitors. Peak current mode control internal compensation provide stable operation fast voltage response without over/undershoot ringing. AAT1142 delivers 800mA output current while consuming 35µA typical load quiescent current. Dynamic Voltage Management provided through AnalogicTech's S2Cwire(Simple Serial ControlTM) single wire interface. user program output from 0.6V 2.0V 50mV steps. AAT1142 optimizes power efficiency throughout load range PWM/PFM mode. Pulling MODE/SYNC high enables Only mode, maintaining constant frequency noise across operating range. Alternatively, converter synchronized external clock input MODE/SYNC pin. Over-temperature short-circuit protection safeguard AAT1142 system components from damage. AAT1142 available Pb-free, space-saving 2.85x3.0x1.0mm TSOPJW-12 package Pb-free, low-profile 3x3x0.8mm TDFN33-12 package. device rated over -40°C +85°C temperature range.
AAT1142
SwitchReg
Range: 2.7V 5.5V VOUT Programmable Range: 0.6V 2.0V Dynamic Voltage Management: 50mV Output Resolution Fast, Stable Response Serial Control Options: Two-Wire Interface S2Cwire Single-Wire Interface 800mA Output Current Efficiency Line, Load Regulation Less Than ±0.5% 2.2MHz Switching Frequency Ultra-Small External Filter 35µA Load Quiescent Current 100% Duty Cycle Dropout Operation Internal Soft Start Over-Temperature Protection Current Limit Protection Multi-Function MODE/SYNC Pin: PFM/PWM High Efficiency Only Noise Clock Input Synchronize System Clock TSOPJW-12 TDFN33-12 Package Temperature Range: -40°C +85°C
Applications
Camcorders Cellular Phones Smartphones Digital Still Cameras Handheld Instruments Microprocessor Core MP3, Portable Music, Portable Media Players PDAs Handheld Computers
Efficiency Load
Typical Application
VIN: 2.7V 5.5V 4.7µF 2.2µH VOUT: 0.6V 2.0V 800mA Maximum
(VOUT 1.8V)
3.6V 2.7V
Efficiency
AAT1142
MODE/SYNC EN/SET AGND PGND 10µF
1000
4.2V 5.0V Only Mode
S2Cwire*
*Optional S2Cwire Input
Output Current (mA)
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800mA Voltage-Scaling Step-Down Converter Descriptions
TSOPJW-12 TDFN33-12
AAT1142
Symbol
PGND MODE/SYNC
EN/SET
AGND PVIN
Function Connect output inductor this pin. switching node internally connected drain both high- low-side MOSFETs. Main power ground return pin. Connect output input capacitor return. Connect ground PFM/PWM mode optimized efficiency throughout load range. Connect high noise Only operation under operating conditions. Connect external clock synchronization (PWM Only). control pin: Data input. control pin: Clock input. enable pin. Pull high enable AAT1142; pull disable AAT1142. Also serves S2Cwire input programmable output voltages. Feedback input pin. This connected directly converter output programmable output. Ground connection pin. Input voltage converter. Input voltage power switches. connected. Exposed paddle (bottom); connect ground closely possible device.
Configuration
TSOPJW-12 (Top View) TDFN33-12 (Top View)
PGND MODE/SYNC EN/SET
AGND AGND AGND AGND
PVIN AGND AGND
PGND MODE/SYNC EN/SET
PVIN tied together TSOPJW-12 package.
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800mA Voltage-Scaling Step-Down Converter Absolute Maximum Ratings1
Symbol
VIN, PVIN VSDA/SCL VMODE/SYNC, VEN/SET TLEAD
AAT1142
Description
Input Voltage Input Power SDA/SCL MODE/SYNC EN/SET Operating Junction Temperature Range Maximum Soldering Temperature leads, sec)
Value
-0.3 -0.3 -0.3 -0.3
Units
Thermal Information2
Symbol
Description
Maximum Power Dissipation Thermal Resistance TSOPJW-12 TDFN33-124 TSOPJW-12 TDFN33-12
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. Derate 6.25mW/°C above 25°C. Derate 20mW/°C above 25°C. 1142.2006.07.1.0
800mA Voltage-Scaling Step-Down Converter Electrical Characteristics1
2.2µH, COUT 10µF, 3.6V, -40°C +85°C, unless otherwise noted. Typical values 25°C. Symbol Description Conditions
Rising Hysteresis Falling IOUT 800mA, 2.7V 5.5V COUT 10µF Load EN/SET AGND PGND -3.0 0.29 0.24 5.5V, 2.7V 5.5V From Enable Output Regulation
AAT1142
Units
mV/µs
Step-Down Converter Input Voltage VUVLO VOUT VOUT VSLEW ISHDN ILIM RDS(ON)H RDS(ON)L ILXLEAK VOUT/ VOUT*VIN ROUT FOSC FSYNC THYS UVLO Threshold Output Voltage Tolerance VOUT Programmable Range Output Voltage Programming Slew Rate Quiescent Current Shutdown Current P-Channel Current Limit High Side Switch Resistance Side Switch Resistance Leakage Current Line Regulation Output Impedance Start-Up Time Oscillator Frequency SYNC Frequency Range Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis
AAT1142 guaranteed meet performance specifications over -40°C +85°C operating temperature range assured design, characterization, correlation with statistical process controls.
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800mA Voltage-Scaling Step-Down Converter Electrical Characteristics1
2.2µH, COUT 10µF, 3.6V, -40°C +85°C, unless otherwise noted. Typical values 25°C. Symbol Description Conditions Units
VEN/SET 0.6V VEN/SET 1.4V VEN/SET 0.6V VEN/SET 1.4V 5.5V
AAT1142
EN/SET MODE/SYNC VEN/SET(L) Enable Threshold VEN/SET(H) Enable Threshold High TEN/SET(L) EN/SET Time TEN/SET(H) EN/SET High Time TOFF EN/SET Timeout TLATCH EN/SET Latch Timeout IEN/SET Input Current VMODE/SYNC(L) VMODE/SYNC(H) IMODE/SYNC Enable Threshold Enable Threshold High Input Current
-1.0
-1.0
Characteristics Lines
Standard Mode Fast Mode
Parameter
Clock Frequency Hold Time START Condition; After this Period, First Clock Pulse Generated Period Clock HIGH Period Clock Set-up Time Repeated START Condition Data Hold Time Data Set-Up Time Set-Up Time STOP Condition Free Time Between STOP START Condition Input Level Input High Level
Symbol
fSCL tHD;STA
Units
tLOW tHIGH tSU;STA tHD;DAT tSU;DAT tSU;STO tBUF
3.45
AAT1142 guaranteed meet performance specifications over -40°C +85°C operating temperature range assured design, characterization, correlation with statistical process controls. 1142.2006.07.1.0
800mA Voltage-Scaling Step-Down Converter Typical Characteristics
Efficiency Load
(VOUT 0.9V)
AAT1142
Regulation
(VOUT 0.9V)
Efficiency
4.2V
Output Accuracy
3.6V 2.7V
2.7V
3.6V
5.0V
Only Mode
-1.0
4.2V
5.0V
1000
-2.0 1000
Output Current (mA)
Output Current (mA)
Efficiency Load
(VOUT 1.0V)
Regulation
(VOUT 1.0V)
Efficiency
4.2V
Output Accuracy
3.6V 2.7V
2.7V
3.6V
5.0V
Only Mode
4.2V
-1.0
5.0V
-2.0 1000
1000
Output Current (mA)
Output Current (mA)
Efficiency Load
(VOUT 1.2V)
Regulation
(VOUT 1.2V)
3.6V 2.7V 4.2V
Efficiency
Output Accuracy
2.7V
3.6V
Only Mode 5.0V
4.2V
-1.0
5.0V
1000
-2.0 1000
Output Current (mA)
Output Current (mA)
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800mA Voltage-Scaling Step-Down Converter Typical Characteristics
Efficiency Load
(VOUT 1.8V)
AAT1142
Regulation
(VOUT 1.8V)
-0.4 -0.8 -1.2 -1.6 -2.0 1000
Output Accuracy
3.6V 2.7V
Efficiency
1000
5.0V 4.2V 2.7V 3.6V
4.2V 5.0V Only Mode
Output Current (mA)
Output Current (mA)
Soft Start
(VIN 3.6V; VOUT 1.8V; IOUT 800mA)
Line Regulation
(VOUT 1.0V)
Output Enable Voltage (top)
-1.0 -2.0 -3.0 -4.0
1.00
Output Accuracy
0.75 0.50 0.25 0.00 -0.25 -0.50 -0.75 -1.00
-0.5
IOUT 650mA
Inductor Current (bottom)
IOUT 100mA
IOUT
Time (50µs/div)
Input Voltage
Output Voltage Accuracy Temperature
(VIN 3.6V; VOUT 1.0V; IOUT 400mA)
Switching Frequency Temperature
(VIN 3.6V; VOUT 1.0V; IOUT 400mA)
Accuracy
Variation
-0.5 -1.0 -1.5 -2.0
-2.0 -4.0 -6.0 -8.0 -10.0
Temperature (°C)
Temperature (°C)
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800mA Voltage-Scaling Step-Down Converter Typical Characteristics
P-Channel RDS(ON) Input Voltage
AAT1142
N-Channel RDS(ON) Input Voltage
125°C
RDS(ON)L
RDS(ON)H
100°C 85°C
125°C 100°C 85°C
25°C
25°C
Input Voltage
Input Voltage
Load Transient Response
(10mA 400mA; 3.6V; VOUT 1.2V)
-0.2 -0.1 -0.2
Load Transient Response
(400mA 800mA; 3.6V; VOUT 1.0V)
Load Inductor Current (bottom) (200mA/div)
Load Inductor Current (bottom) (200mA/div)
Output Voltage (top)
Time (50µs/div)
Output Voltage (top)
Time (50µs/div)
Load Quiescent Current Input Voltage
(VOUT 1.8V)
Line Response
(VOUT 1.2V; IOUT 650mA)
Supply Current (µA)
Output Voltage (top) (VAC)
85°C 25°C -40°C
-0.1 -0.2 -0.3
Input Voltage (bottom)
-0.4
Input Voltage
Time (500µs/div)
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800mA Voltage-Scaling Step-Down Converter Typical Characteristics
Output Ripple
(VIN 4.2V; VOUT 0.8V; Load)
0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.10 0.08 0.06 0.04 0.02 0.00 -0.02 0.82 0.81 0.80 0.79 0.78 0.77 0.76 0.75 0.74 0.73 0.72
AAT1142
Output Ripple
(VIN 4.2V; VOUT 0.8V; IOUT 650mA)
0.80 0.78 0.76 0.74 0.72 0.70 0.68 0.66 0.64 0.62 0.60
Output Voltage (top)
Output Voltage (top)
Inductor Current (bottom)
Inductor Current (bottom)
Time (4µs/div)
Time (200ns/div)
Output Programming Step from 0.9V 1.2V
(VIN 3.6V; ROUT 1.85)
1.30 1.20 1.10 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 1.30 1.20 1.10 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30
Output Programming Step from 1.2V 0.9V
(VIN 3.6V; ROUT 1.85)
0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40
Output Voltage (top)
Output Voltage (top)
Output Current (bottom)
Output Current (bottom)
Time (50µs/div)
Time (50µs/div)
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800mA Voltage-Scaling Step-Down Converter Functional Block Diagram
PVIN
AAT1142
MODE/SYNC
Voltage Reference
Err. Amp.
EN/SET
Logic
Control Logic
PGND AGND
Functional Description
AAT1142 high performance, 800mA stepdown converter with input voltage range from 2.7V 5.5V. AAT1142 uses Dynamic Voltage Management, which allows system host quickly output voltage through integrated S2Cwire interface. Through this interface, host change output voltage track processor idle active states, greatly extending battery life without degrading system performance. provides industry-standard, dual-line interface, while S2Cwire provides single-line, highspeed serial interface. 2.2MHz switching frequency allows small external components. Only three external components needed program output
from 0.6V 2.0V. Typically, 4.7µF capacitor, 10µF capacitor, 2.2µH inductor required. integrated low-loss MOSFET switches provide efficiency. operation maintains high efficiency under light load conditions (typically <50mA). Pulling MODE/SYNC high allows optional Only noise mode. This maintains constant frequency output ripple across load conditions. Alternatively, synchronized external clock MODE/SYNC input. External synchronization maintained between 1MHz 3MHz. input voltages, converter dynamically adjusts operating frequency prior dropout maintain required duty cycle provide accu-
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800mA Voltage-Scaling Step-Down Converter
rate output regulation. Output regulation maintained until dropout voltage, minimum input voltage, reached. AAT1142 achieves better than ±0.5% output regulation across input voltage output load range. Maximum continuous load 800mA. current limit (typical) protects system components from short-circuit damage. Typical load quiescent current 35µA. Thermal protection completely disables switching when maximum junction temperature detected. junction over-temperature threshold 140°C with 15°C hysteresis. Once over-temperature over-current fault condition removed, output voltage automatically recovers. Peak current mode control optimized internal compensation provide high loop bandwidth excellent response input voltage fast load transient events. output voltage stable across operating conditions, ensuring fast transitions with overshoot ringing. Soft start eliminates output voltage overshoot when enable input voltage applied. Under-voltage lockout prevents spurious start-up events. sation terminates transconductance voltage error amplifier output. Loop stability fast transient response maintained across entire input output voltage range with small 2.2µH output inductor 10µF output capacitor.
AAT1142
Soft Start/Enable
Soft start limits current surge seen input eliminates output voltage overshoot. When pulled low, enable input forces AAT1142 into low-power, non-switching state. total input current during shutdown less than 1µA. turn-on time from output regulation 100µs (typical). Alternatively, EN/SET serves input S2Cwire single line control. Details S2Cwire operation timing diagrams provided Applications Information section this datasheet.
Current Limit Over-Temperature Protection
Switching terminated after entering current limit series pulses minimize power dissipation stresses under overload short-circuit conditions. 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 condition removed, output voltage automatically recovers.
Control Loop
AAT1142 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 compen-
Under-Voltage Lockout
Internal bias circuits controlled input. Under-voltage lockout (UVLO) guarantees sufficient bias proper operation internal circuitry prior activation.
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800mA Voltage-Scaling Step-Down Converter
AAT1142
2.2µH (optional) 0.1µF
VOUT 10µF
PGND
AGND
4.7µF
(optional) 10µF
MODE/SYNC AGND EN/SET
AAT1142 TSOPJW-12
AGND AGND
(optional) 1.8K
1.8K
(optional)
AAT1142 TSOPJW-12 CDRH2D14/2R2 4.7µF 0805 10µF 0805 10µF optional 0.1µF optional 0603 optional 0603 0603 1.8K 0603
Figure AAT1142 Evaluation Board Schematic.
Applications Information
AAT1142 output voltage programmed from 0.6V 2.0V through S2Cwire serial interface. When using S2Cwire, output voltage programmed across entire output voltage range increments small ±50mV (see Figure
put. ensure disable event, EN/SET pulse width must greater than latch time (500µs maximum). serial interface requires master initiate communications with slave devices. protocol bidirectional allowing both read write actions take place; while AAT1142 slave device only supports write protocol. AAT1142 receiver-only write-only) slave device Read Write (R/W) low. AAT1142 address preset 0x14 (Hex).
Serial Interface
AAT1142 compatible with interface, which widely used two-line serial interface. two-wire communications consists lines. provides data, while provides clock input. data consists address sequence followed data sequence. data transfer synchronized rising clock edges. When using interface, EN/SET pulled high enable output disable out-
START STOP Conditions
START STOP conditions initialized master. master determines START (beginning) STOP (end) transfer with slave device. Prior initiating START after STOP, both lines bus-free mode. Bus-free mode when both high state (see Figure
1142.2006.07.1.0
800mA Voltage-Scaling Step-Down Converter
AAT1142
Output Voltage Level
(default)
I2C/S2Cwire Register
Figure AAT1142 Graphical Output Voltage Programming Map.
START
STOP
Figure Start Stop Conditions. START: High Transition Line While High STOP: High Transition Line While High
Address
Figure illustrates address format. 7-bit address sent with Most Significant (MSB) first valid when high. This followed Least Significant
(LSB) location. determines direction transfer ('1' read, write). AAT1142 write-only device this must when communicating with AAT1142. Acknowledge (ACK) AAT1142 slave acknowledge receipt address.
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800mA Voltage-Scaling Step-Down Converter
AAT1142
Slave Address
Figure Address Map; 7-bit Slave Address (A6-A0), 1-bit Read/Write (R/W), 1-bit Acknowledge (ACK).
Data
Figure illustrates data format. 8-bit data always sent with most significant first valid when high. AAT1142 slave device acknowledge receipt data.
Software Protocol
master slave data transfer, detailing address data bits, shown Figure programming sequence follows: Send start condition Send slave address with Wait acknowledge within clock cycle Send data bits Wait acknowledge within clock cycle Send stop condition
Acknowledge
ninth address data byte. master must first release line, then slave will pull line low. AAT1142 sends acknowledge receipt each byte. This occurs during ninth clock cycle Address Data transfers (see Figures
Data
Figure Data Map; 8-bit Data (D7-D0), 1-bit Acknowledge (ACK).
Start
Slave Address
Data
Stop
7-bit address (0x14)
Figure SCL, Transfer Protocol Example; 7-bit Slave Address (A6-A0 0x14), 1-bit Read/Write (R/W 1-bit Acknowledge (ACK), 8-bit Data (D7-D0), 1-bit Acknowledge (ACK).
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800mA Voltage-Scaling Step-Down Converter
Output Voltage Programming
AAT1142 output voltage programmed through interface according Table data register encoded lines determines output voltage set-point after initial start-up. Upon power-up prior programming, default output voltage 1.8V.
AAT1142
Data Register
Data Bits
Output Voltage
0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80 (default) 1.85 1.90 1.95 2.00 2.00 2.00 2.00
Table AAT1142 Output Voltage Programming don't care).
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800mA Voltage-Scaling Step-Down Converter
S2Cwire Serial Interface
AnalogicTech's S2Cwire serial interface proprietary high-speed single-wire interface. S2Cwire interface records rising edges EN/SET input decodes them into registers which determines output voltage, shown Table Each state corresponds output voltage setting. When using S2Cwire interface, both inputs should tied ground return. This disables functionality.
AAT1142
S2Cwire Serial Interface Timing
S2Cwire serial interface flexible timing. Data clocked-in speeds 1MHz. After data been submitted, EN/SET held high latch data period TLAT. output subsequently changed predetermined voltage. When EN/SET time greater than TOFF, AAT1142 disabled. When disabled, data register reset default value.
S2Cwire Timing Diagram
TOFF
EN/SET
Data
S2Cwire Output Voltage Programming
AAT1142 programmed through S2Cwire interface according Table rising clock edges received through EN/SET corresponding given data register determine output voltage set-point. Upon power-up prior S2Cwire programming, default output voltage 1.8V.
Rising Clock Edges/ Data Register
Output Voltage
change 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35
Rising Clock Edges/ Data Register
Output Voltage
1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80 (default) 1.85 1.90 1.95 2.00 2.00 2.00 2.00
Table AAT1142 S2Cwire Output Voltage Programming Map.
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800mA Voltage-Scaling Step-Down Converter Component Selection
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 programmable AAT1142 0.61A/µsec. This equates slope compensation that inductor current down slope 1.8V output 2.2µH inductor.
AAT1142
CIN(MIN)
0.75 0.75 1.8V 0.61 2.2µH µsec
Always examine ceramic capacitor voltage coefficient characteristics when selecting proper value. example, capacitance 10F, 6.3V, ceramic capacitor with 5.0V applied actually about 6µF. maximum input capacitor current
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. 2.2µH CDRH2D14 series Sumida inductor 1.5A current rating. full 800mA load, inductor loss 60mW which gives 4.8% loss efficiency 800mA, 1.0V output.
IRMS
input capacitor ripple current varies with input output voltage will always less than equal half total load current.
0.52
Input Capacitor
Select 4.7µF 10µF 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.
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 AAT1142. ESR/ESL ceramic
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800mA Voltage-Scaling Step-Down Converter
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) shown 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 converter performance, high tantalum aluminum electrolytic capacitor should placed parallel with ESR, bypass ceramic capacitor. This dampens high network stabilizes system. current demand. relationship output voltage droop during three switching cycles output capacitance estimated
ILOAD VDROOP
AAT1142
COUT
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.
Thermal Calculations
There three types losses associated with AAT1142 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
(RDS(ON)H RDS(ON)L [VIN VO])
Output Capacitor
output capacitor limits output ripple provides holdup during large load transitions. 4.7µF 10µF ceramic capacitor typically provides sufficient bulk capacitance stabilize output during large load transitions characteristics necessary output ripple. smaller capacitor result slightly increased load output regulation output ripple with input voltages above This should verified under actual operating 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
PTOTAL
(tsw
step-down converter quiescent current. term used estimate full load stepdown converter switching losses. condition where step-down converter dropout 100% duty cycle, total device dissipation reduces
PTOTAL RDS(ON)H
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800mA Voltage-Scaling Step-Down Converter
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 160°C/W.
TJ(MAX) PTOTAL TAMB
AAT1142
Layout
suggested layout AAT1142 TSOPJW-12 package 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 (Pin should short possible. feedback (Pin should separate from power trace connected close VOUT terminal. Sensing along high-current load trace will degrade VOUT load regulation. resistance trace from terminal PGND (Pin 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. When using S2Cwire, connect ground disable functionality. When using TDFN33-12 package, connect exposed paddle (EP) plane.
Figure AAT1142 Evaluation Board Side Layout (TSOPJW-12 Package).
Figure AAT1142 Evaluation Board Bottom Side Layout (TSOPJW-12 Package).
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800mA Voltage-Scaling Step-Down Converter
Inductance (µH)
AAT1142
Manufacturer
Sumida Sumida Taiyo Yuden Taiyo Yuden
Part Number
CDRH3D16-2R2 CDRH2D14-2R2 NR3010T2R2M CBC3225T2R2MR
Current
1.20 1.50 1.10 1.13
0.072 0.094 0.095 0.080
Size (mm) LxWxH
3.8x3.8x1.8 3.2x3.2x1.55 3.0x3.0x1.0 3.2x2.5x2.5
Type
Shielded Shielded Shielded Non-Shielded
Table Typical Surface Mount Inductors.
Manufacturer
MuRata MuRata MuRata MuRata
Part Number
GRM188R60J106ME47D GRM21BR60J106KE19L GRM188R60J475KE19D GRM21BR61A475KA73L
Type
Ceramic Ceramic Ceramic Ceramic
Value
Voltage
Temp.
Case
0603 0805 0603 0805
Table Surface Mount Capacitors.
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800mA Voltage-Scaling Step-Down Converter Ordering Information
Package
TSOPJW-12 TDFN33-12
AAT1142
Marking1
RIXYY
Part Number (Tape Reel)2
AAT1142ITP-1.8-T1 AAT1142IWP-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
TSOPJW-12
0.10 0.05
0.20
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
0.04
0.15 0.05
0.10 1.00 0.065
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. 1142.2006.07.1.0
800mA Voltage-Scaling Step-Down Converter
TDFN33-12
Index Area (D/2 E/2)
AAT1142
Detail
3.00 0.05
2.40 0.05
0.10 0.16 0.375 0.125 0.075 0.075
View
Bottom View
Indicator (optional)
7.5° 7.5°
0.05 -0.20
0.229 0.051
0.05 0.05
Option C0.30 (4x) Chamfered corner
Option R0.30 (4x) Round corner
Detail
Side View
dimensions millimeters.
Detail
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.
Arques Avenue, Sunnyvale, 94085 Phone (408) 737-4600 (408) 737-4611
1142.2006.07.1.0
0.23 0.05
0.45 0.05
Detail
3.00 0.05
1.70 0.05
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