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12V, Synchronous-Rectified Buck Converter Wide Input Voltage from
Top Searches for this datasheetAPW7142 12V, Synchronous-Rectified Buck Converter Wide Input Voltage from 4.3V Output Current Adjustable Output Voltage from 0.8V System Accuracy Integrated Power MOSFETs High Efficiency Automatic Skip/PWM Mode Operation Current-Mode Operation Easy Feedback Compensation Stable with Output Capacitors Fast Load/Line Transient Response General Description APW7142 synchronous-rectified Buck converter with integrated power MOSFETs. APW7142, designed with current-mode control scheme, convert wide input voltage 4.3V output voltage adjustable from 0.8V provide excellent output voltage regulation. high efficiency over load current range, APW7142 equipped with automatic Skip/PWM mode operation. light load, operates Skip mode, which keeps constant minimum inductor peak current, reduce switching losses. heavy load, works mode, which inductor peak current programmed COMP voltage, provide high efficiency excellent output voltage regulation APW7142 also equipped with power-on-reset, soft-start, soft-stop whole protections (undervoltage, overvoltage, over temperature current-limit) into single package. shutdown mode, supply current drops below 3µA. This device, available 8-pin SOP-8 package, provides very compact system solution with minimal external components area. Power-On-Reset Monitoring Fixed 500KHz Switching Frequency mode Built-in Digital Soft-Start Soft-Stop Current-limit Protection with Frequency Foldback 118% Overvoltage Protection Hiccup-mode Undervoltage Protection Over-Temperature Protection <3µA Quiescent Current Shutdown Mode Small SOP-8 Package Lead Free Available (RoHS Compliant) Efficiency, VIN=12V, VOUT=3.3V, L1=4.7µF Applications OLPC, UMPC Notebook Computer Handheld Portable Device Step-down Converters Requiring High Efficiency Output Current 0.001 0.01 VIN=12V, VOUT=5V, L1=6.8µF VIN=5V, VOUT=3.3V, L1=2.2µF Output Current, IOUT(A) ANPEC reserves right make changes improve reliability manufacturability without notice, advise customers obtain latest version relevant information verify before placing orders. Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Ordering Marking Information APW7142 Lead Free Code Handling Code Temperature Range Package Code APW7142 APW7142 XXXXX Package Code SOP-8 Operating Junction Temperature Range Handling Code Tape Reel Lead Free Code Lead Free Device XXXXX Date Code Note1: ANPEC lead-free products contain molding compounds/die attach materials 100% matte plate termination finish; which fully compliant with RoHS compatible with both SnPb lead-free soldering operations. ANPEC lead-free products meet exceed leadfree requirements IPC/JEDEC STD-020C classification lead-free peak reflow temperature. Configuration APW7142 PGND AGND COMP SOP-8 View Absolute Maximum Ratings Symbol (Note Rating -0.3 100ns 100ns VIN+1 VIN+5 -0.3 +0.3 -0.3 VIN+0.3 -0.3 Internally Limited Unit Parameter Supply Voltage (VIN AGND) Voltage PGND AGND Voltage AGND Voltage COMP AGND Voltage TSTG TSDR Power Dissipation Maximum Junction Temperature Storage Temperature Maximum Lead Soldering Temperature, Seconds Note Stresses above those listed "Absolute Maximum Ratings" cause permanent damage device. Thermal Characteristics Symbol Parameter Junction-to-Ambient Thermal Resistance Free (Note SOP-8 Value Unit Note measured with component mounted high effective thermal conductivity test board free air. Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Recommended Operating Conditions (Note Symbol VOUT IOUT COUT LOUT Supply Voltage Converter Output Voltage Converter Output Current Converter Input Capacitor (MLCC) Converter Output Capacitor Effective Series Resistance Converter Output Inductor Resistance Feedback Resistor connected from Ambient Temperature Junction Temperature Parameter Range 1000 Unit Note Refer Typical Application Circuits Electrical Characteristics Refer typical application circuits. These specifications apply over VIN=12V, VOUT=3.3V 85°C, unless otherwise specified. Typical values TA=25°C. Symbol SUPPLY CURRENT IVIN IVIN_SD Supply Current Shutdown Supply Current VREF +50mV, VEN=3V, LX=NC rising Parameter Test Conditions APW7142 Unit POWER-ON-RESET (POR) VOLTAGE THRESHOLD Voltage Threshold Hysteresis REFERENCE VOLTAGE VREF Reference Voltage Output Voltage Accuracy Line Regulation Load Regulation OSCILLATOR DUTY CYCLE FOSC Oscillator Frequency Foldback Frequency Maximum Converter' Duty TON_MIN Minimum Pulse Width 125oC, 4.75 VOUT µA/V Regulated 25oC, IOUT=10mA, VIN=12V IOUT=10mA~3A, VIN=4.75~14V 4.75V IOUT 0.5A -1.0 -2.0 +0.02 -0.04 +1.0 +2.0 CURRENT-MODE CONVERTER Error Amplifier Transconductance VFB=VREF±50mV Error Amplifier Gain COMP Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Electrical Characteristics (Cont.) Refer typical application circuits. These specifications apply over VIN=12V, VOUT=3.3V 85°C, unless otherwise specified. Typical values TA=25°C. Symbol Parameter Current-Sense COMP Voltage Transresistance High-side Switch Resistance TJ=25°C 12V, TJ=25°C TJ=25°C 12V, TJ=25°C Test Conditions APW7142 0.048 Unit Low-side Switch Resistance PROTECTIONS ILIM VTH_UV VTH_OV High-side Switch Current-limit Under-voltage Threshold Over-voltage Threshold Under-Voltage Debounce TOTP Over-temperature Trip Point Over-temperature Hysteresis Dead-Time Peak Current falling rising -0.7V SOFT-START, SOFTSTOP, ENABLE INPUT CURRENTS Soft-Start Soft-Stop Interval Shutdown Voltage Threshold Enable Voltage Threshold High-side Switch Leakage Current Input Current Input Current falling -100 -100 +100 +100 Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Typical Operating Characteristics (Refer application circuit section "Typical Application Circuits", VIN=12V, VOUT=3.3V, L1=4.7µH) Output Current Efficiency 3.38 Output Voltage Output Current Output Voltage, VOUT Efficiency, 0.001 0.01 VIN=5V, VOUT=3.3V, L1=2.2µF VIN=12V, VOUT=5V, L1=6.8µF VIN=12V, VOUT=3.3V, L1=4.7µF 3.36 3.34 3.32 3.28 3.26 3.24 3.22 Output Current, IOUT(A) Output Current, IOUT(A) Current Limit Level (Peak Current) Junction Temperature 3.38 Output Voltage Supply Voltage IOUT=500mA Current Limit Level, ILIM(A) Output Voltage, VOUT 3.36 3.34 3.32 3.28 3.26 3.24 3.22 Junction Temperature, Supply Voltage, Input Current Supply Voltage Reference Voltage Junction Temperature 0.816 VFB=0.85V 0.812 Reference Voltage, VREF Input Current, VIN(mA) 0.808 0.804 0.800 0.796 0.792 0.788 0.784 Supply Voltage, Copyright ANPEC Electronics Corp. Rev. Nov., 2007 Junction Temperature, www.anpec.com.tw APW7142 Typical Operating Characteristics (Cont.) (Refer application circuit section "Typical Application Circuits", VIN=12V, VOUT=3.3V, L1=4.7µH) Oscillator Frequency Junction Temperature Oscillator Frequency, FOSC(KHz) Junction Temperature, Operating Waveforms (Refer application circuit section "Typical Application Circuits", VIN=12V, VOUT=3.3V, L1=4.7µH) Power Power IOUT=3A IOUT=3A VOUT 5V/div VOUT 2V/div 2A/div Time 1ms/div VOUT 5V/div VOUT 2V/div 2A/div Time 10ms/div Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Operating Waveforms (Cont.) (Refer application circuit section "Typical Application Circuits", VIN=12V, VOUT=3.3V, L1=4.7µH) Enable IOUT=3A IOUT=3A Shutdown VOUT VOUT 5V/div VOUT 2V/div 2A/div Time 1ms/div 5V/div VOUT 2V/div IL1, 2A/div Time 100µs/div Short Circuit IOUT =3~7A Short Circuit VOUT shorted short wire VOUT VOUT 10V/div VOUT 2V/div 5A/div Time 20µs/div 5V/div VOUT 200mV/div 5A/div Time 5ms/div Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Operating Waveforms (Cont.) (Refer application circuit section "Typical Application Circuits", VIN=12V, VOUT=3.3V, L1=4.7µH) Load Transient Response IOUT= 50mA-> ->50mA IOUT rising/falling time=10µs VOUT Load Transient Response IOUT= 0.5A-> ->0.5A IOUT rising/falling time=10µs VOUT VOUT 200mV/div 2A/div Time 100µs/div VOUT 100mV/div 2A/div Time 100µs/div Switching Waveform IOUT=0.2A Switching Waveform IOUT=3A 5V/div 2A/div Time 1µs/div 5V/div 2A/div Time 1µs/div Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Operating Waveforms (Cont.) (Refer application circuit section "Typical Application Circuits", VIN=12V, VOUT=3.3V, L1=4.7µH) Line Transient VIN= 5~12V rising/falling time=20µs Over Voltage Protection VOUT VOUT IOUT=-1A 5V/div VOUT 50mV/div (Voffset=3.3V) 2A/div Time 100µs/div 5V/div VOUT 2V/div 5V/div 5A/div Time 20µs/div Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Descriptions NAME PGND FUNCTION Power Ground APW7142, which source N-channel power MOSFET. Connect this system ground with lowest impedance. Power Input. supplies power (4.3V 14V) control circuitry, gate drivers step-down converter switches. Connecting ceramic bypass capacitor suitably large capacitor between both AGND PGND eliminates switching noise voltage ripple input Ground MOSFET Gate Drivers Control Circuitry. Output feedback Input. APW7142 senses feedback voltage regulates voltage 0.8V. Connecting with resistor-divider from converter' output sets output voltage from 0.8V VIN. Output error amplifier. Connect series network from COMP compensate regulation control loop. some cases, additional capacitor from COMP required. Enable Input. digital input that turns regulator off. Drive high turn regulator, drive turn off. Connect this used. Power Switching Output. junction high-side low-side power MOSFETs supply power output filter. AGND COMP Block Diagram Current Sense Amplifier Power-OnReset Current Limit Zero-Crossing Comparator 118%VREF 50%VREF Soft-Start Soft-Stop Soft-Start Soft-Stop Fault Logic Inhibit Gate Control Current Compartor Slope Compensation Gate Driver Gate Driver VREF Error Amplifier COMP PGND 1.5V Enable Over Temperature Protection Oscillator 500kHz AGND Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Typical Application Circuits 4.3~14V Single Power Input Step-down Converter(with Ceramic Output Capacitor) Enable Shutdown VOUT APW7142 PGND COMP AGND 30%, Optional Cost-effective Feedback Compensation connected) VIN(V) VOUT(V) L1(µH) C2(µF) ESR(m) R1(K) 63.0 63.0 46.9 46.9 30.0 30.0 46.9 46.9 R2(K) R3(K) 10.0 20.0 10.0 22.0 10.0 20.0 16.0 20.0 C3(pF) 1500 1500 1500 1500 1500 1500 1800 1800 1800 1800 Fast-Transient-Response Feedback Compensation connected) VIN(V) VOUT(V) L1(µH) C2(µF) ESR(m) R1(K) 63.0 63.0 46.9 46.9 30.0 30.0 46.9 46.9 R2(K) C4(pF) R3(K) 33.0 68.0 22.0 47.0 13.0 27.0 15.0 20.0 43.0 C3(pF) 1200 1200 2200 2200 1800 1500 Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Typical Application Circuits (Cont.) +12V Single Power Input Step-down Converter (with Electrolytic Output Capacitor) Enable Shutdown APW7142 PGND COMP AGND 2.2µF 470µF 4.7µH VOUT 3.3V/3A 470µF (ESR=30m) 680pF 46.9K 47pF Function Descriptions Power-On-Reset (POR) APW7142 keeps monitoring voltage prevent wrong logic operations which occur when voltage high enough internal control circuitry operate. rising threshold 4.1V (typical) with 0.5V hysteresis. During startup, voltage must exceed enable voltage threshold. Then starts start-up process ramps output voltage voltage target. Digital Soft-Start APW7142 built-in digital soft-start control rise rate output voltage limit input current surge during start-up. During soft-start, internal voltage ramp (VRAMP), connected positive inputs error amplifier, rises from 0.95V replace reference voltage (0.8V) until voltage ramp reaches reference voltage. During soft-start without output overvoltage, APW7142 converter' sinking capability disabled until output voltage reaches voltage target. Digital Soft-Stop moment shutdown controlled signal, undervoltage event over-temperature protection, APW7142 initiates digital soft-stop process discharge output voltage output capacitors. course, load current also discharges output voltage. During soft-stop, internal voltage ramp (VRAMP) falls down rises from 0.95V replace reference voltage. Therefore, output voltage falls down slowly light load. After soft-stop interval elapses, softstop process ends turns low-side power MOSFET. Output Undervoltage Protection (UVP) process operation, short-circuit occurs, output voltage will drop quickly. Before current-limit circuit responds, output voltage will fall required regulation range. undervoltage continually monitors voltage after soft-start completed. load step strong enough pull output voltage lower than undervoltage threshold, shuts down converter' output. undervoltage threshold nominal output voltage. undervoltage comparator built-in noise filter prevent chips from wrong shutdown caused noise. undervoltage protection works hiccup mode without latched shutdown. will initiate soft-start process preceding delay. www.anpec.com.tw Copyright ANPEC Electronics Corp. Rev. Nov., 2007 APW7142 Function Descriptions (Cont.) Overvoltage Protection (OVP) overvoltage function monitors output voltage pin. Should voltage increase over 118% reference voltage high-side MOSFET failure, other reasons, overvoltage protection comparator will force low-side MOSFET gate driver high. This action actively pulls down output voltage eventually attempts blow internal bonding wires. soon output voltage within regulation, comparator disengaged. chip will restore normal operation. This scheme only clamps voltage overshoot, does invert output voltage when otherwise activated with continuously high output from low-side MOSFET driver common problem schemes with latch. Over-Temperature Protection (OTP) over-temperature circuit limits junction temperature APW7142. When junction temperature exceeds +150oC, thermal sensor turns both power MOSFETs, allowing devices cool. thermal sensor allows converters start start-up process regulate output voltage again after junction temperature cools 40oC. designed with 40oC hysteresis lowers average during continuous thermal overload conditions, increasing life time APW7142. Enable/Shutdown Driving ground initiates soft-stop process then places 7142 shutdown. shutdown, after soft-stop process completed, internal power MOSFETs turn off, internal circuitry shuts down quiescent supply current reduces less than 3µA. Current-Limit Protection APW7142 monitors output current, flowing through high-side power MOSFET, limits current peak current-limit level prevent loads from damages during overload short-circuit conditions. Frequency Foldback foldback frequency controlled voltage. When output shorted ground, frequency oscillator will reduced about 80KHz. This lower frequency allows inductor current safely discharge, thereby preventing current runaway. oscillator' fres quency will gradually increase designed rate when feedback voltage again approaches 0.8V. Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Application Information Setting Output Voltage regulated output voltage determined VOUT T=1/FOSC IOUT Suggested range from 20K. portable applications, resistor suggested prevent stray pickup, please locate resistors close APW7142. Input Capacitor Selection small ceramic capacitors high frequency decoupling bulk capacitors supply surge current needed each time P-channel power MOSFET (Q1) turns Place small ceramic capacitors physically close between GND. important parameters bulk input capacitor voltage rating current rating. reliable operation, select bulk capacitor with voltage current ratings above maximum input voltage largest current required circuit. capacitor voltage rating should least 1.25 times greater than maximum input voltage voltage rating times conservative guideline. current (IRMS) bulk input capacitor calculated following equation: IOUT ICOUT VOUT VOUT Figure Converter Waveforms Output Capacitor Selection output capacitor required filter output supply load transient current. filtering requirements function switching frequency ripple current (I). output ripple voltages, having phase shift, across ideal output capacitor. peak-to-peak voltage calculated following equations: VOUT VOUT FOSC IRMS IOUT where duty cycle power MOSFET. through hole design, several electrolytic capacitors needed. surface mount designs, solid tantalum capacitors used, caution must exercised with regard capacitor surge current rating. VESR peak-to-peak voltage ideal output capacitor calculated following equations: VCOUT FOSC COUT applications using bulk capacitors, COUT much smaller than ignored. Therefore, peak-to-peak output voltage (VOUT IOUT VOUT COUT shown below: VOUT ICOUT Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Application Information (Cont.) Output Capacitor Selection (Cont.) applications using ceramic capacitors, VESR much smaller than COUT ignored. Therefore, peak-to-peak output voltage (VOUT close VCOUT load transient requirements function slew rate (di/dt) magnitude transient load current. These requirements generally with capacitors careful layout. High frequency capacitors initially supply transient slow current load rate seen bulk capacitors. bulk filter capacitor values generally determined (Effective Series Resistance) voltage rating requirements rather than actual capacitance requirements. High frequency decoupling capacitors should placed close power pins load physically possible. careful inductance circuit board wiring that could cancel usefulness these inductance components. aluminum electrolytic capacitor' value related case size with lower available larger case sizes. However, Equivalent Series Inductance (ESL) these capacitors increases with case size reduce usefulness capacitor high slew-rate transient loading. Inductor Value Calculation operating frequency inductor selection interrelated that higher operating frequencies permit smaller inductor same amount inductor ripple current. However, this expense efficiency increase MOSFET gate charge losses. equation shows that inductance value direct effect ripple current. Accepting larger values ripple current allows inductances, results higher output voltage ripple greater core losses. reasonable starting point setting ripple current IOUT(MAX) Remember, maximum ripple current occurs maximum input voltage. minimum inductance inductor calculated using following equation: VOUT VOUT 500000 VOUT VOUT 600000 where VIN(MAX) Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Layout Considerations high power switching regulator, correct layout important ensure proper operation regulator. general, interconnecting impedance should minimized using short, wide printed circuit traces. Signal power grounds kept separate finally combined using ground plane construction single point grounding. Figure illustrates layout, with bold lines indicating high current paths. Components along bold lines should placed close together. Below checklist your layout: Firstly, initial layout placing power components. Orient power circuitry achieve clean power flow path. possible, make connections side with wide, copper filled areas. Place decoupling ceramic capacitor near close possible. wide power ground plane connect provide impedance path between components large high slew rate current. SOP-8 Ground APW7142 Ground VOUT Figure Recommended Layout Diagram Load VOUT Compensation Network APW7142 COMP PGND AGND (Optional) Feedback Divider Figure loops with same color bold lines conduct high slew rate current. These interconnecting impedances should minimized using wide, short printed circuit traces. Keep sensitive small signal nodes (FB, COMP) away from switching nodes others) PCB. Therefore place feedback divider feedback compensation network close avoid switching noise. Connect ground feedback divider directly AGND using dedicated ground trace. Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Package Information SOP-8 VIEW 0.25 GAUGE PLANE SEATING PLANE VIEW SOP-8 INCHES MIN. MAX. MILLIMETERS MIN. MAX. 0.25 0.40 0.10 1.25 0.31 0.17 4.90 6.00 3.90 1.27 1.75 0.25 0.004 0.049 0.51 0.25 0.012 0.007 0.193 0.236 0.154 0.050 0.50 1.27 0.010 0.016 0.069 0.010 0.020 0.010 0.020 0.050 Note: Followed JEDEC MS-012 Dimension does include mold flash, protrusions gate burrs. Mold flash, protrusion gate burrs shall exceed side. Dimension does include inter-lead flash protrusions. Inter-lead flash protrusions shall exceed side. Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Carrier Tape Reel Dimensions SECTION SECTION Application 5.5± 0.05 330.0± 2.00 MIN. SOP-8(P) 4.0± 0.10 8.0± 0.10 12.4+2.00 13.0+0.50 MIN. -0.00 -0.20 2.0± 0.05 1.5+0.10 -0.00 MIN. 0.30 1.75± 0.10 20.2 MIN. 12.0± 0.6+0.00 6.40± 0.20 5.20± 0.20 2.10± 0.20 -0.40 (mm) Devices Unit Package Type SOP-8 Unit Tape Reel Quantity 2500 Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Reflow Condition Ramp-up Tsmax (IR/Convection Reflow) Critical Zone Temperature Tsmin Ramp-down Preheat 25°C Peak Time Reliability Test Program Test item SOLDERABILITY HOLT Latch-Up Method MIL-STD-883D-2003 MIL-STD-883D-1005.7 JESD-22-B, A102 MIL-STD-883D-1011.9 MIL-STD-883D-3015.7 JESD Description 245°C, 1000 Bias @125°C Hrs, 100%RH, 121°C -65°C~150°C, Cycles VHBM 2KV, 200V 10ms, 100mA Classification Reflow Profiles Profile Feature Average ramp-up rate Preheat Temperature (Tsmin) Temperature (Tsmax) Time (min max) (ts) Time maintained above: Temperature (TL) Time (tL) Peak/Classification Temperature (Tp) Time within actual Peak Temperature (tp) Ramp-down Rate Sn-Pb Eutectic Assembly 3°C/second max. 100°C 150°C 60-120 seconds 183°C 60-150 seconds table 10-30 seconds Pb-Free Assembly 3°C/second max. 150°C 200°C 60-180 seconds 217°C 60-150 seconds table 20-40 seconds 6°C/second max. 6°C/second max. minutes max. minutes max. Time 25°C Peak Temperature Note: temperatures refer topside package. Measured body surface. Copyright ANPEC Electronics Corp. Rev. Nov., 2007 www.anpec.com.tw APW7142 Classification Reflow Profiles (Cont.) Table SnPb Eutectic Process Package Peak Reflow Temperatures Package Thickness Volume <350 <2.5 +0/-5°C +0/-5°C Volume +0/-5°C +0/-5°C Table Pb-free Process Package Classification Reflow Temperatures Package Thickness Volume Volume Volume <350 350-2000 >2000 <1.6 +0°C* +0°C* +0°C* +0°C* +0°C* +0°C* +0°C* +0°C* +0°C* *Tolerance: device manufacturer/supplier shall assure process compatibility including stated classification temperature (this means Peak reflow temperature +0°C. example 260°C+0°C) rated level. Customer Service Anpec Electronics Corp. Head Office No.6, Dusing Road, SBIP, Hsin-Chu, Taiwan 886-3-5642000 886-3-5642050 Taipei Branch Lane 218, Jhongsing Rd., Sindian City, Taipei County 23146, Taiwan 886-2-2910-3838 886-2-2917-3838 Copyright ANPEC Electronics Corp. Rev. 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