LM2614 400mA Sub-Miniature Adjustable DC-DC Converter Optimized Power

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LM2614 400mA Sub-Miniature Adjustable DC-DC Converter Optimized Power

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LM2614 400mA Sub-Miniature Adjustable DC-DC Converter Optimized Power Amplifiers
LM2614 400mA Sub-Miniature Adjustable DC-DC Converter Optimized Power Amplifiers
LM2614 DC-DC converter optimized powering power amplifiers (PAs) from single Lithium-Ion cell. steps down input voltage 2.8V 5.5V output 1.0V 3.6V 400mA (300mA grade). Output voltage using analog input VCON application circuit. device offers three modes mobile phones similar applications. Fixed-frequency mode minimizes interference. SYNC input allows synchronizing switching frequency range 500kHz 1MHz. current hysteretic mode reduces quiescent current 160µA (typ.). Shutdown mode turns device reduces battery consumption 0.02µA (typ.). Current limit thermal shutdown features protect device system during fault conditions. LM2614 available bump micro package. This packaging uses National's chip-scale micro technology offers smallest possible size. high switching frequency (600kHz) allows tiny surface-mount components. LM2614 dynamically controlled output voltage changes from 1.0V 3.6V 30µs. device features external compensation tailor response wide range operating conditions.
Specifications
Operates from single LiION cell (2.8V 5.5V) Adjustable output voltage (1.0V 3.6V) feedback voltage precision 400mA maximum load capability(300mA grade) 600µA mode quiescent current 0.02µA shutdown current 600kHz switching frequency SYNC input mode frequency synchronization from 500kHz 1MHz High efficiency (96% 3.9VIN, 3.6VOUT 200mA) mode from internal synchronous rectification 100% Maximum Duty Cycle Lowest Dropout
Features
Sub-miniature 10-bump thin micro package Uses small ceramic capacitors mode output voltage ripple(COUT 22µF) Internal soft start Current overload protection Thermal Shutdown External compensation
Applications
Mobile Phones Hand-Held Radios Cards Battery Powered Devices
2002 National Semiconductor Corporation
DS200367
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LM2614
Typical Application Circuits
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FIGURE Typical Circuit Powering Power Amplifiers
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FIGURE Typical Circuit 2.5V Output Voltage
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FIGURE Typical Circuit 1.5V Output Voltage
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LM2614
Connection Diagrams
10-Bump micro Package
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View
Bottom View
Ordering Information
Order Number LM2614ATL LM2614BTL LM2614ATLX LM2614BTLX
denotes date code marking digit) production refers run/lot traceability production product line designator Package markings change over course production.
Package Type
Package Marking XYTT S50A XYTT S50B XYTT S50A XYTT S50B
Supplied Tape Reel Tape Reel 3000 Tape Reel 3000 Tape Reel
10-bump Wafer Level Chip Scale (micro SMD)
Description
Number Name EANEG EAOUT SYNC/MODE Feedback Analog Input. Inverting input error amplifier Output error amplifier Synchronization Input. this digital input frequency selection modulation control. Set: SYNC/MODE high low-noise 600kHz mode SYNC/MODE low-current mode SYNC/MODE 500kHz-1MHz external clock synchronization mode. (See Synchronization Operating Modes Device Information section.) Enable Input. this Schmitt trigger digital input high normal operation. shutdown, low. during system power-up other supply voltage conditions. (See Shutdown Mode Device Information section.) Power Ground Switching Node connection internal PFET switch NFET synchronous rectifier. Connect inductor with saturation current rating that exceeds Switch Peak Current Limit LM2614. Power Supply Voltage Input internal PFET switch. Connect input filter capacitor. Analog Supply Input. board layout optimum, optional 0.1µF ceramic capacitor suggested. Analog Control Ground Function
PGND
PVIN SGND
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LM2614
Absolute Maximum Ratings
(Note
Storage Temperature Range Lead Temperature (Soldering, sec.) Junction Temperature (Note Minimum Rating
-45°C +150°C 260°C -25°C +125°C
Military/Aerospace specified devices required, please contact National Semiconductor Sales Office/ Distributors availability specifications. PVIN, SGND PGND SGND, PVIN EAOUT, EANEG, SYNC/MODE SGND -0.2V -0.2V +0.2V -0.2V (GND -0.2V) (VDD +0.2V)
140°C/W
(Human Body Model, Thermal Resistance (JA) (Note
Electrical Characteristics
Specifications with standard typeface 25°C, those boldface type apply over full Operating Temperature Range -25°C +85°C. Unless otherwise specified, PVIN SYNC/MODE 3.6V. Symbol VHYST ISHDN IQ1_PWM IQ2_PFM RDSON RDSON RDSON (TC) ILIM FSYNC FOSC Tmin Pin-Pin Resistance Pin-Pin Resistance Resistance Temperature Coefficient Switch Peak Current Limit (Note Logic High Input, SYNC/MODE Logic Input, SYNC/MODE SYNC/MODE Clock Frequency Range Internal Oscillator Frequency Minimum ON-Time PFET Switch Mode (Note LM2614ATL, Mode LM2614BTL, Mode LM2614ATL LM2614BTL Parameter Input Voltage Range Feedback Voltage Comparator Hysteresis Voltage Shutdown Supply Current Bias Current into Mode (SYNC/MODE (Note 3.6V, SYNC/MODE SYNC/MODE Conditions PVIN (Note 1.485 1.50 0.02 0.95 0.80 1000 1.515 Units
Note Absolute Maximum Ratings indicate limits beyond which damage device occur. Operating Ratings indicate conditions which device functional, device specifications guaranteed. guaranteed specifications associated test conditions, limits Conditions Electrical Characteristics table. Typical (typ) specifications mean average values 25°C guaranteed. Note Thermal shutdown will occur junction temperature exceeds 150°C. Note Thermal resistance specified with layer (0.5/0.5 cu). Note LM2614 designed mobile phone applications where turn-on after system power-up controlled system controller. Thus, should kept shutdown holding until input voltage exceeds 2.8V. Note hysteresis voltage minimum voltage swing that causes internal feedback control circuitry turn internal PFET switch then during mode. When resistor dividers used like operating circuit Figure hysteresis output will value hysteresis feedback times resistor divider ratio. this case, 24mV (typ) ((46.4k 33.2k)/33.2k). Note Current limit built-in, fixed, adjustable. current limit reached while voltage pulled below 0.7V, internal PFET switch turns 2.5µs allow inductor current diminish. Note SYNC driven with external clock switching between GND. When external clock present SYNC; forced mode external clock frequency. LM2614 synchronizes rising edge external clock.
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LM2614
Typical Performance Characteristics
LM2614ATL, Circuit Figure 3.6V, 25°C, unless otherwise noted. Quiescent Supply Current Supply Voltage Shutdown Quiescent Current Temperature (Circuit Figure
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Output Voltage Supply Voltage (VOUT 1.0V, MODE)
Output Voltage Supply Voltage (VOUT 1.5V, MODE)
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Output Voltage Output Current (VOUT 1.0V, MODE)
Output Voltage Output Current (VOUT 1.5V, MODE)
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LM2614
Typical Performance Characteristics
LM2614ATL, Circuit Figure 3.6V, 25°C, unless otherwise noted. (Continued) Output Voltage Output Current (VOUT 3.6V, MODE) Dropout Voltage Output Current (VOUT 3.6V, MODE)
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Switching Frequency Temperature (Circuit Figure MODE)
Feedback Bias Current Temperature (Circuit Figure
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Efficiency Output Current (VOUT 1.0V, MODE)
Efficiency Output Current (VOUT 1.0V, MODE, with Diode)
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LM2614
Typical Performance Characteristics
LM2614ATL, Circuit Figure 3.6V, 25°C, unless otherwise noted. (Continued) Efficiency Output Current (VOUT 1.5V, MODE) Efficiency Output Current (VOUT 1.5V, MODE, with Diode)
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Efficiency Output Current (VOUT 3.6V, MODE)
Efficiency Output Current (VOUT 3.6V, MODE, with Diode)
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LM2614
Typical Performance Characteristics
LM2614ATL, Circuit Figure 3.6V, 25°C, unless otherwise noted. (Continued) Efficiency Output Voltage (PWM MODE, with Diode)
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Device Information
LM2614 simple, step-down DC-DC converter optimized powering power amplifiers (PAs) mobile phones, portable communicators, similar battery powered devices. designed allow operate maximum efficiency over wide range power levels from single LiION battery cell. based current-mode buck architecture, with synchronous rectification mode high efficiency. designed maximum load capability 400mA (300mA grade) mode. Maximum load range vary from this depending input voltage, output voltage inductor chosen. device three pin-selectable operating modes required powering mobile phones other sophisticated portable devices with complex power management needs. Fixed-frequency operation offers full output current capability high efficiency while minimizing interference with sensitive data acquisition circuits. During standby operation, hysteretic mode reduces quiescent current 160µA typ. maximize battery life. Shutdown mode turns device reduces battery consumption 0.02µA (typ). mode feedback voltage precision Efficiency typically 200mA load with 3.6V output,
3.9V input. efficiency further increased using schottky diode like MBRM120 shown Figure mode quiescent current 600µA typ. output voltage dynamically programmable from 1.0V 3.6V adjusting voltage VCON external feedback resistors. This ensures longer battery life being able change supply voltage dynamically depending transmitting power. Additional features include soft-start, current overload protection, over voltage protection thermal shutdown protection. LM2614 constructed using chip-scale 10-pin thin micro package. This package offers smallest possible size, space-critical applications such cell phones, where board area important design consideration. high switching frequency (600kHz) reduces size external components. Board area required implementation only 0.58in2 (375mm2). micro-SMD package requires special design considerations implementation. (See Micro Package Assembly Application Information section.) fine bump-pitch requires careful board design precision assembly equipment.
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LM2614
Device Information
(Continued)
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FIGURE Typical Operating Circuit CIRCUIT OPERATION Referring Figure Figure Figure Figure LM2614 operates follows. During first part each switching cycle, control block LM2614 turns internal PFET switch. This allows current flow from input through inductor output filter capacitor load. inductor limits current ramp with slope (VIN-VOUT)/L, storing energy magnetic field. During second part each cycle, controller turns PFET switch off, blocking current flow from input, then turns NFET synchronous rectifier response, inductor's magnetic field collapses, generating voltage that forces current from ground through synchronous rectifier output filter capacitor load. stored energy transferred back into circuit depleted, inductor current ramps down with slope VOUT/L. inductor current reaches zero before next cycle, synchronous rectifier turned prevent current reversal. output filter capacitor stores charge when inductor current high, releases when low, smoothing voltage across load. output voltage regulated modulating PFET switch time control average current sent load. effect identical sending duty-cycle modulated rectangular wave formed switch synchronous rectifier low-pass filter formed inductor output filter capacitor. output voltage equal average voltage pin.
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FIGURE Simplified Functional Diagram
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LM2614
Device Information
OPERATION
(Continued) Mode Switching Waveform
While (Pulse Width Modulation) mode, output voltage regulated switching constant frequency then modulating energy cycle control power load. Energy cycle modulating PFET switch on-time pulse-width control peak inductor current. This done comparing signal from current-sense amplifier with slope compensated error signal from voltage-feedback error amplifier. beginning each cycle, clock turns PFET switch, causing inductor current ramp When current sense signal ramps past error amplifier signal, comparator turns PFET switch turns NFET synchronous rectifier, ending first part cycle. increase load pulls output voltage down, error amplifier output increases, which allows inductor current ramp higher before comparator turns PFET. This increases average current sent output adjusts increase load. Before going comparator, error signal summed with slope compensation ramp from oscillator stability current feedback loop. During second part cycle, zero crossing detector turns NFET synchronous rectifier inductor current ramps zero. minimum time PFET mode about 200ns. Mode Switching Waveform
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Inductor Current, 500mA/div Pin, 2V/div VOUT, 50mV/div, Coupled
FIGURE OPERATION Connecting SYNC/MODE SGND sets LM2614 hysteretic operation. While (Pulse Frequency Modulation) mode, output voltage regulated switching with discrete energy cycle then modulating cycle rate, frequency, control power load. This done using error comparator sense output voltage. device waits load discharges output filter capacitor, until output voltage drops below lower threshold error-comparator. Then device initiates cycle turning PFET switch. This allows current flow from input, through inductor output, charging output filter capacitor. PFET turned when output voltage rises above regulation threshold error comparator. Thus, output voltage ripple mode proportional hysteresis error comparator. mode, device only switches needed service load. This lowers current consumption reducing power consumed during switching action circuit, transition losses internal MOSFETs, gate drive currents, eddy current losses inductor, etc. also improves light-load voltage regulation. During second half cycle, intrinsic body diode NFET synchronous rectifier conducts until inductor current ramps zero. OPERATING MODE SELECTION LM2614 designed digital control operating modes system controller. This prevents spurious switch over from low-noise mode between transmission intervals mobile phone applications that occur other products. SYNC/MODE digital input used select operating mode. Setting SYNC/MODE high (above 1.3V) selects 600kHz current-mode operation. mode optimized low-noise, high-power operation when load active. Setting SYNC/MODE (below 0.4V) selects hysteretic voltage-mode operation. mode optimized reducing power consumption
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Inductor Current, 500mA/div Pin, 2V/div VOUT, 10mV/div, Coupled
FIGURE
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LM2614
Device Information
(Continued)
extending battery life when load low-power standby mode. mode, quiescent current into 160µA typ. contrast, mode VDD-pin quiescent current 600µA typ. operation intended with loads 50mA more, when noise operation desired. Below 100mA, operation used allow precise regulation, reduced current consumption. However, should noted that applications mode need used output voltage slew rates more concern system designer. LM2614 over-voltage feature that prevents output voltage from rising high, when device left mode under low-load conditions. Overvoltage Protection, more information. Switch modes with SYNC/MODE pin, using signal with slew rate faster than 5V/100µs. comparator, Schmitt trigger logic gate drive SYNC/MODE pin. leave floating allow linger between thresholds. These measures will prevent output voltage errors response indeterminate logic state. LM2614 switches each rising edge SYNC. Ensure minimum load keep output voltage regulation when switching modes frequently. FREQUENCY SYNCHRONIZATION SYNC/MODE input also used frequency synchronization. During synchronization, LM2614 initiates cycles rising edge clock. When synchronized external clock, operates mode. device synchronize duty-cycle clock over frequencies from 500kHz 1MHz. different duty cycle used other than range acceptable duty cycles 70%. following waveform duty cycle guidelines when applying external clock SYNC/MODE pin. Clock under/overshoot should less than 100mV below above VDD. When applying noisy clock signals, especially sharp edged signals from long cable during evaluation, terminate cable characteristic impedance filter SYNC pin, necessary, soften slew rate over/undershoot. Note that sharp edged signals from pulse function generator develop under/overshoot high improperly terminated cable. OVERVOLTAGE PROTECTION LM2614 over-voltage comparator that prevents output voltage from rising high when device left mode under low-load conditions. When output voltage rises about 100mV (Figure over regulation threshold, comparator inhibits operation skip pulses until output voltage returns regulation threshold. When resistor dividers used threshold output will value threshold feedback times resistor divider ratio. over voltage protection, output voltage ripple will increase. SHUTDOWN MODE Setting digital input 0.4V) places LM2614 0.02µA (typ) shutdown mode. During shutdown, PFET switch, NFET synchronous rectifier, reference, control bias circuitry LM2614 turned off. Setting high enables normal operation. While turning soft start activated.
should turn LM2614 during system power-up undervoltage conditions when supply less than 2.8V minimum operating voltage. LM2614 designed compact portable applications, such mobile phones. such applications, system controller determines power supply sequencing. Although LM2614 typically well behaved input voltages, this guaranteed. INTERNAL SYNCHRONOUS RECTIFICATION While mode, LM2614 uses internal NFET synchronous rectifier reduce rectifier forward voltage drop associated power loss. Synchronous rectification provides significant improvement efficiency whenever output voltage relatively compared voltage drop across ordinary rectifier diode. internal NFET synchronous rectifier turned during inductor current down slope during second part each cycle. synchronous rectifier turned prior next cycle, when inductor current ramps zero light loads. NFET designed conduct through intrinsic body diode during transient intervals before turns eliminating need external diode. CURRENT LIMITING current limit feature allows LM2614 protect itself external components during overload conditions. mode cycle-by-cycle current limit normally used. excessive load pulls voltage feedback down approximately 0.7V, then device switches timed current limit mode. timed current limit mode internal P-FET switch turned after current comparator trips beginning next cycle inhibited 2.5µs force instantaneous inductor current ramp down safe value. Timed current limit mode prevents loss current control seen some products when voltage feedback pulled serious overload conditions. DYNAMICALLY ADJUSTABLE OUTPUT VOLTAGE LM2614 used provide dynamically adjustable output voltage using external feedback resistors. output varied from 1.0V 3.6V less than 30µs using analog control signal (VCON) external feedback resistors. This feature useful applications where peak power needed only when handset away from base station when data being transmitted. other instances transmitting power reduced hence supply voltage reduced helping maintain longer battery life. Setting Output Voltage Application Information section further details. dropout conditions output voltage IOUT (Rdc RDSON (P)) where series resistance inductor RDSON resistance PFET.
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LM2614
Device Information
(Continued) Load Transient Response (Circuit Figure
VCON Transient Response (Circuit Figure
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FIGURE
FIGURE Line Transient Response (Circuit Figure
VCON Transient Response Dropout (Circuit Figure
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FIGURE SOFT-START LM2614 soft start reduce current inrush during power-up startup. This reduces stress LM2614 external components. also reduces startup transients power source. Soft start implemented ramping reference input error amplifier LM2614 gradually increase output voltage. THERMAL SHUTDOWN PROTECTION LM2614 thermal shutdown protection function protect itself from short-term misuse overload conditions. When junction temperature exceeds 150°C device turns output stage when temperature drops below 130°C initiates soft start cycle. Prolonged operation thermal shutdown conditions damage device considered practice.
FIGURE
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LM2614
Application Information
SETTING OUTPUT VOLTAGE LM2614 used with external feedback resistors analog signal vary output voltage. Select output voltage from 1.0V 3.6V setting voltage VCON directed Table TABLE Output Voltage Selection VCON VCON VCON VOUT (1+R1/R2) (1+R1/R2)-VCON (R1/R2)
voltage control equation Table Select value allow least times feedback bias current flow through EXTERNAL COMPENSATION LM2614 uses external components connected EANEG EAOUT pins compensate regulator (Figure Typically, that required series connection capacitor (C4) resistor (R3). capacitor (C5) connected across EANEG EAOUT pins improve noise immunity loop. reacts with give high frequency pole. reacts with high open loop gain error amplifier resistance EANEG create dominant pole system, while react create zero frequency response. pole rolls loop gain, give bandwidth somewhere between 10kHz 50kHz, this avoids 100kHz parasitic pole contributed current mode controller. Typical values 220pF (C4) range recommended create pole order 10Hz less. next dominant pole system formed output capacitance (C2) parallel combination load resistance effective output resistance regulator. This combined resistance (Ro) dominated small signal output resistance, which typically range exact value this resistance, therefore this load pole depends steady state duty cycle internal ramp value. Ideally want zero formed cancel this load pole, such that R3=RoC2/C4. large variation this ideal case only achieved operating condition. Therefore compromise about should used determine starting value This value then optimized bench give best transient response load changes changes VCON, under conditions. Typical values 10pF 220pF 470pF ensure good response from dropout conditions VOUT(min). INDUCTOR SELECTION 10µH inductor with saturation current rating higher than peak current rating device. inductor's resistance should less than good efficiency. Table lists suggested inductors suppliers.
Refer Figure relation between VOUT VCON. VOUT VCON (Circuit Figure
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FIGURE When control voltage between 1.85V output voltage will vary monotonic fashion with respect
TABLE Suggested Inductors Their Suppliers Part Number DO1608C-103 P1174.103T ELL6RH100M CDRH5D18-100 P0770.103T Vendor Coilcraft Pulse Panasonic Sumida Pulse Phone 847-639-6400 858-674-8100 714-373-7366 847-956-0666 858-674-8100 847-639-1469 858-674-8262 714-373-7323 847-956-0702 858-674-8262
low-cost applications, unshielded inductor suggested. noise critical applications, toroidal shielded inductor should used. good practice board with footprints accommodating both types design flexibility. This allows substitution low-noise shielded inductor, event that noise from low-cost unshielded models unacceptable. saturation current rating current level beyond which inductor loses inductance. Different manufacturers specify saturation current rating differently. Some specify saturation current point when inductor value falls from original value, others specify 10%.
always better look inductance versus current curve make sure inductor value doesn't fall below peak current rating LM2614. Beyond this rating, inductor loses ability limit current through switch ramp. This cause poor efficiency, regulation errors stress DC-DC converters like LM2614. Saturation occurs when magnetic flux density from current through windings inductor exceeds what inductor's core material support with corresponding magnetic field.
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LM2614
Application Information
CAPACITOR SELECTION
(Continued)
4.7µF 10µF ceramic input capacitor. 10µF ceramic input capacitor recommended represents load 4.7µF ceramic output capacitor getting faster slew rates output voltages from VOUT (min) VOUT (max). types, Y5V. rise time voltage from VOUT (min) VOUT (max) depends slew rate error amp, switch peak current limit value output capacitor. time output change from VOUT (max) VOUT (min) depends RLOAD COUT. tantalum capacitors recommended. Ceramic capacitors provide optimal balance between small size, cost, reliability performance cell phones similar applications. 22µF ceramic output capacitor used applications requiring fixed output voltages
and/or increased tolerance heavy load transients. 10µF ceramic output capacitor used applications where worst case load transient step less than 200mA. Table lists suggested capacitors suppliers. input filter capacitor supplies current PFET switch LM2614 first part each cycle reduces voltage ripple imposed input power source. output filter capacitor smoothes current flow from inductor load, helps maintain steady output voltage during transient load changes reduces output voltage ripple. These capacitors must selected with sufficient capacitance sufficiently perform these functions. Parallel combinations smaller value ceramic capacitors also used output long combined value least 4.7µF application circuit Figure ESR, equivalent series resistance, filter capacitors major factor voltage ripple.
TABLE Suggested Capacitors Their Suppliers Model JMK212BJ475MG LMK316BJ475ML C2012X5R0J475K JMK325BJ226MM JMK212BJ106MG Type Ceramic Ceramic Ceramic Ceramic Ceramic Vendor Taiyo-Yuden Taiyo-Yuden Taiyo-Yuden Taiyo-Yuden Phone 847-925-0888 847-925-0888 847-803-6100 847-925-0888 847-925-0888 847-925-0899 847-925-0899 847-803-6296 847-925-0899 847-925-0899
(Input Output Filter Capacitor)
micro PACKAGE ASSEMBLY micro package requires specialized board layout, precision mounting careful reflow techniques, detailed National Semiconductor Application Note AN-1112. Refer section Surface Mount Technology (SMT) Assembly Considerations. best results assembly, alignment ordinals board should used facilitate placement device. style used with micro package must NSMD (non-solder mask defined) type. This means that solder-mask opening larger than size. This prevents that otherwise forms solder-mask overlap, from holding device surface board interfering with mounting. Application Note AN-1112 specific instructions this. 10-Bump package used LM2614 micron solder balls requires 10.82mil pads mounting circuit board. trace each should enter with entry angle prevent debris from being caught deep corners. Initially, trace each should 6-7mil wide, section approximately 6mil long, thermal relief. Then each trace should neck down optimal width. important criterion symmetry. This ensures solder bumps LM2614 reflow evenly that device solders level board. particular, special attention must paid pads bumps D3-B3. Because PGND PVIN typically connected large copper planes, inadequate thermal reliefs result late inadequate reflow these bumps. micro package optimized smallest possible size applications with infrared opaque cases. Because micro package lacks plastic encapsulation characteristic larger devices, vulnerable light. Backside metalization and/or epoxy coating, along with front-side shading printed circuit board, reduce this sensitivity.
BOARD LAYOUT CONSIDERATIONS board layout important part DC-DC converter design. Poor board layout disrupt performance DC-DC converter surrounding circuitry contributing EMI, ground bounce, resistive voltage loss traces. These send erroneous signals DC-DC converter resulting poor regulation instability. Poor layout also result reflow problems leading poor solder joints between micro package board pads. Poor solder joints result erratic degraded performance. Good layout LM2614 implemented following simple design rules. Place LM2614 10.82 (10.82/1000 in.) pads. thermal relief, connect each with wide, approximately long traces, then incrementally increase each trace optimal width. important criterion symmetry ensure solder bumps LM2614 reflow evenly (see micro Package Assembly Use). Place LM2614, inductor filter capacitors close together make traces short. traces between these components carry relatively high switching currents antennas. Following this rule reduces radiated noise. Place capacitors inductor within LM2614.
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LM2614
Application Information
(Continued)
reduces voltage errors caused resistive losses across traces. Route noise sensitive traces, such voltage feedback path, away from noisy traces between power components. voltage feedback trace must remain close LM2614 circuit should routed directly from VOUT output capacitor should routed opposite noise components. This reduces radiated onto DC-DC converter's voltage feedback trace. Place noise sensitive circuitry, such radio blocks, away from DC-DC converter, CMOS digital blocks other noisy circuitry. Interference with noise-sensitive circuitry system reduced through distance. mobile phones, example, common practice place DC-DC converter corner board, arrange CMOS digital circuitry around (since this also generates noise), then place sensitive preamplifiers stages diagonally opposing corner. Often, sensitive circuitry shielded with metal power post-regulated reduce conducted noise, using low-dropout linear regulators.
Arrange components that switching current loops curl same direction. During first half each cycle, current flows from input filter capacitor, through LM2614 inductor output filter capacitor back through ground, forming current loop. second half each cycle, current pulled from ground, through LM2614 inductor, output filter capacitor then back through ground, forming second current loop. Routing these loops current curls same direction prevents magnetic field reversal between half-cycles reduces radiated noise. Connect ground pins LM2614, filter capacitors together using generous component-side copper fill pseudo-ground plane. Then, connect this ground-plane used) with several vias. This reduces ground-plane noise preventing switching currents from circulating through ground plane. also reduces ground bounce LM2614 giving low-impedance ground connection. wide traces between power components power connections DC-DC converter circuit. This
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LM2614 400mA Sub-Miniature Adjustable DC-DC Converter Optimized Power Amplifiers
Physical Dimensions
inches (millimeters) unless otherwise noted
NOTES: UNLESS OTHERWISE SPECIFIED EPOXY COATING 63Sn/37Pb EUTECTIC BUMP RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. ESTABLISHED LOWER LEFT CORNER WITH RESPECT TEXT ORIENTATION. DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE PACKAGE WIDTH, PACKAGE LENGTH PACKAGE HEIGHT. REFERENCE JEDEC REGISTRATION MO-211. VARIATION
10-Bump micro Package Package Number TLP106WA dimensions given: 2.250 0.030 2.504 0.030 0.600 0.075
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LM2614 400mA Sub-Miniature Adjustable DC-DC Converter Optimized Power

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