LM2608 400mA Sub-miniature, High Efficiency, Programmable DC-DC Conver

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

LM2608 400mA Sub-miniature, High Efficiency, Programmable DC-DC Conver

Datasheet Thumbnail

Top Searches for this datasheet

LM2608 400mA Sub-miniature, High Efficiency, Programmable DC-DC Converter with Linear Mode
LM2608 400mA Sub-miniature, High Efficiency, Programmable DC-DC Converter with Linear Mode
LM2608 step-down DC-DC converter optimized powering ultra-low voltage circuits from single Lithium-Ion cell. provides 400mA over input voltage range 2.8V 5.5V. Operating from 1.35V reference, this device provides pin-selectable output voltages 1.3V/1.5V (300mA) voltage version 1.5V/1.8V (400mA) high voltage version. This allows adjustment voltage options, well dynamic output voltage switching reduced power consumption. Internal synchronous rectification provides high efficiency. LM2608 offers superior features performance mobile phones similar portable applications with complex power management systems. Pin-selectable lownoise linear micropower modes offer improved system control maximizing battery life. During full power operation, fixed-frequency mode reduces interference data acquisition applications minimizing noise harmonics sensitive sampling frequencies. SYNC input allows synchronizing switching frequency range 500kHz 1MHz avoid noise from intermodulation with system frequencies. Linear operation reduces quiescent current 20µA (typ) during system standby extended battery life. provides linear mode. Shutdown reduces battery consumption 0.02µA (typ.). LM2608 available Micro package. This package uses National's wafer level chip-scale Micro technology offers smallest possible size. high switching frequency (600KHz) allows tiny surfacemount components. Only four small external surface-mount components, inductor three ceramic capacitors required. selectable output voltage eliminates need bulky external feedback resistors.
Specifications
Operates from single LiION cell (2.8V 5.5V) selectable output voltage (1.5V/1.8V 1.3V/1.5V versions), without external feedback resistors 400mA maximum load capability mode output voltage precision (Excluding external reference tolerance) mode output voltage ripple quiescent current (Linear Mode) 0.02µA shutdown mode current Internal synchronous rectification high efficiency (91% 2.8VIN, 1.8VOUT) 600kHz mode switching frequency SYNC input mode frequency synchronization from 500kHz 1MHz accuracy FOSC Ilim
Features
Sub-miniature 10-pin thin Micro package Only four tiny surface-mount external components required Uses small ceramic capacitors Internal soft start Current Thermal shutdown protection external compensation required
Applications
Mobile Phones Hand-Held Radios Battery Powered Devices
Typical Application Circuit
20036602
2002 National Semiconductor Corporation
DS200366
www.national.com
LM2608
Connection Diagrams
Micro package
20036604
20036605
VIEW
BOTTOM VIEW
Ordering Information
Order Number 10-Pin Micro LM2608ATL-1.3 LM2608ATL-1.8 LM2608ATLX-1.3 LM2608ATLX-1.8
denotes date code marking digit) production refers run/lot traceability production indication product line designator Note Package Marking change over course production
Package Type
Package Marking XYTT IS43A
Supplied
Units, Tape Reel Units, Tape Reel 3000 Units, Tape Reel 3000 Units, Tape Reel
10-bump Wafer Level Chip Scale (Micro SMD)
XYTT IS44A XYTT IS43A XYTT IS44A
Description
Number Name VSEL Function Feedback Analog Input. Connect output output filter capacitor (Figure Output Voltage Selection Input. this digital input 1.8V output voltage (1.5V LM2608ATL-1.3) SGND 1.5V output voltage (1.3V LM2608ATL-1.3) External Reference Input. Drive this analog input with 1.35V reference output voltage. LM2608 uses internal reference while mode. (see Note Electrical Characteristics table further information.) Synchronization Input. this digital input frequency synchronization mode control. Set: SYNC/MODE high low-noise 600kHz mode SYNC/MODE low-current mode SYNC/MODE 500kHz 1MHz external clock synchronization external clock mode. Synchronization Operating Modes Device Information section. Enable Input. this Schmitt trigger digital input high normal operation. Power Ground Switching Node connection internal PFET switch NFET synchronous rectifier. Connect inductor with saturation current rating that exceeds max. Switch Peak Current Limit specification LM2608 (Figure Power Supply Input internal PFET switch. Connect input filter capacitor (Figure Analog Supply Input. board layout optimum, optional 0.1µF ceramic capacitor suggested (Figure Analog Control Ground
VREF
SYNC/MODE
PGND
www.national.com
PVIN SGND
LM2608
Description
(Continued)
Note that numbering scheme Micro package revised April,2002 conform JEDEC standard. Only numbers were revised. changes physical location inputs/outputs were made. reference purpose, obsolete numbering VSEL VREF SYNC PGND PVIN SGND
www.national.com
LM2608
Absolute Maximum Ratings
(Note
Military/Aerospace specified devices required, please contact National Semiconductor Sales Office/ Distributors availability specifications. PVIN, VDD, SGND PGND SGND SYNC/MODE, VSEL SGND Storage Temperature Range -0.2V -0.2V +0.2V -0.2V (GND -0.2V) (VDD +0.2V) -45°C +150°C
Lead temperature (Soldering, sec.) Junction Temperature (Note Minimum Rating Human body model, 100pF, Thermal Resistance (JA) LM2608ATL(Note
260°C -25°C 125°C
2.0kV
140°C/W
Electrical Characteristics
Specifications with standard typeface 25°C, those bold face type apply over full Operating Temperature Range -25°C +85°C). Unless otherwise specified, PVIN SYNC 3.6V, VSEL VREF 1.35V. Symbol Parameter Input Voltage Range (Note Feedback Voltage Mode SYNC/MODE VIN(Note Feedback Voltage Mode (SYNC/MODE =0V) VIN= 3.6V IOUT 100µA Line Regulation Load Regulation VHYST Comparator Hysteresis Voltage (Note Shutdown Supply Current Bias Current into (PWM Mode) Bias Current into (LDO Mode) Pin-Pin Resistance Pin-Pin Resistance Resistance Temperature Coefficient Short Circuit (LDO) Switch Peak Current Limit (Note Positive Going Threshold Voltage (Note Negative Going Threshold Voltage (Note VOUT SYNC/MODE LM2608ATL-1.3 LM2608ATL-1.8 Conditions PVIN VDD, VSEL LM2608ATL-1.3, VSEL LM2608ATL-1.3, VSEL LM2608ATL-1.8, VSEL LM2608ATL-1.8, VSEL LM2608ATL-1.3, VSEL LM2608ATL-1.3, VSEL LM2608ATL-1.8, VSEL LM2608ATL-1.8, VSEL IOUT 100µA VIN= 3.6V, IOUT 10µA 1.5mA Mode SYNC/MODE =VIN SYNC/MODE IOUT 0.02 0.80 1.287 1.485 1.485 1.782 1.261 1.455 1.455 1.746 1.30 1.50 1.50 1.80 1.30 1.50 1.50 1.80 1.313 1.515 1.515 1.818 1.339 1.545 1.545 1.854 %/mA Units
VFB,
VOUT_LDO
ISHDN RDSON RDSON RDSON ISC, Ilim VEN_H
VEN_L
0.75
www.national.com
LM2608
Electrical Characteristics
(Continued) Specifications with standard typeface 25°C, those bold face type apply over full Operating Temperature Range -25°C +85°C). Unless otherwise specified, PVIN SYNC 3.6V, VSEL VREF 1.35V. Symbol Parameter SYNC/MODE Positive Going Threshold Voltage SYNC/MODE Negative Going Threshold Voltage VSEL Positive Going Threshold Voltage VSEL Negative Going Threshold Voltage VSEL Pull Down Current Input current into VREF SYNC/MODE Clock Frequency Range (Note Internal Oscillator Frequency Minimum ON-Time Switch Mode LM2608ATL-1.3/1.8, Mode VSEL 1.2V Conditions 0.85 0.80 0.80 0.75 0.70 1000 Units
VSYNC_H VSYNC_L VSEL_H VSEL_L ISEL IREF fsync
FOSC Tmin
Note Absolute Maximum Ratings indicate limits beyond which damage device occur. Operating Ratings conditions which device intended functional, parameter specifications guaranteed. guaranteed specifications associated test conditions, limits Conditions Electrical Characteristics table. Electrical Characteristics table limits guaranteed production testing, design correlation using standard Statistical Quality Control methods. Typical (Typ) specifications mean average values from characterization 25°C guaranteed. Note Thermal shutdown will occur junction temperature exceeds 150°C maximum junction temperature device. Note Thermal resistance specified with layer PCB(0.5/0.5 cu). Note LM2608 designed cell phone applications where turn-on after system power-up controlled system processor internal UVLO (Under Voltage LockOut) circuitry unnecessary. LM2608 UVLO circuitry should kept shutdown holding until input voltage exceeds 2.8V. Although LM2608 exhibits safe behavior while enabled input voltages, this guaranteed. Note LM2608 mode output voltage precision when operating from external 1.35V reference voltage. Note hysteresis voltage minimum voltage swing that causes internal feedback control circuitry turn internal PFET switch then off, during test mode. Note Current limit built-in, fixed, adjustable. current limit reached while output pulled below about 0.7V, internal PFET switch turns allow inductor current diminish. Note Schmitt trigger digital input with logic thresholds that independent supply voltage pin. Note SYNC driven with external clock switching between GND. When external clock present SYNC, forced into mode external clock frequency. LM2608 synchronizes rising edge external clock.
www.national.com
LM2608
Typical Operating Characteristics
unless otherwise noted. Quiescent Supply Current Supply Voltage (PWM MODE)
LM2608ATL, Circuit Figure 3.6V, 25°C, Quiescent Supply Current Supply Voltage (LDO MODE)
20036644 20036606
Output Voltage Supply Voltage (PWM MODE)
Output Voltage Supply Voltage (PWM MODE)
20036645
20036646
Shutdown Quiescent Current Temperature
Output Voltage Output Current
20036607
20036652
www.national.com
LM2608
Typical Operating Characteristics LM2608ATL, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Output Voltage Output Current Output Voltage Output Current
20036614
20036613
Output Voltage Supply Voltage (VOUT 1.5V)
Output Voltage Supply Voltage (VOUT 1.8V)
20036611
20036612
Output Voltage Output Current
Output Voltage Output Current
20036616
20036615
www.national.com
LM2608
Typical Operating Characteristics LM2608ATL, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Output Voltage Output Current Short Circuit Output Current
20036617
20036618
Maximum Output Current
Maximum Output Current
20036619
20036620
Switching Frequency Temperature (PWM Mode)
Efficiency Output Current withDiode
20036621
20036650
www.national.com
LM2608
Typical Operating Characteristics LM2608ATL, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Efficiency Output Current without Diode Efficiency Output Current without Diode
20036622 20036651
Efficiency Output Current with Diode
Efficiency Output Current Without Diode
20036642
20036623
Efficiency Output Current with Diode
Load Transient Response
20036643 20036648
www.national.com
LM2608
Typical Operating Characteristics LM2608ATL, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Load Transient Response Load Transient Response
20036636
20036637
Load Transient Response
Load Transient Response
20036632
20036633
Line Transient Response
Line Transient Response
20036639
20036638
www.national.com
LM2608
Typical Operating Characteristics LM2608ATL, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Line Transient Response Start-up Response
20036640
20036649
Mode Change
20036641
www.national.com
LM2608
Device Information
LM2608 easy use, step-down DC-DC converter optimized powering low-voltage CPUs DSPs cell phones other miniature battery powered devices. provides pin-selectable output voltages 1.3V, 1.5V 1.8V from single 2.8V 5.5V LiION battery cell. designed maximum load capability 400mA. uses synchronous rectification mode high efficiency, typically 100mA load with 1.8V output, 2.8V input. device three pin-selectable operating modes required cell phones other complex portable devices. Such applications typically spend small portion their time operating full power. During full power operation, synchronized fixed-frequency mode offers full output current capability while minimizing interference sensitive data acquisition circuits. These applications spend remainder their time low-current standby operation shutdown conserve battery power. During
standby operation, mode reduces quiescent current 20µA (typ.) maximize battery life. Shutdown mode reduces battery consumption 0.02µA (typ.). LM2608 offers good performance full features. based current-mode buck architecture with cycle-by-cycle current limiting. mode output voltage precision SYNC/MODE input accepts external clock between 500kHz 1MHz. output voltage selection eliminates external feedback resistors. Additional features include soft-start, current overload protection, output over-voltage protection thermal shutdown protection. LM2608 constructed using chip-scale 10-pin Micro package. Micro package offers smallest possible size space critical applications, such cell phones. Required external components only small 10µH inductor, tiny 10µF, 22µF 0.1µF ceramic capacitors reduced board area.
20036603
FIGURE Typical Operating Circuit
Circuit Operation
Referring Figure Figure Figure LM2608 operates follows: During first part each switching cycle, control block LM2608 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 on-time control average current sent load. effect identical sending duty-cycle modulated rectangular wave formed switch synchronous rectifier low-pass filter created inductor output filter capacitor. output voltage equal average voltage pin.
www.national.com
LM2608
Circuit Operation
(Continued)
20036601
FIGURE Simplified Functional Diagram
Operation
LM2608 current-mode operation connecting SYNC/MODE VDD. 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 controlling PFET switch using flip-flop driven oscillator comparator that compares ramp from current-sense amplifier with error signal from voltage-feedback error amplifier. beginning each cycle, oscillator sets flip-flop turns PFET switch, causing inductor current ramp When current sense signal ramps past error amplifier signal,
comparator resets flip-flop turns PFET switch, ending first part cycle. NFET synchronous rectifier turns until next clock pulse inductor current ramps zero. increase load pulls output voltage down, error amplifier output increases, which allows inductor current ramp higher before comparator turns PFET switch. This increases average current sent output adjusts increase load. Before going comparator, current sense 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.
www.national.com
LM2608
Operation
(Continued)
Mode Switching Waveform
20036624
FIGURE
Operation
Connecting SYNC/MODE SGND sets LM2608 Linear mode operation. While (Low Dropout regulator) mode, output voltage regulated internal supply 3mA. This done using internal pass transistor error amplifier sense output voltage maintain desired output voltage. During mode, PFET NFET network switch reduce quiescent current.
Operating Mode Selection (SYNC/MODE Pin)
SYNC/MODE digital input used select between operating modes. SYNC/MODE high (above 1.3V) 600kHz operation. SYNC/MODE (below 0.4V) select mode reduced current consumption when system standby. LM2608 over-voltage protection feature that activate device left mode under low-load conditions prevent output voltage from rising high. Overvoltage Protection, more information. Select modes with SYNC/MODE using signal with slew rate faster than 5V/100µs. comparator Schmitt trigger logic gate drive SYNC/MODE pin. leave floating allow linger between logic levels. These measures will prevent output voltage errors that could otherwise occur response indeterminate logic state.
following waveform duty-cycle guidelines when applying external clock SYNC/MODE pin. duty cycle between 70%. 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
LM2608 over-voltage comparator that prevents output voltage from rising high when device left mode under low-load conditions. Otherwise, output voltage could rise regulation from minimum energy transferred cycle 200nS minimum on-time PFET switch while mode. When output voltage rises 45mV over regulation threshold, comparator inhibits operation skip pulses until output voltage returns regulation threshold. over voltage protection, output voltage ripple increase slightly.
Shutdown Mode
Setting input low, SGND, places LM2608 0.02µA (typ) shutdown mode. During shutdown, PFET switch, NFET synchronous rectifier, reference, control bias LM2608 turned off. Setting high enables normal operation. While turning soft start activated. Schmitt trigger digital input with thresholds that independent input voltage VDD. must turn LM2608 during undervoltage conditions when supply less than 2.8V minimum operating voltage. LM2608 designed mobile phones similar applications where power sequencing determined system controller internal UVLO (Under Voltage LockOut) circuitry unnecessary. LM2608
Frequency Synchronization (SYNC/MODE Pin)
SYNC/MODE input also used frequency synchronization. synchronize LM2608 external clock, supply digital signal SYNC/MODE with voltage swing exceeding 0.4V 1.3V. During synchronization, LM2608 initiates cycles rising edge clock. When synchronized external clock, operates mode. device synchronize external clock over frequencies from 500kHz 1MHz.
www.national.com
LM2608
Shutdown Mode
(Continued)
Setting Output Voltage Application Information section further details.
UVLO circuitry. Although LM2608 exhibits good behavior while enabled input voltages, this guaranteed.
Soft-Start
LM2608 designed started mode. Under these conditions, output voltage will increase rate determined current limit output capacitor load. This ramp time typically range. LM2608 started mode well. Under these conditions, reference voltage error ramped about 100µs output voltage will follow. this way, input inrush current output voltage overshoot minimized.
Internal Synchronous Rectification
LM2608 uses internal NFET synchronous rectifier improve efficiency reducing rectifier forward voltage drop associated power loss. general, synchronous rectification provides significant improvement efficiency whenever output voltage relatively compared voltage drop across ordinary rectifier diode. Under moderate heavy loads, internal NFET synchronous rectifier turned during inductor current down-slope second part each cycle. synchronous rectifier turned prior next cycle, when inductor current ramps near zero light loads. NFET designed conduct through intrinsic body diode during transient intervals before turns eliminating need external diode.
Thermal Shutdown Protection
LM2608 thermal shutdown protection mode protect from short-term misuse overload conditions. When junction temperature exceeds 150°C, device shuts down re-starts soft start after temperature drops below 130°C. Prolonged operation thermal overload conditions damage device considered practice.
Current Limiting
current limit feature allows LM2608 protect itself external components during overload conditions. Current limiting implemented using independent internal comparator. mode, cycle-by-cycle current limiting normally used. excessive load pulls output voltage 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 prevents loss current control seen some products when output voltage pulled serious overload conditions.
Application Information
SETTING OUTPUT VOLTAGE LM2608 features pin-selectable output voltage eliminate need external feedback resistors. Select output voltage 1.3V, 1.5V 1.8V configuring VSEL pin, directed Table TABLE VSEL Output Voltage Selection Settings Output Voltage Options LM2608 (300mA) LM2608 (400mA) VOUT 1.3V 1.5V 1.5V 1.8V VSEL
Current Limiting Mode Transient Response Considerations
LM2608 designed fast response moderate load steps. Harsh transient conditions during loads above 300mA cause inductor current swing maximum current limit, resulting mode jitter instability from activation current limit comparator. avoid this jitter instability, power-up start LM2608 into full load (loads near above 400mA). change operating modes output voltages when operating full load. Avoid extremely sharp wide-ranging load steps full load, such from 30mA 350mA.
VSEL high connecting connecting SGND. Optionally, VSEL driven digital gates that provide over 1.2V high state less than 0.4V state ensure valid logic levels. VSEL input internal (typ) pull-down that pulls input low, when left unconnected. Leaving this open acceptable, setting high recommended. INDUCTOR SELECTION 10µH inductor with saturation current rating over current limit ILIM) LM2608 recommended most applications. inductor's resistance should less than good efficiency. Table lists suggested inductors suppliers.
Selectable Output Voltage
LM2608 features pin-selectable output voltage eliminate need external feedback resistors. output 1.3V, 1.5V 1.8V configuring VSEL pin.
TABLE Suggested Inductors Their Suppliers Model DO1608C-103 DO1606T-103 UP1B-100 UP0.4CB-100 Vendor Coilcraft Coilcraft Coiltronics Coiltronics
www.national.com
Phone 847-639-6400 561-241-7876
847-639-1469 561-241-9339
LM2608
Application Information
Model ELL6GM100M ELL6PM100M P1174.103T P0770.103T CDRH5D18-100 CDRH4D28-100 CDC5D23-100 NP05D B100M NP04S B100N SLF6025T-100M1R0 SLF6020T-100MR90 A918CY-100M A915AY-100M
(Continued)
TABLE Suggested Inductors Their Suppliers (Continued) Vendor Panasonic Panasonic Pulse Engineering Pulse Engineering Sumida Sumida Sumida Taiyo Yuden Taiyo Yuden Toko Toko inductor loses ability limit current through PFET switch ramp allows switch current increase rapidly. This cause poor efficiency, regulation errors stress DC-DC converters like LM2608. Saturation occurs when magnetic flux density from current through windings inductor exceeds what inductor's core material support with energy storage corresponding magnetic field. 847-297-0070 847-699-7864 847-803-6100 847-803-6296 847-925-0888 847-925-0899 858-674-8100 858-674-8100 847-956-0666 858-674-8262 858-674-8262 847-956-0702 Phone 714-373-7366 714-373-7323
low-cost applications, unshielded bobbin inductor suggested. noise critical applications, toroidal shielded-bobbin inductor should used. good practice board with overlapping footprints both types design flexibility. This allows substitution low-noise toroidal inductor, event that noise from low-cost bobbin models unacceptable. saturation current rating current level beyond which inductor loses inductance. Beyond this rating,
TABLE Suggested Capacitors Their Suppliers Model C3225X5RIA226M JMK325BJ226MM ECJ4YB0J226M GRM42-2X5R226K6.3 C2012X5R0J106M JMK212BJ106MG ECJ3YB0J106K GRM40X5R106K6.3 Size 1210 1210 1210 1210 0805 0805 1206 0805 Vendor Taiyo-Yuden Panasonic muRata Taiyo Yuden Panasonic muRata Phone 847-803-6100 847-925-0888 714-373-7366 404-436-1300 847-803-6100 847-925-0888 714-373-7366 404-436-1400 847-803-6296 847-925-0899 714-373-7323 404-436-3030 847-803-6296 847-925-0899 714-373-7323 404-436-3030
22µF, Ceramic Capacitor (Output Filter Capacitor)
10µF, 6.3V, Ceramic Capacitor (Input Filter Capacitor)
CAPACITOR SELECTION 10µF, 6.3V, ceramic input filter capacitor 22µF, ceramic output filter capacitor. These provide optimal balance between small size, cost, reliability performance. ceramic capacitors. Table lists suggested capacitors suppliers. 10µF ceramic capacitor used output filter capacitor smaller size applications where worstcase transient load step less than 200mA. 10µF output capacitor trades smaller size increase output voltage ripple, undershoot during line load transient response.
input filter capacitor supplies current PFET switch LM2608 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. ESR, equivalent series resistance, filter capacitors major factor voltage ripple.
www.national.com
LM2608
Application Information
(Continued)
MICRO PACKAGE ASSEMBLY Micro package requires specialized board layout, precision mounting careful reflow techniques, detailed National Semiconductor Application Note AN1112. Refer section Surface Mount Technology (SMT) Assembly Considerations. best results assembly, alignment ordinals board should used facilitate placement device. Since Micro packaging technology, layouts assembly means must thoroughly tested prior production. particular, proper placement, solder reflow resistance thermal cycling must verified. 10-Bump package used LM2608 300micron solder balls requires 10.82mil (0.275mm) pads mounting circuit board. trace each should enter with entry angle prevent debris from being caught deep corners. Initially, trace each should wide, section long longer, thermal relief. Then each trace should neck optimal width over span mils more, that taper extends beyond edge package. important criterion symmetry. This ensures solder bumps LM2608 re-flow evenly that device solders level board. particular, special attention must paid pads bumps Because PVIN PGND typically connected large copper planes, inadequate thermal reliefs result late inadequate reflow these bumps. style used with Micro package must NSMD (non-solder mask defined) type. This means that solder-mask opening larger than size 14.7mils LM2608. This prevents that otherwise forms solder-mask overlap. This hold device surface board interfere with mounting. Applications Note AN-1112 specific instructions. 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 LM2608 implemented following simple design rules: Place LM2608 10.82mil pads Micro package. thermal relief, connect each with 6mil wide trace (Micro SMD), 6mils long longer, then incrementally increase each trace optimal width
over span that taper extends beyond edge package. important criterion symmetry ensure re-flow occurs evenly (see Micro Package Assembly Use). Place LM2608, 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 0.2in (5mm) LM2608. Arrange components that switching current loops curl same direction. During first part each cycle, current flows from input filter capacitor, through LM2608 inductor output filter capacitor back through ground, forming current loop. second part each cycle, current pulled from ground, through LM2608 inductor, output filter capacitor then back through ground, forming second current loop. Routing these loops current curls same direction prevents magnetic field reversal between part-cycles reduces radiated noise.
Connect ground pins LM2608 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 LM2608 giving low-impedance ground connection. wide traces between power components power connections DC-DC converter circuit. This 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 LM2608 circuit should routed away from noisy 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 noisesensitive 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 lowdropout linear regulators, such LP2966.
www.national.com
LM2608 400mA Sub-miniature, High Efficiency, Programmable DC-DC Converter with Linear Mode
Physical Dimensions
unless otherwise noted
inches (millimeters)
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 0.030mm 2.504 0.030mm 0.600+/- 0.075mm
LIFE SUPPORT POLICY NATIONAL'S PRODUCTS AUTHORIZED CRITICAL COMPONENTS LIFE SUPPORT DEVICES SYSTEMS WITHOUT EXPRESS WRITTEN APPROVAL PRESIDENT GENERAL COUNSEL NATIONAL SEMICONDUCTOR CORPORATION. used herein: Life support devices systems devices systems which, intended surgical implant into body, support sustain life, whose failure perform when properly used accordance with instructions provided labeling, reasonably expected result significant injury user.
National Semiconductor Corporation Americas Email: support@nsc.com National Semiconductor Europe Fax: 180-530 Email: europe.support@nsc.com Deutsch Tel: 9508 6208 English Tel: 2171 Tel: 8790
critical component component life support device system whose failure perform reasonably expected cause failure life support device system, affect safety effectiveness.
National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: ap.support@nsc.com
National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507
www.national.com
National does assume responsibility circuitry described, circuit patent licenses implied National reserves right time without notice change said circuitry specifications.

LM2608 400mA Sub-miniature, High Efficiency, Programmable DC-DC Conver

Top Searches for this datasheet

Other recent searches