LM2619MTC LM2619MTC 500mA Step-Down DC-DC Converter General

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

LM2619MTC LM2619MTC 500mA Step-Down DC-DC Converter General

Datasheet Thumbnail

Top Searches for this datasheet

LM2619MTC 500mA Step-Down DC-DC Converter
LM2619MTC
LM2619MTC 500mA Step-Down DC-DC Converter
General Description
LM2619MTC step down DC-DC converter optimized powering circuits from single Lithium-Ion cell. steps down input voltage 2.8V 5.5V output 1.5V 3.6V 500mA. Output voltage using resistor feedback dividers. device offers three modes mobile phones similar portable 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. LM2619MTC available TSSOP package. high switching frequency (600kHz) allows tiny surface-mount components. device features external compensation tailor response wide range operating conditions.
Specifications
Operates from single LiION cell (2.8V 5.5V) Output voltage range 1.5V 3.6V feedback voltage precision 500mA maximum load capability 600µA mode quiescent current 0.02µA shutdown current 600kHz switching frequency SYNC input mode frequency synchronization from 500kHz 1MHz High efficiency 95%) mode from internal synchronous rectification 100% Maximum Duty Cycle Lowest Dropout
Features
14-pin TSSOP 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 Wireless Cards
Typical Application Circuits
20065101
FIGURE Typical Circuit 1.8V Output Voltage
2003 National Semiconductor Corporation
DS200651
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:04 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=1
LM2619MTC
Typical Application Circuits
(Continued)
20065102
FIGURE Typical Circuit 2.5V Output Voltage
20065103
FIGURE Typical Circuit 1.5V Output Voltage
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:04 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=2
LM2619MTC
Connection Diagrams
14-Pin TSSOP
20065104
View
Ordering Information
Order Number LM2619MTC LM2619MTCX Package Type TSSOP Package Drawing MTC14 MTC14 Rail 2500 Tape Reel Supplied
Description
Number Name Function 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.) 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.) Output error amplifier. Inverting Input Error Amplifier. Feedback Analog Input. Analog Control Ground. Analog Supply Input. board layout optimum, optional 0.1µF ceramic capacitor suggested from this SGND. Power Supply Voltage Input internal PFET switch. Connect input filter capacitor. Switching Node connection internal PFET switch NFET synchronous rectifier. Connect inductor with saturation current rating that exceeds Switch Peak Current Limit LM2619MTC. Power Ground.
SYNC/MODE
9,10 11,12
EAOUT EANEG SGND PVIN
13,14
PGND
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:04 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=3
LM2619MTC
Absolute Maximum Ratings
(Note
Storage Temperature Range Lead Temperature (Soldering, sec.) Junction Temperature (Note Ambient Temperature Range Minimum Rating
-45°C +150°C 300°C +125°C -25°C 85°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)
110°C/W
(Human Body Model, Thermal Resistance (JA) (Note
Electrical Characteristics
Specifications with standard typeface 25°C, those boldface type apply over full Operating Junction Temperature Range -25°C +125°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 Mode 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 (Note (Note Conditions PVIN (Note 1.470 1.50 0.02 0.95 0.80 1000 1100 1.530 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 JEDEC layer Cu.) board. Note LM2619MTC 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 RDSON specified having PVIN pins connected together,two PGND pins connected together pins connected together. 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. LM2619MTC synchronizes rising edge external clock.
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=4
LM2619MTC
Typical Performance Characteristics
less otherwise noted. Quiescent Supply Current Supply Voltage
LM2619MTC, Circuit Figure 3.6V, 25°C, unShutdown Quiescent Current Temperature (Circuit Figure
20065108 20065122
Output Voltage Supply Voltage (VOUT 1.5V, MODE)
Output Voltage Supply Voltage (VOUT 1.5V, MODE)
20065109 20065110
Output Voltage Output Current (VOUT 1.5V, MODE)
Output Voltage Output Current (VOUT 1.5V, MODE)
20065111 20065113
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=5
LM2619MTC
Typical Performance Characteristics LM2619MTC, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Output Voltage Output Current (VOUT 3.6V, MODE) (Circuit Figure Dropout Voltage Output Current (VOUT 3.6V, MODE) (Circuit Figure
20065132 20065112
Switching Frequency Temperature (Circuit Figure MODE)
Feedback Bias Current Temperature (Circuit Figure
20065123
20065131
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=6
LM2619MTC
Typical Performance Characteristics LM2619MTC, 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)
20065115
20065116
Efficiency Output Current (VOUT 1.8V, MODE) (Circuit Figure
Efficiency Output Current (VOUT 1.8V, MODE, with Diode) (Circuit Figure
20065129
20065130
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=7
LM2619MTC
Typical Performance Characteristics LM2619MTC, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Efficiency Output Current (VOUT 2.5V, MODE) (Circuit Figure Efficiency Output Current (VOUT 3.6V, MODE) (Circuit Figure
20065117
20065118
Efficiency Output Current (VOUT 1.5V, MODE)
Efficiency Output Current (VOUT 1.5V, MODE, with Diode)
20065133
20065134
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=8
LM2619MTC
Typical Performance Characteristics LM2619MTC, Circuit Figure 3.6V, 25°C,
unless otherwise noted. (Continued) Efficiency Output Current (VOUT 1.8V, MODE) (Circuit Figure Efficiency Output Current (VOUT 1.8V, MODE, with Diode) (Circuit Figure
20065135
20065136
Device Information
LM2619MTC simple, step-down DC-DC converter optimized powering circuits mobile phones, portable communicators, similar battery powered devices. based current-mode buck architecture, with synchronous rectification mode high efficiency. designed maximum load capability 500mA mode. Maximum load range vary from this depending input voltage, output voltage inductor chosen. device three pin-selectable operating modes required powering circuits 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
duces 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, 4.2V input. efficiency increased lower output voltages like 1.5V,1.8V using schottky diode like MBRM120L shown Figure mode quiescent current 600µA typ. output voltage from 1.5V 3.6V using external feedback resistors. Additional features include soft-start, current overload protection, over voltage protection thermal shutdown protection. LM2619MTC constructed using 14-pin TSSOP package. high switching frequency (600kHz) reduces size external components.
20065106
FIGURE Typical Operating Circuit 3.6V Output Voltage CIRCUIT OPERATION Referring Figure Figure Figure Figure LM2619MTC operates follows. During first part each switching cycle, control block LM2619MTC turns internal PFET switch. This allows current flow from input through inductor output filter capaci9 www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=9
LM2619MTC
Device Information
(Continued)
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.
20065107
FIGURE Simplified Functional Diagram OPERATION 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 currentsense 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
www.national.com
synchronous rectifier inductor current ramps zero. minimum time PFET mode about 200ns.
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=10
LM2619MTC
Device Information
(Continued)
Mode Switching Waveform
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 LM2619MTC 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 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. LM2619MTC 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. LM2619MTC 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, LM2619MTC 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
20065125
Inductor Current, 500mA/div Pin, 2V/div VOUT, 10mV/div, Coupled
FIGURE
Mode Switching Waveform
20065126
Inductor Current, 500mA/div Pin, 2V/div VOUT, 50mV/div, Coupled
FIGURE OPERATION Connecting SYNC/MODE SGND sets LM2619MTC 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 errorcomparator. 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
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=11
LM2619MTC
Device Information
(Continued)
from pulse function generator develop under/ overshoot high improperly terminated cable. OVERVOLTAGE PROTECTION LM2619MTC 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 LM2619MTC 0.02µA (typ) shutdown mode. During shutdown, PFET switch, NFET synchronous rectifier, reference, control bias circuitry LM2619MTC turned off. Setting high enables normal operation. While turning soft start activated. should turn LM2619MTC during system power-up undervoltage conditions when supply less than 2.8V minimum operating voltage. LM2619MTC designed compact portable applications, such mobile phones. such applications, system controller determines power supply sequencing. Although LM2619MTC typically well behaved input voltages, this guaranteed. INTERNAL SYNCHRONOUS RECTIFICATION While mode, LM2619MTC 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 LM2619MTC 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.
DROPOUT CONSIDERATIONS LM2619MTC used provide fixed output voltages using external feedback resistors. output voltage from 1.5V 3.6V. internal reference voltage error amplifier 1.5V. cases where output voltage 2.5V higher, part will into dropout 100% duty cycle when input voltage gets close output voltage. Near dropout time P-FET exceed clock cycle cause higher ripple output load currents greater than 300mA. This increased ripple will exist narrow range input voltages close 100% duty cycle once input voltage goes down further P-FET will fully Setting Output Voltage Application Information section further details. dropout conditions output voltage IOUT (Rdc RDSON (P)) where series resistance inductor RDSON resistance PFET. Load Transient Response (Circuit Figure
20065127
FIGURE
Line Transient Response (Circuit Figure
20065128
FIGURE
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:05 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=12
LM2619MTC
Device Information
(Continued)
SOFT-START LM2619MTC soft start reduce current inrush during power-up startup. This reduces stress LM2619MTC external components. also reduces startup transients power source. Soft start implemented ramping reference input error amplifier LM2619MTC gradually increase output voltage. THERMAL SHUTDOWN PROTECTION LM2619MTC 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.
Application Information
SETTING OUTPUT VOLTAGE LM2619MTC used with external feedback resistors output voltage. Select value allow atleast times feedback bias current flow through VOUT= (1+R1/R2) EXTERNAL COMPENSATION LM2619MTC 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, under conditions. Typical values 10pF 220pF 100K 20000 Open loop gain error amplifier Transresistance output stage 362000 Corrective ramp slope VOUT/VIN duty cycle (VIN VOUT)/L1 slope current through inductor during PFET time effective resistance inverting input error (Mc/M1)+ where effective small signal output resistance power stage 1/(2 frequency pole (Rload pole Rload,Ro high frequency pole from current mode control 1/(2 high frequency pole 1/(2 zero R2/(R1+ Rload)/Rf)/(2 where gives approximate crossover frequency.This equation crossover frequency assumes that fZ1. 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.
TABLE Suggested Inductors Their Suppliers Part Number DO1608C-103 ELL6SH100M ELL6RH100M CDRH5D18-100 P0770.103T Vendor Coilcraft Panasonic Panasonic Sumida Pulse Phone 847-639-6400 714-373-7366 714-373-7366 847-956-0666 858-674-8100 847-639-1469 714-373-7323 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 manufactur13
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 LM2619MTC. Beyond this rating, inductor loses ability limit current through switch ramp. This cause poor efficiency, regulation errors stress DC-DC converters like
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:06 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=13
LM2619MTC
Application Information
(Continued)
LM2619MTC. Saturation occurs when magnetic flux density from current through windings inductor exceeds what inductor's core material support with corresponding magnetic field. CAPACITOR SELECTION 10µF ceramic input capacitor. types, Y5V. tantalum capacitors recommended. Ceramic capacitors provide optimal balance between small size, cost, reliability performance cell phones similar applications. 22µF ceramic output capacitor recomended applications that require increased tolerance heavy load transients. 10µF ceramic output
pacitor used applications where worst case load transient step less than 200mA. 10µF output capacitor trades smaller size increase output voltage ripple, undershoot during load transients. Table lists suggested capacitors suppliers. input filter capacitor supplies current PFET switch LM2619MTC 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.
TABLE Suggested Capacitors Their Suppliers Model C2012X5ROJ106M JMK212BJ106MG ECJ3YB0J106K JMK325BJ226MM C3225X5RIA226M Type Ceramic Ceramic Ceramic Ceramic Ceramic Vendor Taiyo-Yuden Panasonic Taiyo-Yuden Phone 847-803-6100 847-925-0888 714-373-7366 847-925-0888 847-803-6100 847-803-6296 847-925-0899 714-373-7323 847-925-0899 847-803-6296
(Input Output Filter Capacitor)
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 TSSOP package board pads. Poor solder joints result erratic degraded performance. Good layout LM2619MTC implemented following simple design rules. Follow land pattern recomendation datasheet. Place LM2619MTC, 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 LM2619MTC. Arrange components that switching current loops curl same direction. During first half each cycle, current flows from input filter capacitor, through LM2619MTC inductor output filter capacitor back through ground, forming current loop. second half each cycle, current pulled from ground, through LM2619MTC 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 LM2619MTC, 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 LM2619MTC 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. Connect dual pins device together high efficiency. Route noise sensitive traces, such voltage feedback path, away from noisy traces between power components. voltage feedback trace must remain close LM2619MTC 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 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.
Book Extract
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:06 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=14
LM2619MTC
Physical Dimensions
inches (millimeters) unless otherwise noted
NOTES: UNLESS OTHERWISE SPECIFIED REFERENCE JEDEC REGISTRATION MO-153. VARIATION NOTE DATED 7/93
14-pin TSSOP Package Number MTC14
www.national.com
PrintDate=2003/08/20 PrintTime=18:54:06 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=15
LM2619MTC 500mA Step-Down DC-DC Converter
Notes
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 Americas Customer Support Center Email: new.feedback@nsc.com Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center 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 Support Center Email: ap.support@nsc.com
National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: jpn.feedback@nsc.com Tel: 81-3-5639-7560
National does assume responsibility circuitry described, circuit patent licenses implied National reserves right time without notice change said circuitry specifications.
PrintDate=2003/08/20 PrintTime=18:54:06 801627bc ds200651_p Rev. 1.25
cmserv
Proof
Seq=16

LM2619MTC LM2619MTC 500mA Step-Down DC-DC Converter General

Top Searches for this datasheet

Other recent searches