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LME49830TB Ultra-High Fidelity High Power Amplifier Reference Design
LME49830TB Ultra-High Fidelity High Power Amplifier Reference Design
LME49830 EF125WT1 amplifier module showcases National Semiconductor's ultra-high fidelity power amplifier input stage (drivers). LME49830 fully complementary bipolar 200V input stage with 56mA (typical) output current that been optimized audio applications. With 56mA current drive, drive numerous power transistors achieve high levels output power. LME49830's ultra-low distortion low-noise, combined with user adjustable compensation scheme results tightly controlled, highly dynamic listening experience. User adjustable compensation provides high-frequency distortion minimization slew rate power bandwidth optimization. IC's high performance level, features user customization make driver highly reliable, unique input stage solution high power amplifiers. While amplifier module provides convenient performance measurement verification, also used
National Semiconductor Application Note 1850 Troy Huebner John DeCelles December 2008
validate solution's sonic performance desired test environment. solution presented undergone listening evaluations dedicated sound room verification sonic performance.
Overview
LME49830 combination with properly designed high-current output stage, with adequate thermal management, provide output power levels excess 1kW. Figure represents simple schematic typical power amplifier utilizing LME49830. LME49830 simplifies power amplifier design providing highly reliable, consistent performing distortion input stage. With addition output stage simple biasing circuit, result very high fidelity power amplifier. LME49830 designed output stages using MOSFET devices used with other output device types well. LME49830 used with just about MOSFET desired result bias range output stage.
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FIGURE Simple Power Amplifier Schematic
2008 National Semiconductor Corporation
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With 200V operating voltage range, amplifier solution using LME49830 mainly limited number output power stage transistors conjunction with adequate thermal management keep power transistors operating within their safe operating area (SOA).
LME49830 configured with number different output stage topologies, providing end-product differentiation customization. Shown Figure common source-follower output stage with three transistors paralleled side.
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FIGURE Source-Follower Output Stage
Operational Details
complete amplifier schematic EF125WT1 shown Figure Important aspects explanation various sections circuit will covered below. amplifier module device side MOSFET output stage driven directly from LME49830. With only devices side output stage there need additional current gain stage higher output stage drive current. LME49830's drive current 56mA (typical) provides plenty drive current high slew rate excellent
THD. higher device count output stages, LME49830's drive current sufficient meet design target specifications. LME49830 amplifier module when running ±60V power supplies capable providing output power levels shown below with 1kHz signal. Load 0.1% THD+N 335W 175W THD+N 350W 185W THD+N 430W 230W
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FIGURE LME49830 EF125WT1 Amplifier Schematic
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important note that LME49830 EF125WT1 amplifier module contains output stage protection mechanisms. proper current limit evaluation power supply minimum precaution safety. power supply voltage limitation EF125WT1 module based Toshiba 2SK1530/2SJ201 MOSFET devices, which have VDSS 200V well LME49830 which absolute maximum supply voltage rating ±100V (200V). Based this, recommended that maximum power supply voltage applied amplifier module less than ±80V. allow additional safety margin recommended that maximum power supply voltage ±75V. While power supply voltages ±75V applied amplifier module, recommended that caution applied when driving load with impedance less than with continuous sinusoidal signals. Only output power transistors side with limited power dissipation capabilities provided heat sink does allow continuous total output stage power dissipation levels above 140W with only convection cooling. amplifier module's limiting factor output stage power transistor safe operating area (SOA) along with power dissipation capabilities provided heat sink. Continuous operation both high supply voltages into loads less than with sinusoidal signals will require additional thermal capacity. Utilizing high velocity will power dissipation, although this method will still guarantee violations under high supply voltage continuous signal driving situations. recommended that amplifier module operated with ±60V, driving resistive load with sinusoidal signals standard performance characterization. When operating above ±60V supply rails into impedance loads, care must taken keep from exceeding output power transistor SOA. highly recommended minimize time that continuous signals applied amplifier under extreme operating conditions. Standard audio performance measurements obtained higher supply voltages with time heat sink devices cool between measurements. LME49830 EF125WT1 amplifier module intended used performance verification critical listening evaluations. module indicates high level performance that achieved from minimal external components, while still providing significant user design flexibility end-product differentiation. module intended used long-term temperature reliability testing significant high-power analysis limited thermal capabilities. continual high-power driving analysis, long-term temperature reliability testing, recommended that amplifier designed with adequate thermal management operating conditions. OUTPUT STAGE POWER DISSIPATION output stage's worst-case maximum power dissipation purely resistive loads determined following equation. PD(AMP)MAX VCC2/(22RL) (Watts)
TABLE Output Stage Maximum Power Dissipation Output Stage Maximum Power Dissipation Load ±60V 182W ±75V 142W 285W
With power transistors side LME49830 EF125WT1 amplifier module, each transistor will dissipate average 1/4th total output stage power dissipation. easy that each power transistor would need dissipate average when driving sinewave continuously into resistive load with ±75V power supply. Each output device rated 150W power dissipation case temperature 25°C. power dissipation each device must de-rated linearly based case temperature. case temperature 75°C power dissipation rating each device down 90W, based device datasheets. Instantaneous power dissipation when driving reactive loads will even greater exceed transistor's safe operating area (SOA). heat sink used amplifier module inch extrusion from Aavid Thermalloy, part number 65605 with rating 0.62°C/W. Adding heat sink greatly reduce thermal resistance depending flow rate fan. More information thermal modeling amplifier heat sink found Aavid Thermalloy's website. Determining maximum power dissipation while de-rating output devices base case temperature with provided heat sink determined mathematical derivation. power dissipation output devices de-rated linearly with case temperature. general formula line both output devices, 2SJ201 2SK1530, thermal properties same. power dissipation de-rating graph points power dissipation rating case temperature (TC) 25°C maximum channel temperature, which power dissipation. These specifications 150W 150°C respectively. points line know allowing solution general formula resulting Equation PD(IC) -1.2W/°C 180W determine case temperature from device power dissipation equation given Equation -0.83°C/W PD(IC) 150°C (°C) Inspection formula above reveals that junction-tocase thermal resistance, device absolute value slope curve °C/W which 0.83°C/W. determine maximum device power dissipation while de-rating increase device case temperature with given heat sink ambient temperature second equation case temperature determined resulting Device Case Temperature (°C) Heat Sink Temp (°C) [Device Power Dissipation Case Thermal Resistance (°C/ (°C) (°C) [PD(IC) (°C/W)] heat sink temperature total power dissipation multiplied it's thermal resistance plus ambient temperature: (°C) [PD(TOTAL) (°C/W)] (°C) number output devices, PD(TOTAL) Number Output Devices PD(IC) (W). Combining above gives Equation (PD(TOTAL) (PD(IC) (°C)
Where total supply voltage. ±75V calculations used equation would 150V. Table represents output stage's maximum power dissipation stated power supply voltages purely resistive loads.
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Setting Equation equal equation gives: -0.83°C/W PD(IC) 150°C (PD(TOTAL) (PD(IC) Solving PD(IC) with four output devices results Equation PD(IC) (150°C Given: 25°C 0.25°C/W, flat, thermal greased surface. 0.62°C/W, rating provided heat sink. 0.83°C/W (TJ(MAX) (PD(MAX) TA). Results PD(IC) 35.1W maximum average power dissipation device de-rating case temperature rise with provided heat sink ambient temperature 25°C. total average output stage power dissipation 140.4W. Under these conditions each device's channel temperature will 150°C, each device case temperature will 120.9°C, heat sink will 112.1°C. With some additional substitutions inspection gives Equation very general version Equation PD(IC) (TJ(MAX) Devices [(TJ(MAX) (PD(MAX) TA)]}
heat sink used EF125WT1 amplifier module from Aavid Thermalloy, part number 530101B00150, with thermal resistance 6.3°C/W. shown equation below, even ±100V rails, heat sink sufficient. [(TJ(MAX) PD(MAX)(JC CS)] PD(MAX) [(150°C 50°C) 5W(4°C/W 0.5°C/W)] 15.5°C/W This heat sink used LME49830 selected intentionally ease mounting, thermal robustness, mechanical stability. recommended that separate heat sink from output stage heat sink used LME49830 maintain operating temperature minimize thermal interaction.
Connections
INPUT CONNECTIONS analog input signal applied LME49830 EF125WT1 through either header, through standard input connector, optimum performance shielded twisted pair cable should used between signal source amplifier module with shield terminated only signal source. input coupled, unbalanced terminated 6.8k resistor. input termination, accompanying gain-setting feedback resistor, changed higher value such 47k, resulting slightly higher THD+N specification added resistor thermal noise. should also adjusted maintain same gain setting. input high-frequency roll-off filter capacitor limiting high-frequency amplification, parallel with combination these values pole location 130kHz. input sensitivity this amplifier 1.37V, resulting output power 175W 0.1% THD+N into running ±60V power supply rails. OUTPUT CONNECTIONS output connected through header, intended impedance this amplifier running ±60V power supply rails. While amplifier module capable running supply rails ±100V, main limitation safe operating area output stage power transistors. Please refer Operational Details section limitations recommendations. output snubber network been provided acting high-frequency load. 0.1µF capacitor, CSN1 series with resistor, RSN1, which watt rating output. snubber needed provide snubbing high-frequency instabilities output waveform, generally created quasi-saturation region when close clipping. However, output snubbers commonly employed provide load impedance amplifier high frequencies. POWER SUPPLY CONNECTIONS power supply amplifier module applied connector This connector powers both output stage power transistors LME49830. Operating voltages from ±20V ±100V applied amplifier module. Please refer Operational Details section limitations precautions when operating elevated supply voltages. power supply cabling amplifier should have sufficient current handling capability desired amplifier output power. recommended that gauge stranded wire
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above calculations continuous average power dissipation with sine waves. Music other program material will have average power dissipation levels lower than sine wave reducing heat sink device temperatures. LME49830 POWER DISSIPATION LME49830 contained TO-247 package with junction-to-ambient thermal resistance, 73°C/W junction-to-case thermal resistance, 4°C/W. TO-247 package non-isolated package attached heat sink will same potential negative supply rail. LME49830 integrates complete power amplifier input stage output current drive capability 56mA. LME49830 intended drive MOSFET transistors output stage providing high-impedance load LME49830. Shown Table maximum power dissipation levels required minimum heat sink thermal resistances stated power supply voltages keep LME49830 temperature below 150°C. calculations 50°C ambient, LME49830 4°C/W, plus 0.5°C/W additional thermal resistance from case-to-sink (CS). TABLE LME49830 Power Dissipation Heat Sink Information LME49830 Power Dissipation Heat Sink Thermal Resistances LME49830 ICCQ(max) 25mA ±60V 28.8°C/W ±75V 3.75W 22°C/W
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used connect low-impedance power supply PCB, keeping connections short possible. CONNECTION OPTIMIZATION Shown Figure detailed diagram showing optimum ground connections with options clean signal connection. important note that separate ground connection must made from signal generator
power supply star GND, providing reference between input output. Only option Figure should used clean GND. This because there electrical ground connection between input stage output stage power supply bypass capacitors amplifier module. This done intentionally eliminate interaction ground currents between input output stages.
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FIGURE Amplifier Module Test Setup Connections signal source grounded back power supply star point, output will float drawing large amount current from positive power supply. Therefore, important that PCB's low-level clean signal ground referenced back star ground from either connection Audio Precision from analog ground, PCB, only connection typically gives best THD+N performance. Also note that there output load ground return connection PCB. This also done intentionally ensure that high-current output ground return current tied back star ground point. order obtain lowest level distortion measurements, important make oscilloscope chassis ground connection power supply star ground point while using scope probe ground clip. Connecting scope probe ground clip AGND, while probing output stage, significantly increase distortion. physical size limitation providing large valued reservoir capacitors PCB, expected that user provide low-inductance connection either impedance power supply bulk capacitance. order minimize amplifier distortion environment, recommended provide high-valued reservoir capacitors between power supply amplifier module. also recommended keep connections between reservoir capacitors amplifier module short possible. 39,000µF reservoir capacitance supply rail used bench testing obtain performance indicated this document. MUTE FUNCTION reference voltage used mute circuit EF125WT1 amplifier module, shown Figure This reference voltage allows varying power supply voltages applied LME49830 without continually adjusting mute resistance. mute current 160A using on-board (+12V) mute voltage. allow external mute voltage 2.6V used user adjust value mute resistor desired voltage.
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FIGURE Gain Frequency Response Experimentation with high quality film capacitors these locations result additional sonic improvements. Such investigation covered this document.
Output Stage Biasing
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FIGURE Mute Circuit Reference Voltage Detailed design information proper mute circuit operation reference voltage found LME49830 datasheet. Also shown datasheet excellent level mute attenuation -120dB audio signals. LME49830 mute function smooth turn-on/off transition that clicks pops minimized. Adding capacitor MUTE totally eliminate clicks pops that occur with trade-off being delay when changing modes. Mute capacitor supplied EF125WT1 virtually silent mode change with minimal delay. GAIN FREQUENCY RESPONSE amplifier module configured non-inverting mode. gain (V/V) gain 28.3V/V (29dB) with 6.8k 249. frequency response combination equation: 1/(2CI1RI) (Hz) frequency -3dB roll-off point 2.9Hz. Additionally, there component footprints additional capacitors parallel with (CI2) (CI3) shown Figure
LME49830 robust, consistently high-performing amplifier input stage that eliminates numerous discrete input stage design issues. Intricate inter-stage design dependencies that commonly affect optimum distortion performance longer problem discrete designers, ensuring that amplifier designs market faster more reliably. benefits designing with LME49830 ability select preferred output stage topology power devices. This simple, flexible input stage solution makes easy combine preferred output topology achieve ultra high-fidelity performance with integrated form-factor. System designers continue differentiate their power amplifier solutions from their competitors, utilizing their time-developed output stage intellectual property. LME49830 also provides integration factor that increases number channels chassis area, while maintaining ultra high-fidelity level never before obtained from integrated circuit. With benefits flexibility that this solution provides, there little complexity some variability setting output stage's bias voltage. bias voltage, mode operation Class A/B, designer partially dependent upon topology output power device selected. Different MOSFET devices have significantly varying threshold voltages. There other topology configurations other topologies beyond scope this document. Besides voltage bias setting, there bias circuit difference depending upon whether BJTs MOSFETs used power delivery device. BJTs subject thermal runaway therefore require thermally compensated bias circuit. MOSFETs selected power device, there need thermally compensated bias circuit depending specific MOSFET devices. Shown below Table list recommended MOSFETs that have been evaluated with LME49830. This list parts meant exhaustive list, rather some more common power devices that currently used audio power amplifiers. more information regarding MOSFET driving issues recommendations, please refer AN-1645, "LM4702 Driving MOSFET Output Stage".
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TABLE Recommended MOSFET Power Devices Manufacturer Toshiba International Rectifier Renesas(1) NFET 2SK1530 IRFP240 2SK1058 PFET 2SJ201 IRFP9240 2SJ162
Renesas devices have different compared Toshiba devices (Source Drain pins reversed) requiring different PCB. LME49830 maximum bias voltage with just about MOSFET device. high output drive current from LME49830 makes ideal very high power amplifier applications. MULTIPLIER LME49830's BIASP BIASM pins available create bias output stage. Depending device characteristics design goals, thermally compensated circuit needed order have stable bias desired current across temperature. non-compensated bias circuit would consist resistor potentiometer capacitors between BIAS pins LME49830. EF125WT1 uses thermally compensated multiplier bias circuit with Toshiba 2SK1530/2SJ201 devices output stage. multiplier's transistor, which needs mounted directly next power transistors heat sink, will sense output device's temperature with some temperature gradient through common heat sink. With correctly designed multiplier circuit bias current output stage will remain relatively stable over device temperature operating range. multiplier circuit created QVBE1 with associated resistors capacitors shown Figure output stage bias initially adjusted through potentiometer, order optimize lowest crossover distortion, desired sound quality mode operation Class
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FIGURE Output Stage Biasing Multiplier Circuit bias voltage measured connecting voltmeter between pins bias voltage measured from gate-to-gate output stage. When minimum, total output stage bias current will approximately 500mA. When maximum, total output stage bias current will approximately 175mA. bias current setting EF125WT1 module before leaving factory, performance data, approximately 225mA. This equates approximately 112mA power transistor power stage quiescent current (~250mA from each supply rail ±60V). Changing value will change bias range approximately 115mA 325mA. should noted that bias adjustment potentiometer, RP1, available your convenience analyzing performance effects output stage bias adjustment. potentiometer replaced final design with simple resistor once desired biasing voltage been selected. Please also note that Multiplier terminals very sensitive loading, when obtaining performance measurements, sure that multi-meter scope probe been removed from Bias Monitoring header, QVBE1 thermal properties exact match MOSFET output device thermal properties. additional, temperature independent bias resistor, RB3, used adjust bias voltage more closely match output devices stable bias current over temperature. This resistor changes slope bias voltage temperature curve reducing effect voltage QVBE1. Shown equation below relationship between voltage setting resistors multiplier's output voltage, VCE.
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VBIAS (RB3 2mA) (RB1 RP1)] Class amplifier design, bias current chosen such that crossover distortion minimized while also keeping quiescent power dissipation low. Higher bias current reduces harmonic distortion levels cost increased power dissipation. some point there little reduction with increased bias current resulting power dissipation. tradeoff bias current level must made between performance power dissipation. MOSFET output stages typically need higher bias current than output stages good performance Class amplifier design. What amount bias current each solution's output stage will require depends completely user's specific tastes and/or target specifications. Shown Table THD+N measurements with 1kHz signal into load with 22kHz measurement bandwidth different total supply current settings. LM49830 current approximately 25mA output stage bias current equal total supply current minus 25mA. TABLE Bias Current Measured THD+N Supply Current Supply 50mA 100mA 150mA 200mA 250mA 300mA 500mA 1kHz THD+N 10W/8, 22kHz 0.00364% 0.00176% 0.00120% 0.00089% 0.00078% 0.00070% 0.00067% 0.00067%
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FIGURE THD+N Versus Frequency Versus Bias Current
Table indicates that range 200mA 300mA supply current power supply produces magnitude harmonics manageable power dissipation. Different bias current levels shown graphs oscilloscope photos below. each graph output power level into resistive load with 1kHz signal. Each oscilloscope photo shows input output signal plus time domain distortion residual. measurement equipment notch fundamental frequency test signal. fundamental reduced more than -110dB relative 0dB. equal voltage into graphs show insufficient bias current results that dominated crossover distortion. Under bias also indicated high level number harmonics graphs. THD+N curves over frequency representing level crossover distortion associated with varying output stage bias currents shown Figure output power level into load with 80kHz measurement bandwidth plots.
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FIGURE 100mA Bias Current Distortion Residual under biased output stage clearly exhibited sharp, narrow glitches distortion residual zero crossing point output voltage.
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FIGURE 100mA Bias Current Output
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under biased time domain distortion residual represented above that exhibits high harmonic distortion over large number harmonics. harmonics increase significantly from optimally biased FFT, while even order harmonics remain relatively unchanged.
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FIGURE Bias Current Distortion Residual high bias (Class output stage shows crossover distortion very flat time domain distortion residual.
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FIGURE 250mA Bias Current Distortion Residual correctly biased output stage shows very flat distortion residual except zero crossing point where very small glitches observed. Notice that while distortion residual crossover region quite small, overall distortion amplifier with this level residual 0.00078% THD+N.
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FIGURE Bias Current Output class bias level shows very harmonics number amplitude. tradeoff high power dissipation efficiency. BIAS STABILITY Total Quiescent Current versus Time graph (Figure created running output stage into resistive load until steady state device case heat sink temperature reached. input signal turned (Time bias current recorded over time. should noted that graph units linear indicated. Bias current measured second intervals first minutes after input signal turned then second intervals five minutes. final measurement taken minutes. time steps reason different slopes time curve. There plots graph, indicating quiescent bias heat sink temperature 35°C other indicating bias over time after producing output power. There several factors that affect data such package heat sink size which contribute thermal delay.
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FIGURE 250mA Bias Current Output correctly biased time domain distortion residual represented above that exhibits fairly evenly balanced amplitudes even harmonics they decrease over frequency. Most distortion products below fundamental test signal 1kHz.
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FIGURE Bias Current Time possible measure exact instantaneous channel temperature discrete devices. There temperature gradient from channel junction output device heat sink. additional temperature gradient exist along heat sink QVBE1 transistor thermal resistances QVBE1 transistor case. When output devices producing power (and dissipating more power than quiescent conditions) temperature gradient from channel output devices junction QVBE1 transistor greater than under quiescent conditions. thermal resistance relatively constant power dissipation increases temperature gradient linearly increases. With channel temperature higher than bias voltage setting, output device current higher. current will reduce down quiescent levels channel cools temperature gradient from output device channel QVBE1 junction equal quiescent steady state conditions. graph Figure shows phenomenon total current higher when input signal first turned then returns down steady state bias levels minutes. should noted that within seconds bias current returned within ~4mA steady state bias current. With different heat sink device mounting placement response will different. Figure shows bias current function heat sink temperature. bias current when heat sink reaches 30°C thermal gradients established steady state mode. Using different values with shows thermal compensation increased (over compensated) reduced current higher heat sink temperatures. data Figures taken heat sink temperature increases under quiescent conditions signal) 50°C. higher heat sink temperatures, heat sink heated 87°C driving load then current recorded heat sink cools. Because larger temperature gradients when driving signal data collected starting 70°C when temperature gradients near steady state quiescent conditions. remove differences bias settings, bias currents normalized 250mA.
FIGURE Bias Current Heat Sink Temperature Figure shows bias current changes percent verses heat sink temperature. percent change uses bias current heat sink temperature 30°C baseline.
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FIGURE Bias Current Change Percent Heat Sink Temperature Based data above bias resistors 392, 750, 1.10k. BIASING PROCEDURE Where bias current output stage entirely designer, essentially features solution. however, important biasing output stage after being warmed while, allowing amplifier first warm distortion optimized temperature that amplifier will normally operated. amplifier will then operating optimum bias point with reduced distortion under normal operating temperature conditions. bias voltage your preference distortion level once amplifier warmed temperature indicative normal operation. common evaluate distortion residual time domain and/or residual's harmonics frequency domain when optimizing bias. Additionally, common evaluate bias setting higher
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frequencies where crossover distortion easily recognized above measurement unit's noise floor. Frequencies 3kHz 5kHz generally allow significant harmonics present even when using 30kHz measurement-unit lowpass filter. goal determine desired potentiometer setting eventually fixed resistance) that will required enddesign. This accomplished optimizing distortion residuals from measurement perspective optimizing desired sound quality from listening perspective. Removing amplifier's input signal allows measurement bias voltage quiescent current running through each power transistors. Simple voltage measurement across source degeneration resistors provides each leg's quiescent current. Please note that multiplier terminals very sensitive loading, when obtaining performance measurements, sure that multi-meter scope probe been removed from Bias Monitoring header,
TABLE LME49830 Slew Rate Compensation Capacitor Compensation Capacitor, CCOMP (pF) Slew Rate (V/µs)
Compensation
SINGLE-POLE COMPENSATION slew rate specification amplifier defines "speed" establishing upper limit fast output respond input signal transient changes. amplifier's slew rate defined equation below. features LME49830 ability amplifier's slew rate power bandwidth through selection external compensation capacitor value. Lowering value compensation capacitor increases amplifier's slew rate hence power bandwidth. Slew Rate 2fMAXVOpk amplifier's power bandwidth also determined through this equation related amplifier's slew rate shown below. fPBW Slew Rate/2VOpk power bandwidth equation indicates that higher output power amplifiers will require larger slew rates maintain constant power bandwidth. Shown Table required amplifier slew rates 100kHz power bandwidth different output power levels. TABLE Slew Rates 100kHz Power Bandwidth Output Power VO(PEAK) 44.7 63.2 89.4 Slew Rate (fBW 100kHz)
Since slew rate requirements different depending upon desired power bandwidth output power level, calculate needed compensation capacitor given design based equation below. CCOMP ITAIL 2fVOpk Shown Table appropriate compensation capacitor values 100kHz power bandwidths stated amplifier output power levels. TABLE Compensation Capacitor Required Reference Design Reference Compensation Design Capacitor, CCOMP (pF) 125W 250W 450W Slew Rate (V/µs) Power Bandwidt (kHz)
Figure represents 24V/µs slew rate from 20pF compensation capacitor. This value estimated 27V/µs, however, taking into account tolerances compensation capacitor (±5%) IC's tail current, 24V/ slew rate realistic value.
maximum slew rate amplifier will dependent upon value compensation capacitor, conjunction with maximum tail current input differential transistor pair. Slew Rate dV/dt IMAX CCOMP LME49830 maximum input differential pair tail current 550µA, corresponding slew rates compensation capacitor values shown Table
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FIGURE Single-Pole Compensation Slew Rate
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power bandwidth power amplifier 150W into when using 20pF compensation capacitor 10Hz 90kHz (±0.5dB) 10Hz 130kHz (±3dB) shown Figure below. snubber removed before taking graph with capacitor still place. slew rate limitation 24V/µs dominates frequency response.
comes from factory with installed single-pole compensation scheme must removed order effective circuit. Mica capacitors from Cornell Dubilier used frequency compensation. Typically, second compensation capacitor chosen between times value CC1. value five times safe starting point. resistance value then selected based location desired pole. Recommended starting values 12pF 5.1k RC1.
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FIGURE Single-Pole Compensation Power Bandwidth Frequency TWO-POLE COMPENSATION addition single-pole compensation, there component placeholders EF125WT1 amplifier module two-pole compensation scheme shown Figure addition passive components create pole frequency stated equation below. 1/2CC2RC1 1/2(62pF)(6.2k) 414kHz two-pole compensation scheme allows increased loop gain higher frequencies, resulting increased slew rate, dynamics reduced high-frequency distortion. Experimentation with these components will show benefit reduced distortion higher frequencies, care must taken extend pole instabilities result.
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FIGURE Two-Pole Compensation Connections only there reduction higher frequency distortion, there also power bandwidth benefit from using 2-pole compensation result increase slew rate.
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Performance Graphs (±60V)
following pages contain standard audio performance graphs amplifier module, running ±60V power supFFT Frequency (Reading) 1kHz, POUT 22kHz
rails driving either load. These performance graphs represent high performance capabilities solution.
Frequency (Reading) 1kHz, POUT 10W, 22kHz
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Frequency (Reading) 1kHz, POUT 50W, 22kHz
Frequency (Reading) 1kHz, POUT 150W, 22kHz
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THD+N Frequency POUT 50W, 150W, 80kHz
THD+N Output Power 20Hz, 1kHz, 20kHz, 80kHz
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THD+N Output Power 1kHz, 22kHz 80kHz
THD+N Output Power 20Hz, 22kHz 80kHz
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Frequency (Reading) 1kHz, POUT 22kHz
Frequency (Reading) 1kHz, POUT 10W, 22kHz
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Frequency (Reading) 1kHz, POUT 50W, 22kHz
Frequency (Reading) 1kHz, POUT 300W, 22kHz
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THD+N Frequency POUT 50W, 300W, 80kHz
THD+N Output Power 20Hz, 1kHz, 20kHz, 80kHz
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THD+N Output Power 1kHz, 22kHz 80kHz
THD+N Output Power 20Hz, 22kHz 80kHz
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Frequency Response POUT 300W,
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Board Layer Views
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FIGURE Composite View From
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FIGURE Silk Screen View
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FIGURE Layer View
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FIGURE Bottom Layer View
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Bill Materials
Reference CS1, CS2, CS3, CS4, CS10, CS11, CS9, CSN1 Value Tolerance Description 250V, metalized polyester film, 7.5mm lead spacing 100V, radial electrolytic, 7.5mm lead spacing 500V multilayer mica, 3.6mm lead spacing 500V multilayer mica, 3.6mm lead spacing 16V, radial electrolytic, lead spacing radial electrolytic, 3.5mm lead spacing Polyester film, lead spacing Used 500mW Zener Diode, DO-35 Zener diode, DO-41 Complementary MOSFET power amplifier input stage transistor, TO-126 N-Channel MOSFET, 150W, TO-3PL (2-21F1B) P-Channel MOSFET, 150W, TO-3PL(2-21F1B) Watt metail oxide, axial through hole Watt metal film, axial through hole Watt metal film, axial through hole Watt silicone wirewound, through hole Fairchild Semiconductor Fairchild Semiconductor 1N5242BTR Manufacturer Part Number
0.1µF
Panasonic
ECQ-E2104KF
CS7,
470µF
Panasonic
EEU-FC2A471
20pF
Cornell Dubilier Cornell Dubilier
CD15ED200J03
30pF
CD15ED300J03
CB2,
47µF
Panasonic
EEU-FC1C470
220µF
Panasonic
EEU-FC1V221L
CC2, CI2, DG1, DG2, DG3, DG4, DG5, DG6, DG7,
180pF
Panasonic
ECQ-B1H181KF
1N4740A
200V
National Semiconductor Fairchild Semiconductor
LME49830TB
QVBE1
80V, 1.5A
BD13916STU
200V,
Toshiba
2SK1530-YF
200V,
Toshiba
2SJ201-YF
RSN1
22.1 10.0
Vishay/ BCcomponents International Yageo Corp. International Yageo Corp. Vishay/Dale
NFR0300001009J AC00 MFR-25FBF-22R1 MFR-25FBF-10R0
RG1, RG2, RE1, RE2, RE3,
RS005R1000FS73
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AN-1850
Reference
Value 1.10k
Tolerance
Description Watt metail film, 1206 (3216) Watt metal film, axial through hole Watt metal film, axial through hole Watt metal film, axial through hole Watt single turn potentiometer, through hole Watt metal film, axial through hole Watt metal film, axial through hole Watt metal film, axial through hole Watt metal film, axial through hole Watt metal film, axial through hole Used SPDT On-On right angle, through hole 156mil header, straight, plating 156mil header, straight, plating phono jack, mount, black 100mil header, straight, plating 100mil header, straight, plating
Manufacturer Panasonic International Yageo Corp. International Yageo Corp. International Yageo Corp.
Part Number ERJ-S080R00V MFR-25FBF-392R MFR-25FBF-750R MFR-25FBF-1K10
Bourns Inc.
3306W-1-201
RIN, RBO1, RBO2,
6.81k 75.0k 20.0k 39.2k
International Yageo Corp. International Yageo Corp. International Yageo Corp. International Yageo Corp. International Yageo Corp.
MFR-25FBF-249R MFR-25FBF-6K81 MFR-25FBF-75K0 MFR-25FBF-20K0 MFR-25FBF-39K2
Components Molex/Waldom Electronics Corp. Molex/Waldom Electronics Corp. Kobiconn Molex/Waldom Electronics Corp. Molex/Waldom Electronics Corp. Aavid Thermalloy
ET01MD1ABE
26-60-4030
26-60-4020
161-0097-E
J10,
22-23-2021
22-03-2031
6.3°C/W 0.62°C/W
LME49830 heat sink
530101B00150 65605
Output stage heat Aavid Thermalloy sink, inch length
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AN-1850
Revision History
1.01 Date 07/01/08 12/02/08 Description Initial release. Text edits.
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LME49830TB Ultra-High Fidelity High Power Amplifier Reference Design
Notes
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AN-1850
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