LT®3080-1 1.1A dropout linear regulator that incorporates internal bal
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LT3080-1 Parallelable 1.1A Adjustable Single Resistor Dropout Regulator DESCRIPTION
LT®3080-1 1.1A dropout linear regulator that incorporates internal ballast resistor allow direct paralleling devices without need board trace resistors. internal ballast resistor allows multiple devices paralleled directly surface mount board higher output current power dissipation while keeping board layout simple easy. device brings collector pass transistor allow dropout operation-down 350mV-when used with multiple input supplies. LT3080-1 capable supplying wide output voltage range. reference current through single resistor programs output voltage level between zero 36V. LT3080-1 stable with 2.2F ceramic capacitance output, requiring additional common with other regulators. Internal protection includes current limiting thermal limiting. LT3080-1 regulator offered 8lead MSOP (with Exposed better thermal characteristics) packages.
Lare registered trademarks Linear Technology Corporation. other trademarks property their respective owners.
Internal Ballast Resistor Permits Direct Connection Power Plane Higher Current Heat Spreading Output Current: 1.1A Single Resistor Programs Output Voltage Initial Accuracy Current Output Adjustable Output Noise: 40VRMS (10Hz 100kHz) Wide Input Voltage Range: 1.2V Dropout Voltage: 350mV <0.001%/ Line Regulation Minimum Load Current: 0.5mA Stable with 2.2F Minimum Ceramic Output Capacitor Current Limit with Foldback Overtemperature Protected Available 8-Lead MSOP
APPLICATIONS
High Current Surface Mount Supply High Efficiency Linear Regulator Post Regulator Switching Supplies Parts Count Variable Voltage Supply Output Voltage Power Supplies
TYPICAL APPLICATION
Paralleling Regulators
VCONTROL LT3080-1 13250
Offset Voltage Distributio
4.8V VCONTROL LT3080-1
OUT*
165k
OUT*
VOUT 3.3V 2.2A *OUTPUTS DIRECTLY MOUNTED POWER PLANE
DISTRIBUTION (mV)
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LT3080-1 ABSOLUTE MAXIMUM RATINGS
(Note Voltages Relative VOUT
VCONTROL Voltage .40V, -0.3V Voltage .40V, -0.3V Current (Note .±10mA Voltage (Relative OUT) .±0.3V Output Short-Circuit Duration Indefinite
Operating Junction Temperature Range (Notes 10).-40°C 125°C Storage Temperature Range:.-65°C 150°C Lead Temperature (Soldering, sec) MS8E Package Only 300°C
CONFIGURATION
VIEW VIEW VCONTROL VCONTROL
PACKAGE 8-LEAD (3mm 3mm) PLASTIC TJMAX 125°C, 64°C/W, 3°C/W EXPOSED (PIN OUT, MUST SOLDERED
MS8E PACKAGE 8-LEAD PLASTIC MSOP TJMAX 125°C, 60°C/W, 10°C/W EXPOSED (PIN OUT, MUST SOLDERED
ORDER INFORMATION
LEAD FREE FINISH LT3080EDD-1#PBF LT3080EMS8E-1#PBF LEAD BASED FINISH LT3080EDD-1 LT3080EMS8E-1 TAPE REEL LT3080EDD-1#TRPBF LT3080EMS8E-1#TRPBF TAPE REEL LT3080EDD-1#TR LT3080EMS8E-1#TR PART MARKING LDPM LTDPN PART MARKING LDPM LTDPN PACKAGE DESCRIPTION 8-Lead (3mm 3mm) Plastic 8-Lead Plastic MSOP PACKAGE DESCRIPTION 8-Lead (3mm 3mm) Plastic 8-Lead Plastic MSOP TEMPERATURE RANGE -40°C 125°C -40°C 125°C TEMPERATURE RANGE -40°C 125°C -40°C 125°C
Consult Marketing parts specified with wider operating temperature ranges. more information lead free part marking, http://www.linear.com/leadfree/ more information tape reel specifications,
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LT3080-1 ELECTRICAL CHARACTERISTICS
PARAMETER Current Output Offset Voltage (VOUT VSET) Load Regulation ISET ISET ISET CONDITIONS VCONTROL 2.0V, ILOAD 1mA, 25°C VCONTROL 2.0V, ILOAD 1.1A (Note VCONTROL IOUT ILOAD 1.1A ILOAD 1.1A (Note ILOAD 1.1A (Note 22V, VCONTROL=1V 22V, ILOAD=1mA 22V, VCONTROL=1V 22V, ILOAD=1mA VCONTROL VCONTROL ILOAD 100mA ILOAD 1.1A ILOAD 100mA ILOAD 1.1A ILOAD 100mA ILOAD 1.1A VCONTROL VSET VOUT -0.1V ILOAD 1.1A, 10Hz 100kHz, COUT 10F, CSET 0.1F 120Hz, VRIPPLE 0.5VP-P, ILOAD 0.2A, CSET 0.1F, COUT 2.2F 10kHz 1MHz 10ms Pulse
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C.
9.90 9.80 -3.5 -0.1 27.5
10.10 10.20
UNITS nA/V mV/V VRMS nARMS
Line Regulation (Note Minimum Load Current (Notes VCONTROL Dropout Voltage (Note Dropout Voltage (Note CONTROL Current (Note Current Limit (Note
0.003 1.35 0.003
Error Amplifier Output Noise (Note Ripple Rejectio
Reference Current Output Noise (Note 10Hz 100kHz
Thermal Regulation, ISET
Note Stresses beyond those listed under Absolute Maximum Ratings cause permanent damage device. Exposure Absolute Maximum Rating condition extended periods affect device reliability lifetime. Note Unless otherwise specified, voltages with respect VOUT. LT3080-1 tested specified under pulse load conditions such that LT3080-1 100% tested 25°C. Performance 40°C 125°C assured design, characterization correlation with statistical process controls. Note Minimum load current equivalent quiescent current part. Since quiescent drive current delivered output part, minimum load current minimum current required maintain regulation. Note LT3080-1, dropout caused either minimum control voltage (VCONTROL) minimum input voltage (VIN). Both parameters specified with respect output voltage. specifications represent minimum input-to-output differential voltage required maintain regulation. Note CONTROL current drive current required output transistor. This current will track output current with roughly 1:60 ratio. minimum value equal quiescent current device.
Note Output noise lowered adding small capacitor across voltage setting resistor. Adding this capacitor bypasses voltage setting resistor shot noise reference current noise; output noise then equal error amplifier noise (see Applications Information section). Note clamped output with diodes. These diodes only carry current under transient overloads. Note Load regulation Kelvin sensed package. Note Current limit decrease zero input-to-output differential voltages (VIN VOUT) greater than 22V. Operation voltages both VCONTROL allowed maximum long difference between input output voltage below specified differential (VIN VOUT) voltage. Line load regulation specifications applicable when device current limit. Note This includes over-temperature protection that intended protect device during momentary overload conditions. Junction temperature will exceed maximum operating junction temperature when over-temperature protection active. Continuous operation above specified maximum operating junction temperature impair device reliability.
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LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS
Current
10.20 10.15 CURRENT OFFSET VOLTAGE (mV) 10.10 10.05 10.00 9.95 9.90 9.85 9.80 TEMPERATURE (°C)
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Current DistributioN 13792 -0.5 -1.0 -1.5 9.80 10.00 10.20 9.90 10.10 CURRENT DISTRIBUTION
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Offset Voltage (VOUT VSET)
-2.0
TEMPERATURE (°C)
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Offset Voltage DistributioN 13250 1.00 0.75 OFFSET VOLTAGE (mV)
Offset Voltage
ILOAD 0.50 0.25 -0.25 -0.50 -0.75 OFFSET VOLTAGE (mV) INPUT-TO-OUTPUT VOLTAGE *SEE NOTE ELECTRICAL 30801 CHARACTERISTICS TABLE
Offset Voltage
25°C
125°C
DISTRIBUTION (mV)
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-1.00
LOAD CURRENT
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Load RegulatioCHANGE OFFSET VOLTAGE WITH LOAD (mV) CHANGE REFERENCE CURRENT CHANGE OFFSET VOLTAGE (VOUT VSET) ILOAD 1.1A VOUT TEMPERATURE (°C)
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Minimum Load Current
MINIMUM VOLTAGE (VIN VOUT) (mV) MINIMUM LOAD CURRENT (mA) VIN, CONTROL VOUT 1.5V TEMPERATURE (°C)
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Dropout Voltage (Minimum Voltage)
125°C OUTPUT CURRENT 25°C
CHANGE REFERENCE CURRENT WITH LOAD (nA)
VIN, CONTROL VOUT 36V*
*SEE NOTE ELECTRICAL CHARACTERISTICS TABLE
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LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS
MINIMUM CONTROL VOLTAGE (VCONTROL VOUT) MINIMUM CONTROL VOLTAGE (VCONTROL VOUT)
Dropout Voltage (Minimum Voltage)
MINIMUM VOLTAGE (VIN VOUT) (mV) TEMPERATURE (°C)
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Dropout Voltage (Minimum VCONTROL Voltage)
-50°C 125°C OUTPUT CURRENT 25°C
Dropout Voltage (Minimum VCONTROL Voltage)
TEMPERATURE (°C)
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ILOAD 1.1A
ILOAD 1.1A
ILOAD
ILOAD 500mA
ILOAD 100mA
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Current Limit
CURRENT LIMIT CURRENT LIMIT VOUT TEMPERATURE (°C)
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Current Limit
INPUT-TO-OUTPUT DIFFERENTIAL OUTPUT VOLTAGE DEVIATION (mV) 25°C LOAD CURRENT (mA)
Load Transient Response
VOUT 1.5V CSET 0.1F VCONTROL
COUT CERAMIC COUT 2.2F CERAMIC
TIME
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*SEE NOTE ELECTRICAL CHARACTERISTICS TABLE
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Load Transient Response
OUTPUT VOLTAGE DEVIATION (mV) OUTPUT VOLTAGE DEVIATION (mV) -100 LOAD CURRENT IN/CONTROL VOLTAGE VCONTROL VOUT 1.5V COUT CERAMIC CSET 0.1F
Line Transient Response
INPUT VOLTAGE OUTPUT VOLTAGE VOUT 1.5V ILOAD 10mA COUT 2.2F CERAMIC CSET 0.1F CERAMIC
Turn-On Response
COUT 2.2F CERAMIC RSET 100k CSET RLOAD TIME
TIME 30801
TIME
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LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS
VCONTROL Current
125°C 25°C VCONTROL VOUT VOUT OUTPUT VOLTAGE
VCONTROL Current
Residual Output Voltage with Less Than Minimum Load
VOUT RTEST
CONTROL CURRENT (mA)
ILOAD 1.1A DEVICE CURRENT LIMIT
CONTROL CURRENT (mA)
-50°C
RTEST
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ILOAD INPUT-TO-OUTPUT DIFFERENTIAL
LOAD CURRENT
*SEE NOTE ELECTRICAL CHARACTERISTICS TABLE
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Ripple Rejection Single Supply
RIPPLE REJECTION (dB) COUT 2.2F CERAMIC FREQUENCY (Hz) 100k
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Ripple Rejection Dual Supply VCONTROL Pi100 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) VOUT (NOMINAL) VCONTROL VOUT (NOMINAL) COUT 2.2F CERAMIC RIPPLE 50mVP-P FREQUENCY (Hz) 100k
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Ripple Rejection Dual Supply Pi100
VCONTROL VOUT (NOMINAL) RIPPLE 50mVP-P ILOAD 100mA ILOAD 1.1A
ILOAD 100mA ILOAD 1.1A
VOUT (NOMINAL) VCONTROL VOUT (NOMINAL) RIPPLE 50mVP-P COUT 2.2F CERAMIC ILOAD 1.1A 100k FREQUENCY (Hz)
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Ripple Rejection (120Hz)
Noise Spectral Density
REFERENCE CURRENT NOISE SPECTRAL DENSITY (pA/
ERROR AMPLIFIER NOISE SPECTRAL DENSITY (nV/Hz)
RIPPLE REJECTION (dB) SINGLE SUPPLY OPERATION VOUT(NOMINAL) RIPPLE 500mVP-P, f=120Hz ILOAD 1.1A CSET 0.1F, COUT 2.2F TEMPERATURE
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FREQUENCY (Hz)
100k
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LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Noise
VOUT 100V/DIV GAIN (dB) FREQUENCY (Hz) 100k 100mA 1.1A 100mA 1.1A
Error Amplifier Gain Phase
-100 -150 -200
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PHASE (DEGREES)
TIME 1ms/DIV VOUT RSET 100k CSET O.1F COUT ILOAD 1.1A
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FUNCTIONS (DD/MS8E)
VCONTROL (Pin 5/Pin This supply control circuitry device. current flow into this about 1.7% output current. device regulate, this voltage must more than 1.2V 1.35V greater than output voltage (see Dropout specifications). (Pins 8/Pins This collector power device LT3080-1. output load current supplied through this pin. device regulate, voltage this must more than 0.1V 0.5V greater than output voltage (see Dropout specifications). (Pin 6/Pin Connection. Connect pins have connection internal circuitry tied VCONTROL, VOUT, GND, floated. (Pins 1-3/Pins 1-3): This power output device. There must minimum load current output regulate. (Pin 4/Pin This input error amplifier regulation point device. fixed current flows this through single external resistor, which programs output voltage device. Output voltage range zero absolute maximum rated output voltage. Transient performance improved adding small capacitor from ground. Exposed (Pin 9/Pin MS8E packages.
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LT3080-1 BLOCK DIAGRAM
VCONTROL
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APPLICATIONS INFORMATION
LT3080-1 regulator easy protection features expected high performance regulators. Included short-circuit protection safe operating area protection, well thermal shutdown. LT3080-1 especially well suited applications needing multiple rails. architecture adjusts down zero with single resistor handling modern voltage digital IC's well allowing easy parallel operation thermal management without heat sinks. Adjusting "zero" output allows shutting powered circuitry when input pre-regulated-such 3.3V input supply-external resistors help spread heat. precision internal current source connected non-inverting input power operational amplifier. power operational amplifier provides impedance buffered output voltage non-inverting input. single resistor from non-inverting input ground sets output voltage this resistor zero, zero output results. seen, output voltage obtained from zero maximum defined input power supply. What obvious from this architecture benefits using true internal current source reference opposed bootstrapped reference older regulators. true current source allows regulator have gain frequency response independent impedance positive input. Older adjustable regulators, such LT1086 have change loop gain with output voltage well bandwidth changes when adjustment bypassed ground. LT3080-1, loop gain unchanged changing output voltage bypassing. Output regulation fixed percentage output voltage fixed fraction millivolts. true current source allows gain buffer amplifier provide regulation none that gain needed amplify reference higher output voltage. LT3080-1 also incorporates internal ballast resistor allow direct paralleling devices without need board trace resistors sense resistors. This internal ballast resistor allows multiple devices paralleled directly surface mount board higher output current higher power dissipation while keeping board layout simple easy. difficult more regulators higher output current; inputs devices tied together, outputs devices tied directly together, pins devices tied directly together. Because internal ballast resistor, devices automatically share load power dissipation. LT3080-1 collector output transistor connected separate from control input. Since dropout collector pin) only 300mV, supplies used power LT3080-1 reduce
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LT3080-1 APPLICATIONS INFORMATION
VCONTROL LT3080-1
VCONTROL
insulating surfaces remove fluxes other residues will probably required. Surface coating necessary provide moisture barrier high humidity environments.
VOUT COUT
RSET
CSET
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Figure Basic Adjustable Regulator
dissipation: higher voltage supply control circuitry lower voltage supply collector. This increases efficiency reduces dissipation. further spread heat, resistor inserted series with collector move some heat spread board. LT3080-1 operated modes. Three terminal mode control connected power input which gives limitation 1.35V dropout. Alternatively, "control" tied higher voltage power lower voltage giving 300mV dropout minimizing power dissipation. This allows 1.1A supply regulating from 2.5VIN 1.8VOUT 1.8VIN 1.2VOUT with dissipation. Output Voltage LT3080-1 generates reference current that flows pin. Connecting resistor from ground generates voltage that becomes reference point error amplifier (see Figure reference voltage straight multiplication current value resistor. voltage generated there minimum output voltage regulator. minimum load current required maintain regulation regardless output voltage. true zero voltage output operation, this load current must returned negative supply voltage. With level current used generate reference voltage, leakage paths from create errors reference output voltages. High quality insulation should used (e.g., Teflon, Kel-F); cleaning
Board leakage minimized encircling circuitry with guard ring operated potential close itself; guard ring should tied pin. Guarding both sides circuit board required. Bulk leakage reduction depends guard ring width. nanoamperes leakage into associated circuitry creates 0.1% error reference voltage. Leakages this magnitude, coupled with other sources leakage, cause significant offset voltage reference drift, especially over possible operating temperature range. guardring techniques used, this bootstraps stray capacitance pin. Since high impedance node, unwanted signals couple into cause erratic behavior. This will most noticeable when operating with minimum output capacitors full load current. easiest remedy this bypass with small amount capacitance from ground, 10pF 20pF sufficient. Stability Output Capacitance LT3080-1 requires output capacitor stability. designed stable with most capacitors (typically ceramic, tantalum electrolytic). minimum output capacitor 2.2F with less recommended prevent oscillations. Larger values output capacitance decrease peak deviations provide improved transient response larger load current changes. Bypass capacitors, used decouple individual components powered LT3080-1, increase effective output capacitor value. improvement transient performance, place capacitor across voltage setting resistor. Capacitors used. This bypass capacitor reduces system noise well, start-up time proportional time constant voltage setting resistor (RSET Figure bypass capacitor.
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LT3080-1 APPLICATIONS INFORMATION
Extra consideration must given ceramic capacitors. Ceramic capacitors manufactured with variety dielectrics, each with different behavior across temperature applied voltage. most common dielectrics used specified with temperature characteristic codes Z5U, Y5V, X7R. dielectrics good providing high capacitances small package, they tend have strong voltage temperature coefficients shown Figures When used with regulator, capacitor exhibit effective value bias voltage applied over operating temperature range. dielectrics result more stable characteristics more suitable output capacitor. type better stability across temperature, while less expensive available higher values. Care still must exercised when using capacitors; codes only specify operating temperature range maximum
CHANGE VALUE -100 BIAS VOLTAGE
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capacitance change over temperature. Capacitance change bias with capacitors better than capacitors, still significant enough drop capacitor values below appropriate levels. Capacitor bias characteristics tend improve component case size increases, expected capacitance operating voltage should verified. Voltage temperature coefficients only sources problems. Some ceramic capacitors have piezoelectric response. piezoelectric device generates voltage across terminals mechanical stress, similar piezoelectric microphone works. ceramic capacitor stress induced vibrations system thermal transients.
Paralleling Devices
LT3080-1's directly paralleled obtain higher output current. pins tied together pins tied together. This same whether it's three terminal mode separate input supplies. outputs connected common; internal ballast resistor equalizes currents. worst-case offset between output only millivolts allows very small ballast resistors used. shown Figure devices have internal ballast resistors, which full output current gives
LT3080-1
BOTH CAPACITORS 16V, 1210 CASE SIZE,
VCONTROL
Figure Ceramic Capacitor Bias Characteristics
CHANGE VALUE BOTH CAPACITORS 16V, 1210 CASE SIZE, TEMPERATURE (°C)
3080
4.8V
VCONTROL
LT3080-1
VOUT 3.3V 2.2A
165k
30801
-100
Figure Ceramic Capacitor Temperature Characteristics
Figure Parallel Devices
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LT3080-1 APPLICATIONS INFORMATION
better than percent equalized sharing current. internal resistance milliohms (per device) only adds about millivolts output regulation drop output output voltage, this adds 2.5% regulation. output 19mV high lower absolute error ±1.3%. course, more than LT3080-1's paralleled even higher output current. They spread board, spreading heat. Input resistors further spread heat input-to-output difference high. Thermal Performance this example, LT3080-1 devices mounted copper 4-layer board. They placed approximately inches apart board mounted vertically convection cooling. tests were measure cooling performance current sharing these devices. first test done with approximately 0.7V inputto-output device. This gave milliwatt dissipation each device output current. temperature rise above ambient approximately 28°C both devices were within plus minus 1°C. Both thermal electrical sharing these devices excellent. thermograph Figure shows temperature distribution between these devices board reaches ambient temperature within about half inch from devices. power then increased with 1.7V across each device. This gives watts dissipation each device device temperature about 90°C, about 65°C above ambient shown Figure Again, temperature matching between devices within 2°C, showing excellent tracking between devices. board temperature reached approximately 40°C within about 0.75 inches each device. While 90°C acceptable operating temperature these devices, this 25°C ambient. higher ambients, temperature must controlled prevent device temperature from exceeding 125°C. three meter second airflow across devices will decrease device temperature about 20°C providing margin higher operating ambient temperatures. Both power relatively high power levels devices paralleled higher output current. Current sharing thermal sharing excellent, showing that acceptable operation while keeping peak temperatures below excessive operating temperatures board. This technique allows higher operating current linear regulation used systems where could never used before.
Figure Temperature Rise 700mW Dissipatio
Figure Temperature Rise 1.7W Dissipatio
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LT3080-1 APPLICATIONS INFORMATION
Quieting Noise LT3080-1 offers numerous advantages when comes dealing with noise. There several sources noise linear regulator. most critical noise source reference; from there, noise contribution from error amplifier must considered, gain created using resistor divider cannot forgotten. Traditional noise regulators bring voltage reference external (usually through large value resistor) allow bypassing noise reduction reference noise. LT3080-1 does traditional voltage reference like other linear regulators, instead uses reference current. That current operates with typical noise current levels 3.2pA/Hz (1nARMS over 10Hz 100kHz bandwidth). voltage noise this equal noise current multiplied resistor value. resistor generates spot noise equal 4kTR Boltzmann's constant, 1.38 10-23 J/°K, absolute temperature) which summed with reference current noise. lower reference noise, voltage setting resistor bypassed with capacitor, though this causes start-up time increase factor time constant. LT3080-1 uses unity-gain follower from drive output, there requirement resistor output voltage. high accuracy voltage reference placed remove errors output voltage reference current tolerance resistor tolerance. Active driving acceptable; limitations creativity ingenuity circuit designer. problem that normal linear regulator sees with reference voltage noise that noise gained along with output when using resistor divider operate levels higher than normal reference voltage. With LT3080-1, unity-gain follower presents gain whatsoever from output, noise figures increase accordingly. Error amplifier noise typically 125nV/Hz (40VRMS over 10Hz 100kHz bandwidth); this another factor that summed give final noise figure regulator. Curves Typical Performance Characteristics show noise spectral density peak-to-peak noise characteristics both reference current error amplifier over 10Hz 100kHz bandwidth. Overload Recovery Like many power regulators, LT3080-1 safe operating area (SOA) protection. protection decreases current limit input-to-output voltage increases keeps power dissipation safe levels values input-to-output voltage. LT3080-1 provides some output current values input-to-output voltage device breakdown. Current Limit curve Typical Performance Characteristics section. When power first turned input voltage rises output follows input, allowing regulator start into very heavy loads. During start-up, input voltage rising, input-to-output voltage differential small, allowing regulator supply large output currents. With high input voltage, problem occur wherein removal output short will allow output voltage recover. Other regulators, such LT1085 LT1764A, also exhibit this phenomenon unique LT3080-1. problem occurs with heavy output load when input voltage high output voltage low. Common situations immediately after removal short circuit. load line such load intersect output current curve points. this happens, there stable operating points regulator. With this double intersection, input power supply need cycled down zero brought again make output recover.
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LT3080-1 APPLICATIONS INFORMATION
Load Regulation Because LT3080-1 floating device (there ground part, quiescent drive current delivered load), possible provide true remote load sensing. Load regulation will limited resistance connections between regulator load. data sheet specification load regulation Kelvin sensed pins package. Negative side sensing true Kelvin connection, with bottom voltage setting resistor returned negative side load (see Figure Connected shown, system load regulation will LT3080-1 load regulation parasitic line resistance multiplied output current. important keep positive connection between regulator load short possible large wire board traces. internal ballast resistor outside LT3080-1's feedback loop. Therefore, voltage drop across ballast resistor appears additional load regulation. However, this additional load regulation actually improve transient response performance decreasing peak-to-peak output voltage deviation even save total output capacitance. This technique called active voltage positioning especially useful applications that must withstand large output load current transients. more information, Design Note 224, "Active Voltage Positioning Reduces Output Capacitors." basic principle uses fact that output voltage function output load current. Output voltage based midpoint output load current range: IOUT(MIN) IOUT(MAX
output current decreases below midpoint, output voltage increases above nominal set-point. Correspondingly, output current increases above midpoint, output voltage decreases below nominal set-point. During large output load transient, output voltage perturbation contained within window that tighter than what would result active voltage positioning employed. Choose resistor value using formula below: BALLAST ISET where IMID (IOUT(MIN) IOUT(MAX)) RBALLAST ISET Thermal Considerations LT3080-1 internal power thermal limiting circuitry designed protect under overload conditions. continuous normal load conditions, maximum junction temperature must exceeded. important
VCONTROL
LT3080-1
RSET
PARASITIC RESISTANCE
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LOAD
Figure Connections Best Load Regulatio
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LT3080-1 APPLICATIONS INFORMATION
give consideration sources thermal resistance from junction ambient. This includes junction-to-case, case-to-heat sink interface, heat sink resistance circuit board-to-ambient application dictates. Additional heat sources nearby must also considered. surface mount devices, heat sinking accomplished using heat spreading capabilities board copper traces. Surface mount heat sinks plated through-holes also used spread heat generated power devices. Junction-to-case thermal resistance specified from junction bottom case directly below die. This lowest resistance path heat flow. Proper mounting required ensure best possible thermal flow from this area package heat sinking material. Note that Exposed electrically connected output. following tables list thermal resistance several different copper areas given fixed board size. measurements were taken still two-sided 1/16" FR-4 board with ounce copper.
Table Package, 8-Lead MSOP
COPPER AREA TOPSIDE* 2500mm2 1000mm2 225mm2 100mm2 BACKSIDE 2500mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 55°C/W 57°C/W 60°C/W 65°C/W
layers, copper weight, board layout thermal vias affect resultant thermal resistance. Although Tables provide thermal resistance numbers 2-layer board with ounce copper, modern multilayer PCBs provide better performance than found these tables. example, 4-layer, ounce copper board with five thermal vias from MSOP exposed backside inner layers (connected VOUT) achieves 40°C/W thermal resistance. Demo circuit 995A's board layout achieves this 40°C/W performance. This approximately improvement over numbers shown Tables Calculating Junction Temperature Example: Given output voltage 0.9V, VCONTROL voltage 3.3V ±10%, voltage 1.5V ±5%, output current range from maximum ambient temperature 50°C, what will maximum junction temperature package 2500mm2 board with topside copper area 500mm2? power drive circuit equals: PDRIVE (VCONTROL VOUT)(ICONTROL) where ICONTROL equal IOUT /60. ICONTROL function output current. curve ICONTROL IOUT found Typical Performance Characteristics curves. power output transistor equals: POUTPUT (VIN VOUT)(IOUT) total power equals: PTOTAL PDRIVE POUTPUT current delivered negligible ignored.
*Device mounted topside
Table Package, 8-Lead
COPPER AREA TOPSIDE* 2500mm2 1000mm2 225mm2 100mm2 BACKSIDE 2500mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 60°C/W 62°C/W 65°C/W 68°C/W
VCONTROL(MAX CONTINUOUS) 3.630V (3.3V 10%) VIN(MAX CONTINUOUS) 1.575V (1.5V VOUT 0.9V, IOUT 50°C
*Device mounted topside
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LT3080-1 APPLICATIONS INFORMATION
Power dissipation under these conditions equal PDRIVE (VCONTROL VOUT)(ICONTROL) ICONTROL 17mA PDRIVE (3.630V 0.9V)(17mA) 46mW POUTPUT (VIN VOUT)(IOUT) POUTPUT (1.575V 0.9V)(1A) 675mW Total Power Dissipation 721mW Junction Temperature will equal PTOTAL (approximated using tables) 50°C 721mW 64°C/W 96°C this case, junction temperature below maximum rating, ensuring reliable operation. Reducing Power Dissipation some applications necessary reduce power dissipation LT3080-1 package without sacrificing output current capability. techniques available. first technique, illustrated Figure employs resistor series with regulator's input. voltage drop across decreases LT3080-1's IN-toOUT differential voltage correspondingly decreases LT3080-1's power dissipation. example, assume: VCONTROL VOUT 3.3V IOUT(MAX) formulas from Calculating Junction Temperature section previously discussed. Without series resistor power dissipation LT3080-1 equals:
PTOTAL 3.3V 3.3V 1.73W
voltage differential (VDIFF) across pass transistor chosen 0.5V, then equals: 3.3V 0.5V
Power dissipation LT3080-1 equals: PTOTAL 3.3V 0.5V 0.53W LT3080-1's power dissipation only compared series resistor. dissipates 1.2W power. Choose appropriate wattage resistors handle dissipate power properly.
VCONTROL LT3080-1
RSET
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VOUT
Figure Reducing Power Dissipation Using Series Resistor
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LT3080-1 APPLICATIONS INFORMATION
second technique reducing power dissipation, shown Figure uses resistor parallel with LT3080-1. This resistor provides parallel path current flow, reducing current flowing through LT3080-1. This technique works well input voltage reasonably constant output load current changes small. This technique also increases maximum available output current expense minimum load requirements. example, assume: VCONTROL VIN(MAX) 5.5V, VOUT 3.3V, VOUT(MIN) 3.2V, IOUT(MAX) IOUT(MIN) 0.7A. Also, assuming that carries more than IOUT(MIN) 630mA. Calculating yields: 5.5V 3.2V 3.65 0.63A Standard value 3.6) maximum total power dissipation (5.5V 3.2V) 2.3W. However, LT3080-1 supplies only: 5.5V 3.2V 0.36
Therefore, LT3080-1's power dissipation only: PDIS (5.5V 3.2V) 0.36A 0.83W dissipates 1.47W power. with first technique, choose appropriate wattage resistors handle dissipate power properly. With this configuration, LT3080-1 supplies only 0.36A. Therefore, load current increase 0.64A 1.64A while keeping LT3080-1 normal operating range.
VCONTROL LT3080-1
RSET
VOUT
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Figure Reducing Power Dissipation Using Parallel Resistor
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LT3080-1 TYPICAL APPLICATIONS
Adding ShutdowIN VCONTROL LT3080-1
LT3080-1
VCONTROL
VN2222LL
VOUT VN2222LL
SHUTDOWN
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INSURES ZERO OUTPUT ABSENCE OUTPUT LOAD
Current Source
VCONTROL LT3080-1
VCONTROL
LT3080-1
2.2F
100k
IOUT
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LT3080-1 TYPICAL APPLICATIONS
Using Lower Value Resistor
VCONTROL LT3080-1
VCONTROL 2.2F LT3080-1
24.9k RSET 4.99k
VOUT 0.5V RSET VOUT 0.5V
COUT
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Adding Soft-Start
4.8V VCONTROL IN4148 LT3080-1
VOUT 3.3V 2.2A
VCONTROL 2.2F
LT3080-1
0.01F 165k
COUT
30801 TA05
30801fa
LT3080-1 TYPICAL APPLICATIONS
Supply
VCONTROL LT3080-1 VCONTROL LT3080-1
VCONTROL LT3080-1
VCONTROL
LT3080-1
VOUT
CURRENT LIMIT
500k
100F
3080 TA06
Boosting Fixed Output Regulators
LT3080-1
LT1963-3.3
3.3VOUT 2.6A
30801 TA07
*4mV DROP ENSURES LT3080-1 WITH NO-LOAD MULTIPLE LT3080-1'S USED PARALLEL
30801fa
LT3080-1 TYPICAL APPLICATIONS
Voltage, High Current Adjustable High Efficiency Regulator*
0.47H PVIN 2.7V 5.5V SVIN 2.2MEG 100k LTC3414 PGOOD RUN/SS 1000pF 78.7k SYNC/MODE SGND PGND 124k 12.1k 294k 470pF
100F 2N3906
VCONTROL
LT3080-1
100F
VCONTROL
LT3080-1
DIFFERENTIAL VOLTAGE LT3080-1 0.6V 2N3906
MAXIMUM OUTPUT VOLTAGE 1.5V
BELOW INPUT VOLTAGE
VCONTROL
LT3080-1
VCONTROL
LT3080-1
100k
100F
30801 TA08
30801fa
LT3080-1 TYPICAL APPLICATIONS
Adjustable High Efficiency Regulator*
CMDSH-4E
4.5V 100k
BOOST LT3493 0.1F MBRM140 TP0610L
SHDN 0.1F
VCONTROL
LT3080-1
4.7F
*DIFFERENTIAL VOLTAGE LT3080-1 1.4V TPO610L P-CHANNEL THRESHOLD. MAXIMUM OUTPUT VOLTAGE BELOW INPUT VOLTAGE
1MEG
30801 TA09
Terminal Current Source
CCOMP*
VCONTROL
LT3080-1
100k
30801 TA10
*CCOMP 2.2F
CURRENT IOUT
30801fa
LT3080-1 PACKAGE DESCRIPTION
Package 8-Lead Plastic (3mm 3mm)
(Reference 05-08-1698)
0.675 ±0.05
±0.05 1.65 ±0.05 2.15 ±0.05 SIDES) PACKAGE OUTLINE 0.25 0.05 0.50 2.38 ±0.05 SIDES) RECOMMENDED SOLDER PITCH DIMENSIONS 0.115 0.38 0.10
3.00 ±0.10 SIDES) MARK (NOTE
1.65 0.10 SIDES)
(DD) 1203
0.200
0.75 ±0.05
0.25 0.05 2.38 ±0.10 SIDES)
0.50
0.00 0.05
BOTTOM VIEW-EXPOSED NOTE: DRAWING MADE JEDEC PACKAGE OUTLINE M0-229 VARIATION (WEED-1) DRAWING SCALE DIMENSIONS MILLIMETERS DIMENSIONS EXPOSED BOTTOM PACKAGE INCLUDE MOLD FLASH. MOLD FLASH, PRESENT, SHALL EXCEED 0.15mm SIDE EXPOSED SHALL SOLDER PLATED SHADED AREA ONLY REFERENCE LOCATION BOTTOM PACKAGE
30801fa
LT3080-1 PACKAGE DESCRIPTION
MS8E Package 8-Lead Plastic MSOP
(Reference 05-08-1662)
BOTTOM VIEW EXPOSED OPTION 2.06 0.102 (.081 .004) 1.83 0.102 (.072 .004)
2.794 0.102 (.110 .004)
0.889 0.127 (.035 .005)
5.23 (.206)
2.083 0.102 3.20 3.45 (.082 .004) (.126 .136)
0.42 0.038 (.0165 .0015)
0.65 (.0256)
3.00 0.102 (.118 .004) (NOTE
0.52 (.0205)
RECOMMENDED SOLDER LAYOUT
DETAIL 4.90 0.152 (.193 .006) 3.00 0.102 (.118 .004) (NOTE
0.254 (.010) GAUGE PLANE
0.53 0.152 (.021 .006) DETAIL 0.18 (.007) SEATING PLANE 0.22 0.38 (.009 .015) 1.10 (.043)
0.86 (.034)
0.65 (.0256) NOTE: DIMENSIONS MILLIMETER/(INCH) DRAWING SCALE DIMENSION DOES INCLUDE MOLD FLASH, PROTRUSIONS GATE BURRS. MOLD FLASH, PROTRUSIONS GATE BURRS SHALL EXCEED 0.152mm (.006") SIDE DIMENSION DOES INCLUDE INTERLEAD FLASH PROTRUSIONS. INTERLEAD FLASH PROTRUSIONS SHALL EXCEED 0.152mm (.006") SIDE LEAD COPLANARITY (BOTTOM LEADS AFTER FORMING) SHALL 0.102mm (.004")
0.1016 0.0508 (.004 .002)
MSOP (MS8E) 0307
30801fa
Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
LT3080-1 TYPICAL APPLICATION
Paralleling Regulators
VCONTROL LT3080-1
4.8V
VCONTROL
LT3080-1
165k
VOUT 3.3V 2.2A
30801 TA11
RELATED PARTS
PART NUMBER LDOs LT1086 LT1117 LT1118 LT1963A LT1965 1.5A Dropout Regulator 800mA Dropout Regulator 800mA Dropout Regulator 1.5A Noise, Fast Transient Response 1.1A Noise Fixed 2.85V, 3.3V, 3.6V, Output Dropout, Adjustable Fixed Output, DD-Pak, SOT-223 Packages Okay Sinking Sourcing, S0-8 SOT-223 Packages 340mV Dropout Voltage, Noise 40VRMS 2.5V 20V, TO-220, SOT-223 SO-8 Packages 290mV Dropout Voltage, Noise 40VRMS 1.8V 20V, VOUT 1.2V 19.5V, Stable with Ceramic Caps, TO-220, DDPak, MSOP Packages 1.14V 3.5V (Boost Enabled), 1.14V 5.5V (with External 5V), 0.1V, 950A, Stable with Ceramic Capacitors, 10-Lead MSOP Packages 300mV Dropout Voltage (2-Supply Operation), Noise: 40VRMS 1.2V 36V, VOUT 35.7V, Current-Based Reference with 1-Resistor VOUT Set, Directly Parallelable Required), Stable with Ceramic Capacitors, TO-220, SOT-223, MSOP Packages. Efficiency, VIN: 2.25V 5.5V, VOUT(MIN) 0.8V, TSSOP Package Efficiency, VIN: 2.5V 5.5V, VOUT(MIN) 0.6V, 20A, ThinSOTPackage Efficiency, VIN: 2.5V 5.5V, VOUT(MIN) 0.8V, 60A, 10-Lead Packages
30801fa
DESCRIPTION
COMMENTS
LTC®3026 LT3080
1.5A Input Voltage VLDORegulator 1.1A, Parallelable, Noise, Dropout Linear Regulator
Switching Regulators LTC3414 LTC3406/LTC3406B LTC3411 (IOUT), 4MHz Synchronous Step-Down DC/DC Converter 600mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter 1.25A (IOUT), 4MHz Synchronous Step-Down DC/DC Converter
VLDO ThinSOT trademarks Linear Technology Corporation.
Linear Technology Corporatio(408) 432-1900 FAX: (408) 434-0507
1008 PRINTED
1630 McCarthy Blvd., Milpitas, 95035-7417
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2008
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