LT3080EDD-1

FEATURES n LT3080-1 Parallelable 1.1A Adjustable Single Resistor Low Dropout Regulator DESCRIPTION The LT®3080-1 is a 1.1A low dropout linear regulator that incorporates an internal ballast resistor to allow direct paralleling of devices without the need for PC board trace resistors. The internal ballast resistor allows multiple devices to be paralleled directly on a surface mount board for higher output current and power dissipation while keeping board layout simple and easy. The device brings out the collector of the pass transistor to allow low dropout operation—down to 350mV—when used with multiple input supplies. The LT3080-1 is capable of supplying a wide output voltage range. A reference current through a single resistor programs the output voltage to any level between zero and 36V. The LT3080-1 is stable with 2.2μF of ceramic capacitance on the output, not requiring additional ESR as is common with other regulators. Internal protection includes current limiting and thermal limiting. The LT3080-1 regulator is offered in the 8lead MSOP (with an Exposed Pad for better thermal characteristics) and 3mm × 3mm DFN packages. , LT LTC and LTM are registered trademarks of Linear Technology Corporation. All other , trademarks are the property of their respective owners. n n n n n n n n n n n n Internal Ballast Resistor Permits Direct Connection to Power Plane for Higher Current and Heat Spreading Output Current: 1.1A Single Resistor Programs Output Voltage 1% Initial Accuracy of SET Pin Current Output Adjustable to 0V Low Output Noise: 40μVRMS (10Hz to 100kHz) Wide Input Voltage Range: 1.2V to 36V Low Dropout Voltage: 350mV < 0.001%/ V Line Regulation Minimum Load Current: 0.5mA Stable with 2.2μF Minimum Ceramic Output Capacitor Current Limit with Foldback and Overtemperature Protected Available in 8-Lead MSOP and 3mm × 3mm DFN APPLICATIONS n n n n n High Current All Surface Mount Supply High Efficiency Linear Regulator Post Regulator for Switching Supplies Low Parts Count Variable Voltage Supply Low Output Voltage Power Supplies TYPICAL APPLICATION Paralleling Regulators IN VCONTROL LT3080-1 N = 13250 Offset Voltage Distribution + – SET VIN 4.8V TO 28V IN VCONTROL LT3080-1 25mΩ OUT* 1μF + – SET 165k 25mΩ OUT* VOUT 3.3V 2.2A 10μF *OUTPUTS CAN BE DIRECTLY MOUNTED TO POWER PLANE –2 0 –1 1 VOS DISTRIBUTION (mV) 2 30801 TA01b 30801 TA01 30801fa 1 LT3080-1 ABSOLUTE MAXIMUM RATINGS (Note 1) All Voltages Relative to VOUT VCONTROL Pin Voltage .....................................40V, –0.3V IN Pin Voltage ................................................40V, –0.3V SET Pin Current (Note 7) .....................................±10mA SET Pin Voltage (Relative to OUT) .........................±0.3V Output Short-Circuit Duration .......................... Indefinite Operating Junction Temperature Range (Notes 2, 10)......................................–40°C to 125°C Storage Temperature Range:..................–65°C to 150°C Lead Temperature (Soldering, 10 sec) MS8E Package Only .......................................... 300°C PIN CONFIGURATION TOP VIEW TOP VIEW OUT 1 OUT 2 OUT 3 SET 4 9 8 7 6 5 IN IN NC VCONTROL OUT OUT OUT SET 1 2 3 4 8 7 6 5 IN IN NC VCONTROL 9 DD PACKAGE 8-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 64°C/W, θJC = 3°C/W EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB MS8E PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 60°C/W, θJC = 10°C/W EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH LT3080EDD-1#PBF LT3080EMS8E-1#PBF LEAD BASED FINISH LT3080EDD-1 LT3080EMS8E-1 TAPE AND REEL LT3080EDD-1#TRPBF LT3080EMS8E-1#TRPBF TAPE AND REEL LT3080EDD-1#TR LT3080EMS8E-1#TR PART MARKING LDPM LTDPN PART MARKING LDPM LTDPN PACKAGE DESCRIPTION 8-Lead (3mm × 3mm) Plastic DFN 8-Lead Plastic MSOP PACKAGE DESCRIPTION 8-Lead (3mm × 3mm) Plastic DFN 8-Lead Plastic MSOP TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 30801fa 2 LT3080-1 ELECTRICAL CHARACTERISTICS PARAMETER SET Pin Current Output Offset Voltage (VOUT – VSET) Load Regulation ISET VOS ΔISET ΔVOS ΔVOS ΔISET ΔVOS CONDITIONS VIN = 1V, VCONTROL = 2.0V, ILOAD = 1mA, TJ = 25°C VIN ≥ 1V, VCONTROL ≥ 2.0V, 1mA ≤ ILOAD ≤ 1.1A (Note 9) VIN = 1V, VCONTROL = 2V, IOUT = 1mA ΔILOAD = 1mA to 1.1A ΔILOAD = 1mA to 1.1A (Note 8) ΔILOAD = 1mA to 1.1A (Note 8) VIN = 1V to 22V, VCONTROL=1V to 22V, ILOAD=1mA VIN = 1V to 22V, VCONTROL=1V to 22V, ILOAD=1mA VIN = VCONTROL = 10V VIN = VCONTROL = 22V ILOAD = 100mA ILOAD = 1.1A ILOAD = 100mA ILOAD = 1.1A ILOAD = 100mA ILOAD = 1.1A VIN = 5V, VCONTROL = 5V, VSET = 0V, VOUT = – 0.1V ILOAD = 1.1A, 10Hz ≤ f ≤ 100kHz, COUT = 10μF, CSET = 0.1μF f = 120Hz, VRIPPLE = 0.5VP-P, ILOAD = 0.2A, CSET = 0.1μF, COUT = 2.2μF f = 10kHz f = 1MHz 10ms Pulse ● ● The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. MIN 9.90 9.80 –2 –3.5 –0.1 27.5 ● ● ● ● ● ● ● ● ● ● TYP 10 10 MAX 10.10 10.20 2 3.5 34 48 0.5 500 1 1.6 200 500 6 30 UNITS μA μA mV mV nA mV mV nA/V mV/V μA mA V V mV mV mA mA A μVRMS nARMS dB dB dB %/W Line Regulation (Note 9) Minimum Load Current (Notes 3, 9) VCONTROL Dropout Voltage (Note 4) VIN Dropout Voltage (Note 4) CONTROL Pin Current (Note 5) Current Limit (Note 9) 0.1 0.003 300 1.2 1.35 100 350 4 17 1.1 1.4 40 1 75 55 20 0.003 Error Amplifier RMS Output Noise (Note 6) Ripple Rejection Reference Current RMS Output Noise (Note 6) 10Hz ≤ f ≤ 100kHz Thermal Regulation, ISET Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Unless otherwise specified, all voltages are with respect to VOUT. The LT3080-1 is tested and specified under pulse load conditions such that TJ ≈ TA. The LT3080-1 is 100% tested at TA = 25°C. Performance at – 40°C and 125°C is assured by design, characterization and correlation with statistical process controls. Note 3: Minimum load current is equivalent to the quiescent current of the part. Since all quiescent and drive current is delivered to the output of the part, the minimum load current is the minimum current required to maintain regulation. Note 4: For the LT3080-1, dropout is caused by either minimum control voltage (VCONTROL) or minimum input voltage (VIN). Both parameters are specified with respect to the output voltage. The specifications represent the minimum input-to-output differential voltage required to maintain regulation. Note 5: The CONTROL pin current is the drive current required for the output transistor. This current will track output current with roughly a 1:60 ratio. The minimum value is equal to the quiescent current of the device. Note 6: Output noise is lowered by adding a small capacitor across the voltage setting resistor. Adding this capacitor bypasses the voltage setting resistor shot noise and reference current noise; output noise is then equal to error amplifier noise (see the Applications Information section). Note 7: SET pin is clamped to the output with diodes. These diodes only carry current under transient overloads. Note 8: Load regulation is Kelvin sensed at the package. Note 9: Current limit may decrease to zero at input-to-output differential voltages (VIN – VOUT) greater than 22V. Operation at voltages for both IN and VCONTROL is allowed up to a maximum of 36V as long as the difference between input and output voltage is below the specified differential (VIN – VOUT) voltage. Line and load regulation specifications are not applicable when the device is in current limit. Note 10: This IC includes over-temperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed the maximum operating junction temperature when over-temperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. 30801fa 3 LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS Set Pin Current 10.20 10.15 SET PIN CURRENT (μA) OFFSET VOLTAGE (mV) 10.10 10.05 10.00 9.95 9.90 9.85 9.80 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 30801 G01 Set Pin Current Distribution N = 13792 2.0 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 9.80 10.00 10.20 9.90 10.10 SET PIN CURRENT DISTRIBUTION (μA) 30801 G02 Offset Voltage (VOUT – VSET) IL = 1mA –2.0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 30801 G03 Offset Voltage Distribution N = 13250 1.00 0.75 OFFSET VOLTAGE (mV) Offset Voltage ILOAD = 1mA 0.50 0.25 0 –0.25 –0.50 –0.75 5 0 –5 OFFSET VOLTAGE (mV) –10 –15 –20 –25 –30 –35 –40 0 12 24 36* 30 18 INPUT-TO-OUTPUT VOLTAGE (V) *SEE NOTE 9 IN ELECTRICAL 30801 G05 CHARACTERISTICS TABLE 6 –45 Offset Voltage TJ = 25°C TJ = 125°C –2 0 –1 1 VOS DISTRIBUTION (mV) 2 30801 G04 –1.00 0 0.2 0.4 0.8 0.6 LOAD CURRENT (A) 1.0 1.2 30801 G06 Load Regulation CHANGE IN OFFSET VOLTAGE WITH LOAD (mV) 0 –5 –10 –15 –20 –25 –30 –35 –40 –45 –50 –50 –25 0 CHANGE IN REFERENCE CURRENT CHANGE IN OFFSET VOLTAGE (VOUT – VSET) ΔILOAD = 1mA TO 1.1A VIN – VOUT = 2V 80 70 60 50 40 30 20 10 0 –10 –20 25 50 75 100 125 150 TEMPERATURE (°C) 30801 G07 Minimum Load Current 0.8 MINIMUM IN VOLTAGE (VIN – VOUT) (mV) MINIMUM LOAD CURRENT (mA) 0.7 0.6 0.5 0.4 VIN, CONTROL – VOUT = 1.5V 0.3 0.2 0.1 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 30801 G08 Dropout Voltage (Minimum IN Voltage) 400 350 TJ = 125°C 300 250 200 150 100 50 0 0 0.2 0.4 0.8 0.6 OUTPUT CURRENT (A) 1.0 1.2 TJ = 25°C CHANGE IN REFERENCE CURRENT WITH LOAD (nA) VIN, CONTROL – VOUT = 36V* *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 30801 G09 30801fa 4 LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS MINIMUM CONTROL VOLTAGE (VCONTROL – VOUT) (V) MINIMUM CONTROL VOLTAGE (VCONTROL – VOUT) (V) Dropout Voltage (Minimum IN Voltage) 400 MINIMUM IN VOLTAGE (VIN – VOUT) (mV) 350 300 250 200 150 100 50 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 30801 G10 Dropout Voltage (Minimum VCONTROL Pin Voltage) 1.6 TJ = –50°C 1.4 1.2 TJ = 125°C 1.0 0.8 0.6 0.4 0.2 0 0 0.2 0.8 0.6 OUTPUT CURRENT (A) 0.4 1.0 1.2 TJ = 25°C Dropout Voltage (Minimum VCONTROL Pin Voltage) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 30801 G12 ILOAD = 1.1A ILOAD = 1.1A ILOAD = 1mA ILOAD = 500mA ILOAD = 100mA 30801 G11 Current Limit 1.6 1.4 CURRENT LIMIT (A) CURRENT LIMIT (A) 1.2 1.0 0.8 0.6 0.4 0.2 VIN = 7V VOUT = 0V 0 25 50 75 100 125 150 TEMPERATURE (°C) 30801 G13 Current Limit 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 24 30 18 INPUT-TO-OUTPUT DIFFERENTIAL (V) 6 12 36* 60 OUTPUT VOLTAGE DEVIATION (mV) TJ = 25°C 40 20 0 –20 –40 LOAD CURRENT (mA) 400 300 200 100 0 Load Transient Response VOUT = 1.5V CSET = 0.1μF VIN = VCONTROL = 3V COUT = 10μF CERAMIC COUT = 2.2μF CERAMIC 0 –50 –25 0 5 10 15 20 25 30 35 40 45 50 TIME (μs) 30801 G15 *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 30801 G14 Load Transient Response 150 OUTPUT VOLTAGE DEVIATION (mV) OUTPUT VOLTAGE DEVIATION (mV) 100 50 0 –50 –100 LOAD CURRENT (A) 1.2 0.9 0.6 0.3 0 0 5 IN/CONTROL VOLTAGE (V) VIN = VCONTROL = 3V VOUT = 1.5V COUT = 10μF CERAMIC CSET = 0.1μF 75 50 25 0 –25 –50 6 5 4 3 2 Line Transient Response INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) VOUT = 1.5V ILOAD = 10mA COUT = 2.2μF CERAMIC CSET = 0.1μF CERAMIC 5 4 3 2 1 0 2.0 1.5 1.0 0.5 0 Turn-On Response COUT = 2.2μF CERAMIC RSET = 100k CSET = 0 RLOAD = 1Ω 0 1 2 3 456 TIME (μs) 7 8 9 10 10 15 20 25 30 35 40 45 50 TIME (μs) 30801 G16 0 10 20 30 40 50 60 70 80 90 100 TIME (μs) 30801 G17 30801 G18 30801fa 5 LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS VCONTROL Pin Current 25 30 25 20 15 10 5 0 TJ = 125°C TJ = 25°C VCONTROL – VOUT = 2V VIN – VOUT = 1V OUTPUT VOLTAGE (V) VCONTROL Pin Current 0.8 0.7 0.6 0.5 0.4 Residual Output Voltage with Less Than Minimum Load SET PIN = 0V VIN VOUT RTEST VIN = 20V CONTROL PIN CURRENT (mA) 20 ILOAD = 1.1A DEVICE IN CURRENT LIMIT CONTROL PIN CURRENT (mA) 15 TJ = –50°C 10 VIN = 10V 0.3 VIN = 5V 0.2 0.1 0 0 1k RTEST (Ω) 2k 30801 G21 5 ILOAD = 1mA 0 0 30 12 18 24 6 INPUT-TO-OUTPUT DIFFERENTIAL (V) 36* 0 0.2 0.4 0.6 0.8 LOAD CURRENT (A) 1.0 1.2 *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 30801 G19 30801 G20 Ripple Rejection - Single Supply 100 90 80 RIPPLE REJECTION (dB) 70 60 50 40 30 20 10 0 10 COUT = 2.2μF CERAMIC 100 1k 10k FREQUENCY (Hz) 100k 1M 30801 G22 Ripple Rejection - Dual Supply - VCONTROL Pin 100 90 80 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) 70 60 50 40 30 20 10 0 10 VIN = VOUT (NOMINAL) + 1V VCONTROL = VOUT (NOMINAL) +2V COUT = 2.2μF CERAMIC RIPPLE = 50mVP–P 100 1k 10k FREQUENCY (Hz) 100k 1M 30801 G23 Ripple Rejection - Dual Supply - IN Pin 100 90 80 VIN = VCONTROL = VOUT (NOMINAL) + 2V RIPPLE = 50mVP–P ILOAD = 100mA ILOAD = 1.1A ILOAD = 100mA ILOAD = 1.1A 70 60 50 40 VIN = VOUT (NOMINAL) + 1V VCONTROL = VOUT (NOMINAL) +2V 30 RIPPLE = 50mVP–P 20 10 COUT = 2.2μF CERAMIC ILOAD = 1.1A 0 10 100 1k 10k 100k FREQUENCY (Hz) 1M 30801 G24 Ripple Rejection (120Hz) 80 79 10k Noise Spectral Density 1k REFERENCE CURRENT NOISE SPECTRAL DENSITY (pA/ √Hz) ERROR AMPLIFIER NOISE SPECTRAL DENSITY (nV/√Hz) 78 RIPPLE REJECTION (dB) 77 76 75 74 73 72 71 SINGLE SUPPLY OPERATION VIN = VOUT(NOMINAL) + 2V RIPPLE = 500mVP-P, f=120Hz ILOAD = 1.1A CSET = 0.1μF, COUT = 2.2μF 0 25 50 75 100 125 150 TEMPERATURE ( C) 30801 G25 1k 100 100 10 10 1.0 70 –50 –25 1 10 100 1k 10k FREQUENCY (Hz) 0.1 100k 30801 G26 30801fa 6 LT3080-1 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage Noise 20 15 10 VOUT 100μV/DIV GAIN (dB) 5 0 –5 –10 –15 –20 –25 –30 10 100 1k 10k FREQUENCY (Hz) 100k IL = 100mA IL = 1.1A IL = 100mA IL = 1.1A Error Amplifier Gain and Phase 300 250 200 150 100 50 0 –50 –100 –150 –200 1M 30801 G28 PHASE (DEGREES) TIME 1ms/DIV VOUT = 1V RSET = 100k CSET = O.1μF COUT = 10μF ILOAD = 1.1A 30801 G27 PIN FUNCTIONS (DD/MS8E) VCONTROL (Pin 5/Pin 5): This pin is the supply pin for the control circuitry of the device. The current flow into this pin is about 1.7% of the output current. For the device to regulate, this voltage must be more than 1.2V to 1.35V greater than the output voltage (see Dropout specifications). IN (Pins 7, 8/Pins 7, 8): This is the collector to the power device of the LT3080-1. The output load current is supplied through this pin. For the device to regulate, the voltage at this pin must be more than 0.1V to 0.5V greater than the output voltage (see Dropout specifications). NC (Pin 6/Pin 6): No Connection. No Connect pins have no connection to internal circuitry and may be tied to VIN , VCONTROL, VOUT, GND, or floated. OUT (Pins 1-3/Pins 1-3): This is the power output of the device. There must be a minimum load current of 1mA or the output may not regulate. SET (Pin 4/Pin 4): This pin is the input to the error amplifier and the regulation set point for the device. A fixed current of 10μA flows out of this pin through a single external resistor, which programs the output voltage of the device. Output voltage range is zero to the absolute maximum rated output voltage. Transient performance can be improved by adding a small capacitor from the SET pin to ground. Exposed Pad (Pin 9/Pin 9): OUT on MS8E and DFN packages. 30801fa 7 LT3080-1 BLOCK DIAGRAM IN VCONTROL 10μA + – 25mΩ 30801 BD SET OUT APPLICATIONS INFORMATION The LT3080-1 regulator is easy to use and has all the protection features expected in high performance regulators. Included are short-circuit protection and safe operating area protection, as well as thermal shutdown. The LT3080-1 is especially well suited to applications needing multiple rails. The new architecture adjusts down to zero with a single resistor handling modern low voltage digital IC’s as well as allowing easy parallel operation and thermal management without heat sinks. Adjusting to “zero” output allows shutting off the powered circuitry and when the input is pre-regulated—such as a 5V or 3.3V input supply—external resistors can help spread the heat. A precision “0” TC 10μA internal current source is connected to the non-inverting input of a power operational amplifier. The power operational amplifier provides a low impedance buffered output to the voltage on the non-inverting input. A single resistor from the non-inverting input to ground sets the output voltage and if this resistor is set to zero, zero output results. As can be seen, any output voltage can be obtained from zero up to the maximum defined by the input power supply. What is not so obvious from this architecture are the benefits of using a true internal current source as the reference as opposed to a bootstrapped reference in older regulators. A true current source allows the regulator to have gain and frequency response independent of the impedance on the positive input. Older adjustable regulators, such as the LT1086 have a change in loop gain with output voltage as well as bandwidth changes when the adjustment pin is bypassed to ground. For the LT3080-1, the loop gain is unchanged by changing the output voltage or bypassing. Output regulation is not fixed at a percentage of the output voltage but is a fixed fraction of millivolts. Use of a true current source allows all the gain in the buffer amplifier to provide regulation and none of that gain is needed to amplify up the reference to a higher output voltage. The LT3080-1 also incorporates an internal ballast resistor to allow for direct paralleling of devices without the need for PC board trace resistors or sense resistors. This internal ballast resistor allows multiple devices to be paralleled directly on a surface mount board for higher output current and higher power dissipation while keeping board layout simple and easy. It is not difficult to add more regulators for higher output current; inputs of devices are all tied together, outputs of all devices are tied directly together, and SET pins of all devices are tied directly together. Because of the internal ballast resistor, devices automatically share the load and the power dissipation. The LT3080-1 has the collector of the output transistor connected to a separate pin from the control input. Since the dropout on the collector (IN pin) is only 300mV, two supplies can be used to power the LT3080-1 to reduce 30801fa 8 LT3080-1 APPLICATIONS INFORMATION IN VCONTROL LT3080-1 + VIN + VCONTROL + – SET of all insulating surfaces to remove fluxes and other residues will probably be required. Surface coating may be necessary to provide a moisture barrier in high humidity environments. 25mΩ OUT VOUT COUT RSET CSET 30801 F01 Figure 1. Basic Adjustable Regulator dissipation: a higher voltage supply for the control circuitry and a lower voltage supply for the collector. This increases efficiency and reduces dissipation. To further spread the heat, a resistor can be inserted in series with the collector to move some of the heat out of the IC and spread it on the PC board. The LT3080-1 can be operated in two modes. Three terminal mode has the control pin connected to the power input pin which gives a limitation of 1.35V dropout. Alternatively, the “control” pin can be tied to a higher voltage and the power IN pin to a lower voltage giving 300mV dropout on the IN pin and minimizing the power dissipation. This allows for a 1.1A supply regulating from 2.5VIN to 1.8VOUT or 1.8VIN to 1.2VOUT with low dissipation. Output Voltage The LT3080-1 generates a 10μA reference current that flows out of the SET pin. Connecting a resistor from SET to ground generates a voltage that becomes the reference point for the error amplifier (see Figure 1). The reference voltage is a straight multiplication of the SET pin current and the value of the resistor. Any voltage can be generated and there is no minimum output voltage for the regulator. A minimum load current of 1mA is required to maintain regulation regardless of output voltage. For true zero voltage output operation, this 1mA load current must be returned to a negative supply voltage. With the low level current used to generate the reference voltage, leakage paths to or from the SET pin can create errors in the reference and output voltages. High quality insulation should be used (e.g., Teflon, Kel-F); cleaning Board leakage can be minimized by encircling the SET pin and circuitry with a guard ring operated at a potential close to itself; the guard ring should be tied to the OUT pin. Guarding both sides of the circuit board is required. Bulk leakage reduction depends on the guard ring width. Ten nanoamperes of leakage into or out of the SET pin and associated circuitry creates a 0.1% error in the reference voltage. Leakages of this magnitude, coupled with other sources of leakage, can cause significant offset voltage and reference drift, especially over the possible operating temperature range. If guardring techniques are used, this bootstraps any stray capacitance at the SET pin. Since the SET pin is a high impedance node, unwanted signals may couple into the SET pin and cause erratic behavior. This will be most noticeable when operating with minimum output capacitors at full load current. The easiest way to remedy this is to bypass the SET pin with a small amount of capacitance from SET to ground, 10pF to 20pF is sufficient. Stability and Output Capacitance The LT3080-1 requires an output capacitor for stability. It is designed to be stable with most low ESR capacitors (typically ceramic, tantalum or low ESR electrolytic). A minimum output capacitor of 2.2μF with an ESR of 0.5Ω or less is recommended to prevent oscillations. Larger values of output capacitance decrease peak deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT3080-1, increase the effective output capacitor value. For improvement in transient performance, place a capacitor across the voltage setting resistor. Capacitors up to 1μF can be used. This bypass capacitor reduces system noise as well, but start-up time is proportional to the time constant of the voltage setting resistor (RSET in Figure 1) and SET pin bypass capacitor. 30801fa 9 LT3080-1 APPLICATIONS INFORMATION Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior across temperature and applied voltage. The most common dielectrics used are specified with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but they tend to have strong voltage and temperature coefficients as shown in Figures 2 and 3. When used with a 5V regulator, a 16V 10μF Y5V capacitor can exhibit an effective value as low as 1μF to 2μF for the DC bias voltage applied and over the operating temperature range. The X5R and X7R dielectrics result in more stable characteristics and are more suitable for use as the output capacitor. The X7R type has better stability across temperature, while the X5R is less expensive and is available in higher values. Care still must be exercised when using X5R and X7R capacitors; the X5R and X7R codes only specify operating temperature range and maximum 20 0 CHANGE IN VALUE (%) X5R –20 –40 –60 Y5V –80 –100 VIN 0 2 4 8 6 10 12 DC BIAS VOLTAGE (V) 14 16 30801 F02 capacitance change over temperature. Capacitance change due to DC bias with X5R and X7R capacitors is better than Y5V and Z5U capacitors, but can still be significant enough to drop capacitor values below appropriate levels. Capacitor DC bias characteristics tend to improve as component case size increases, but expected capacitance at operating voltage should be verified. Voltage and temperature coefficients are not the only sources of problems. Some ceramic capacitors have a piezoelectric response. A piezoelectric device generates voltage across its terminals due to mechanical stress, similar to the way a piezoelectric microphone works. For a ceramic capacitor the stress can be induced by vibrations in the system or thermal transients. Paralleling Devices LT3080-1’s may be directly paralleled to obtain higher output current. The SET pins are tied together and the IN pins are tied together. This is the same whether it’s in three terminal mode or has separate input supplies. The outputs are connected in common; the internal ballast resistor equalizes the currents. The worst-case offset between the SET pin and the output of only ±2 millivolts allows very small ballast resistors to be used. As shown in Figure 4, the two devices have internal ballast resistors, which at full output current gives LT3080-1 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF VCONTROL Figure 2. Ceramic Capacitor DC Bias Characteristics 40 20 CHANGE IN VALUE (%) 0 –20 –40 –60 SET –80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF 50 25 75 0 TEMPERATURE (°C) 100 125 3080 F03 + – SET 25mΩ OUT X5R VIN 4.8V TO 28V VIN VCONTROL LT3080-1 1μF Y5V + – 25mΩ OUT VOUT 3.3V 2.2A 10μF 165k 30801 F04 –100 –50 –25 Figure 3. Ceramic Capacitor Temperature Characteristics Figure 4. Parallel Devices 30801fa 10 LT3080-1 APPLICATIONS INFORMATION better than 90 percent equalized sharing of the current. The internal resistance of 25 milliohms (per device) only adds about 25 millivolts of output regulation drop at an output of 2A. At low output voltage, 1V, this adds 2.5% regulation. The output can be set 19mV high for lower absolute error ±1.3%. Of course, more than two LT3080-1’s can be paralleled for even higher output current. They are spread out on the PC board, spreading the heat. Input resistors can further spread the heat if the input-to-output difference is high. Thermal Performance In this example, two LT3080-1 3mm × 3mm DFN devices are mounted on a 1oz copper 4-layer PC board. They are placed approximately 1.5 inches apart and the board is mounted vertically for convection cooling. Two tests were set up to measure the cooling performance and current sharing of these devices. The first test was done with approximately 0.7V inputto-output and 1A per device. This gave a 700 milliwatt dissipation in each device and a 2A output current. The temperature rise above ambient is approximately 28°C and both devices were within plus or minus 1°C. Both the thermal and electrical sharing of these devices is excellent. The thermograph in Figure 5 shows the temperature distribution between these devices and the PC board reaches ambient temperature within about a half an inch from the devices. The power is then increased with 1.7V across each device. This gives 1.7 watts dissipation in each device and a device temperature of about 90°C, about 65°C above ambient as shown in Figure 6. Again, the temperature matching between the devices is within 2°C, showing excellent tracking between the devices. The board temperature has reached approximately 40°C within about 0.75 inches of each device. While 90°C is an acceptable operating temperature for these devices, this is in 25°C ambient. For higher ambients, the temperature must be controlled to prevent device temperature from exceeding 125°C. A three meter per second airflow across the devices will decrease the device temperature about 20°C providing a margin for higher operating ambient temperatures. Both at low power and relatively high power levels devices can be paralleled for higher output current. Current sharing and thermal sharing is excellent, showing that acceptable operation can be had while keeping the peak temperatures below excessive operating temperatures on a board. This technique allows higher operating current linear regulation to be used in systems where it could never be used before. Figure 5. Temperature Rise at 700mW Dissipation Figure 6. Temperature Rise at 1.7W Dissipation 30801fa 11 LT3080-1 APPLICATIONS INFORMATION Quieting the Noise The LT3080-1 offers numerous advantages when it comes to dealing with noise. There are several sources of noise in a linear regulator. The most critical noise source for any LDO is the reference; from there, the noise contribution from the error amplifier must be considered, and the gain created by using a resistor divider cannot be forgotten. Traditional low noise regulators bring the voltage reference out to an external pin (usually through a large value resistor) to allow for bypassing and noise reduction of reference noise. The LT3080-1 does not use a traditional voltage reference like other linear regulators, but instead uses a reference current. That current operates with typical noise current levels of 3.2pA/√Hz (1nARMS over the 10Hz to 100kHz bandwidth). The voltage noise of this is equal to the noise current multiplied by the resistor value. The resistor generates spot noise equal to √4kTR (k = Boltzmann’s constant, 1.38 • 10-23 J/°K, and T is absolute temperature) which is RMS summed with the reference current noise. To lower reference noise, the voltage setting resistor may be bypassed with a capacitor, though this causes start-up time to increase as a factor of the RC time constant. The LT3080-1 uses a unity-gain follower from the SET pin to drive the output, and there is no requirement to use a resistor to set the output voltage. Use a high accuracy voltage reference placed at the SET pin to remove the errors in output voltage due to reference current tolerance and resistor tolerance. Active driving of the SET pin is acceptable; the limitations are the creativity and ingenuity of the circuit designer. One problem that a normal linear regulator sees with reference voltage noise is that noise is gained up along with the output when using a resistor divider to operate at levels higher than the normal reference voltage. With the LT3080-1, the unity-gain follower presents no gain whatsoever from the SET pin to the output, so noise figures do not increase accordingly. Error amplifier noise is typically 125nV/√Hz (40μVRMS over the 10Hz to 100kHz bandwidth); this is another factor that is RMS summed in to give a final noise figure for the regulator. Curves in the Typical Performance Characteristics show noise spectral density and peak-to-peak noise characteristics for both the reference current and error amplifier over the 10Hz to 100kHz bandwidth. Overload Recovery Like many IC power regulators, the LT3080-1 has safe operating area (SOA) protection. The SOA protection decreases current limit as the input-to-output voltage increases and keeps the power dissipation at safe levels for all values of input-to-output voltage. The LT3080-1 provides some output current at all values of input-to-output voltage up to the device breakdown. See the Current Limit curve in the Typical Performance Characteristics section. When power is first turned on, the input voltage rises and the output follows the input, allowing the regulator to start into very heavy loads. During start-up, as the input voltage is rising, the input-to-output voltage differential is small, allowing the regulator to supply large output currents. With a high input voltage, a problem can occur wherein removal of an output short will not allow the output voltage to recover. Other regulators, such as the LT1085 and LT1764A, also exhibit this phenomenon so it is not unique to the LT3080-1. The problem occurs with a heavy output load when the input voltage is high and the output voltage is low. Common situations are immediately after the removal of a short circuit. The load line for such a load may intersect the output current curve at two points. If this happens, there are two stable operating points for the regulator. With this double intersection, the input power supply may need to be cycled down to zero and brought up again to make the output recover. 30801fa 12 LT3080-1 APPLICATIONS INFORMATION Load Regulation Because the LT3080-1 is a floating device (there is no ground pin on the part, all quiescent and drive current is delivered to the load), it is not possible to provide true remote load sensing. Load regulation will be limited by the resistance of the connections between the regulator and the load. The data sheet specification for load regulation is Kelvin sensed at the pins of the package. Negative side sensing is a true Kelvin connection, with the bottom of the voltage setting resistor returned to the negative side of the load (see Figure 7). Connected as shown, system load regulation will be the sum of the LT3080-1 load regulation and the parasitic line resistance multiplied by the output current. It is important to keep the positive connection between the regulator and load as short as possible and use large wire or PC board traces. The internal 25mΩ ballast resistor is outside of the LT3080-1’s feedback loop. Therefore, the voltage drop across the ballast resistor appears as additional DC load regulation. However, this additional load regulation can actually improve transient response performance by decreasing peak-to-peak output voltage deviation and even save on total output capacitance. This technique is called active voltage positioning and is especially useful for applications that must withstand large output load current transients. For more information, see Design Note 224, “Active Voltage Positioning Reduces Output Capacitors.” The basic principle uses the fact that output voltage is a function of output load current. Output voltage is set based on the midpoint of the output load current range: 1 • IOUT(MIN) + IOUT(MAX ) 2 ( ) As output current decreases below the midpoint, output voltage increases above the nominal set-point. Correspondingly, as output current increases above the midpoint, output voltage decreases below the nominal set-point. During a large output load transient, output voltage perturbation is contained within a window that is tighter than what would result if active voltage positioning is not employed. Choose the SET pin resistor value by using the formula below: (V +I •R ) R SET = OUT MID BALLAST ISET where IMID = 1/2 (IOUT(MIN) + IOUT(MAX)) RBALLAST = 25mΩ ISET = 10μA Thermal Considerations The LT3080-1 has internal power and thermal limiting circuitry designed to protect it under overload conditions. For continuous normal load conditions, maximum junction temperature must not be exceeded. It is important to IN VCONTROL LT3080-1 + – SET RSET PARASITIC RESISTANCE 25mΩ OUT RP RP RP 30801 F07 LOAD Figure 7. Connections for Best Load Regulation 30801fa 13 LT3080-1 APPLICATIONS INFORMATION give consideration to all sources of thermal resistance from junction to ambient. This includes junction-to-case, case-to-heat sink interface, heat sink resistance or circuit board-to-ambient as the application dictates. Additional heat sources nearby must also be considered. For surface mount devices, heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Surface mount heat sinks and plated through-holes can also be used to spread the heat generated by power devices. Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the die. This is the lowest resistance path for heat flow. Proper mounting is required to ensure the best possible thermal flow from this area of the package to the heat sinking material. Note that the Exposed Pad is electrically connected to the output. The following tables list thermal resistance for several different copper areas given a fixed board size. All measurements were taken in still air on two-sided 1/16" FR-4 board with one ounce copper. Table 1. MSE 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 PCB layers, copper weight, board layout and thermal vias affect the resultant thermal resistance. Although Tables 1 and 2 provide thermal resistance numbers for a 2-layer board with 1 ounce copper, modern multilayer PCBs provide better performance than found in these tables. For example, a 4-layer, 1 ounce copper PCB board with five thermal vias from the DFN or MSOP exposed backside pad to inner layers (connected to VOUT) achieves 40°C/W thermal resistance. Demo circuit 995A’s board layout achieves this 40°C/W performance. This is approximately a 33% improvement over the numbers shown in Tables 1 and 2. Calculating Junction Temperature Example: Given an output voltage of 0.9V, a VCONTROL voltage of 3.3V ±10%, an IN voltage of 1.5V ±5%, output current range from 1mA to 1A and a maximum ambient temperature of 50°C, what will the maximum junction temperature be for the DFN package on a 2500mm2 board with topside copper area of 500mm2? The power in the drive circuit equals: PDRIVE = (VCONTROL – VOUT)(ICONTROL) where ICONTROL is equal to IOUT /60. ICONTROL is a function of output current. A curve of ICONTROL vs IOUT can be found in the Typical Performance Characteristics curves. The power in the output transistor equals: POUTPUT = (VIN – VOUT)(IOUT) The total power equals: PTOTAL = PDRIVE + POUTPUT The current delivered to the SET pin is negligible and can be ignored. *Device is mounted on topside Table 2. DD Package, 8-Lead DFN 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 + 5%) VOUT = 0.9V, IOUT = 1A, TA = 50°C *Device is mounted on topside 30801fa 14 LT3080-1 APPLICATIONS INFORMATION Power dissipation under these conditions is equal to: PDRIVE = (VCONTROL – VOUT)(ICONTROL) I 1A ICONTROL = OUT = = 17mA 60 60 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 be equal to: TJ = TA + PTOTAL • θJA (approximated using tables) TJ = 50°C + 721mW • 64°C/W = 96°C In this case, the junction temperature is below the maximum rating, ensuring reliable operation. Reducing Power Dissipation In some applications it may be necessary to reduce the power dissipation in the LT3080-1 package without sacrificing output current capability. Two techniques are available. The first technique, illustrated in Figure 8, employs a resistor in series with the regulator’s input. The voltage drop across RS decreases the LT3080-1’s IN-toOUT differential voltage and correspondingly decreases the LT3080-1’s power dissipation. As an example, assume: VIN = VCONTROL = 5V, VOUT = 3.3V and IOUT(MAX) = 1A. Use the formulas from the Calculating Junction Temperature section previously discussed. Without series resistor RS , power dissipation in the LT3080-1 equals: ⎛ 1A ⎞ PTOTAL = ( 5V – 3.3V ) • ⎜ ⎟ + ( 5V – 3.3V ) • 1A = 1.73W 7 ⎝ 60 ⎠ If the voltage differential (VDIFF) across the NPN pass transistor is chosen as 0.5V, then RS equals: RS = 5V – 3.3V − 0.5V = 1.2Ω 1A Power dissipation in the LT3080-1 now equals: ⎛ 1A ⎞ PTOTAL = ( 5V – 3.3V ) • ⎜ ⎟ + ( 0.5V ) • 1A = 0.53W ⎝ 60 ⎠ The LT3080-1’s power dissipation is now only 30% compared to no series resistor. RS dissipates 1.2W of power. Choose appropriate wattage resistors to handle and dissipate the power properly. VIN C1 VCONTROL LT3080-1 IN RS VIN + – SET RSET 25mΩ OUT C2 30801 F08 VOUT Figure 8. Reducing Power Dissipation Using a Series Resistor 30801fa 15 LT3080-1 APPLICATIONS INFORMATION The second technique for reducing power dissipation, shown in Figure 9, uses a resistor in parallel with the LT3080-1. This resistor provides a parallel path for current flow, reducing the current flowing through the LT3080-1. This technique works well if input voltage is reasonably constant and output load current changes are small. This technique also increases the maximum available output current at the expense of minimum load requirements. As an example, assume: VIN = VCONTROL = 5V, VIN(MAX) = 5.5V, VOUT = 3.3V, VOUT(MIN) = 3.2V, IOUT(MAX) = 1A and IOUT(MIN) = 0.7A. Also, assuming that RP carries no more than 90% of IOUT(MIN) = 630mA. Calculating RP yields: 5.5V – 3.2V = 3.65Ω 0.63A (5% Standard value = 3.6Ω) RP = The maximum total power dissipation is (5.5V – 3.2V) • 1A = 2.3W. However, the LT3080-1 supplies only: 1A – 5.5V – 3.2V = 0.36 A 3.6Ω Therefore, the LT3080-1’s power dissipation is only: PDIS = (5.5V – 3.2V) • 0.36A = 0.83W RP dissipates 1.47W of power. As with the first technique, choose appropriate wattage resistors to handle and dissipate the power properly. With this configuration, the LT3080-1 supplies only 0.36A. Therefore, load current can increase by 0.64A to 1.64A while keeping the LT3080-1 in its normal operating range. VIN C1 VCONTROL LT3080-1 IN + – SET RSET RP 25mΩ OUT C2 VOUT 30801 F09 Figure 9. Reducing Power Dissipation Using a Parallel Resistor 30801fa 16 LT3080-1 TYPICAL APPLICATIONS Adding Shutdown IN VCONTROL LT3080-1 + – SET LT3080-1 25mΩ OUT VIN IN VCONTROL + – SET Q1 VN2222LL R1 25mΩ OUT VOUT Q2* VN2222LL ON OFF SHUTDOWN 30801 TA02 *Q2 INSURES ZERO OUTPUT IN THE ABSENCE OF ANY OUTPUT LOAD Current Source VIN 10V IN VCONTROL LT3080-1 + – SET 25mΩ OUT IN VCONTROL LT3080-1 2.2μF + – SET 100k 25mΩ OUT 1Ω IOUT 0A TO 2A 10μF 30801 TA03 30801fa 17 LT3080-1 TYPICAL APPLICATIONS Using a Lower Value SET Resistor VIN 10V IN VCONTROL LT3080-1 + – SET IN VCONTROL C1 2.2μF LT3080-1 25mΩ OUT + – SET R1 24.9k 1% RSET 4.99k 1% VOUT = 0.5V + 2mA • RSET 25mΩ OUT VOUT 0.5V TO 10V R2 249Ω 1% 2mA COUT 10μF 30801 TA04 Adding Soft-Start VIN 4.8V TO 28V IN VCONTROL D1 IN4148 LT3080-1 + – SET 25mΩ OUT VOUT 3.3V 2.2A IN VCONTROL C1 2.2μF LT3080-1 + – SET C2 0.01μF R1 165k 25mΩ OUT COUT 10μF 30801 TA05 30801fa 18 LT3080-1 TYPICAL APPLICATIONS Lab Supply VIN 13V TO 18V IN VCONTROL LT3080-1 IN VCONTROL LT3080-1 + – SET IN VCONTROL LT3080-1 25mΩ OUT SET IN VCONTROL + – 25mΩ OUT LT3080-1 + – SET 25mΩ OUT 0.5Ω SET + – 25mΩ OUT VOUT 0V TO 10V 50k 0A TO 2A CURRENT LIMIT + 15μF + 15μF R4 500k + 10μF 100μF 3080 TA06 Boosting Fixed Output Regulators LT3080-1 + – SET 20mΩ 5V 10μF LT1963-3.3 42Ω* 25mΩ OUT 3.3VOUT 2.6A 47μF 30801 TA07 33k *4mV DROP ENSURES LT3080-1 IS OFF WITH NO-LOAD MULTIPLE LT3080-1’S CAN BE USED IN PARALLEL 30801fa 19 LT3080-1 TYPICAL APPLICATIONS Low Voltage, High Current Adjustable High Efficiency Regulator* 0.47μH PVIN 2.7V TO 5.5V † 2× + SVIN 2.2MEG 100k LTC3414 PGOOD RUN/SS 1000pF VFB 78.7k SYNC/MODE SGND PGND 124k SW 12.1k ITH RT 294k 470pF 10k + 2× 100μF 2N3906 IN VCONTROL LT3080-1 100μF + – SET IN VCONTROL 25mΩ OUT LT3080-1 * DIFFERENTIAL VOLTAGE ON LT3080-1 IS 0.6V SET BY THE VBE OF THE 2N3906 PNP † MAXIMUM OUTPUT VOLTAGE IS 1.5V + – SET 25mΩ OUT BELOW INPUT VOLTAGE 0V TO 4V † 4A IN VCONTROL LT3080-1 + – SET 25mΩ OUT IN VCONTROL LT3080-1 + – SET 100k 25mΩ OUT + 100μF 30801 TA08 30801fa 20 LT3080-1 TYPICAL APPLICATIONS Adjustable High Efficiency Regulator* CMDSH-4E 4.5V TO 25V † 10μF 1μF 100k VIN BOOST LT3493 0.1μF 10μH SW MBRM140 68μF TP0610L GND FB 10k SET SHDN 0.1μF IN VCONTROL LT3080-1 + – 25mΩ OUT 4.7μF 0V TO 10V † 1A *DIFFERENTIAL VOLTAGE ON LT3080-1 ≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD. † MAXIMUM OUTPUT VOLTAGE IS 2V BELOW INPUT VOLTAGE 1MEG 10k 30801 TA09 2 Terminal Current Source CCOMP* IN VCONTROL LT3080-1 + – SET 25mΩ 100k OUT R1 30801 TA10 *CCOMP R1 ≤ 10Ω 10μF R1 ≥ 10Ω 2.2μF CURRENT SET IOUT = 1V R1 30801fa 21 LT3080-1 PACKAGE DESCRIPTION DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ± 0.05 3.5 ± 0.05 1.65 ± 0.05 2.15 ± 0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ± 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 5 0.38 ± 0.10 8 3.00 ± 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) 1.65 ± 0.10 (2 SIDES) (DD) DFN 1203 0.200 REF 0.75 ± 0.05 4 0.25 ± 0.05 2.38 ± 0.10 (2 SIDES) 1 0.50 BSC 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE 30801fa 22 LT3080-1 PACKAGE DESCRIPTION MS8E Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1662) BOTTOM VIEW OF EXPOSED PAD OPTION 1 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) MIN 2.083 ± 0.102 3.20 – 3.45 (.082 ± .004) (.126 – .136) 8 0.42 ± 0.038 (.0165 ± .0015) TYP 0.65 (.0256) BSC 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 8 7 65 0.52 (.0205) REF RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 0° – 6° TYP 4.90 ± 0.152 (.193 ± .006) 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 0.254 (.010) GAUGE PLANE 1 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.18 (.007) SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP 1.10 (.043) MAX 23 4 0.86 (.034) REF 0.65 (.0256) NOTE: BSC 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 0.1016 ± 0.0508 (.004 ± .002) MSOP (MS8E) 0307 REV D 30801fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 23 LT3080-1 TYPICAL APPLICATION Paralleling Regulators IN VCONTROL LT3080-1 + – SET 25mΩ OUT VIN 4.8V TO 28V IN VCONTROL LT3080-1 + – 1μF SET 165k 25mΩ OUT VOUT 3.3V 2.2A 10μF 30801 TA11 RELATED PARTS PART NUMBER LDOs LT1086 LT1117 LT1118 LT1963A LT1965 1.5A Low Dropout Regulator 800mA Low Dropout Regulator 800mA Low Dropout Regulator 1.5A Low Noise, Fast Transient Response LDO 1.1A Low Noise LDO Fixed 2.85V, 3.3V, 3.6V, 5V and 12V Output 1V Dropout, Adjustable or Fixed Output, DD-Pak, SOT-223 Packages Okay for Sinking and Sourcing, S0-8 and SOT-223 Packages 340mV Dropout Voltage, Low Noise = 40μVRMS , VIN : 2.5V to 20V, TO-220, DD, SOT-223 and SO-8 Packages 290mV Dropout Voltage, Low Noise 40μVRMS , VIN : 1.8V to 20V, VOUT : 1.2V to 19.5V, Stable with Ceramic Caps, TO-220, DDPak, MSOP and 3mm × 3mm DFN Packages VIN : 1.14V to 3.5V (Boost Enabled), 1.14V to 5.5V (with External 5V), VDO = 0.1V, IQ = 950μA, Stable with 10μF Ceramic Capacitors, 10-Lead MSOP and DFN Packages 300mV Dropout Voltage (2-Supply Operation), Low Noise: 40μVRMS , VIN : 1.2V to 36V, VOUT : 0V to 35.7V, Current-Based Reference with 1-Resistor VOUT Set, Directly Parallelable (No Op Amp Required), Stable with Ceramic Capacitors, TO-220, SOT-223, MSOP and 3mm × 3mm DFN Packages. 95% Efficiency, VIN: 2.25V to 5.5V, VOUT(MIN) = 0.8V, TSSOP Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN) = 0.6V, IQ = 20μA, ISD < 1μA, ThinSOTTM Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN) = 0.8V, IQ = 60μA, ISD < 1μA, 10-Lead MS or DFN Packages 30801fa DESCRIPTION COMMENTS LTC®3026 LT3080 1.5A Low Input Voltage VLDOTM Regulator 1.1A, Parallelable, Low Noise, Low Dropout Linear Regulator Switching Regulators LTC3414 LTC3406/LTC3406B LTC3411 4A (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 and ThinSOT are trademarks of Linear Technology Corporation. 24 Linear Technology Corporation (408) 432-1900 ● FAX: (408) 434-0507 ● LT 1008 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 www.linear.com © LINEAR TECHNOLOGY CORPORATION 2008