LT3080 Adjustable1.1A Single Resistor Low Dropout Regulator FEATURES DESCRIPTION n The LT®3080 is a 1.1A low dropout linear regulator that can be paralleled to increase output current or spread heat in surface mounted boards. Architected as a precision current source and voltage follower allows this new regulator to be used in many applications requiring high current, adjustability to zero, and no heat sink. Also the device brings out the collector of the pass transistor to allow low dropout operation —down to 350 millivolts— when used with multiple supplies. n n n n n n n n n n n n n Outputs May be Paralleled 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 (Except SOT-223 Package) <1mV Load Regulation <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, 3mm × 3mm DFN, 5-Lead DD-Pak, TO-220 and 3-Lead SOT-223 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 A key feature of the LT3080 is the capability to supply a wide output voltage range. By using a reference current through a single resistor, the output voltage is programmed to any level between zero and 36V. The LT3080 is stable with 2.2μF of capacitance on the output, and the IC uses small ceramic capacitors that do not require additional ESR as is common with other regulators. Internal protection circuitry includes current limiting and thermal limiting. The LT3080 regulator is offered in the 8-lead MSOP (with an exposed pad for better thermal characteristics), a 3mm × 3mm DFN, 5-lead DD-Pak, TO-220 and a simple-to-use 3-lead SOT-223 version. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and VLDO and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Set Pin Current Distribution Variable Output Voltage 1.1A Supply LT3080 IN VIN 1.2V TO 36V N = 13792 VCONTROL + – 1μF OUT VOUT SET RSET VOUT = RSET • 10μA 3080 TA01a 2.2μF 9.80 10.00 10.20 9.90 10.10 SET PIN CURRENT DISTRIBUTION (μA) 3080 G02 3080fb 1 LT3080 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, Q, T and ST Packages Only.................... 300°C PIN CONFIGURATION TOP VIEW FRONT VIEW OUT 1 8 IN OUT 2 7 IN 6 NC 5 VCONTROL OUT 3 SET 4 9 DD PACKAGE 8-LEAD (3mm × 3mm) PLASTIC DFN TOP VIEW OUT OUT OUT SET 1 2 3 4 9 5 8 7 6 5 IN IN NC VCONTROL TAB IS OUT MS8E PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 64°C/W, θJC = 3°C/W EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB OUT 2 SET 1 NC TJMAX = 125°C, θJA = 30°C/W, θJC = 3°C/W FRONT VIEW FRONT VIEW TAB IS OUT VCONTROL 3 Q PACKAGE 5-LEAD PLASTIC DD-PAK TJMAX = 125°C, θJA = 60°C/W, θJC = 10°C/W EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB 5 IN 4 IN 4 VCONTROL 3 OUT 2 SET 1 NC TAB IS OUT 3 IN* 2 OUT 1 SET ST PACKAGE 3-LEAD PLASTIC SOT-223 *IN IS VCONTROL AND IN TIED TOGETHER T PACKAGE 5-LEAD PLASTIC TO-220 TJMAX = 125°C, θJA = 40°C/W, θJC = 3°C/W TJMAX = 125°C, θJA = 55°C/W, θJC = 15°C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING LT3080EDD#PBF LT3080EDD#TRPBF LCBN LT3080EMS8E#PBF LT3080EMS8E#TRPBF LTCBM LT3080EQ#PBF LT3080EQ#TRPBF LT3080EQ LT3080ET#PBF LT3080ET#TRPBF LT3080ET LT3080EST#PBF LT3080EST#TRPBF 3080 LEAD BASED FINISH TAPE AND REEL PART MARKING LT3080EDD LT3080EDD#TR LCBN LT3080EMS8E LT3080EMS8E#TR LTCBM LT3080EQ LT3080EQ#TR LT3080EQ LT3080ET LT3080ET#TR LT3080ET LT3080EST LT3080EST#TR 3080 Consult LTC Marketing for parts specified with wider operating temperature ranges. PACKAGE DESCRIPTION 8-Lead (3mm × 3mm) Plastic DFN 8-Lead Plastic MSOP 5-Lead Plastic DD-Pak 5-Lead Plastic TO-220 3-Lead Plastic SOT-223 PACKAGE DESCRIPTION 8-Lead (3mm × 3mm) Plastic DFN 8-Lead Plastic MSOP 5-Lead Plastic DD-Pak 5-Lead Plastic TO-220 3-Lead Plastic SOT-223 TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C 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/ 3080fb 2 LT3080 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 11) PARAMETER SET Pin Current Output Offset Voltage (VOUT – VSET) VIN = 1V, VCONTROL = 2V, IOUT = 1mA CONDITIONS ISET VIN = 1V, VCONTROL = 2.0V, ILOAD = 1mA, TJ = 25°C VIN ≥ 1V, VCONTROL ≥ 2.0V, 1mA ≤ ILOAD ≤ 1.1A (Note 9) VOS DFN and MSOP Package SOT-223, DD-Pak and T0-220 Package Load Regulation Line Regulation (Note 9) DFN and MSOP Package ΔISET ΔILOAD = 1mA to 1.1A ΔVOS ΔILOAD = 1mA to 1.1A (Note 8) ΔISET VIN = 1V to 25V, VCONTROL = 2V to 25V, ILOAD = 1mA ΔVOS VIN = 1V to 25V, VCONTROL = 2V to 25V, ILOAD = 1mA Line Regulation (Note 9) SOT-223, DD-Pak and T0-220 Package ΔISET VIN = 1V to 26V, VCONTROL = 2V to 26V, ILOAD = 1mA ΔVOS VIN = 1V to 26V, VCONTROL = 2V to 26V, ILOAD = 1mA MIN TYP MAX UNITS l 9.90 9.80 10 10 10.10 10.20 μA μA l –2 –3.5 2 3.5 mV mV l –5 –6 5 6 mV mV 1.3 nA mV –0.1 0.6 l l 0.1 0.003 0.5 nA/V mV/V l 0.1 0.003 0.5 nA/V mV/V 300 500 1 1 μA mA mA Minimum Load Current (Notes 3, 9) VIN = VCONTROL = 10V VIN = VCONTROL = 25V (DFN and MSOP Package) VIN = VCONTROL = 26V (SOT-223, DD-Pak and T0-220 Package) l l l VCONTROL Dropout Voltage (Note 4) ILOAD = 100mA ILOAD = 1.1A l 1.2 1.35 1.6 V V VIN Dropout Voltage (Note 4) ILOAD = 100mA ILOAD = 1.1A l l 100 350 200 500 mV mV VCONTROL Pin Current ILOAD = 100mA ILOAD = 1.1A l l 4 17 6 30 mA mA Current Limit VIN = 5V, VCONTROL = 5V, VSET = 0V, VOUT = –0.1V l Error Amplifier RMS Output Noise (Note 6) ILOAD = 1.1A, 10Hz ≤ f ≤ 100kHz, COUT = 10μF, CSET = 0.1μF 1.1 1.4 A 40 μVRMS Reference Current RMS Output Noise (Note 6) 10Hz ≤ f ≤ 100kHz 1 nARMS Ripple Rejection f = 120Hz, VRIPPLE = 0.5VP-P, ILOAD = 0.2A, CSET = 0.1μF, COUT = 2.2μF f = 10kHz f = 1MHz 75 55 20 dB dB dB Thermal Regulation, ISET 10ms Pulse 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 is tested and specified under pulse load conditions such that TJ ≈ TA. The LT3080 E-Grade 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, 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 VCONTROL 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 0.003 %/W resistor shot noise and reference current noise; output noise is then equal to error amplifier noise (see 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 25V (DFN and MSOP package) or 26V (SOT-223, DD-Pak and T0-220 Package). 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 overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed the maximum operating junction temperature when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 11: The SOT-223 package connects the IN and VCONTROL pins together internally. Therefore, test conditions for this pin follow the VCONTROL conditions listed in the Electrical Characteristics Table. 3080fb 3 LT3080 TYPICAL PERFORMANCE CHARACTERISTICS Set Pin Current Set Pin Current Distribution Offset Voltage (VOUT – VSET) 10.20 2.0 1.5 10.10 OFFSET VOLTAGE (mV) SET PIN CURRENT (μA) IL = 1mA N = 13792 10.15 10.05 10.00 9.95 9.90 9.85 0 9.80 25 50 75 100 125 150 TEMPERATURE (°C) –0.5 –1.0 Offset Voltage Offset Voltage 0.25 ILOAD = 1mA 0.75 0 0.50 –0.25 OFFSET VOLTAGE (mV) OFFSET VOLTAGE (mV) N = 13250 0.25 0 –0.25 –0.50 –0.75 –1.00 2 3080 G04 20 ΔILOAD = 1mA TO 1.1A VIN – VOUT = 2V 10 CHANGE IN REFERENCE CURRENT 0 –0.3 –0.4 –10 CHANGE IN OFFSET VOLTAGE –20 (VOUT – VSET) –0.5 –30 –0.6 –40 –0.7 –50 –0.8 –50 –25 0 –60 25 50 75 100 125 150 TEMPERATURE (°C) 3080 G07 TJ = 125°C –0.75 –1.00 –1.25 –1.50 6 24 30 18 INPUT-TO-OUTPUT VOLTAGE (V) *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 0 12 36* –1.75 0.2 0.4 0.8 0.6 LOAD CURRENT (A) 1.2 1.0 3080 G06 Dropout Voltage (Minimum IN Voltage) 400 0.8 0.7 0.6 0 3080 G05 Minimum Load Current MINIMUM LOAD CURRENT (mA) 0 CHANGE IN REFERENCE CURRENT WITH LOAD (nA) Load Regulation TJ = 25°C –0.50 MINIMUM IN VOLTAGE (VIN – VOUT) (mV) 0 –1 1 VOS DISTRIBUTION (mV) 25 50 75 100 125 150 TEMPERATURE (°C) 3080 G03 1.00 –2 0 3080 G02 Offset Voltage Distribution CHANGE IN OFFSET VOLTAGE WITH LOAD (mV) 0 –2.0 –50 –25 10.00 10.20 9.90 10.10 SET PIN CURRENT DISTRIBUTION (μA) 3080 G01 –0.2 0.5 –1.5 9.80 –50 –25 –0.1 1.0 VIN, CONTROL – VOUT = 36V* 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) *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 3080 G08 350 TJ = 125°C 300 250 TJ = 25°C 200 150 100 50 0 0 0.2 0.4 0.8 0.6 OUTPUT CURRENT (A) 1.0 1.2 3080 G09 3080fb 4 LT3080 ILOAD = 1.1A 300 250 ILOAD = 500mA 150 100 ILOAD = 100mA 50 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 1.4 1.2 TJ = 125°C 1.0 TJ = 25°C 0.8 0.6 0.4 0.2 0 0.2 0 0.4 0.8 0.6 OUTPUT CURRENT (A) 1.4 1.4 1.2 1.2 CURRENT LIMIT (A) 1.0 0.8 0.6 SOT-223, DD-PAK AND TO-220 1.0 0.8 0 25 50 75 100 125 150 TEMPERATURE (°C) MSOP AND DFN Load Transient Response OUTPUT VOLTAGE DEVIATION (mV) –50 1.2 VIN = VCONTROL = 3V VOUT = 1.5V COUT = 10μF CERAMIC CSET = 0.1μF 0 5 10 15 20 25 30 35 40 45 50 TIME (μs) 3080 G16 IN/CONTROL VOLTAGE (V) OUTPUT VOLTAGE DEVIATION (mV) 0 0.3 0.8 0.6 0.4 0.2 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) VOUT = 1.5V CSET = 0.1μF VIN = VCONTROL = 3V 50 25 0 –25 COUT = 10μF CERAMIC 24 30 18 INPUT-TO-OUTPUT DIFFERENTIAL (V) 36* 300 200 100 0 0 –25 VOUT = 1.5V ILOAD = 10mA COUT = 2.2μF CERAMIC CSET = 0.1μF CERAMIC 5 4 3 2 0 5 10 15 20 25 30 35 40 45 50 TIME (μs) 3080 G15 Turn-On Response 25 6 0 3080 G14 50 –50 COUT = 2.2μF CERAMIC 400 Line Transient Response –100 LOAD CURRENT (A) 12 75 50 0 6 0 *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 150 100 ILOAD = 1mA –50 0.6 3080 G13 0.6 1.0 Load Transient Response 0.2 VIN = 7V VOUT = 0V 0.9 1.2 75 TJ = 25°C 0.4 0.4 ILOAD = 1.1A 1.4 3080 G12 INPUT VOLTAGE (V) CURRENT LIMIT (A) 1.6 0 1.6 Current Limit Current Limit 1.6 0 –50 –25 Dropout Voltage (Minimum VCONTROL Pin Voltage) 3080 G11 3080 G10 0.2 1.2 1.0 OUTPUT VOLTAGE DEVIATION (mV) 200 TJ = –50°C LOAD CURRENT (mA) 350 1.6 10 20 30 40 50 60 70 80 90 100 TIME (μs) 3080 G17 5 4 3 2 1 RSET = 100k CSET = 0 RLOAD = 1Ω COUT = 2.2μF CERAMIC 0 OUTPUT VOLTAGE (V) MINIMUM IN VOLTAGE (VIN – VOUT) (mV) 400 Dropout Voltage (Minimum VCONTROL Pin Voltage) MINIMUM CONTROL VOLTAGE (VCONTROL – VOUT) (V) Dropout Voltage (Minimum IN Voltage) MINIMUM CONTROL VOLTAGE (VCONTROL – VOUT) (V) TYPICAL PERFORMANCE CHARACTERISTICS 2.0 1.5 1.0 0.5 0 0 1 2 3 4 5 6 TIME (μs) 7 8 9 10 3080 G27 3080fb 5 LT3080 TYPICAL PERFORMANCE CHARACTERISTICS 25 0.8 30 ILOAD = 1.1A 20 DEVICE IN CURRENT LIMIT 15 10 5 VCONTROL – VOUT = 2V VIN – VOUT = 1V 25 20 TJ = –50°C 15 TJ = 25°C 10 TJ = 125°C 5 0 30 12 18 24 6 INPUT-TO-OUTPUT DIFFERENTIAL (V) *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 0 36* 0.5 VIN = 20V 0.3 VIN = 5V 0.2 0.2 0.4 0.6 0.8 LOAD CURRENT (A) 1.0 0 1.2 100 100 90 90 90 80 80 50 40 30 20 V = V IN CONTROL = VOUT (NOMINAL) + 2V 10 RIPPLE = 50mVP-P COUT = 2.2µF CERAMIC 0 10 100 1k 10k 100k FREQUENCY (Hz) 1M 70 ILOAD = 100mA RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) ILOAD = 1.1A 2k Ripple Rejection, Dual Supply, IN Pin 100 60 1k RTEST (Ω) 3080 G20 Ripple Rejection, Dual Supply, VCONTROL Pin ILOAD = 100mA VIN = 10V 0.4 3080 G19 80 RIPPLE REJECTION (dB) 0.6 0 0 3080 G18 Ripple Rejection, Single Supply 70 VOUT RTEST 0.1 ILOAD = 1mA 0 SET PIN = 0V VIN 0.7 OUTPUT VOLTAGE (V) CONTROL PIN CURRENT (mA) CONTROL PIN CURRENT (mA) Residual Output Voltage with Less Than Minimum Load VCONTROL Pin Current VCONTROL Pin Current ILOAD = 1.1A 60 50 40 30 VIN = VOUT (NOMINAL) + 1V 20 V CONTROL = VOUT (NOMINAL) +2V 10 COUT = 2.2µF CERAMIC RIPPLE = 50mVP-P 0 10 100 1k 10k 100k FREQUENCY (Hz) 3080 G21 70 60 50 40 30 20 10 VIN = VOUT (NOMINAL) + 1V VCONTROL = VOUT (NOMINAL) +2V RIPPLE = 50mVP-P COUT = 2.2µF CERAMIC ILOAD = 1.1A 0 1M 10 100 1k 10k FREQUENCY (Hz) 100k 1M 3080 G23 3080 G22 Noise Spectral Density Ripple Rejection (120Hz) 80 10k 1k 1k 100 79 ERROR AMPLIFIER NOISE SPECTRAL DENSITY (nV/√Hz) 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 70 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3080 G24 100 10 10 1.0 1 10 100 1k 10k FREQUENCY (Hz) REFERENCE CURRENT NOISE SPECTRAL DENSITY (pA/ √Hz) 78 0.1 100k 3080 G25 3080fb 6 LT3080 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage Noise Error Amplifier Gain and Phase 300 20 250 200 IL = 1.1A VOUT = 1V RSET = 100k CSET = O.1μF COUT = 10μF ILOAD = 1.1A TIME 1ms/DIV 3080 G26 GAIN (dB) 5 150 100 0 IL = 100mA –5 50 IL = 1.1A –10 –15 0 –50 IL = 100mA –20 –100 –150 –25 –30 10 PHASE (DEGREES) VOUT 100μV/DIV 15 10 100 1k 10k FREQUENCY (Hz) 100k –200 1M 3080 G28 PIN FUNCTIONS (DD/MS8E/Q/T/ST) VCONTROL (Pin 5/Pin 5/Pin 4/Pin 4/NA): 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/Pin 5/Pin 5/Pin 3): This is the collector to the power device of the LT3080. 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/Pin 1/Pin 1/NA): 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/Pin 3/Pin 3/Pin 2): 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/Pin 2/Pin 2/Pin 1): 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/NA/NA/NA): OUT on MS8E and DFN packages. TAB: OUT on DD-Pak, TO-220 and SOT-223 packages. 3080fb 7 LT3080 BLOCK DIAGRAM IN VCONTROL 10μA + – 3080 BD SET OUT APPLICATIONS INFORMATION The LT3080 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 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 noninverting input of a power operational amplifier. The power operational amplifier provides a low impedance buffered output to the voltage on the noninverting input. A single resistor from the noninverting 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, 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 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 350mV, two supplies can be used to power the LT3080 to reduce 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 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 350mV 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. 3080fb 8 LT3080 APPLICATIONS INFORMATION LT3080 IN VCONTROL + + – + VIN VCONTROL OUT VOUT SET COUT RSET CSET 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. 3080 F01 Figure 1. Basic Adjustable Regulator Output Voltage The LT3080 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 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. 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. Stability and Output Capacitance The LT3080 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, 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. 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 3080fb 9 LT3080 APPLICATIONS INFORMATION 20 ceramic capacitor the stress can be induced by vibrations in the system or thermal transients. BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF CHANGE IN VALUE (%) 0 X5R Paralleling Devices –20 –40 –60 Y5V –80 –100 0 2 4 14 8 6 10 12 DC BIAS VOLTAGE (V) 16 3080 F02 CHANGE IN VALUE (%) Figure 2. Ceramic Capacitor DC Bias Characteristics LT3080’s may be 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 using a small piece of PC trace as a ballast resistor to equalize the currents. PC trace resistance in milliohms/inch is shown in Table 1. Only a tiny area is needed for ballasting. Table 1. PC Board Trace Resistance WEIGHT (oz) 10 mil WIDTH 20 mil WIDTH 40 1 54.3 27.1 20 2 27.1 13.6 Trace resistance is measured in mOhms/in X5R 0 –20 –40 Y5V –60 –80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF –100 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 The worse 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 a small 10 milliohm ballast resistor, which at full output current gives better than 80 percent equalized sharing of the current. The external resistance of 10 milliohms VIN 3080 F03 Figure 3. Ceramic Capacitor Temperature Characteristics 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 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 LT3080 VCONTROL + – OUT 10mΩ SET VIN 4.8V TO 28V VIN LT3080 VCONTROL + – 1μF OUT 10mΩ SET VOUT 3.3V 2A 10μF 165k 3080 F04 Figure 4. Parallel Devices 3080fb 10 LT3080 APPLICATIONS INFORMATION (5 milliohms for the two devices in parallel) only adds about 10 millivolts of output regulation drop at an output of 2A. Even with an output voltage as low as 1V, this only adds 1% to the regulation. Of course, more than two LT3080’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 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 Figure 5. Temperature Rise at 700mW Dissipation 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 3-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. Quieting the Noise The LT3080 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 Figure 6. Temperature Rise at 1.7W Dissipation 3080fb 11 LT3080 APPLICATIONS INFORMATION 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 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 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, 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 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 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. 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. 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. Load Regulation Because the LT3080 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 IN LT3080 VCONTROL PARASITIC RESISTANCE + – OUT SET RSET RP RP LOAD RP 3080 F07 Figure 7. Connections for Best Load Regulation 3080fb 12 LT3080 APPLICATIONS INFORMATION 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 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. Thermal Considerations The LT3080 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 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. For the TO-220 package, thermal compound is strongly recommended for mechanical connections to a heat sink. A thermally conductive spacer can be used for electrical isolation as long as the added contribution to thermal resistance is considered. Note that the Tab or Exposed Pad (depending on package) 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 2. MSE Package, 8-Lead MSOP COPPER AREA TOPSIDE* BACKSIDE BOARD AREA 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 55°C/W 1000mm2 2500mm2 2500mm2 57°C/W 225mm2 2500mm2 2500mm2 60°C/W 100mm2 2500mm2 2500mm2 65°C/W *Device is mounted on topside Table 3. DD Package, 8-Lead DFN COPPER AREA TOPSIDE* BACKSIDE BOARD AREA 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 60°C/W 1000mm2 2500mm2 2500mm2 62°C/W 225mm2 2500mm2 2500mm2 65°C/W 100mm2 2500mm2 2500mm2 68°C/W *Device is mounted on topside Table 4. ST Package, 3-Lead SOT-223 COPPER AREA TOPSIDE* BACKSIDE BOARD AREA 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 48°C/W 1000mm2 2500mm2 2500mm2 48°C/W 225mm2 2500mm2 2500mm2 56°C/W 100mm2 2500mm2 2500mm2 62°C/W *Device is mounted on topside Table 5. Q Package, 5-Lead DD-Pak COPPER AREA TOPSIDE* BACKSIDE BOARD AREA 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 25°C/W 1000mm2 2500mm2 2500mm2 30°C/W 125mm2 2500mm2 2500mm2 35°C/W *Device is mounted on topside T Package, 5-Lead TO-220 Thermal Resistance (Junction-to-Case) = 3°C/W 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? 3080fb 13 LT3080 APPLICATIONS INFORMATION The power in the drive circuit equals: Junction Temperature will be equal to: PDRIVE = (VCONTROL – VOUT)(ICONTROL) TJ = TA + PTOTAL • θJA (approximated using tables) 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. TJ = 50°C + 721mW • 64°C/W = 96°C In this case, the junction temperature is below the maximum rating, ensuring reliable operation. The power in the output transistor equals: Reducing Power Dissipation POUTPUT = (VIN – VOUT)(IOUT) The total power equals: PTOTAL = PDRIVE + POUTPUT The current delivered to the SET pin is negligible and can be ignored. VCONTROL(MAX CONTINUOUS) = 3.630V (3.3V + 10%) VIN(MAX CONTINUOUS) = 1.575V (1.5V + 5%) VOUT = 0.9V, IOUT = 1A, TA = 50°C Power dissipation under these conditions is equal to: PDRIVE = (VCONTROL – VOUT)(ICONTROL) ICONTROL = In some applications it may be necessary to reduce the power dissipation in the LT3080 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’s IN-to-OUT differential voltage and correspondingly decreases the LT3080’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 equals: IOUT 1A = = 17mA 60 60 PDRIVE = (3.630V – 0.9V)(17mA) = 46mW PTOTAL = (5V – 3.3V ) • POUTPUT = (VIN – VOUT)(IOUT) =1.73W POUTPUT = (1.575V – 0.9V)(1A) = 675mW Total Power Dissipation = 721mW If the voltage differential (VDIFF) across the NPN pass transistor is chosen as 0.5V, then RS equals: RS = VIN C1 VCONTROL LT3080 RS IN VINʹ + – OUT SET RSET 1A + (5V – 3.3V ) • 1A 60 VOUT C2 3080 F08 5V – 3.3V −0.5V =1.2Ω 1A Power dissipation in the LT3080 now equals: PTOTAL = (5V – 3.3V ) • 1A + (0.5V ) • 1A = 0.53W 60 The LT3080’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. Figure 8. Reducing Power Dissipation Using a Series Resistor 3080fb 14 LT3080 APPLICATIONS INFORMATION The second technique for reducing power dissipation, shown in Figure 9, uses a resistor in parallel with the LT3080. This resistor provides a parallel path for current flow, reducing the current flowing through the LT3080. 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. The maximum total power dissipation is (5.5V – 3.2V) • 1A = 2.3W. However the LT3080 supplies only: 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. 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 supplies only 0.36A. Therefore, load current can increase by 0.64A to 1.64A while keeping the LT3080 in its normal operating range. Calculating RP yields: 1A – 5.5V – 3.2V = 0.36A 3.6Ω Therefore, the LT3080’s power dissipation is only: PDIS = (5.5V – 3.2V) • 0.36A = 0.83W 5.5V – 3.2V = 3.65Ω 0.63A (5% Standard value = 3.6Ω) RP = VIN C1 VCONTROL LT3080 IN RP + – OUT SET RSET VOUT C2 3080 F09 Figure 9. Reducing Power Dissipation Using a Parallel Resistor 3080fb 15 LT3080 TYPICAL APPLICATIONS Higher Output Current Adding Shutdown MJ4502 VIN 6V 50Ω LT3080 IN LT3080 IN VIN VCONTROL + – VCONTROL + + – 100μF 1μF VOUT VOUT 3.3V 5A OUT + SET 4.7μF SET Q1 VN2222LL ON OFF Q2* VN2222LL 1N4148 SHUTDOWN 3080 TA04 *Q2 INSURES ZERO OUTPUT IN THE ABSENCE OF ANY OUTPUT LOAD. 3080 TA02 Current Source Low Dropout Voltage LED Driver VIN LT3080 IN R1 100μF 332k VIN 10V OUT VCONTROL C1 LT3080 100mA D1 IN VCONTROL + – 1μF OUT 1Ω + – IOUT 0A TO 1A SET OUT 4.7μF SET R1 24.9k 100k 3080 TA03 R2 2.49Ω 3080 TA05 Using a Lower Value SET Resistor IN VIN 12V LT3080 VCONTROL C1 1μF + – OUT SET R1 49.9k 1% 1mA VOUT 0.5V TO 10V R2 499Ω 1% VOUT = 0.5V + 1mA • RSET COUT 4.7μF RSET 10k 3080 TA06 3080fb 16 LT3080 TYPICAL APPLICATIONS Coincident Tracking LT3080 IN VCONTROL LT3080 IN + – VCONTROL OUT LT3080 IN VIN 7V TO 28V + – VCONTROL SET 169k OUT + – C1 1.5μF SET R2 80.6k OUT SET R1 249k VOUT3 5V 4.7μF 3080 TA08 VOUT2 3.3V C3 4.7μF C2 4.7μF VOUT1 2.5V 1A Adding Soft-Start LT3080 IN VIN 4.8V to 28V VCONTROL C1 1μF + – D1 1N4148 OUT SET C2 0.01μF VOUT 3.3V 1A COUT 4.7μF R1 332k 3080 TA07 Lab Supply LT3080 IN VIN 12V TO 18V LT3080 IN VCONTROL VCONTROL + – + 15μF + – OUT 1Ω OUT + SET 100k 0A TO 1A + SET 15μF R4 1MEG VOUT 0V TO 10V 4.7μF 100μF 3080 TA09 3080fb 17 LT3080 TYPICAL APPLICATIONS High Voltage Regulator 6.1V 10k VIN 50V 1N4148 IN LT3080 BUZ11 VCONTROL + + – 10μF VOUT 1A OUT SET RSET 2MEG + 15μF VOUT = 20V VOUT = 10μA • RSET 4.7μF 3080 TA10 Reference Buffer Ramp Generator LT3080 IN VIN 5V LT3080 IN VIN VCONTROL VCONTROL + – 1μF + – OUT OUT VOUT INPUT SET VN2222LL 1μF 1N4148 LT1019 4.7μF VN2222LL OUTPUT SET C1 1μF GND VOUT* C2 4.7μF 3080 TA11 *MIN LOAD 0.5mA 3080 TA12 Ground Clamp Boosting Fixed Output Regulators LT3080 LT3080 IN VIN VEXT + – VCONTROL 20Ω + – OUT OUT 1μF 20mΩ SET VOUT 20mΩ 5V 1N4148 4.7μF 3.3VOUT 2.6A LT1963-3.3 10μF 42Ω* 47μF 5k 3080 TA20 33k 3080 TA13 *4mV DROP ENSURES LT3080 IS OFF WITH NO LOAD MULTIPLE LT3080’S CAN BE USED 3080fb 18 LT3080 TYPICAL APPLICATIONS Low Voltage, High Current Adjustable High Efficiency Regulator* 0.47μH 2.7V TO 5.5V† 2× + 100μF 2.2MEG 100k PVIN SW SVIN ITH LTC3414 10k + 12.1k RT 470pF 294k PGOOD 2× 100μF 2N3906 LT3080 IN VCONTROL RUN/SS + – VFB 1000pF OUT 78.7k SGND PGND 20mΩ SET SYNC/MODE 124k LT3080 IN VCONTROL + – *DIFFERENTIAL VOLTAGE ON LT3080 IS 0.6V SET BY THE VBE OF THE 2N3906 PNP. OUT †MAXIMUM OUTPUT VOLTAGE IS 1.5V BELOW INPUT VOLTAGE 20mΩ SET 0V TO 4V† 4A LT3080 IN VCONTROL + – OUT 20mΩ SET LT3080 IN VCONTROL + – OUT 3080 TA18 SET 100k 20mΩ + 100μF 3080fb 19 LT3080 TYPICAL APPLICATIONS Adjustable High Efficiency Regulator* CMDSH-4E 4.5V TO 25V† VIN 10μF 1μF 100k BOOST LT3493 SHDN 0.1μF 10μH 0.1μF MBRM140 GND LT3080 IN SW 68μF 200k TP0610L VCONTROL + – FB OUT 10k 3080 TA19 SET 0V TO 10V† 1A 4.7μF 1MEG *DIFFERENTIAL VOLTAGE ON LT3080 ≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD. 10k †MAXIMUM OUTPUT VOLTAGE IS 2V BELOW INPUT VOLTAGE 2 Terminal Current Source CCOMP* IN LT3080 VCONTROL + – R1 SET 100k 3080 TA21 *CCOMP R1 ≤ 10Ω 10μF R1 ≥ 10Ω 2.2μF IOUT = 1V R1 3080fb 20 LT3080 PACKAGE DESCRIPTION DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698 Rev C) 0.70 p0.05 3.5 p0.05 1.65 p0.05 2.10 p0.05 (2 SIDES) PACKAGE OUTLINE 0.25 p 0.05 0.50 BSC 2.38 p0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 3.00 p0.10 (4 SIDES) R = 0.125 TYP 5 0.40 p 0.10 8 1.65 p 0.10 (2 SIDES) PIN 1 TOP MARK (NOTE 6) (DD8) DFN 0509 REV C 0.200 REF 0.75 p0.05 4 0.25 p 0.05 1 0.50 BSC 2.38 p0.10 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 3080fb 21 LT3080 PACKAGE DESCRIPTION MS8E Package 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 Rev F) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 (.074) 1 0.889 p 0.127 (.035 p .005) 1.88 p 0.102 (.074 p .004) 0.29 REF 1.68 (.066) 0.05 REF 5.23 (.206) MIN DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 1.68 p 0.102 3.20 – 3.45 (.066 p .004) (.126 – .136) 8 0.42 p 0.038 (.0165 p .0015) TYP 3.00 p 0.102 (.118 p .004) (NOTE 3) 0.65 (.0256) BSC 8 7 6 5 0.52 (.0205) REF RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 3.00 p 0.102 (.118 p .004) (NOTE 4) 4.90 p 0.152 (.193 p .006) DETAIL “A” 0o – 6o TYP GAUGE PLANE 1 0.53 p 0.152 (.021 p .006) DETAIL “A” 2 3 4 1.10 (.043) MAX 0.86 (.034) REF 0.18 (.007) SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP 0.65 (.0256) BSC 0.1016 p 0.0508 (.004 p .002) MSOP (MS8E) 0210 REV F NOTE: 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 6. EXPOSED PAD DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE. 3080fb 22 LT3080 PACKAGE DESCRIPTION Q Package 5-Lead Plastic DD-Pak (Reference LTC DWG # 05-08-1461) .256 (6.502) .060 (1.524) TYP .060 (1.524) .390 – .415 (9.906 – 10.541) .165 – .180 (4.191 – 4.572) .045 – .055 (1.143 – 1.397) 15o TYP .060 (1.524) .183 (4.648) +.008 .004 –.004 +0.203 0.102 –0.102 .059 (1.499) TYP .330 – .370 (8.382 – 9.398) .095 – .115 (2.413 – 2.921) .075 (1.905) .300 (7.620) .067 (1.702) .028 – .038 BSC (0.711 – 0.965) TYP +.012 .143 –.020 +0.305 3.632 –0.508 BOTTOM VIEW OF DD-PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK Q(DD5) 0502 .420 .276 .080 .420 .050 p .012 (1.270 p 0.305) .013 – .023 (0.330 – 0.584) .325 .350 .205 .565 .565 .320 .090 .090 .067 .042 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT TO SCALE .067 .042 RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS 3080fb 23 LT3080 PACKAGE DESCRIPTION T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) .165 – .180 (4.191 – 4.572) .147 – .155 (3.734 – 3.937) DIA .390 – .415 (9.906 – 10.541) .045 – .055 (1.143 – 1.397) .230 – .270 (5.842 – 6.858) .570 – .620 (14.478 – 15.748) .460 – .500 (11.684 – 12.700) .620 (15.75) TYP .330 – .370 (8.382 – 9.398) .700 – .728 (17.78 – 18.491) .095 – .115 (2.413 – 2.921) SEATING PLANE .152 – .202 .260 – .320 (3.861 – 5.131) (6.60 – 8.13) .155 – .195* (3.937 – 4.953) .013 – .023 (0.330 – 0.584) BSC .067 (1.70) .135 – .165 (3.429 – 4.191) .028 – .038 (0.711 – 0.965) * MEASURED AT THE SEATING PLANE T5 (TO-220) 0801 ST Package 3-Lead Plastic SOT-223 (Reference LTC DWG # 05-08-1630) .248 – .264 (6.30 – 6.71) .129 MAX .114 – .124 (2.90 – 3.15) .059 MAX .264 – .287 (6.70 – 7.30) .248 BSC .130 – .146 (3.30 – 3.71) .039 MAX .059 MAX .181 MAX .033 – .041 (0.84 – 1.04) .0905 (2.30) BSC RECOMMENDED SOLDER PAD LAYOUT 10o – 16o .010 – .014 (0.25 – 0.36) 10o MAX .071 (1.80) MAX .090 BSC 10o – 16o .024 – .033 (0.60 – 0.84) .181 (4.60) BSC .012 (0.31) MIN .0008 – .0040 (0.0203 – 0.1016) ST3 (SOT-233) 0502 3080fb 24 LT3080 REVISION HISTORY (Revision history begins at Rev B) REV DATE DESCRIPTION B 6/10 Made minor updates to Features and Description sections PAGE NUMBER 1 Revised Line Regulation Conditions and Note 2 3 Made minor text edits in Applications Information section 9 Added 200k resistor to drawing 3080 TA19 in Typical Applications section Updated Package Description drawings 20 21, 22 3080fb 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. 25 LT3080 TYPICAL APPLICATION Paralleling Regulators LT3080 IN VCONTROL + – OUT 20mΩ SET LT3080 IN VIN 4.8V TO 28V VCONTROL + – 1μF OUT 20mΩ VOUT 3.3V 2A SET 10μF 165k 3080 TA14 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1086 1.5A Low Dropout Regulator Fixed 2.85V, 3.3V, 3.6V, 5V and 12V Output LT1117 800mA Low Dropout Regulator 1V Dropout, Adjustable or Fixed Output, DD-Pak, SOT-223 Packages LT1118 800mA Low Dropout Regulator OK for Sinking and Sourcing, S0-8 and SOT-223 Packages LT1963A 1.5A Low Noise, Fast Transient Response LDO 340mV Dropout Voltage, Low Noise: 40μVRMS, VIN = 2.5V to 20V, TO-220, DD-Pak, SOT-223 and SO-8 Packages LT1965 1.1A Low Noise LDO 290mV Dropout Voltage, Low Noise 40μVRMS, VIN = 1.8V to 20V, VOUT = 1.2V to 19.5V, Stable with Ceramic Caps TO-220, DD-Pak, MSOP and 3mm × 3mm DFN packages. LTC®3026 1.5A Low Input Voltage VLDOTM Regulator 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 LT1976 High Voltage, 1.5A Step-Down Switching Regulator f = 200kHz, IQ = 100μA, TSSOP-16E Package LTC3414 4A (IOUT), 4MHz Synchronous Step-Down DC/DC Converter 95% Efficiency, VIN: 2.25V to 5.5V, VOUT(MIN) = 0.8V, TSSOP Package LTC3406/LTC3406B 600mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter 95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN) = 0.6V, IQ = 20μA, ISD < 1μA, ThinSOTTM Package LTC3411 1.25A (IOUT), 4MHz Synchronous Step-Down DC/DC Converter 95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN) = 0.8V, IQ = 60μA, ISD < 1μA, 10-Lead MS or DFN Packages LDOs Switching Regulators 3080fb 26 Linear Technology Corporation LT 0610 REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007