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LT3080

3080fc

Adjustable1.1A Single

Resistor Low Dropout

Regulator

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 cur-

rent 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.

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.

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

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: 40µV

RMS

(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

Variable Output Voltage 1.1A Supply

–

LT3080

1.2V TO 36V

CONTROL

OUT

3080 TA01a

SET

1µF

2.2µF

SET

OUT

= R

SET

• 10µA

OUT

Set Pin Current Distribution

SET PIN CURRENT DISTRIBUTION (µA)

10.20

3080 G02

9.90

10.00

10.10

9.80

N = 13792

Typical applicaTion

DescripTion

FeaTures

applicaTions

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.

Summary of content (28 pages)

PAGE 1
LT3080 Adjustable1.1A Single Resistor Low Dropout Regulator Description Features n 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.
PAGE 2
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) E-, I-Grades..............................
PAGE 3
LT3080 Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3080EDD#PBF LT3080EDD#TRPBF LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C LT3080IDD#PBF LT3080IDD#TRPBF LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C LT3080EMS8E#PBF LT3080EMS8E#TRPBF LTCBM 8-Lead Plastic MSOP –40°C to 125°C LT3080IMS8E#PBF LT3080IMS8E#TRPBF LTCBM 8-Lead Plastic MSOP –40°C to 125°C LT3080EQ#PBF LT3080EQ#TRPBF LT3080Q 5-Lead Plastic DD-Pak –40°C
PAGE 4
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 ISET CONDITIONS MIN TYP MAX UNITS VIN = 1V, VCONTROL = 2.0V, ILOAD = 1mA, TJ = 25°C VIN ≥ 1V, VCONTROL ≥ 2.0V, 1mA ≤ ILOAD ≤ 1.1A (Note 9) l 9.90 9.80 10 10 10.10 10.20 µA µA l –2 –3.5 2 3.
PAGE 5
LT3080 Typical Performance Characteristics Set Pin Current Set Pin Current Distribution Offset Voltage (VOUT – VSET) 10.20 2.0 N = 13792 10.10 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 N = 13250 0 0.50 OFFSET VOLTAGE (mV) OFFSET VOLTAGE (mV) Offset Voltage ILOAD = 1mA 0.75 0.25 0 –0.25 –0.50 –1.00 2 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.
PAGE 6
LT3080 ILOAD = 1.1A 300 250 ILOAD = 500mA 150 ILOAD = 100mA 50 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 1.2 TJ = 125°C 1.0 TJ = 25°C 0.8 0.6 0.4 0.2 0 0 0.2 0.4 0.8 0.6 OUTPUT CURRENT (A) 1.0 1.6 1.4 1.4 1.2 1.2 CURRENT LIMIT (A) CURRENT LIMIT (A) 1.6 1.0 0.8 0.6 1.0 25 50 75 100 125 150 TEMPERATURE (°C) OUTPUT VOLTAGE DEVIATION (mV) 1.2 VIN = VCONTROL = 3V VOUT = 1.5V COUT = 10µF CERAMIC CSET = 0.
PAGE 7
LT3080 Typical Performance Characteristics 30 DEVICE IN CURRENT LIMIT 15 10 5 0.8 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* 0.6 0.5 0.2 0.4 0.6 0.8 LOAD CURRENT (A) 1.0 90 90 80 80 30 20 V = V IN CONTROL = VOUT (NOMINAL) + 2V 10 RIPPLE = 50mVP-P COUT = 2.
PAGE 8
LT3080 Typical Performance Characteristics Error Amplifier Gain and Phase Output Voltage Noise 20 300 15 250 10 200 IL = 1.1A VOUT = 1V RSET = 100k CSET = O.1µF COUT = 10µF ILOAD = 1.1A TIME 1ms/DIV 3080 G27 GAIN (dB) 5 150 0 100 IL = 100mA –5 50 IL = 1.
PAGE 9
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.
PAGE 10
LT3080 Applications Information LT3080 IN VCONTROL + VIN + + – VCONTROL OUT SET RSET VOUT COUT CSET 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.
PAGE 11
LT3080 Applications Information 20 0 CHANGE IN VALUE (%) ceramic capacitor the stress can be induced by vibrations in the system or thermal transients. BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 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.
PAGE 12
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.
PAGE 13
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.
PAGE 14
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.
PAGE 15
LT3080 Applications Information The power in the drive circuit equals: Junction Temperature will be equal to: TJ = TA + PTOTAL • qJA (approximated using tables) 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: In this case, the junction temperature is below the maximum rating, ensuring reliable operation.
PAGE 16
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.
PAGE 17
LT3080 Typical Applications Higher Output Current Adding Shutdown MJ4502 VIN 6V 50Ω + LT3080 IN LT3080 IN VIN VCONTROL + – VCONTROL + – 100µF 1µF VOUT 3.3V 5A OUT SET 4.7µF 332k + Q1 VN2222LL ON OFF 100µF R1 Q2* VN2222LL 1N4148 SHUTDOWN 3080 TA04 *Q2 INSURES ZERO OUTPUT IN THE ABSENCE OF ANY OUTPUT LOAD.
PAGE 18
LT3080 Typical Applications Coincident Tracking LT3080 IN VCONTROL LT3080 IN + – VCONTROL LT3080 IN VIN 7V TO 28V + – VCONTROL + – C1 1.5µF SET SET R1 249k 169k OUT SET R2 80.6k OUT OUT C2 4.7µF VOUT3 5V 4.7µF 3080 TA07 VOUT2 3.3V C3 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.
PAGE 19
LT3080 Typical Applications High Voltage Regulator 6.1V 10k VIN 50V 1N4148 IN LT3080 BUZ11 VCONTROL + + – 10µF 15µF SET RSET 2MEG + VOUT 1A OUT VOUT = 20V VOUT = 10µA • RSET 4.7µF 3080 TA10 Ramp Generator LT3080 IN VIN 5V Reference Buffer LT3080 IN VIN VCONTROL VCONTROL + – 1µF + – OUT VOUT SET VN2222LL 1µF 1N4148 LT1019 4.7µF VN2222LL OUT INPUT OUTPUT SET C1 1µF GND VOUT* C2 4.7µF 3080 TA12 *MIN LOAD 0.
PAGE 20
LT3080 Typical Applications Low Voltage, High Current Adjustable High Efficiency Regulator* 0.47µH PVIN 2.7V TO 5.5V† 2× 100µF + ITH SVIN 2.2MEG 100k 10k SW LTC3414 RT + 12.1k 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.
PAGE 21
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 SET 3080 TA16 0V TO 10V† 1A 4.7µF 1MEG *DIFFERENTIAL VOLTAGE ON LT3080 ≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD. †MAXIMUM OUTPUT VOLTAGE IS 2V BELOW INPUT VOLTAGE 10k 2 Terminal Current Source CCOMP* IN LT3080 VCONTROL + – SET *CCOMP R1 ≤ 10Ω 10µF R1 ≥ 10Ω 2.
PAGE 22
LT3080 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698 Rev C) 0.70 ±0.05 3.5 ±0.05 1.65 ±0.05 2.10 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED PIN 1 TOP MARK (NOTE 6) 0.200 REF 3.00 ±0.10 (4 SIDES) R = 0.125 TYP 5 0.40 ± 0.10 8 1.65 ± 0.
PAGE 23
LT3080 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. MS8E Package 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWGPackage # 05-08-1662 Rev F) MS8E 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 ± 0.127 (.035 ± .005) 1.88 ± 0.102 (.074 ± .004) 0.29 REF 1.68 (.066) 0.05 REF 5.23 (.
PAGE 24
LT3080 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. 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) 15° 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.
PAGE 25
LT3080 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) .390 – .415 (9.906 – 10.541) .165 – .180 (4.191 – 4.572) .147 – .155 (3.734 – 3.937) DIA .045 – .055 (1.143 – 1.397) .230 – .270 (5.842 – 6.858) .460 – .500 (11.684 – 12.700) .570 – .620 (14.478 – 15.748) .330 – .370 (8.382 – 9.398) .700 – .728 (17.78 – 18.491) .620 (15.75) TYP SEATING PLANE .
PAGE 26
LT3080 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. 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 10° – 16° .010 – .014 (0.25 – 0.36) 10° MAX .071 (1.80) MAX .
PAGE 27
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 C 9/11 20 21, 22 Added I-grade information to the Absolute Maximum Ratings section and the Order Information table.
PAGE 28
LT3080 Typical Application Paralleling Regulators LT3080 IN VCONTROL + – OUT 20mΩ SET LT3080 IN VIN 4.8V TO 28V VCONTROL + – OUT 20mΩ 1µF SET VOUT 3.3V 2A 10µF 165k 3080 TA18 Related Parts PART NUMBER DESCRIPTION COMMENTS LT1086 1.5A Low Dropout Regulator Fixed 2.85V, 3.3V, 3.