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LT3080-1

30801fb

–

LT3080-1

4.8V TO 28V

CONTROL

OUT*

25mΩ

10µF

OUT

3.3V

2.2A

*OUTPUTS CAN BE

DIRECTLY MOUNTED

TO POWER PLANE

30801 TA01

165k

SET

1µF

–

LT3080-1

CONTROL

OUT*

25mΩ

SET

Typical applicaTion

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

applicaTions

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: 40µV

RMS

(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

FeaTures DescripTion

Parallelable 1.1A

Adjustable Single Resistor

Low Dropout Regulator

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 de-

vices 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 volt-

age 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 8-lead

MSOP (with an Exposed Pad for better thermal charac-

teristics) and 3mm × 3mm DFN packages.

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.

Paralleling Regulators Offset Voltage Distribution

DISTRIBUTION (mV)

30801 TA01b

–1

–2

N = 13250

Summary of content (24 pages)

PAGE 1
LT3080-1 Parallelable 1.1A Adjustable Single Resistor Low Dropout Regulator Description Features n 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.
PAGE 2
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) E-, I-grades.............................
PAGE 3
LT3080-1 Electrical Characteristics The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS MIN TYP MAX UNITS l 9.90 9.80 10 10 10.10 10.20 µA µA ● –2 –3.5 2 3.5 mV mV 34 48 nA mV mV Output Offset Voltage (VOUT – VSET) VOS VIN = 1V, VCONTROL = 2.0V, ILOAD = 1mA, TJ = 25°C VIN ≥ 1V, VCONTROL ≥ 2.0V, 1mA ≤ ILOAD ≤ 1.
PAGE 4
LT3080-1 Typical Performance Characteristics Set Pin Current Offset Voltage (VOUT – VSET) Set Pin Current Distribution 10.20 2.0 N = 13792 10.10 1.0 OFFSET VOLTAGE (mV) 1.5 SET PIN CURRENT (µA) 10.15 10.05 10.00 9.95 9.90 0.5 0 –0.5 –1.0 –1.5 9.85 9.80 –50 –25 0 9.80 25 50 75 100 125 150 TEMPERATURE (°C) –2.0 –50 –25 10.00 10.20 9.90 10.10 SET PIN CURRENT DISTRIBUTION (µA) Offset Voltage Distribution Offset Voltage 0 –5 0.50 OFFSET VOLTAGE (mV) OFFSET VOLTAGE (mV) 5 ILOAD = 1mA 0.
PAGE 5
LT3080-1 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 0.2 0.4 0.8 0.6 OUTPUT CURRENT (A) Current Limit 1.4 1.2 1.2 1.0 0.8 0.6 1.0 0.6 0 25 50 75 100 125 150 TEMPERATURE (°C) 100 50 OUTPUT VOLTAGE DEVIATION (mV) 75 0 –50 –100 1.2 0.6 0.3 0 5 10 15 20 25 30 35 40 45 50 TIME (µs) 30801 G16 6 12 24 30 18 INPUT-TO-OUTPUT DIFFERENTIAL (V) 0.6 0.4 0.
PAGE 6
LT3080-1 Typical Performance Characteristics VCONTROL Pin Current 30 CONTROL PIN CURRENT (mA) CONTROL PIN CURRENT (mA) ILOAD = 1.1A 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 30 12 18 24 6 INPUT-TO-OUTPUT DIFFERENTIAL (V) *SEE NOTE 9 IN ELECTRICAL CHARACTERISTICS TABLE 0 36* 0 RIPPLE REJECTION (dB) ILOAD = 100mA ILOAD = 1.1A 60 50 40 30 0 100 1k 10k FREQUENCY (Hz) 100k VIN = 10V 0.3 VIN = 5V 0.2 0 1.
PAGE 7
LT3080-1 Typical Performance Characteristics Error Amplifier Gain and Phase Output Voltage Noise 20 300 15 250 200 10 IL = 1.1A VOUT = 1V RSET = 100k CSET = O.1µF COUT = 10µF ILOAD = 1.1A TIME 1ms/DIV 30801 G27 GAIN (dB) 5 150 100 0 IL = 100mA –5 50 IL = 1.
PAGE 8
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.
PAGE 9
LT3080-1 Applications Information probably be required. Surface coating may be necessary to provide a moisture barrier in high humidity environments. LT3080-1 IN VCONTROL + VIN + + – VCONTROL 25mΩ OUT SET RSET VOUT COUT CSET 30801 F01 Figure 1. Basic Adjustable Regulator and a lower voltage supply for the collector. This increases efficiency and reduces dissipation.
PAGE 10
LT3080-1 Applications Information 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.
PAGE 11
LT3080-1 Applications Information 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.
PAGE 12
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.
PAGE 13
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.
PAGE 14
LT3080-1 Applications Information 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.
PAGE 15
LT3080-1 Applications Information C1 VIN VCONTROL LT3080-1 + – IN 25mΩ SET RSET RS VIN′ OUT VOUT C2 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.
PAGE 16
LT3080-1 Typical Applications Adding Shutdown LT3080-1 IN VCONTROL + – 25mΩ OUT 25mΩ OUT SET LT3080-1 IN VIN VCONTROL + – VOUT SET Q1 VN2222LL ON OFF Q2* VN2222LL R1 SHUTDOWN *Q2 INSURES ZERO OUTPUT IN THE ABSENCE OF ANY OUTPUT LOAD 30801 TA02 Current Source LT3080-1 IN VIN 10V VCONTROL + – 25mΩ OUT 25mΩ OUT SET LT3080-1 IN VCONTROL + – 2.
PAGE 17
LT3080-1 Typical Applications Using a Lower Value SET Resistor LT3080-1 IN VIN 10V VCONTROL + – 25mΩ OUT 25mΩ OUT SET LT3080-1 IN VCONTROL + – C1 2.2µF VOUT = 0.5V + 2mA • RSET VOUT 0.5V TO 10V SET R1 24.9k 1% 2mA R2 249Ω 1% COUT 10µF RSET 4.99k 1% 30801 TA04 Adding Soft-Start VIN 4.8V TO 28V LT3080-1 IN VCONTROL + – D1 IN4148 25mΩ OUT 25mΩ OUT SET VOUT 3.3V 2.2A LT3080-1 IN VCONTROL + – C1 2.2µF SET C2 0.
PAGE 18
LT3080-1 Typical Applications Lab Supply LT3080-1 IN VIN 13V TO 18V VCONTROL VCONTROL + – 25mΩ + – OUT SET 25mΩ OUT 25mΩ OUT SET LT3080-1 IN LT3080-1 IN VCONTROL VCONTROL + – 25mΩ OUT + – 0.5Ω 50k 0A TO 2A SET + LT3080-1 IN CURRENT LIMIT 15µF VOUT 0V TO 10V SET + R4 500k 15µF 10µF + 100µF 3080 TA06 Boosting Fixed Output Regulators LT3080-1 + – 25mΩ OUT SET LT1963-3.3 5V 10µF 20mΩ 42Ω* 3.3VOUT 2.
PAGE 19
LT3080-1 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 470pF RT 294k PGOOD 2× 100µF 2N3906 LT3080-1 IN VCONTROL RUN/SS + – VFB 1000pF 78.7k PGND OUT 25mΩ OUT 25mΩ OUT 25mΩ OUT SET SYNC/MODE SGND 25mΩ 124k IN LT3080-1 VCONTROL + – * DIFFERENTIAL VOLTAGE ON LT3080-1 IS 0.6V SET BY THE VBE OF THE 2N3906 PNP † MAXIMUM OUTPUT VOLTAGE IS 1.
PAGE 20
LT3080-1 Typical Applications Adjustable High Efficiency Regulator* CMDSH-4E 4.5V TO 25V † VIN 10µF 1µF 100k BOOST LT3493 SHDN 0.1µF 10µH 0.1µF LT3080-1 IN SW 68µF MBRM140 VCONTROL TP0610L GND + – FB 10k 25mΩ OUT SET 4.7µF 0V TO 10V † 1A 1MEG *DIFFERENTIAL VOLTAGE ON LT3080-1 ≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD.
PAGE 21
LT3080-1 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 22
LT3080-1 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. MS8E Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1662 Rev I) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 (.074) 1 1.88 ± 0.102 (.074 ± .004) 0.29 REF 1.68 (.066) 0.889 ± 0.127 (.035 ± .005) 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 ± 0.102 3.20 – 3.45 (.066 ± .004) (.
PAGE 23
LT3080-1 Revision History (Revision history begins at Rev B) REV DATE DESCRIPTION PAGE NUMBER B 9/11 Updated the Absolute Maximum Ratings, Order Information, and Note 2 in the Electrical Characteristics sections to include I-grade parts. 2, 3 30801fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 24
LT3080-1 Typical Application Paralleling Regulators LT3080-1 IN VCONTROL + – 25mΩ OUT 25mΩ OUT SET LT3080-1 IN VIN 4.8V TO 28V VCONTROL + – 1µF VOUT 3.3V 2.2A SET 165k 10µF 30801 TA11 Related Parts PART NUMBER DESCRIPTION COMMENTS LT1086 1.5A Low Dropout Regulator Fixed 2.85V, 3.3V, 3.