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LT3082

3082f

TYPICAL APPLICATION

DESCRIPTION

200mA Single Resistor Low

Dropout Linear Regulator

The LT

3082 is a 200mA 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, this regulator beneﬁ ts

many applications requiring high current, adjustability to

zero and no heat sink. The LT3082 withstands reverse

input voltages and reverse output-to-input voltages without

reverse-current ﬂ ow.

A key feature of the LT3082 is the capability to supply a

wide output voltage range. A precision “0” TC 10µA ref-

erence current source drives a single resistor to program

the output voltage to any level between zero and 38.5V.

The LT3082 is stable with only 2.2µF of capacitance on

the output; the IC uses small ceramic capacitors that

do not require additional ESR as is common with other

regulators.

Internal protection circuitry includes reverse-battery and

reverse-current protection, current limiting and ther-

mal limiting. The LT3082 is offered in the thermally en-

hanced 8-lead TSOT-23, 3-lead SOT-223 and 8-lead 3mm

× 3mm DFN packages.

Variable Output Voltage Battery Powered Supply

FEATURES

APPLICATIONS

Outputs May Be Paralleled for Higher Output

Current or Heat Spreading

Maximum Output Current: 200mA

Wide Input Voltage Range: 1.2V to 40V

Output Adjustable to 0V

Stable with Minimum 2.2μF Ceramic Capacitors

Single Resistor Sets Output Voltage

Initial Set Pin Current Accuracy: 1%

Low Output Noise: 33μV

RMS

(10Hz to 100kHz)

Reverse-Battery Protection

Reverse-Current Protection

<1mV Load Regulation Typical

<0.001%/V Line Regulation Typical

Current Limit and Thermal Shutdown Protection

Available in 8-Lead SOT-23, 3-Lead SOT-223 and

8-Lead 3mm × 3mm DFN Packages

All-Surface Mount Power Supply

Post Regulator for Switching Supplies

Low Parts Count Variable Voltage Supply

Low Output Voltage Supply

Battery Powered Regulator

SET Pin Current vs Temperature

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

TEMPERATURE (°C)

–50

9.900

SET PIN CURRENT (µA)

9.950

10.000

10.050

–25

25 50 10075 125

10.100

9.925

9.975

10.025

10.075

150

3082 TA01b

3082 TA01a

SET OUT

–

LT3082

OUT

= 10µA • R

SET

0.1µF

SET

500k

1µF

10µA

OUT

2.2µF

Summary of content (20 pages)

PAGE 1
LT3082 200mA Single Resistor Low Dropout Linear Regulator FEATURES n n n n n n n n n n n n n n DESCRIPTION Outputs May Be Paralleled for Higher Output Current or Heat Spreading Maximum Output Current: 200mA Wide Input Voltage Range: 1.2V to 40V Output Adjustable to 0V Stable with Minimum 2.
PAGE 2
LT3082 ABSOLUTE MAXIMUM RATINGS (Note 1) All Voltages Relative to VOUT IN Pin Voltage Relative to SET, OUT ........................±40V SET Pin Current (Note 6) .....................................±15mA SET Pin Voltage (Relative to OUT, Note 6) ...............±10V Output Short-Circuit Duration .......................... Indeﬁnite Operating Junction Temperature Range (Notes 2, 8) E, I Grades ......................................... –40°C to 125°C MP Grade...........................................
PAGE 3
LT3082 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TJ = 25°C. (Note 2) PARAMETER SET Pin Current CONDITIONS MIN TYP MAX UNITS 10 10 10.10 10.20 μA μA 2 4 mV mV –0.1 –0.5 –2 nA mV 0.03 0.003 0.2 0.010 ISET VIN = 2V, ILOAD = 1mA 2V ≤ VIN ≤ 40V, 1mA ≤ ILOAD ≤ 200mA l 9.90 9.
PAGE 4
LT3082 TYPICAL PERFORMANCE CHARACTERISTICS SET Pin Current 2.0 N = 1326 10.075 1.5 10.050 1.0 OFFSET VOLTAGE (mV) SET PIN CURRENT (μA) Offset Voltage (VOUT – VSET) SET Pin Current Distribution 10.100 10.025 10.000 9.975 9.950 9.925 0.5 0 –0.5 –1.0 –1.5 9.900 –50 –25 0 9.80 25 50 75 100 125 150 TEMPERATURE (°C) 3082 G01 –2.0 –50 –25 10 10.20 9.90 10.
PAGE 5
LT3082 TYPICAL PERFORMANCE CHARACTERISTICS Dropout Voltage Dropout Voltage TJ = –55°C 1.2 TJ = 25°C 1.0 TJ = 125°C 0.8 0.6 0.4 0.2 0 50 75 100 125 150 175 200 LOAD CURRENT (mA) 1.2 ILOAD = 200mA 1.0 ILOAD = 100mA 0.8 0.6 0.4 0.
PAGE 6
LT3082 TYPICAL PERFORMANCE CHARACTERISTICS Residual Output for Less Than Minimum Load Current Ripple Rejection 800 SET PIN = 0V 89 VOUT 600 100 VIN = 36V RTEST 500 VIN = 5V 400 300 200 80 60 CSET = 0.1μF 40 20 100 0 0 0 1000 RTEST (Ω) 2000 88 RIPPLE REJECTION (dB) VIN RIPPLE REJECTION (dB) 700 OUTPUT VOLTAGE (mV) Ripple Rejection (120Hz) 90 120 VIN = VOUT(NOMINAL) + 3V RIPPLE = 500mVP-P ILOAD = 200mA COUT = 2.
PAGE 7
LT3082 PIN FUNCTIONS (DD/ST/TS8) IN (Pins 7, 8/Pin 3/Pins 7, 8): Input. This pin supplies power to regulate internal circuitry and supply output load current. For the device to operate properly and regulate, the voltage on this pin must be 1.2V to 1.4V above the OUT pin (depending on output load current—see the dropout voltage speciﬁcations in the Electrical Characteristics table). NC (Pins 3, 5, 6/NA/Pins 1, 6): No Connection.
PAGE 8
LT3082 APPLICATIONS INFORMATION Introduction The LT3082 regulator is easy to use and has all the protection features expected in high performance regulators. Included are reverse-input, reverse-output and reverse input-to-output protection for sensitive circuitry and loads. Additional protection includes short-circuit protection and thermal shutdown with hysteresis. The LT3082 ﬁts well in applications needing multiple rails.
PAGE 9
LT3082 APPLICATIONS INFORMATION Table 1. 1% Resistors for Common Output Voltages VOUT (V) RSET (k) 1 100 1.2 121 1.5 150 1.8 182 2.5 249 3.3 332 5 499 With a 10μA current source generating 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). The cleaning of all insulating surfaces to remove ﬂuxes and other residues may be required.
PAGE 10
LT3082 APPLICATIONS INFORMATION electrics, 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 3 and 4.
PAGE 11
LT3082 APPLICATIONS INFORMATION two equal inductors in parallel, but placing them in close proximity gives the wires mutual inductance adding to the self-inductance. The second and most effective way to reduce overall inductance is to place both forward and return current conductors (the input and GND wires) in very close proximity. Two 30-AWG wires separated by only 0.
PAGE 12
LT3082 APPLICATIONS INFORMATION The LT3082 uses a unity-gain follower from the SET pin to the OUT pin. Therefore, multiple possibilities exist (besides a SET pin resistor) to set output voltage. For example, using a high accuracy voltage reference from SET to GND removes the errors in output voltage due to reference current tolerance and resistor tolerance. Active driving of the SET pin is acceptable.
PAGE 13
LT3082 APPLICATIONS INFORMATION Tables 3 through 5 list thermal resistance as a function of copper areas in a ﬁxed board size. All measurements were taken in still air on a 4-layer FR-4 board with 1oz solid internal planes and 2oz external trace planes with a total ﬁnished board thickness of 1.6mm. Table 3.
PAGE 14
LT3082 APPLICATIONS INFORMATION Protection Features greater than IN, is less than 1mA (typically under 100μA), protecting the LT3082 and sensitive loads. The LT3082 incorporates several protection features ideal for battery-powered circuits, among other applications. In addition to normal monolithic regulator protection features such as current limiting and thermal limiting, the LT3082 protects itself against reverse-input voltages, reverseoutput voltages, and reverse OUT-to-SET pin voltages.
PAGE 15
LT3082 TYPICAL APPLICATIONS Using a Lower Value SET Resistor VIN 12V LT3082 IN 10μA + – C1 1μF VOUT 0.5V TO 10V VOUT = 0.5V + 1mA • RSET OUT SET R1 49.9k 1% 1mA R2 499Ω 1% COUT 4.7μF RSET 10k 3082 TA04 Adding Soft-Start LT3082 IN VIN 4.8V to 40V 10μA + – D1 1N4148 C1 1μF C2 0.01μF VOUT 3.3V 0.2A OUT SET COUT 4.7μF R1 332k 3082 TA05 Coincident Tracking LT3082 IN 10μA IN LT3082 + – 10μA VIN 7V TO 40V LT3082 IN + – 10μA C1 1.5μF + – SET R1 249k R2 80.6k OUT C2 4.
PAGE 16
LT3082 TYPICAL APPLICATIONS Adding Shutdown VIN Reference Buffer LT3082 IN LT3082 IN VIN 10μA 10μA + – + – OUT SET ON OFF Q1 VN2222LL INPUT OUTPUT LT1019 Q2* VN2222LL R1 GND SHUTDOWN OUT SET VOUT C1 1μF 3082 TA07 VOUT* C2 4.7μF * MINIMUM LOAD 0.5mA 3082 TA08 *Q2 INSURES ZERO OUTPUT IN THE ABSENCE OF ANY OUTPUT LOAD. High Voltage Regulator 6.1V 10k VIN 50V 1N4148 LT3082 IN BUZ11 10μA + + – 10μF + RSET 2MEG 15μF VOUT 0.2A OUT SET VOUT = 20V VOUT = 10μA • RSET 4.
PAGE 17
LT3082 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 3.00 ±0.10 (4 SIDES) 0.38 ± 0.10 8 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (NOTE 6) (DD) DFN 1203 0.200 REF 0.75 ±0.05 0.00 – 0.05 4 0.25 ± 0.05 1 0.50 BSC 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1.
PAGE 18
LT3082 PACKAGE DESCRIPTION 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 .090 BSC RECOMMENDED SOLDER PAD LAYOUT 10° – 16° .010 – .014 (0.25 – 0.36) 10° MAX .071 (1.80) MAX 10° – 16° .024 – .033 (0.60 – 0.84) .181 (4.60) BSC .012 (0.31) MIN .0008 – .0040 (0.0203 – 0.
PAGE 19
LT3082 PACKAGE DESCRIPTION TS8 Package 8-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1637) 0.52 MAX 2.90 BSC (NOTE 4) 0.65 REF 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.22 – 0.36 8 PLCS (NOTE 3) 0.65 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) 1.95 BSC TS8 TSOT-23 0802 NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3.
PAGE 20
LT3082 TYPICAL APPLICATIONS Active-Driven Regulator VIN LT3082 IN 10μA + – OUT V1 0V TO 5V SET R1, 100k R2 100k 2.2μF ⎛ R2 ⎞ VOUT = ⎜ • V1 + 10µA • (R1 || R2) ⎝ R1 + R2 ⎟⎠ VOUT 0.5V TO 3V 3082 TA11 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1761 100mA, Low Noise LDO 300mV Dropout Voltage, Low Noise = 20μVRMS, VIN: 1.8V to 20V, ThinSOT™ Package LT1762 150mA, Low Noise LDO 300mV Dropout Voltage, Low Noise = 20μVRMS, VIN: 1.