Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsVoltage RegulatorsPrecision Adjustment Low Drop Voltage Regulator, Positive

LT1083/LT1084/LT1085

108345fg

TYPICAL APPLICATION

DESCRIPTION

7.5A, 5A, 3A Low Dropout

Positive Adjustable Regulators

The LT

1083 series of positive adjustable regulators are

designed to provide 7.5A, 5A and 3A with higher efﬁ ciency

than currently available devices. All internal circuitry is

designed to operate down to 1V input-to-output differential

and the dropout voltage is fully speciﬁ ed as a function of

load current. Dropout is guaranteed at a maximum of 1.5V

at maximum output current, decreasing at lower load cur-

rents. On-chip trimming adjusts the reference voltage to

1%. Current limit is also trimmed, minimizing the stress

on both the regulator and power source circuitry under

overload conditions.

The LT1083/LT1084/LT1085 devices are pin compatible

with older 3-terminal regulators. A 10μF output capacitor

is required on these new devices. However, this is included

in most regulator designs.

Unlike PNP regulators, where up to 10% of the output cur-

rent is wasted as quiescent current, the LT1083 quiescent

current ﬂ ows into the load, increasing efﬁ ciency.

FEATURES

APPLICATIONS

3-Terminal Adjustable

Output Current of 3A, 5A or 7.5A

Operates Down to 1V Dropout

Guaranteed Dropout Voltage at Multiple Current Levels

Line Regulation: 0.015%

Load Regulation: 0.1%

100% Thermal Limit Functional Test

Fixed Versions Available

Available in 3-Lead Plastic TO-220, TO-3P and DD

Packages

High Efﬁ ciency Linear Regulators

Post Regulators for Switching Supplies

Constant Current Regulators

Battery Chargers

DEVICE

OUTPUT CURRENT*

LT1083

LT1084

LT1085

7.5A

5.0A

3.0A

*For a 1.5A low dropout regulator see the LT1086 data sheet.

, LT, LTM and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

121Ω

OUT

ADJ

365Ω

10μF

5V AT 7.5A

LT1083

≥ 6.5V

1083/4/5 ADJ TA01

10μF*

TANTALUM

*REQUIRED FOR STABILITY

5V, 7.5A Regulator

OUTPUT CURRENT

INPUT/OUTPUT VOLTAGE DIFFERENTIAL (V)

1083/4/5 ADJ TA02

FULL LOAD

Dropout Voltage vs Output Current

Summary of content (18 pages)

PAGE 1
LT1083/LT1084/LT1085 7.5A, 5A, 3A Low Dropout Positive Adjustable Regulators FEATURES DESCRIPTION n The LT®1083 series of positive adjustable regulators are designed to provide 7.5A, 5A and 3A with higher efﬁciency than currently available devices. All internal circuitry is designed to operate down to 1V input-to-output differential and the dropout voltage is fully speciﬁed as a function of load current. Dropout is guaranteed at a maximum of 1.
PAGE 2
LT1083/LT1084/LT1085 ABSOLUTE MAXIMUM RATINGS (Note 1) Power Dissipation ................................Internally Limited Input-to-Output Voltage Differential C-Grades ..............................................................30V I-Grades ................................................................30V M-Grades (OBSOLETE) .........................................35V Operating Junction Temperature Range (Note 9) C-Grades: Control Section .................. 0°C to 125°C Power Transistor ...........
PAGE 3
LT1083/LT1084/LT1085 ORDER INFORMATION LEAD FREE FINISH LT1083CP#PBF TAPE AND REEL LT1083CP#TRPBF PART MARKING* LT1083CP PACKAGE DESCRIPTION 3-Lead Plastic TO-3P LT1084CP#PBF LT1084CP#TRPBF LT1084CP 3-Lead Plastic TO-3P LT1084CT#PBF LT1084CT#TRPBF LT1084CT 3-Lead Plastic TO-220 LT1084IT#PBF LT1084IT#TRPBF LT1084IT 3-Lead Plastic TO-220 LT1085CT#PBF LT1085CT#TRPBF LT1085CT 3-Lead Plastic TO-220 LT1085IT#PBF LT1085IT#TRPBF LT1085IT 3-Lead Plastic TO-220 LT1085CM#PBF LT1085CM#TRPBF LT
PAGE 4
LT1083/LT1084/LT1085 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. PARAMETER CONDITIONS Reference Voltage IOUT = 10mA, TJ = 25°C, (VIN – VOUT) = 3V 10mA ≤ IOUT ≤ IFULL_LOAD 1.5V ≤ (VIN – VOUT) ≤ 25V (Notes 4, 6, 7) l TYP MAX UNITS 1.238 1.250 1.262 V 1.225 1.250 1.270 V 0.2 0.2 % % l 0.015 0.035 M-Grade: 15V ≤ (VIN – VOUT) ≤ 35V (Notes 2, 3) l 0.05 0.
PAGE 5
LT1083/LT1084/LT1085 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. PARAMETER CONDITIONS Thermal Resistance Junction-to-Case LT1083 Control Circuitry/Power Transistor K Package P Package K Package P Package T Package K Package M, T Package LT1084 LT1085 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device.
PAGE 6
LT1083/LT1084/LT1085 TYPICAL PERFORMANCE CHARACTERISTICS LT1083 Short-Circut Current 0.10 INDICATES GUARANTEED TEST POINT 0°C ≤ TJ ≤ 125°C 1 TJ = 150°C TJ = 25°C TJ = –55°C 25°C 10 150°C 8 6 –55°C 4 2 IFULL LOAD GUARANTEED 2 3 4 5 6 7 8 OUTPUT CURRENT (A) 9 10 0 20 30 15 25 5 10 INPUT/OUTPUT DIFFERENTIAL (V) 10 2 INDICATES GUARANTEED TEST POINT SHORT-CIRCUIT CURRENT (A) 0°C ≤ TJ ≤ 125°C 1 TJ = –55°C TJ = 25°C 5 –0.
PAGE 7
LT1083/LT1084/LT1085 TYPICAL PERFORMANCE CHARACTERISTICS Minimum Operating Current 9 8 7 6 5 TJ = 150°C 4 TJ = 25°C 3 2 ADJUST PIN CURRENT (μA) 90 REFERENCE VOLTAGE (V) 1.26 1.25 1.
PAGE 8
LT1083/LT1084/LT1085 TYPICAL PERFORMANCE CHARACTERISTICS LT1085 Ripple Rejection 80 (VIN – VOUT) ≥ VDROPOUT 50 40 30 CADJ = 200μF AT FREQUENCIES < 60Hz CADJ = 25μF AT FREQUENCIES > 60Hz IOUT = 3A 0 100 10 1k 10k FREQUENCY (Hz) fR = 20kHz VRIPPLE ≤ 0.5VP-P 50 40 LT1085CT VOUT = 5V CADJ = 25μF COUT = 25μF 10 10 LT1085CK 0 0 0 0.5 2.5 2.0 1.0 1.5 OUTPUT CURRENT (A) 1083/4/5 ADJ G19 OUTPUT VOLTAGE DEVIATION (V) 0.4 CADJ = 1μF 0 CIN = 1μF COUT = 10μF TANTALUM –0.
PAGE 9
LT1083/LT1084/LT1085 BLOCK DIAGRAM VIN + – THERMAL LIMIT VOUT 1083/4/5 ADJ BD VADJ APPLICATIONS INFORMATION The LT1083 family of 3-terminal adjustable regulators is easy to use and has all the protection features that are expected in high performance voltage regulators. They are short-circuit protected, and have safe area protection as well as thermal shutdown to turn off the regulator should the junction temperature exceed about 165°C.
PAGE 10
LT1083/LT1084/LT1085 APPLICATIONS INFORMATION Normally, capacitor values on the order of 100μF are used in the output of many regulators to ensure good transient response with heavy load current changes. Output capacitance can be increased without limit and larger values of output capacitor further improve stability and transient response of the LT1083 regulators. pin instantaneously shorted to ground, can damage occur.
PAGE 11
LT1083/LT1084/LT1085 APPLICATIONS INFORMATION The problem occurs with a heavy output load when the input voltage is high and the output voltage is low, such as immediately after removal of a short. The load line for such a load may intersect the output current curve at two points. If this happens, there are two stable output operating points for the regulator. With this double intersection, the power supply may need to be cycled down to zero and brought up again to make the output recover.
PAGE 12
LT1083/LT1084/LT1085 APPLICATIONS INFORMATION Connected as shown, RP is not multiplied by the divider ratio. RP is about 0.004Ω per foot using 16-gauge wire. This translates to 4mV/ft at 1A load current, so it is important to keep the positive lead between regulator and load as short as possible and use large wire or PC board traces. compound at the case-to-heat sink interface is strongly recommended.
PAGE 13
LT1083/LT1084/LT1085 TYPICAL APPLICATION 7.5A Variable Regulator T1 TRIAD F-269U L 1mH C30B IN 20Ω 3 110VAC 20Ω T2 1 C1 50,000μF + 750Ω* 1.5k 0V TO 35V OA TO 7.5A 100μF LT1004-1.2 2 1N914 C30B 1N4003 OUT ADJ + 1N4003 LT1083 2k OUTPUT ADJUST 1N4003 16k* 1μF 82k 560Ω 15V 15k –15V 8 2 + 4 LT1011 3 10k LT1004-1.2 16k* 200k 11k* 7 –15V 0.1μF – 1 1N4148 NC 15V * 1% FILM RESISTOR L: DALE TO-5 TYPE T2: STANCOR 11Z-2003 100pF 2N3904 8 –15V 4 7 2.
PAGE 14
LT1083/LT1084/LT1085 TYPICAL APPLICATION Paralleling Regulators VIN IN LT1083 2 FEET #18 WIRE* OUT ADJ ( ) VOUT = 1.25V 1 + R2 R1 IOUT = 0A TO 15A 0.015Ω IN LT1083 OUT *THE #18 WIRE ACTS AS BALLAST RESISTANCE INSURING CURRENT SHARING BETWEEN BOTH DEVICES ADJ R1 120Ω LT1083/4/5 ADJ TA03 R2 Improving Ripple Rejection VIN IN LT1083 R1 121Ω 1% ADJ + VOUT 5V OUT 10μF + 150μF R2 365Ω 1% + C1 25μF* *C1 IMPROVES RIPPLE REJECTION.
PAGE 15
LT1083/LT1084/LT1085 TYPICAL APPLICATION High Efﬁciency Regulator with Switching Preregulator 1mH VIN 28V IN + MR1122 LT1083 OUT ADJ 10,000μF VOUT 240Ω 470Ω 10k 1N914 28V 1k 1M 2k 4N28 10k + 1083/4/5 ADJ TA06 LT1011 10k – 28V 1N914 1.2V to 15V Adjustable Regulator VIN IN LT1083 R1 90.9Ω ADJ + C1* 10μF VOUT† OUT + C2 100μF R2 1k *NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS †V R2 OUT = 1.
PAGE 16
LT1083/LT1084/LT1085 PACKAGE DESCRIPTION K Package 2-Lead TO-3 Metal Can (Reference LTC DWG # 05-08-1310) 1.177 – 1.197 (29.90 – 30.40) .760 – .775 (19.30 – 19.69) .320 – .350 (8.13 – 8.89) .655 – .675 (16.64 – 17.15) .060 – .135 (1.524 – 3.429) .210 – .220 (5.33 – 5.59) .151 – .161 (3.86 – 4.09) DIA, 2PLCS .420 – .480 (10.67 – 12.19) .167 – .177 (4.24 – 4.49) R .425 – .435 (10.80 – 11.05) .038 – .043 (0.965 – 1.09) .067 – .077 (1.70 – 1.96) .490 – .510 (12.45 – 12.
PAGE 17
LT1083/LT1084/LT1085 PACKAGE DESCRIPTION P Package 3-Lead Plastic TO-3P (Similar to TO-247) (Reference LTC DWG # 05-08-1450) .560 (14.224) .325 (8.255) .580 (14.732) .700 (17.780) .187 – .207 (4.75 – 5.26) .620 – .64O (15.75 – 16.26) .275 (6.985) .830 – .870 (21.08 – 22.10) .170 – .2OO (4.32 – 5.08) EJECTOR PIN MARKS .105 – .125 (2.67 – 3.18) DIA .580 – .6OO (14.73 – 15.24) .098 (2.489) .124 (3.149) .060 – .080 (1.52 – 2.03) MOUNTING HOLE 18° – 22° .115 – .145 (2.92 – 3.68) DIA 3° – 7° .170 (4.
PAGE 18
LT1083/LT1084/LT1085 TYPICAL APPLICATIONS Automatic Light Control VIN IN LT1083 OUT ADJ + 1.2k 100μF 10μF 1083/4/5 ADJ TA10 Protected High Current Lamp Driver 12V 5A OUT LT1083 IN 15V ADJ TTL OR CMOS 1083/4/5 ADJ TA11 10k 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 Fixed 2.85V, 3.3V, 5V or Adjustable Output LT1584/LT1585/LT1587 7A/4.