OBSOLETE PRODUCT DATA SHEET FOR REFERENCE ONLY Regulator

LT1038 1 TYPICAL APPLICATION U S APPLICATIO S U FEATURES DESCRIPTIO U The LT ®1038 is a three terminal regulator which is capable of providing in exce...

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LT1038 10A Positive Adjustable Voltage Regulator

OBSOLETE PRODUCT DATA SHEET FOR REFERENCE ONLY Consult www.linear.com for possible alternate source.

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FEATURES ■ ■ ■ ■ ■ ■ ■

DESCRIPTIO

The LT®1038 is a three terminal regulator which is capable of providing in excess of 10A output current over 1.2V to 32V range. The device is packaged in a standard T0-3 power package and is plug-in compatible with industry standard adjustable regulators, such as the LM117 and LM138. Also, the LT1038 is a functional replacement for the LM396.

Guaranteed 0.8% Initial Tolerance Guaranteed 0.4% Load Regulation Guaranteed 10A Output Current 100% Thermal Limit Burn-In 24A Transient Output Current Standard Adjustable Pinout Operates to 35V

In addition to excellent load and line regulations, the LT1038 is fully protected by current limiting, safe area protection and thermal shutdown. New current limiting circuitry allows transient load currents up to 24A to be supplied for 500µs without causing the regulator to current limit and drop out of regulation during the transient.

U APPLICATIO S ■ ■ ■ ■ ■

System Power Supplies High Power Linear Regulator Battery Chargers Power Driver Constant Current Regulator

On-chip trimming of initial reference voltage to ±0.8% combined with 0.4% load regulation minimize errors in all high current applications. Further, the LT1038 is manufactured with standard bipolar processing and has Linear Technology’s high reliability. , LTC and LT are registered trademarks of Linear Technology Corporation.

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TYPICAL APPLICATIONS 5V, 10A Regulator

Load Regulation

LT1038 VIN VOUT

VIN ≥ 8V

+

ADJ

5V AT 10A 121Ω 1%

1µF

+ 10µF

365Ω 1% 1038 TA01

OUTPUT VOLTAGE DEVIATION (%)

0.2 0.1

VIN = 15V VOUT = 10V PRELOAD = 100mA

0 – 0.1

IOUT = 6A IOUT = 10A

– 0.2 – 0.3 – 0.4 – 75 – 50 – 25

0 25 50 75 100 125 150 TEMPERATURE (°C) 1038 TA02

1

LT1038

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ABSOLUTE

AXI U RATI GS

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(Note 1) BOTTOM VIEW

Power Dissipation ............................... Internally Limited Input to Output Voltage Differential ......................... 35V Operating Junction Temperature Range LT1038M Control Circuitry ................ –55°C to 150°C LT1038M Power Transistor ............... –55°C to 200°C LT1038C Control Circuitry ..................... 0°C to 125°C LT1038C Power Transistor .................... 0°C to 175°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C

ORDER PART NUMBER

VIN 2

LT1038MK LT1038CK

1 CASE IS OUTPUT

ADJ K PACKAGE 2-LEAD TO-3 METAL CAN

TJMAX = 3°C, θJA = 35°C/W

OBSOLETE PACKAGE

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PRECO DITIO I G 100% Thermal Limit Burn-in ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 2) SYMBOL

PARAMETER

VREF

Reference Voltage

CONDITIONS IOUT = 20mA, Tj = 25°C 3V ≤ (VIN – VOUT) ≤ 35V 20mA ≤ IOUT ≤ 10A, P ≤ 75W

∆VOUT ∆VIN

Line Regulation

∆VOUT ∆IOUT

Load Regulation

ISC

1.26

1.23

1.25

1.275

V

1.25

1.285

1.22

1.25

1.285

V

MAX

UNITS

0.005 0.02

0.02 0.03

%/V %/V

20mA ≤ IOUT ≤ 10A (Note 3) 3V ≤ (VIN – VOUT) ≤ 35V 3V ≤ (VIN – VOUT) ≤ 35V



0.1 0.3

0.4 0.8

0.1 0.3

0.6 1.0

% %

0.002

0.005

0.002

0.01

%/W

● ●

60

60 75



50

20mA ≤ IOUT ≤ 10A 3V ≤ (VIN – VOUT) ≤ 35V



Minimum Load Current

(VIN – VOUT) = 35V (VIN – VOUT) ≤ 20V

● ●

Current Limit

(VIN – VOUT) ≤ 10V DC Transient (0.5ms)



(VIN – VOUT) = 30V, Tj = 25°C ∆VOUT ∆Temp

Temperature Stability

∆VOUT ∆Time

Long Term Stability

TA = 125°C, 1000 Hours

en

RMS Output Noise (% of VOUT)

10Hz ≤ f ≤ 10kHz

θJC

Thermal Resistance Junction to Case

Power Transistor Control Circuity

2

LT1038C TYP

0.01 0.03

VOUT = 10V, f = 120Hz CADJ = 0µF CADJ = 10µF

Adjust Pin Current Change

1.25

1.22

MIN

0.005 0.02

Ripple Rejection

∆IADJ

1.24

MAX



20ms Pulse

Adjust Pin Current

LT1038M TYP

3V ≤ (VIN – VOUT) ≤ 35V, IOUT = 20mA (Note 3)

Thermal Regulation

IADJ



MIN



60

dB dB 100

µA

100

50

0.2

3

0.2

3

µA

7

20 10

7

20 10

mA mA

10 14

14 22

10 12

14 22

A A

1

2

1

2

A %

1

2

1

0.3

1

0.3

0.001 ●

60 75

1

0.001 1 0.5

% %

1 0.5

°C/W °C/W

LT1038

ELECTRICAL CHARACTERISTICS Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Unless otherwise specified, these specifications apply: VIN – VOUT = 5V and IOUT = 5A. These specifications are applicable for power dissipations up to 75W. At input-output voltage differentials greater

than 10V, achievable output current and power dissipation decrease due to protection circuitry. Note 3: See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are measured at a constant junction temperature by low duty cycle pulse testing.

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TYPICAL PERFOR A CE CHARACTERISTICS Dropout Voltage

Adjustment Current

Temperature Stability 1.27

65

∆VOUT = 100mV

3 IOUT = 10A IOUT = 6A 2 IOUT = 2A

REFERENCE VOLTAGE (V)

60

ADJUSTMENT CURRENT (µA)

55 50 45 40

1 – 75 – 50 – 25

30 – 75 – 50 – 25

0 25 50 75 100 125 150 TEMPERATURE (°C)

1.25

1.24

CADJ = 0µF COUT = 0µF

0.1

CADJ = 10µF COUT = 10µF

0.01

Ripple Rejection

10

100

8

80

CADJ = 10µF QUIESCENT CURRENT (mA)

1

0.001

Tj = 150°C 6

Tj = 25°C Tj = – 55°C

4

2

100

10k 1k FREQUENCY (Hz)

100k

1M 1038 G04

CADJ = 0µF 60

40 VIN – VOUT = 5V IOUT = 1A f = 120Hz Tj = 25°C

20

0

0.0001 10

25 50 75 100 125 150 TEMPERATURE (°C) 1038 G03

Minimum Operating Current

VIN = 15V VOUT = 10V IOUT = 1A

0

1038 G02

Output Impedance 10

1.23 –50 –25

0 25 50 75 100 125 150 TEMPERATURE (°C)

1038 TA02

OUTPUT IMPEDANCE (Ω)

1.26

35

RIPPLE REJECTION (dB)

INPUT-OUTPUT DIFFERENTIAL (V)

4

0 0

25 30 35 5 10 15 20 INPUT-OUTPUT DIFFERENTIAL (V)

40

1038 G05

0

5

20 15 10 25 OUTPUT VOLTAGE (V)

30

35

1038 G06

3

LT1038 U W

TYPICAL PERFOR A CE CHARACTERISTICS Ripple Rejection

Ripple Rejection

40

70

60

50

20

40

10k 1k FREQUENCY (Hz)

100k

1M

CADJ = 0µF

VIN = 15V VOUT = 10V f = 120Hz TCASE = 25°C

PRELOAD = 0A

12 8

20 VIN – VOUT = 10V 16

0

0

100

1

TIME (ms)

10

100

TIME (ms) LTXXX GXX

1038 G11

Load Transient Response 3

OUTPUT VOLTAGE DEVIATION (V)

2 1

VIN = 15V VOUT = 10V TCASE = 25°C PRELOAD = 200mA

0 CL = 0µF; CADJ = 0µF

–1 –2

CL = 1µF; CADJ = 10µF

LOAD CURRENT (A)

–3 6 4 2 0 0

10

20 TIME (µs)

30

CL = 1µF; CL = 10µF

0.5

VOUT = 10V IOUT = 100mA Tj = 25°C

0 – 0.5 COUT = 0A CADJ = 0A

–1.5

VIN – VOUT = 30V

0.1

1.0

–1.0

VIN – VOUT = 20V

8 4

10

VIN – VOUT = 15V

12

4

1

Line Transient Response

OUTPUT VOLTAGE DEVIATION (V)

PRELOAD = 10A

40 1195 G20

1.5

PRELOAD CURRENT = 0A TCASE = 25°C

24 OUTPUT CURRENT (A)

OUTPUT CURRENT (A)

28

VIN = 10V VOUT = 5V TCASE = 25°C

20

20 10 30 INPUT-OUTPUT DIFFERENTIAL (V)

0

Current Limit

24

40 1038 G13

4

PRELOAD = 2A 8

1038 G08

Current Limit 28

0.1

PRELOAD = 10A 16

10

1038 G07

16

24

0

1 OUTPUT CURRENT (A)

0.1

INPUT VOLTAGE CHANGE (V)

100

OUTPUT CURRENT (A)

CADJ = 0µF

10

PEAK CURRENT LIMIT DC CURRENT LIMIT TCASE = 25°C PRELOAD = 0A

CADJ = 10µF RIPPLE REJECTION (dB)

RIPPLE REJECTION (dB)

80

60

32

VIN = 15V VOUT = 10V IOUT = 1A

CADJ = 10µF

0

Current Limit

80

100

1.0 0.5 0 0

10

20 TIME (µs)

30

40 1038 G12

LT1038

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APPLICATIO S I FOR ATIO General

The LT1038 develops a 1.25V reference voltage between the output and the adjustment terminal (see Figure 1). By placing a resistor, R1, between these two terminals, a constant current is caused to flow through R1 and down through R2 to set the overall output voltage. Normally this current is the specified minimum load current of 10mA or 20mA. Because IADJ is very small and constant when compared with the current through R1, it represents a small error and can usually be ignored. Bypass Capacitors Input bypassing using a 1µF tantalum or 25µF electrolytic is recommended when the input filter capacitors are more than 5 inches from the device. Improved ripple rejection (80dB) can be accomplished by adding a 10µF capacitor from the ADJ pin to ground. Increasing the size of the capacitor to 20µF will help ripple rejection at low output voltage since the reactance of this capacitor should be small compared to the voltage setting resistor, R2. For improved AC transient response and to prevent the possibility of oscillation due to unknown reactive load, a 1µF capacitor is also recommended at the output. Because of their low impedance at high frequencies, the best type of capacitor to use is solid tantalum. Protection Diodes The LT1038 does not require a protection diode from the adjustment terminal to the output (see Figure 2). Improved internal circuitry eliminates the need for this diode when the adjustment pin is bypassed with a capacitor to improve ripple rejection.

If a very large output capacitor is used, such as a 100µF shown in Figure 2, the regulator could be damaged or destroyed if the input is accidentally shorted to ground or crowbarred, due to the output capacitor discharging into the output terminal of the regulator. To prevent this, a diode, D1 as shown, is recommended to safely discharge the capacitor. Load Regulation Because the LT1038 is a three-terminal device, it is not possible to provide true remote load sensing. Load regulation will be limited by the resistance of the wire connecting the regulator to the load. The data sheet specification for load regulation is measured at the bottom of the package. Negative side sensing can be a true Kelvin connection if the bottom of resistor R2 is returned to the negative side of the load. Although it may not be immediately obvious, best load regulation is obtained when the top of the resistor divider, R1, is connected directly to the case, not to the load. This is illustrated in Figure 3. If R1 were connected to the load, the effective resistance between the regulator and the load would be:  R2 + R1 Rp •   R = Parasitic Line Resistance  R1  p

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 lead between the regulator and the load as short as possible, and use large wire or PC board traces.

D1 1N4002

VIN

VIN

LT1038 VOUT ADJ

VOUT VREF

VIN

LT1038 VIN VOUT

R1

ADJ

IADJ 50µA R2 ) + IADJ R2 R1 1038 F01

+ R1

*

VOUT COUT 100µF

VIN

LT1038 VOUT

CONNECT R1 TO CASE

ADJ

RL

R1 R2

R2 VOUT = VREF (1 +

VIN

Rp PARASITIC LINE RESISTANCE

CADJ 10µF

+

R2

*NOT NEEDED

1038 F02

CONNECT R2 TO LOAD 1038 F03

Figure 1. Basic Adjustable Regulator

Figure 2

Figure 3. Connections for Best Load Regulation

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LT1038 U

TYPICAL APPLICATIO S Paralleling Regulators

VIN

VIN

LT1038 VOUT

2 FEET #18 WIRE*

ADJ

VOUT = 1.25 (1 + 0.015Ω

LT1038 VIN

IOUT = 0A TO 20A

R2 ) R1

VOUT * THE #18 WIRE ACTS AS BALLAST RESISTANCE R1 INSURING CURRENT SHARING 120Ω BETWEEN BOTH DEVICES

ADJ

R2 1038 TA03

10A Variable Regulator* T1 TRIAD F-269U

L 1MHz

C30B

VIN 1N4003

20Ω 3

110V AC 20Ω

+

T2

1

LT1038 VOUT ADJ

C1 50,000µF

750Ω*

1.5k

+

0V TO 35V 0A TO 10A 100µF

4 2

LT1004-1.2

C30B LT1004-2.5 1N4003

1N4003

1µF

560Ω

16k*

15V

82k

LT1004-1.2

15k

8 2

3 10k

200k

–15V

+

4 LT1011



–15V 4



–15V

NC 100pF 2N3904

3

LT1011 1

+

10k

2

6

1

+

8 6

15V

3

LM301A 7

15k GENERAL PURPOSE REGULATOR WITH SCR PREREGULATOR TO LOWER POWER DISSIPATION. ABOUT 4V DIFFERENTIAL IS MAINTAINED ACROSS THE LT1038 INDEPENDENT OF OUTPUT VOLTAGE AND LOAD CURRENT.

2.7k

0.1µF 15V 8

7

16k*

11k*

7

1

1N4148

*1% FILM RESISTOR L-DALE TO-5 TYPE T2-STANCOR 11Z-2003

20k OUTPUT ADJUST

15V

– 4 1µF –15V

2 11k* 1038 TA04

LT1038 U

TYPICAL APPLICATIO S Improving Ripple Rejection VIN

VIN

LT1038 VOUT

5V

+

VIN

VIN

R1 121Ω 1%

ADJ

1µF

LT1038 VOUT

VOUT††

VIN

R1 121Ω

ADJ

LT1038 VOUT

VIN

5V 121Ω 1%

ADJ

+ 1µF

+ R2 365Ω 1%

5V Regulator with Shutdown

1.2V to 25V Adjustable Regulator

+

C1* 1µF

C1* 10µF

+

R2 5k

C2† 1µF

1k 2N3904

TTL

365Ω 1%

1k *C1 IMPROVES RIPPLE REJECTION. XC SHOULD BE SMALL COMPARED TO R2.

*NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS † OPTIONAL—IMPROVES TRANSIENT RESPONSE †† VOUT = 1.25V (1 + R2/R1) 1038 TA06

1038 TA05

Remote Sensing

VIN

Temperature Compensated Lead Acid Battery Charger 10A

Rp (MAX DROP 300mV)

LT1038 VOUT VIN ADJ

1038 TA07

VIN

VIN

5V OUTPUT

LT1038 VOUT ADJ

121Ω 1%

VIN 7 6



LM301A

+

25Ω

1

121Ω

2

50Ω

10k*

THERMALLY COUPLED

+

25k

3 1k

RL



2N3906

12V

8 4

+

365Ω

5µF

2k*

CHARGE

100pF

50k*

2N3904 RETURN 25Ω

RETURN

*LOAD ON BATTERY ≈ 200µA WHEN NOT CHARGING

1038 TA08

1038 TA09

W

W

SCHE ATIC DIAGRA

VIN

Q24 310Ω

310Ω

190Ω

50Ω

5.6k

20k 300Ω Q23

Q11

200Ω Q4

Q6

Q27

Q9

Q26

Q2

Q15 30k

Q21 C3 5pF

3k Q18

4k

Q1

130Ω

D1 6.3V

400Ω 160Ω

18k 16k Q25

D2 6.3V

Q17 C1 30pF

Q12 Q13 Q3 160k

Q20

Q10

Q8

Q28

Q22

Q16

12.4k

12k 120Ω

1.6k

Q14

Q5

6.7k

Q19

C2 30pF

2.4k

160Ω

Q7 3Ω 180Ω

4.1k

6k

10k

5.1k

12k 0.005Ω

ADJ

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.

VOUT

1038 SD

7

LT1038 U

TYPICAL APPLICATIO S Lamp Flasher VIN

15V

12V

LT1038 VOUT

Automatic Light Control

Protected High Current Lamp Driver

ADJ

1µF

+

ADJ 12k

OFF

VOUT

VIN

15V

ADJ

1.2k

TTL OR CMOS

10µF

+

1k

12V 10A

LT1038

LT1038 VIN VOUT

10µF

2N3904 12k

10µF

10k

+

1039 TA12

1039 TA11

12k

1039 TA10

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PACKAGE DESCRIPTIO

Dimensions in inches (millimeters) unless otherwise noted. K Package 2-Lead TO-3 Metal Can (60mil Diameter Leads) (LTC DWG # 05-08-1312) 1.177 – 1.197 (29.90 – 30.40) 0.655 – 0.675 (16.64 – 17.15)

0.760 – 0.775 (19.30 – 19.69)

0.320 – 0.350 (8.13 – 8.89)

0.060 – 0.135 (1.524 – 3.429)

0.420 – 0.480 (10.67 – 12.19)

0.210 – 0.220 (5.33 – 5.59)

0.167 – 0.177 (4.24 – 4.49) R

0.425 – 0.435 (10.80 – 11.05) 0.058 – 0.062 (1.47 – 1.57)

0.151 – 0.161 (3.86 – 4.09) DIA, 2 PLACES

0.067 – 0.077 (1.70 – 1.96)

0.490 – 0.510 (12.45 – 12.95) R

K2(TO-3) 1098

OBSOLETE PACKAGE

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8

Linear Technology Corporation

1038fa LT/TP 0701 1.5K REV A • PRINTED IN USA

1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507



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