LT1038 10A Positive OBSOLETE PRODUCT Adjustable DATA SHEET FOR REFERENCE ONLY Regulator Consult www.linear.com for possible alternate source.

FEATURES DESCRIPTIO U ■ Guaranteed 0.8% Initial Tolerance The LT®1038 is a three terminal regulator which is capable ■ Guaranteed 0.4% Load Regulation of providing in excess of 10A output current over 1.2V to ■ Guaranteed 10A Output Current 32V range. The device is packaged in a standard T0-3 ■ 100% Thermal Limit Burn-In power package and is plug-in compatible with industry ■ 24A Transient Output Current standard adjustable regulators, such as the LM117 and ■ Standard Adjustable Pinout LM138. Also, the LT1038 is a functional replacement for

■ Operates to 35V the LM396. U In addition to excellent load and line regulations, the APPLICATIO S LT1038 is fully protected by , safe area protection and thermal shutdown. New current limiting ■ System Power Supplies circuitry allows transient load currents up to 24A to be ■ High Power supplied for 500µs without causing the regulator to cur- ■ Battery Chargers rent limit and drop out of regulation during the transient. ■ 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 manufac- tured with standard bipolar processing and has Linear Technology’s high reliability. , LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIONU S

5V, 10A Regulator Load Regulation 0.2 VIN = 15V VOUT = 10V 0.1 PRELOAD = 100mA LT1038 5V V ≥ 8V VIN VOUT IN AT 10A 0 ADJ 121Ω IOUT = 6A + 1% + 1µF10µF –0.1 IOUT = 10A 365Ω 1% –0.2

1038 TA01 –0.3 OUTPUT VOLTAGE DEVIATION (%)

–0.4 –75 –50–25 0 25 5075 100 125 150 TEMPERATURE (°C)

1038 TA02 1

LT1038

WW U W W

ABSOLUTE AXI U RATI GS PACKAGE/ORDER IUU FOR ATIO (Note 1) Power Dissipation...... Internally Limited BOTTOM VIEW ORDER PART Input to Output Voltage Differential ...... 35V VIN NUMBER 2 Operating Junction Temperature Range LT1038MK LT1038M Control Circuitry ...... –55°C to 150°C 1 LT1038CK LT1038M Power ...... –55°C to 200°C CASE ADJ IS OUTPUT LT1038C Control Circuitry ...... 0°C to 125°C K PACKAGE ° ° 2-LEAD TO-3 METAL CAN LT1038C Power Transistor ...... 0 C to 175 C TJMAX = 3°C, θJA = 35°C/W

Storage Temperature Range ...... –65°C to 150°C OBSOLETE PACKAGE

Lead Temperature (Soldering, 10 sec)...... 300°C UU

PRECO U 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)

LT1038M LT1038C SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

VREF Reference Voltage IOUT = 20mA, Tj = 25°C 1.24 1.25 1.26 1.23 1.25 1.275 V

3V ≤ (VIN – VOUT) ≤ 35V ● 1.22 1.25 1.285 1.22 1.25 1.285 V 20mA ≤ IOUT ≤ 10A, P ≤ 75W

∆VOUT Line Regulation 3V ≤ (VIN – VOUT) ≤ 35V, 0.005 0.01 0.005 0.02 %/V ∆VIN IOUT = 20mA (Note 3) ● 0.02 0.03 0.02 0.03 %/V

∆VOUT Load Regulation 20mA ≤ IOUT ≤ 10A (Note 3) ∆IOUT 3V ≤ (VIN – VOUT) ≤ 35V 0.1 0.4 0.1 0.6 % 3V ≤ (VIN – VOUT) ≤ 35V ● 0.3 0.8 0.3 1.0 % Thermal Regulation 20ms Pulse 0.002 0.005 0.002 0.01 %/W

Ripple Rejection VOUT = 10V, f = 120Hz CADJ = 0µF ● 60 60 dB CADJ = 10µF ● 60 75 60 75 dB

IADJ Adjust Pin Current ● 50 100 50 100 µA

∆IADJ Adjust Pin Current Change 20mA ≤ IOUT ≤ 10A 3V ≤ (VIN – VOUT) ≤ 35V ● 0.2 3 0.2 3 µA

Minimum Load Current (VIN – VOUT) = 35V ● 720 720mA (VIN – VOUT) ≤ 20V ● 10 10 mA

ISC Current Limit (VIN – VOUT) ≤ 10V DC ● 10 14 10 14 A Transient (0.5ms) 14 22 12 22 A

(VIN – VOUT) = 30V, Tj = 25°C12 12 A

∆VOUT Temperature Stability ● 12 1 % ∆Temp

∆VOUT Long Term Stability TA = 125°C, 1000 Hours 0.3 1 0.3 1 % ∆Time en RMS Output Noise 10Hz ≤ f ≤ 10kHz 0.001 0.001 % (% of VOUT)

θJC Thermal Resistance Power Transistor ● 11°C/W Junction to Case Control Circuity 0.5 0.5 °C/W 2 LT1038 ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life than 10V, achievable output current and power dissipation decrease due to of a device may be impaired. protection circuitry. Note 2: Unless otherwise specified, these specifications apply: Note 3: See thermal regulation specifications for changes in output voltage

VIN – VOUT = 5V and IOUT = 5A. These specifications are applicable for due to heating effects. Load and line regulation are measured at a constant power dissipations up to 75W. At input-output voltage differentials greater junction temperature by low duty cycle pulse testing.

TYPICAL PERFOR A UW CE CHARACTERISTICS

Dropout Voltage Adjustment Current Temperature Stability 4 65 1.27 ∆VOUT = 100mV 60 A)

µ 1.26 55 3

IOUT = 10A 50 1.25

IOUT = 6A 45 2 40 IOUT = 2A REFERENCE VOLTAGE (V) 1.24 ADJUSTMENT CURRENT (

INPUT-OUTPUT DIFFERENTIAL (V) 35

1 30 1.23 –75 –50–25 0 25 5075 100 125 150 –75 –50–25 0 25 5075 100 125 150 –50 –250 2550 75 100 125 150 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C)

1038 TA02 1038 G02 1038 G03

Output Impedance Minimum Operating Current Rejection 10 10 100 VIN = 15V CADJ = 10µF VOUT = 10V I = 1A 1 OUT 8 80 ) Ω CADJ = 0µF Tj = 150°C CADJ = 0µF 0.1 6 Tj = 25°C 60 COUT = 0µF

µ Tj = –55°C 0.01 CADJ = 10 F 4 40 COUT = 10µF RIPPLE REJECTION (dB)

OUTPUT IMPEDANCE ( VIN – VOUT = 5V QUIESCENT CURRENT (mA) 0.001 2 20 IOUT = 1A f = 120Hz Tj = 25°C 0.0001 0 0 10 100 1k 10k 100k 1M 0 5101520 2530 35 40 0 5 10 15 20 25 30 35 FREQUENCY (Hz) INPUT-OUTPUT DIFFERENTIAL (V) OUTPUT VOLTAGE (V)

1038 G04 1038 G05 1038 G06

3 LT1038

TYPICAL PERFOR A UW CE CHARACTERISTICS

Ripple Rejection Ripple Rejection Current Limit 100 80 32 VIN = 15V PEAK CURRENT LIMIT C = 10µF DC CURRENT LIMIT CADJ = 10µF VOUT = 10V ADJ T = 25°C 80 IOUT = 1A CASE 70 24 PRELOAD = 0A

60 CADJ = 0µF PRELOAD = 10A 60 16 CADJ = 0µF 40 PRELOAD = 2A OUTPUT CURRENT (A) RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) 50 8 VIN = 15V 20 VOUT = 10V f = 120Hz TCASE = 25°C 0 40 0 10 100 1k 10k 100k 1M 0.1 1100 10 20 30 40 FREQUENCY (Hz) OUTPUT CURRENT (A) INPUT-OUTPUT DIFFERENTIAL (V) 1038 G08 1038 G07 1195 G20 Current Limit Current Limit Line Transient Response 28 28 1.5 VIN = 10V PRELOAD CURRENT = 0A VOUT = 10V VOUT = 5V T = 25°C 1.0 IOUT = 100mA 24 ° 24 CASE TCASE = 25 C Tj = 25°C 0.5 CL = 1µF; CL = 10µF 20 20 PRELOAD = 0A 0 PRELOAD = 10A VIN – VOUT = 10V 16 16 –0.5 DEVIATION (V)

VIN – VOUT = 15V OUTPUT VOLTAGE COUT = 0A 12 12 –1.0 CADJ = 0A –1.5 8 VIN – VOUT = 20V OUTPUT CURRENT (A) 8 OUTPUT CURRENT (A) 1.0 4 4 VIN – VOUT = 30V 0.5

0 0 CHANGE (V) 0

0.1 1 10 100 0.1 1 10 100 INPUT VOLTAGE 0102030 40 TIME (ms) TIME (ms) TIME (µs)

LTXXX GXX 1038 G11 1038 G12 Load Transient Response 3 VIN = 15V 2 VOUT = 10V ° 1 TCASE = 25 C PRELOAD = 200mA 0

–1 CL = 0µF; CADJ = 0µF

DEVIATION (V) –2 OUTPUT VOLTAGE CL = 1µF; CADJ = 10µF –3 6 4 2 0 LOAD CURRENT (A) 0102030 40 TIME (µs)

1038 G13

4

LT1038

U U

APPLICATIO S I FOR ATIOWU General If a very large output is used, such as a 100µF shown in Figure 2, the regulator could be damaged or The LT1038 develops a 1.25V reference voltage between destroyed if the input is accidentally shorted to or the output and the adjustment terminal (see Figure 1). By crowbarred, due to the output capacitor discharging into placing a , R1, between these two terminals, a the output terminal of the regulator. To prevent this, a constant current is caused to flow through R1 and down , D1 as shown, is recommended to safely discharge through R2 to set the overall output voltage. Normally this the capacitor. current is the specified minimum load current of 10mA or 20mA. Because IADJ is very small and constant when Load Regulation compared with the current through R1, it represents a small error and can usually be ignored. Because the LT1038 is a three-terminal device, it is not possible to provide true remote load sensing. Load regu- Bypass lation will be limited by the resistance of the connect- ing the regulator to the load. The data sheet specification Input bypassing using a 1µF tantalum or 25µF electrolytic for load regulation is measured at the bottom of the is recommended when the input filter capacitors are more package. Negative side sensing can be a true Kelvin than 5 inches from the device. Improved ripple rejection connection if the bottom of resistor R2 is returned to the (80dB) can be accomplished by adding a 10µF capacitor negative side of the load. Although it may not be immedi- from the ADJ pin to ground. Increasing the size of the ately obvious, best load regulation is obtained when the capacitor to 20µF will help ripple rejection at low output top of the resistor divider, R1, is connected voltage since the reactance of this capacitor should be directly to the small compared to the voltage setting resistor, R2. For case, not to the load. This is illustrated in Figure 3. If R1 improved AC transient response and to prevent the possi- were connected to the load, the effective resistance be- bility of oscillation due to unknown reactive load, a 1µF tween the regulator and the load would be: capacitor is also recommended at the output. Because of  +  their low impedance at high frequencies, the best type of RR21 Rp •   R = Parasitic Line Resistance capacitor to use is solid tantalum.  R1  p

Protection Connected as shown, Rp is not multiplied by the divider ratio. Rp is about 0.004Ω per foot using 16 gauge wire. The LT1038 does not require a protection diode from the This translates to 4mV/ft at 1A load current, so it is adjustment terminal to the output (see Figure 2). Im- important to keep the lead between the regulator and the proved internal circuitry eliminates the need for this diode load as short as possible, and use large wire or PC board when the adjustment pin is bypassed with a capacitor to traces. improve ripple rejection. D1 1N4002 Rp PARASITIC LT1038 LT1038 LINE RESISTANCE LT1038 VIN VIN VOUT VOUT VIN VIN VOUT VIN VIN VOUT VOUT CONNECT ADJ V ADJ REF R1 + R1 TO CASE ADJ COUT IADJ R1 * 100µF 50µA R1 RL R2 R2 R2 C + R2 *NOT NEEDED VOUT = VREF (1 + ) + IADJ R2 ADJ R1 10µF 1038 F01 CONNECT R2 1038 F02 TO LOAD 1038 F03 Figure 1. Basic Adjustable Regulator Figure 2 Figure 3. Connections for Best Load Regulation 5 LT1038

TYPICAL APPLICATIO SU

Paralleling Regulators

LT1038 V VIN VOUT IN 2 FEET #18 WIRE* ADJ R2 VOUT = 1.25 (1 + ) R1 IOUT = 0A TO 20A 0.015Ω LT1038 VIN VOUT ADJ * THE #18 WIRE ACTS AS BALLAST RESISTANCE R1 INSURING CURRENT SHARING 120Ω BETWEEN BOTH DEVICES

R2

1038 TA03

10A Variable Regulator*

T1 TRIAD L C30B 1MHz LT1038 F-269U 0V TO 35V V V IN OUT 0A TO 10A + + C1 ADJ Ω 1N4003 750Ω* 1.5k 100µF 20 50,000µF T2 34 110V AC Ω 20 12 LT1004-1.2 C30B

LT1004-2.5 20k 1N4003 1N4003 1µF 560Ω OUTPUT 15V 16k* ADJUST

82k LT1004-1.2 15k 8 –15V 200k 11k* 16k* 2.7k 2 + 4 7 LT1011 –15V 3 µ 10k – 1 0.1 F 1N4148 NC 15V 100pF 8 –15V 2N3904 3 1 4 – *1% FILM RESISTOR 7 3 L-DALE TO-5 TYPE LT1011 8 + 2 10k 6 T2-STANCOR 11Z-2003 + LM301A 1 7 2 15k – 15V 4 GENERAL PURPOSE REGULATOR WITH SCR PREREGULATOR TO LOWER 11k* 15V µ POWER DISSIPATION. ABOUT 4V DIFFERENTIAL IS MAINTAINED ACROSS 1 F –15V THE LT1038 INDEPENDENT OF OUTPUT VOLTAGE AND LOAD CURRENT. 1038 TA04

6 LT1038

TYPICAL APPLICATIO SU Improving Ripple Rejection 1.2V to 25V Adjustable Regulator 5V Regulator with Shutdown

LT1038 LT1038 LT1038 †† VIN VIN VOUT 5V VIN VIN VOUT VOUT VIN VIN VOUT 5V R1 ADJ R1 121Ω ADJ Ω ADJ + 121 121Ω + 1% 1µF 1% 1µF + + † C1* R2 C2 1k R2 + 1µF 5k 1µF C1* TTL 2N3904 365Ω 10µF 365Ω 1% 1% 1k

*C1 IMPROVES RIPPLE *NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS † REJECTION. XC SHOULD OPTIONAL—IMPROVES TRANSIENT RESPONSE 1038 TA07 BE SMALL COMPARED TO R2. 1038 TA05 †† VOUT = 1.25V (1 + R2/R1) 1038 TA06

Remote Sensing Temperature Compensated Lead Acid Battery Charger

10A LT1038 Rp V LT1038 (MAX DROP 300mV) IN VIN VOUT V 5V VIN VIN OUT ADJ Ω OUTPUT 121 10k* 1%

ADJ VIN 7 – 2 THERMALLY Ω Ω COUPLED 25 6 50 +

LM301A 25k

12V + 1k 3 RL 121Ω 1 2N3906 – 8 4 5µF 2k* + CHARGE Ω 365 100pF 50k* 2N3904 RETURN

25Ω *LOAD ON BATTERY ≈ 200µA

RETURN 1038 TA08 WHEN NOT CHARGING 1038 TA09 W

SCHE ATIC DIAGRA W

VIN

Q24 310Ω 310Ω 190Ω 50Ω 5.6k 20k 300Ω

Q11 Q23 200Ω Q27 Q4 Q6 Q9 Q26 12k Q2 Q15 Q19 6.7k 120Ω Q28 Q14 1.6k Q21 D1 30k Q5 6.3V C3 400Ω 160Ω 3k 5pF 4k Q18 Q22 18k 16k Q16 Q20 12.4k Q25 D2 6.3V Ω Q17 Q1 130 Q8 Q10 Q12 C1 C2 Q13 2.4k Ω 30pF 30pF 160 Q3 Q7 160k 3Ω 12k 180Ω 4.1k 6k 10k 5.1k 0.005Ω

ADJ VOUT 1038 SD

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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7 LT1038

TYPICAL APPLICATIO SU Lamp Flasher

12V LT1038 15V VIN VOUT Automatic Light Control Protected High Current Lamp Driver 12V 1µF ADJ LT1038 LT1038 10A 10µF + VIN VOUT VOUT VIN 15V ADJ ADJ 1.2k 12k TTL OR OFF 10µF 1k + CMOS 2N3904

12k 10µF + 10k

12k 1039 TA11 1039 TA12

1039 TA10

PACKAGE DESCRIPTIO U 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)

0.760 – 0.775 0.655 – 0.675 0.320 – 0.350 (19.30 – 19.69) (16.64 – 17.15) (8.13 – 8.89) 0.060 – 0.135 0.210 – 0.220 0.151 – 0.161 (1.524 – 3.429) (5.33 – 5.59) (3.86 – 4.09) DIA, 2 PLACES

0.167 – 0.177 0.420 – 0.480 (4.24 – 4.49) (10.67 – 12.19) 0.425 – 0.435 R (10.80 – 11.05) 0.067 – 0.077 0.490 – 0.510 0.058 – 0.062 (1.70 – 1.96) (12.45 – 12.95) (1.47 – 1.57) K2(TO-3) 1098 R OBSOLETE PACKAGE

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS LT1084 Low Dropout, 0.01% Load Regulation 7.5A Max Current Output LT1581 Low Dropout, 430mV at 10A Best Replacement LT1584 Low Dropout, 0.05% Load Regulation 7A Max Current Output LT1585 Low Dropout, 0.05% Load Regulation 5A Max Current Output

Linear Technology Corporation 1038fa LT/TP 0701 1.5K REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 8 ● ●  (408) 432-1900 FAX: (408) 434-0507 www.linear.com LINEAR TECHNOLOGY CORPORATION 2000