LT1038 10A Positive Adjustable Voltage Regulator OBSOLETE PRODUCT DATA SHEET FOR REFERENCE ONLY Consult www.linear.com for possible alternate source. U 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. U 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 U W W W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (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 UU U 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. U W 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 U U W U 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 5 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 U 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 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 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 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2000