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LT1038
OBSOLETE PRODUCT
DATA SHEET FOR REFERENCE ONLY
Consult www.linear.com for possible alternate source.
10A Positive Adjustable Voltage Regulator
DESCRIPTIO U
Load Regulation
0.2
OUTPUT VOLTAGE DEVIATION (%)
FEATURES
s s s s s s s
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
The LT(R)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. 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 500s without causing the regulator to current limit and drop out of regulation during the transient. 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.
APPLICATIO S
s s s s s
System Power Supplies High Power Linear Regulator Battery Chargers Power Driver Constant Current Regulator
TYPICAL APPLICATIONS
5V, 10A Regulator
VIN = 15V VOUT = 10V PRELOAD = 100mA
VIN 8V
LT1038 VIN VOUT
+
1F
ADJ
U
U
0.1 0 - 0.1 - 0.2 - 0.3
5V AT 10A 121 1% 365 1%
1038 TA01
IOUT = 6A IOUT = 10A
+
10F
- 0.4 - 75 - 50 - 25
0 25 50 75 100 125 150 TEMPERATURE (C)
1038 TA02
1
LT1038
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
BOTTOM VIEW VIN 2
Power Dissipation ............................... Internally Limited Input to Output Voltage Differential ......................... 35V Operating Junction Temperature Range LT1038M Control Circuitry ................ -55C to 150C LT1038M Power Transistor ............... -55C to 200C LT1038C Control Circuitry ..................... 0C to 125C LT1038C Power Transistor .................... 0C to 175C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LT1038MK LT1038CK
1 ADJ K PACKAGE 2-LEAD TO-3 METAL CAN CASE IS OUTPUT
TJMAX = 3C, JA = 35C/W
OBSOLETE PACKAGE
PRECO DITIO I G 100% Thermal Limit Burn-in
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 2)
SYMBOL VREF PARAMETER Reference Voltage CONDITIONS IOUT = 20mA, Tj = 25C 3V (VIN - VOUT) 35V 20mA IOUT 10A, P 75W VOUT VIN VOUT IOUT Line Regulation Load Regulation 3V (VIN - VOUT) 35V, IOUT = 20mA (Note 3) 20mA IOUT 10A (Note 3) 3V (VIN - VOUT) 35V 3V (VIN - VOUT) 35V 20ms Pulse VOUT = 10V, f = 120Hz CADJ = 0F CADJ = 10F 20mA IOUT 10A 3V (VIN - VOUT) 35V (VIN - VOUT) = 35V (VIN - VOUT) 20V (VIN - VOUT) 10V DC Transient (0.5ms) (VIN - VOUT) = 30V, Tj = 25C VOUT Temp VOUT Time en JC Temperature Stability Long Term Stability RMS Output Noise (% of VOUT) Thermal Resistance Junction to Case TA = 125C, 1000 Hours 10Hz f 10kHz Power Transistor Control Circuity
q q q q q q q q q q
ELECTRICAL CHARACTERISTICS
MIN 1.24 1.22
LT1038M TYP 1.25 1.25 0.005 0.02 0.1 0.3 0.002 60 75 50 0.2 7
MAX 1.26 1.285 0.01 0.03 0.4 0.8 0.005
MIN 1.23 1.22
LT1038C TYP 1.25 1.25 0.005 0.02 0.1 0.3 0.002 60 75 50 0.2 7
MAX 1.275 1.285 0.02 0.03 0.6 1.0 0.01
UNITS V V %/V %/V % % %/W dB dB
q
q
Thermal Regulation Ripple Rejection
60
60 100 3 20 10 10 12 1 2 1
IADJ IADJ
Adjust Pin Current Adjust Pin Current Change Minimum Load Current
100 3 20 10
ISC
Current Limit
10 14 1
14 22 2 1 0.3 0.001 1 0.5
14 22 2 1 0.3 0.001 1 0.5 1
C/W C/W
2
U
A A mA mA A A A % % %
W
U
U
WW
UU
W
U
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.
TYPICAL PERFOR A CE CHARACTERISTICS
Dropout Voltage
4 VOUT = 100mV 65 60
INPUT-OUTPUT DIFFERENTIAL (V)
ADJUSTMENT CURRENT (A)
REFERENCE VOLTAGE (V)
3 IOUT = 10A IOUT = 6A 2 IOUT = 2A
1 - 75 - 50 - 25
0 25 50 75 100 125 150 TEMPERATURE (C)
1038 TA02
Output Impedance
10 10 VIN = 15V VOUT = 10V IOUT = 1A
QUIESCENT CURRENT (mA)
OUTPUT IMPEDANCE ()
1
RIPPLE REJECTION (dB)
0.1
CADJ = 0F COUT = 0F CADJ = 10F COUT = 10F
0.01
0.001
0.0001 10 100 10k 1k FREQUENCY (Hz) 100k 1M
1038 G04
UW
Adjustment Current
1.27
Temperature Stability
55 50 45 40 35 30 - 75 - 50 - 25
1.26
1.25
1.24
0 25 50 75 100 125 150 TEMPERATURE (C)
1038 G02
1.23 -50 -25
0
25 50 75 100 125 150 TEMPERATURE (C)
1038 G03
Minimum Operating Current
100
Ripple Rejection
CADJ = 10F
8 Tj = 150C 6 Tj = 25C Tj = - 55C
80 CADJ = 0F 60
4
40 VIN - VOUT = 5V IOUT = 1A f = 120Hz Tj = 25C 0 5 20 15 10 25 OUTPUT VOLTAGE (V) 30 35
2
20
0 0 25 30 35 5 10 15 20 INPUT-OUTPUT DIFFERENTIAL (V) 40
0
1038 G05
1038 G06
3
LT1038 TYPICAL PERFOR A CE CHARACTERISTICS
Ripple Rejection
100 CADJ = 10F 80
RIPPLE REJECTION (dB)
VIN = 15V VOUT = 10V IOUT = 1A
RIPPLE REJECTION (dB)
60
OUTPUT CURRENT (A)
CADJ = 0F
40
20
0
10
100
10k 1k FREQUENCY (Hz)
100k
Current Limit
28 24
OUTPUT CURRENT (A)
OUTPUT VOLTAGE DEVIATION (V)
VIN = 10V VOUT = 5V TCASE = 25C
OUTPUT CURRENT (A)
20 16 12 8 4 0 0.1 1 TIME (ms)
LTXXX GXX
PRELOAD = 10A
PRELOAD = 0A
INPUT VOLTAGE CHANGE (V)
10
OUTPUT VOLTAGE DEVIATION (V)
LOAD CURRENT (A)
4
UW
1M
1038 G07
Ripple Rejection
80 CADJ = 10F 70
24 32
Current Limit
PEAK CURRENT LIMIT DC CURRENT LIMIT TCASE = 25C PRELOAD = 0A
PRELOAD = 10A 16
60
CADJ = 0F
PRELOAD = 2A 8
50
40
VIN = 15V VOUT = 10V f = 120Hz TCASE = 25C 0.1 1 OUTPUT CURRENT (A) 10
1038 G08
0 0 20 10 30 INPUT-OUTPUT DIFFERENTIAL (V) 40
1195 G20
Current Limit
28 24 20 VIN - VOUT = 10V 16 12 8 4 0 VIN - VOUT = 15V VIN - VOUT = 20V VIN - VOUT = 30V PRELOAD CURRENT = 0A TCASE = 25C 1.5 1.0 0.5 0 - 0.5 -1.0 -1.5 1.0 0.5 0
Line Transient Response
VOUT = 10V IOUT = 100mA Tj = 25C
CL = 1F; CL = 10F
COUT = 0A CADJ = 0A
100
0.1
1 TIME (ms)
10
100
1038 G11
0
10
20 TIME (s)
30
40
1038 G12
Load Transient Response
3 2 1 0 -1 -2 -3 6 4 2 0 0 10 20 TIME (s) 30 40
1038 G13
VIN = 15V VOUT = 10V TCASE = 25C PRELOAD = 200mA CL = 0F; CADJ = 0F CL = 1F; CADJ = 10F
LT1038
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 1F tantalum or 25F 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 10F capacitor from the ADJ pin to ground. Increasing the size of the capacitor to 20F 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 1F 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.
D1 1N4002
VIN
VIN
LT1038 VOUT ADJ VREF
VOUT
VIN
R1
IADJ 50A R2 VOUT = VREF (1 + R2 ) + IADJ R2 R1
1038 F01
Figure 1. Basic Adjustable Regulator
U
If a very large output capacitor is used, such as a 100F 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
W
U
U
Connected as shown, Rp is not multiplied by the divider ratio. Rp is about 0.004 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.
Rp PARASITIC LINE RESISTANCE CONNECT R1 TO CASE R1 R2 RL
LT1038 VIN VOUT ADJ R1 *
VIN
VIN
LT1038 VOUT ADJ
+
VOUT COUT 100F
CADJ 10F
+
R2
*NOT NEEDED
1038 F02
CONNECT R2 TO LOAD
1038 F03
Figure 2
Figure 3. Connections for Best Load Regulation
5
LT1038
TYPICAL APPLICATIO S
Paralleling Regulators
T1 TRIAD F-269U
C30B
20 110V AC 20 C30B 3 1 T2 4 2
1N4003
1N4003
1F
82k
10k 1N4148
*1% FILM RESISTOR L-DALE TO-5 TYPE T2-STANCOR 11Z-2003
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.
6
U
VIN
VIN
LT1038 VOUT ADJ
2 FEET #18 WIRE* VOUT = 1.25 (1 + 0.015 IOUT = 0A TO 20A R2 ) R1
LT1038 VIN ADJ VOUT
* THE #18 WIRE ACTS AS BALLAST RESISTANCE R1 INSURING CURRENT SHARING 120 BETWEEN BOTH DEVICES
R2
1038 TA03
10A Variable Regulator*
L 1MHz VIN 1N4003
LT1038 VOUT ADJ 750* 1.5k
+
C1 50,000F
+
0V TO 35V 0A TO 10A 100F
LT1004-1.2 LT1004-2.5
560 15V
16k*
20k OUTPUT ADJUST
15k 2
LT1004-1.2 8 -15V 4 LT1011 3 7 0.1F 15V 8 -15V 4 7 LT1011 1 NC 100pF 3 2N3904 8 6 7 15k 15V 15V 4 1F -15V LM301A 1 200k
+ -
1
11k*
16k*
2.7k -15V
- +
2
10k
+ -
3
2 11k*
1038 TA04
LT1038
TYPICAL APPLICATIO S
Improving Ripple Rejection
VIN VIN LT1038 VOUT ADJ 5V R1 121 1%
+
1F
R2 365 1%
+
C1* 10F
*C1 IMPROVES RIPPLE REJECTION. XC SHOULD BE SMALL COMPARED TO R2.
1038 TA05
Remote Sensing
LT1038 VOUT VIN ADJ Rp (MAX DROP 300mV) VIN 25 121
VIN
6 1
LM301A 8 4
365
100pF RETURN 25
RETURN
SCHE ATIC DIAGRA
310 310
190
Q4 Q2 30k Q5
Q6
Q9 Q15 Q14 3k 4k 12.4k Q16 Q10 Q12 Q13 C1 30pF C2 30pF Q17 2.4k Q18 Q20 Q22 16k Q25 Q19 1.6k Q21 C3 5pF 6.7k 12k
Q1
130
Q8
Q3 160k 180
Q7 3 4.1k 6k 10k 5.1k 12k 0.005
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.
-
+
W
U
7
1.2V to 25V Adjustable Regulator
VIN VIN LT1038 VOUT ADJ R1 121 R2 5k VOUT
5V Regulator with Shutdown
VIN VIN LT1038 VOUT ADJ 1F 5V 121 1%
+
C2 1F
+
C1* 1F
+
1k TTL 1k 2N3904 365 1%
*NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS OPTIONAL--IMPROVES TRANSIENT RESPONSE VOUT = 1.25V (1 + R2/R1) 1038 TA06
1038 TA07
Temperature Compensated Lead Acid Battery Charger
10A VIN
5V OUTPUT 2
VIN
LT1038 VOUT ADJ 121 1% THERMALLY COUPLED 10k*
50
3 1k 5F
25k
RL
+ -
2k* 50k* 12V
2N3906 CHARGE 2N3904 *LOAD ON BATTERY 200A WHEN NOT CHARGING
+
1038 TA08
1038 TA09
W
VIN
Q24 50 Q11 5.6k 20k 300 Q23 200 Q27 Q26 120 400 160 Q28 D1 6.3V 18k D2 6.3V
160
ADJ
VOUT
1038 SD
7
LT1038
TYPICAL APPLICATIO S
Lamp Flasher
15V 1F VIN LT1038 VOUT ADJ 10F 12V
+
OFF 1k 2N3904 12k 12k
+ +
12k
10F
10F
1039 TA10
PACKAGE DESCRIPTIO
0.320 - 0.350 (8.13 - 8.89)
0.760 - 0.775 (19.30 - 19.69) 0.060 - 0.135 (1.524 - 3.429) 0.210 - 0.220 (5.33 - 5.59)
0.420 - 0.480 (10.67 - 12.19)
0.058 - 0.062 (1.47 - 1.57)
RELATED PARTS
PART NUMBER LT1084 LT1581 LT1584 LT1585 DESCRIPTION Low Dropout, 0.01% Load Regulation Low Dropout, 430mV at 10A Low Dropout, 0.05% Load Regulation Low Dropout, 0.05% Load Regulation COMMENTS 7.5A Max Current Output Best Replacement 7A Max Current Output 5A Max Current Output
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
q
U
U
Automatic Light Control
LT1038 VIN VOUT ADJ 1.2k
Protected High Current Lamp Driver
LT1038 VOUT ADJ TTL OR CMOS VIN 12V 10A 15V
10k
1039 TA11
1039 TA12
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) 0.151 - 0.161 (3.86 - 4.09) DIA, 2 PLACES 0.167 - 0.177 (4.24 - 4.49) R 0.067 - 0.077 (1.70 - 1.96) 0.490 - 0.510 (12.45 - 12.95) R
0.425 - 0.435 (10.80 - 11.05)
K2(TO-3) 1098
OBSOLETE PACKAGE
1038fa LT/TP 0701 1.5K REV A * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2000

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