FEATURES U U PRECO DITIO I G APPLICATIO S TYPICAL APPLICATIO. LT1033 3A Negative Adjustable Regulator DESCRIPTIO

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1 NOT RECOMMENDED FOR NEW DESIGNS Contact Linear Technology for Potential Replacement FEATRES Guaranteed 1% Initial Voltage Tolerance Guaranteed.15%/V Line Regulation Guaranteed.2%/ W Thermal Regulation PRECO DITIO I G 1% Thermal Limit Burn-in APPLICATIO S Adjustable Power Supplies System Power Supplies Precision Voltage/Current Regulators On-Card Regulators 3A Negative Adjustable Regulator DESCRIPTIO The LT 133 negative adjustable regulator will deliver up to 3A output current over an output voltage range of 1.2V to 32V. Linear Technology has made significant improvements in these regulators compared to previous devices, such as better line and load regulation, and a maximum output voltage error of 1%. The is easy to use and difficult to damage. Internal current and power limiting as well as true thermal limiting prevents device damage due to overloads or shorts, even if the regulator is not fastened to a heat sink. Maximum reliability is attained with Linear Technology s advanced processing techniques combined with a 1% burn-in in the thermal limit mode. This assures that all device protection circuits are working and eliminates field failures experienced with other regulators that receive only standard electrical testing., LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO Negative 5V Regulator Current Limit 6 31Ω TANT IN OT 1Ω TA1 TANT 5V, 3A OTPT CRRENT (A) INPT-OTPT DIFFERENTIAL (V) G1 1

2 ABSOLTE AXI RATI GS W W W (Note 1) Power Dissipation... Internally Limited Input to Output Voltage Differential... 35V Operating Junction Temperature Range M (OBSOLETE) C to 15 C C... C to 125 C Storage Temperature Range M (OBSOLETE) C to 15 C C C to 15 C Lead Temperature (Soldering, 1 sec.)... 3 C W PACKAGE/ORDER I FOR ATIO BOTTOM VIEW FRONT VIEW FRONT VIEW 1 2 V OT CASE IS K PACKAGE 4-LEAD TO-3 METAL CAN T JMAX = 15 C, θ JA = 35 C/W(MK) T JMAX = 125 C, θ JA = 35 C/W(CK) OBSOLETE PACKAGE Consider the P or T Packages for Alternate Source ORDER PART NMBER MK CK CASE IS T PACKAGE 3-LEAD PLASTIC TO-22 T JMAX = 125 C, θ JA = 5 C/W V OT ORDER PART NMBER CT CASE IS P PACKAGE 3-LEAD PLASTIC TO-3P T JMAX = 125 C, θ JA = 35 C/W ORDER PART NMBER CP V OT Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS (Note 2) The denotes specifications which apply over the full operating temperature range, otherwise specifications are T A = 25 C. M C SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX NITS V REF Reference Voltage V OT = 5V, I OT = 5mA, V 2 3V V OT 35V 5mA I OT I MAX, P P MAX V V OT Load Regulation 1mA I OT I MAX, (Note 3) I OT, V OT 5V mv, V OT 5V % V OT 5V mv V OT 5V % V OT Line Regulation 3V V OT 35V, (Note 2) %/V %/V Ripple Rejection V OT = 1V, f = 12Hz C = db C = 1µF db Thermal Regulation, 1ms Pulse %/W

3 ELECTRICAL CHARACTERISTICS (Note 2) The denotes specifications which apply over the full operating temperature range, otherwise specifications are T A = 25 C. M C SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX NITS I Adjust Pin Current µa I Adjust Pin Current Change 1mA I OT I MAX µa 3V V OT 35V µa Minimum Load Current V OT 35V ma V OT 1V ma I SC Current Limit V OT 1V, (Note 3) A V OT = 35V, A V OT Temperature Stability of T MIN T T MAX % Temp Output Voltage V OT Long Term Stability T A = 125 C, 1 Hours % Time e n RMS Output Noise T A = 25 C, 1Hz f 1kHz.3.3 % (% of V OT ) θ JC Thermal Resistance T Package C/W Junction to Case K Package C/W P Package C/W Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: nless otherwise indicated, these specifications apply: V OT = 5V; and I OT = 5mA. Power dissipation is internally limited. However, these specifications apply for power dissipation up to 3W. See guaranteed minimum output current curve. I MAX = 3A. Note 3: Testing is done using a pulsed low duty cycle technique. See thermal regulation specifications for output changes due to heating effects. Load regulation is measured on the output pin at a point 1/8" below the base of the package. TYPICAL PERFOR A CE CHARACTERISTICS W 2.8 Dropout Voltage 1.27 Temperature Stability 1.8 Minimum Load Current INPT-OTPT DIFFERENTIAL (V) T J = 55 C T J = 15 C REFERENCE VOLTAGE (V) CRRENT (ma) T J = 15 C T J = 55 C OTPT CRRENT (A) TEMPERATRE ( C) INPT-OTPT DIFFERENTIAL (V) G2 G3 G4 3

4 TYPICAL PERFORMANCE CHARACTERISTICS W Ripple Rejection Ripple Rejection Ripple Rejection RIPPLE REJECTION (db) C = 1µF C = V OT = 5V 2 I L = 5mA f = 12Hz OTPT VOLTAGE (V) RIPPLE REJECTION (db) C = C = 1µF = 15V 2 V OT = 1V I L = 5mA 1 1 1k 1k 1k 1M FREQENCY (Hz) RIPPLE REJECTION (db) C = 1µF C = = 15V 2 V OT = 1V f = 12Hz OTPT CRRENT (A) G5 G6 G7 OTPT IMPEDANCE (Ω) Output Impedance Line Transient Response Load Transient Response = 15V V OT = 1V I L = 5mA C L = 1µF C = C = 1µF k 1k 1k 1M FREQENCY (Hz) OTPT VOLTAGE DEVIATION (V) INPT VOLTAGE CHANGE (V) C = C = 1µF V OT = 1V I L = 5mA C L = 1µF 1 2 TIME (µs) 3 4 OTPT VOLTAGE DEVIATION (V) LOAD CRRENT (A) C = C = 1µF = 15V V OT = 1V I NL = 5mA C L = 1µF 1 2 TIME (µs) 3 4 G8 G9 G1 Load Regulation* Guaranteed Minimum Output Current Adjustment Current OTPT VOLTAGE DEVIATION (%) OTPT CRRENT (A) STMENT CRRENT (µa) OTPT CRRENT (A) *THE HAS LOAD REGLATION COMPENSATION WHICH MAKES THE TYPICAL NIT READ CLOSE TO ZERO. THIS BAND REPRESENTS THE TYPICAL PRODCTION SPREAD INPT-OTPT DIFFERENTIAL (V) G TEMPERATRE ( C) G13 G11 4

5 APPLICATIONS INFORMATION Output Voltage The output voltage is determined by two external resistors, and (see Figure 1). The exact formula for the output voltage is: V = V 1 I ( ) OT REF Where: V REF = Reference Voltage, I = Adjustment Pin Current. In most applications, the second term is small enough to be ignored, typically about.5% of V OT. In more critical applications, the exact formula should be used, with I equal to 65µA. Solving for yields: VOT V = VREF I C2 5µF REF W Smaller values of and will reduce the influence of I on the output voltage, but the no-load current drain on the regulator will be increased. Typical values for are between 1Ω and 3Ω, giving 12.5mA and 4.2mA no-load current respectively. There is an additional consideration in selecting, the minimum load current specification of the regulator. The operating current of the flows from input to output. If this current is not absorbed by the load, the output of the regulator will rise above the regulated value. The current drawn by and is normally high enough to absorb the current, but care must be taken in no-load situations where and have high values. The maximum value for the operating current, C1 1µF V OT I V REF C3 V OT F1 EXAMPLE: 1. A PRECISION 1V REGLATOR TO SPPLY P TO 3A LOAD CRRENT. A. SELECT = 1Ω TO MINIMIZE EFFECT OF I B. CALCLATE = V OT V REF 1V 1.25V = = 74Ω V REF 1.25V I 1Ω 65µA Figure 1 which must be absorbed, is 5mA for the. If inputoutput voltage differential is less than 1V, the operating current that must be absorbed drops to 3mA. Capacitors and Protection Diodes An output capacitor, C3, is required to provide proper frequency compensation of the regulator feedback loop. A or larger solid tantalum capacitor is generally sufficient for this purpose if the 1MHz impedance of the capacitor is 1Ω or less. High Q capacitors, such as Mylar, are not recommended because their extremely low ESR (effective series resistance) can drastically reduce phase margin. When these types of capacitors must be used because of other considerations, add a.5ω carbon resistor in series with 1µF. Aluminum electrolytic capacitors may be used, but the minimum value should be 25µF to ensure a low impedance at 1MHz. The output capacitor should be located within a few inches of the regulator to keep lead impedance to a minimum. The following caution should be noted: if the output voltage is greater than 6V and an output capacitor greater than has been used, it is possible to damage the regulator if the input voltage becomes shorted, due to the output capacitor discharging into the regulator. This can be prevented by using diode D1 (see Figure 2) between the input and the output. The input capacitor, C2, is only required if the regulator is more than 4 inches from the raw supply filter capacitor. Bypassing the Adjustment Pin The adjustment pin of the may be bypassed with a capacitor to ground, C1, to reduce output ripple, noise, and impedance. These parameters scale directly with output voltage if the adjustment pin is not bypassed. A bypass capacitor reduces ripple, noise and impedance to that of a 1.25V regulator. In a 15V regulator for example, these parameters are improved by 15V/1.25V = 12 to 1. This improvement holds only for those frequencies where the impedance of the bypass capacitor is less than. Ten microfarads is generally sufficient for 6Hz power line applications where the ripple frequency is 12Hz, since X C = 13Ω. The capacitor should have a voltage rating at least as high as the output voltage of the regulator. Values 5

6 APPLICATIONS INFORMATION W larger than 1µF may be used, but if the output is larger than 25V, a diode, D2, should be added between the output and adjustment pins (see Figure 2). Proper Connection of Divider Resistors The has a load regulation specification of.8% and is measured at a point 1/8" from the bottom of the package. To prevent degradation of load regulation, the resistors which set output voltage, and, must be connected as shown in Figure 3. Note that the positive side of the load has a true force and sense (Kelvin) connection, but the negative side of the load does not. should be connected directly to the output lead of the regulator, as close as possible to the specified point 1/8" from the case. should be connected to the positive side of the load separately from the positive (ground) connection to the raw supply. With this arrangement, load regulation is degraded only by the resistance between the regulator output pin and the load. If is connected to the load, regulation will be degraded. C1 V OT D1* 1N42 F2 D2** 1N42 C3 V OT *D1 PROTECTS THE REGLATOR FROM INPT SHORTS TO GROND. IT IS REQIRED ONLY WHEN C3 IS LARGER THAN AND V OT IS LARGER THAN 6V ** D2 PROTECTS THE ST PIN OF THE REGLATOR FROM OTPT SHORTS IF C2 IS LARGER THAN 1µF AND V OT IS LARGER THAN 25V Figure 2 LEAD RESISTANCE HERE DOES NOT AFFECT LOAD REGLATION LOAD V OT F3 CONNECT DIRECTLY TO REGLATOR PIN Figure 3 LEAD RESISTANCE HERE DEGRADES LOAD REGLATION. MINIMIZE THE LENGTH OF THIS LEAD 6

7 TYPICAL APPLICATIO S The output stability, load regulation, line regulation, thermal regulation, temperature drift, long term drift, and noise can be improved by a factor of 6.6 over the standard regulator configuration. This assumes a zener whose drift and noise is considerably better than the regulator itself. The LM329B has 2ppm/ C maximum drift and about 1 times lower noise than the regulator. In the application shown below, regulators #2 to N will track regulator #1 to within ±24mV initially, and to ±6mV over all load, line, and temperature conditions. If any regulator output is shorted to ground, all other outputs will drop to 2V. Load regulation of regulators #2 to N will be improved by V OT /1.25V compared to a standard regulator, so regulator #1 should be the one which has the lowest load current. Multiple Tracking Regulators REG #1 V OT REG #2 V OT C3 1µF 1N42 1N42 12Ω C1 SOLID TANTALM V OT1 SOLID TANTALM V OT2 V OT High Stability Regulator 7V LM329B R3 1.5k 1% * 1k 1% V OT V OT * = 98Ω Dual Tracking 3A Supply ± 1.25V to ± 2V ** 1Ω 1% 1µF 5k R3 1% 5k 1µF LT15A V OT R4 5k 1% V OT R5** 1Ω 1% 2.* *SOLID TANTALM ** OR R5 MAY BE TRIMMED SLIGHTLY TO IMPROVE TRACKING 2.* 1µF SOLID TANTALM TA6 V OT D1 1N42 D2 1N42 V OT TA7 REG #N V OT SOLID TANTALM V OT3 TA5 Current Regulator ( ) V OT C1 SOLID TANTALM R S I () 1.25V (O.5Ω R S 25Ω) I = 65µA R S TA8 7

8 8 6Ω Q16 Q31 V OT 2k 2k D4 D3 D5 D2 D1 5k 1k 6k 75Ω 2k 15pF 2k 15pF 18k 6Ω 25pF 8Ω 2Ω 2Ω 1k 22Ω 5pF 2pF 2k 4.2k 4k 8k 1k 4k 1k 2.4k 6.8k 5Ω 25Ω.2Ω 1Ω 1Ω 46Ω 12k 12k 1Ω 15Ω 15k 6k 2k 12k 27Ω Q7 SC1 1k Q8 Q1 Q3 Q4 Q2 Q32 Q34 Q33 Q9 Q1 Q12 Q11 Q25 Q24 Q22 Q23 Q27 Q28 Q3 Q21 Q19 Q2 Q17 Q15 Q18 Q14 Q13 Q6 Q26 Q29 SCHE ATIC DIAGRA W W

9 PROGRAM RESISTOR SELECTIO W The following table allows convenient selection of program resistors from standard 1% values. OTPT ERROR V OT (%) PACKAGE DESCRIPTION K Package 2-Lead TO-3 Metal Can (Reference LTC DWG # ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) DIA, 2PLCS ( ) R ( ) OBSOLETE ( ) ( ) PACKAGE R K2 (TO-3) 198 9

10 PACKAGE DESCRIPTION T Package 3-Lead Plastic TO-22 (Reference LTC DWG # ) ( ) ( ) DIA ( ) ( ) ( ).46.5 ( ) ( ) ( ) ( ) ( ) ( ).1 (2.54) BSC ( ) ( ) (1.27) ( ) TYP T3 (TO-22) 198 1

11 PACKAGE DESCRIPTION P Package 3-Lead Plastic TO-3P (Similar to TO-247) (Reference LTC DWG # ).56 (14.224).325 (8.255).275 (6.985).62.64O ( ) MONTING HOLE ( ) DIA ( ).6.8 ( ).58 (14.732).7 (17.78) ( ).58.6OO ( ).17.2OO ( ) EJECTOR PIN MARKS ( ) DIA.98 (2.489).124 (3.149).78.8 ( ).17 (4.32) MAX 3 7 BOTTOM VIEW OF TO-3P HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK ( ) ( ).215 (5.46) BSC ( ) ( ).2.4 ( ) P3 996 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. 11

12 RELATED PARTS PART NMBER DESCRIPTION COMMENTS LT mA Low Dropout Regulator with 2µA I Q Includes 2.5V Reference and Comparator LT mA Micropower Low Dropout Regulator 3µA I Q, SOT-223 Package LT1129 7mA Micropower Low Dropout Regulator 5µA Quiescent Current LT1175 5mA Negative Low Dropout Micropower Regulator 45µA I Q,.26V Dropout Voltage, SOT-223 Package LT A, 5kHz Step-Down Converter 4.5A,.7Ω Internal Switch, SO-8 Package LT1521 3mA Low Dropout Micropower Regulator with Shutdown 15µA I Q, Reverse Battery Protection LT1529 3A Low Dropout Regulator with 5µA I Q 5mV Dropout Voltage LT1573 ltrafast Transient Response Low Dropout Regulator Drives External PNP LT1575 ltrafast Transient Response Low Dropout Regulator Drives External N-Channel MOSFET LT1735 Synchronous Step-Down Converter High Efficiency, OPTI-LOOP Compensation LT1761 Series 1mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 2µA Quiescent Current, 2µV RMS Noise, SOT-23 Package LT1762 Series 15mA, Low Noise, LDO Micropower Regulators 25µA Quiescent Current, 2µV RMS Noise, MSOP Package LT1763 Series 5mA, Low Noise, LDO Micropower Regulators 3µA Quiescent Current, 2µV RMS Noise, SO-8 Package LT1764 3A, Low Noise, Fast Transient Response LDO 4µV RMS Noise LT1962 3mA, Low Noise, LDO Micropower Regulator 2µV RMS Noise, MSOP Package LT A, Low Noise, Fast Transient Response LDO 4µV RMS Noise, SOT-223 Package OPTI-LOOP is a registered trademark of Linear Technology Corporation. ltrafast is a trademark of Linear Technology Corporation. 12 Linear Technology Corporation 163 McCarthy Blvd., Milpitas, CA (48) FAX: (48) LT/CPI K REV C PRINTED IN SA LINEAR TECHNOLOGY CORPORATION 1991

FEATURES DESCRIPTIO TYPICAL APPLICATIO. LM / LM /LM Micropower Voltage Reference APPLICATIO S

FEATURES DESCRIPTIO TYPICAL APPLICATIO. LM / LM /LM Micropower Voltage Reference APPLICATIO S Micropower Voltage Reference FEATRES 2µA to 2mA Operating Range Guaranteed % Initial Voltage Tolerance Guaranteed Ω Dynamic Impedance Very Low Power Consumption APPLICATIO S Portable Meter References Portable