LT137A/LM137 LT337A/LM337 TECHNOLOGY . Negative Adjustable Regulator FEATURES DESCRIPTION = Guaranteed 1% Initial Voltage Tolerance The LT137A/LT337A negative adjustable regulators = Guaranteed 0.01%/V Line Regulation will deliver up to 1.5Amps output current over an out- = Guaranteed 0.5% Load Regulation put voltage range of 1.2V to 37V. Linear Technol- = Guaranteed 0.02%/W Thermal Regulation ogy has made significant improvements in these 100% Burn-in in Thermal Limit regulators compared to previous devices, such as bet- ter line and load regulation, and a maximum output voltage error of 1%. Every effort has been made to make these devices APPLICATIONS easy to use and difficult to damage. Internal current and power limiting coupled with true thermal limiting a Adjustable Power Supplies prevents device damage due to overloads or shorts, = System Power Supplies even if the regulator is not fastened to a heat sink. # Precision Voltage/Current Regulators a On-Card Regulators Maximum reliability is attained with Linear Technol- ogys advanced processing techniques combined with a 100% burn-in in the thermal limit mode. This as- sures that all device protection circuits are working and eliminates field failures experienced with other regulators that receive only standard electrical testing. : Output Voltage Error Negative Regulator 2 , 9 _ , " Cc L 5 $ F2* = 2 3 + 4 + & ge, os. = 8 LM337 SOLID $n1_ | SOLD TANTALUM e 7 TANTALUM > 1212 i 6 LM337 i) = 5 LT337A _ Oo R2 => 4 N Vour = 128 (1+ 5) 53 LT337A 2 2 Vout | *R2 = At ( a ) 0 1.25V 2 4 6810 20 40 100 OUTPUT VOLTAGE AT ee 4-157LT137A/LM137 Power Dissipation ............. Internally Limited . . BOTTOM VIEW BOTTOM VIEW Input to Output Voltage Differential .......... 40V Pane D ORDER Operating Junction Temperature Range ADJ Vout " LT137A/LM137............. 55C to 150C MM oe LT337A/LM337..............-. 0C to 125C p vy LISSTAK | cascisnput LT337AH Storage Temperature Range CASEISYN 141337K LM337H LT137A/LM137............. 65C to 150C K PACKAGE H PACKAGE LT337A/LM337............. 65C to 150C =a VW : ORDER Lead Temperature (Soldering, 10 sec.)...... 300C + Vout PART NO. Vs PRECONDITIONING CO] E= =" unser LM337T 100% THERMAL LIMIT BURN-IN T PACKAGE ELECTRICAL CHARACTERISTICS (See Note 1) LT137A LM137 SYMBOL _| PARAMETER CONDITIONS nN OTYP Min = TYP,) MAX UNITS VpeF Reference Voltage |Vin~Vour| = 5V, lour = 10mA, a Ty = 25C = 1.225 1.250 1.275 v 3V <|Viww Vour| <40V 10MA < lout < Imax, P < Puax e 1.200 1.250 1.300 V AVout Load Regulation 10mA < lout < Iwax, (See Note 2) Alout T; = 25C, |Vour| < 5V 5 25 15 =. mV T; = 25C, |Vour| > 5V 0.1 05 03 05 % |Vour | < 5V e 10 50 20 50 mV |Vour| > 5V e 02 10 03 10 % AVoyt Line Regulation 3V <|VinVour| < 40V, (See AVin Note 2) T, = 25C 0.01 0.02 %/V 0.02 0.05 %/V Ripple Rejection Vour = 10V, f = 120Hz Cans = 60 dB Cans = 10uF 6 020 O77 dB Thermal Regulation T, = 25C, 10msec Pulse 0.002 0.02 0.002 0.02 S/W laps Adjust Pin Current 65 100 pA Alay Adjust Pin Current Change 10mA < lout < Iwax 0.5 5 pA 3V < Vin Vour < 40V 2 5 pA Minimum Load Current |VinVour| < 40V 25 50 mA |VinVour | < 10V 12 3.0 mA Ise Current Limit |VinVour| < 15V, K and T Package (Note 5) @,; 15 2.2 15 2.2 A H Package @| 05 08 05 08 A IVinVour| = 40V, K and T Package 0.24 04 0.24 04 A T, = 25C H Package 0.15 0.25 0.15 0.25 A AVout Temperature Stability of Output iTemp- Voltage (Note 4) Twn < T < Tyax 0.6 % AVour Long Term Stability Ta = 125C, 1000 Hours 0.3 1.0 % ATime e, RMS Output Noise Ta = 25C, 10Hz < f < 10kHz 0.003 0.003 % (% of Vour) Bic Thermal Resistance H Package 12 15 12 1 C/W Junction to Case K Package 2.3 3.0 23 3.0 C/W meee a es 4-158 LY ireLT137A/LM137 LT337A/LM337 ELECTRICAL CHARACTERISTICS (See Note 1) LT337A LM337 SYMBOL PARAMETER CONDITIONS _ MIN TYP ~OMAX WIN TYP MAX UNITS Veer Reference Voltage \Via Nour! = = 5V, lout = 10mA, oe 7, = 26 |] 1.213 1.250 1.287 V Vi< \Vov - Vout | <40V oe : : 10MA < lout < Imax, P < Prax or = V2e0 | 1.200 1.250 1.300 Vv AVout Load Regulation 10mA < lout < Imax, (See Note 2 & Alour 3) T; = 25C, [Vour| < 5V 5 25 15 50 mV T, = 25C, [Vour| > 5V 01 05 03 10 % |Vour| < 5V e 10 50 20 70 mV [Vour| > 5V eo; 28.0 03 15 % AVoyt Line Regulation 3V <|Vm- Vour| < 40V, (See Note | bo AVin T = 25C 0.01 0.04 %/V 0.02 0.07 %/V Rippie Rejection Vour = 10V, f = 120Hz Capy = 60 dB Can) = 10uF 77 dB Thermal Regulation T, = 25C, 10msec Pulse 0.003 0.04 %/W laps Adjust Pin Current 65 100 uA Alans Adjust Pin Current Change 10mA < four < | 0.5 5 pA 3V_ <|Vw Vour| < 40V 2 5 pA Minimum Load Current |VinVour| < 40V 25 10 mA |VinVour| < 10V 1 6 mA Isc Current Limit |VinVour | < 15V, K and T Package 2.2 A H Package 0.8 A |VinVour | = 40V, K and T Package 0.4 A T, = 25C H Package 0.17 A AVour Temperature Stability of Output Atemp Voltage (Note 4) 0.6 % AVour Long Term Stability Tx = 125C, 1000 Hours 0.3 1.0 % ATime Cn RMS Output Noise Ta = 25C, 10Hz < f < 10kHz 0.003 0.003 % (% of Vour) Osc Thermal Resistance H Package 12 16 C/W Junction to Case K Package 2.3 3.0 C/W T Package 3 5 C/W The @ denotes the specifications which apply over the full operating temperature range. The shaded electrical specifications indicate those parameters which have been improved or guaranteed test limits provided for the first time. Note 1: Unless otherwise indicated, these specifications apply: [Vin Vout] = 5V; and loyr = 0.1A for the H package, Igy == 0.5A for the K and T packages. Power dissipation is internally limited. However, these specifications apply for power dissipation up to 2W for the H package and 20W for the K and T packages. Imax = 1.5A for the K and T packages, and 0.2A for the H package. Note 2: 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 K and H package and at the junction of the wide and narrow portion of the lead on the T package. Note 3: Load Regulation for the LT337AT is the same as for LM337T. Note 4: Guaranteed on LT137A and LT337A, but not 100% tested in production. Note 5: Isc is tested at the ambient temperatures of 25C and -55C. Ise cannot he tested at the maximum ambient temperature of 150C due to the high power level required. Isp specification at 150C ambient is guaranteed by characteriz- ation and correlation to 25C testing. LY We 4-159LT137A/LM137 LT337A/LM337 TYPICAL PERFORMANCE CHARACTERISTICS Temperature Stability Dropout Voltage INPUT-OUTPUT DIFFERENTIAL 0.4 0.8 1.2 1.6 QUTPUT CURRENT (A) Ripple Rejection RIPPLE REJECTION (dB) Vin-VouT = IL = 500mA {= 120Hz Tj- 25C -10 -20 ~30 QUTPUT VOLTAGE (V) Output Impedance VouT = - 10V OUTPUT IMPEDANCE (2) 1k 10k FREQUENCY (Hz) 100k 2.0 -40 iM 1.270 REFERENCE VOLTAGE (V) 1.260 1.250 1.240 1.230 ~75-50-25 0 25 50 75 100 125 150 TEMPERATURE (C) RIPPLE REJECTION (dB) OUTPUT VOLTAGE DEVIATION (V} INPUT VOLTAGE CHANGE (V} 100 60 20 0 08 0.6 0.4 0.2 0 -0.2 -0.4 0 ~0.5 -1.0 Ripple Rejection ae sy ee x oN *Caps = 10,F Capy = 0 ADJ NX Ne. x aN . Vin = - 15V NK - Vout = -10V ~! i, = 500mA sy Tj 25C 10 100 1k 10k = 100k = 1M FREQUENCY (Hz) Line Transient Response Vout = - 10 IL = 50mA Tj = 25C Cu = IF 0 10 20 30 40 TIME (us) CURRENT (mA) RIPPLE REJECTION (dB) QUTPUT VOLTAGE DEVIATION (V) LOAD CURRENT (A) 1.8 1.6 1.4 1.2 o oe 990 oO fMPOlUFSlUDDUlUCUD 100 Qa So QD So os oOo nN Oo Minimum Load Current 0 10 T= -55CZ 20 30 40 INPUT-OUTPUT DIFFERENTIAL (V} Ripple Rejection CapJ = 104F Candy = 0 Vin = 15V Vout = - 10V f= 120 Hz Tj= 25C pei til ith 0.01 0.1 1 10 OUTPUT CURRENT (A) Load Transient Response VouT = 10V = 50mA Tj = 25C Cy = 1,F 0 10 20 40 TIME (48) 30 4-160 LI WARLT137A/LM137 LT337A/LM337 TYPICAL PERFORMANCE CHARACTERISTICS Load Regulation* Current Limit Adjustment Current , 2 = 70 NX at l o to ~~ OUTPUT VOLTAGE DEVIATION (%) QUTPUT CURRENT (A) | S b> 0 0.4 0.8 1.2 1.6 2.0 0 10 QUTPUT CURRENT (A) The LT137A/337A has load regulation com- pensation which makes the typical unit read Close to zero. This band represents the typi- cal production spread. H PACKAGED | DEVICE INPUT-OUTPUT DIFFERENTIAL (V) 65 60 ADJUSTMENT CURRENT (A) 5 50 -75-50-25 0 25 50 75 100 125 150 TEMPERATURE (C) 20 30 40 APPLICATION INFORMATION Output Voltage: The output voltage is determined by two external resistors, R; & Rp (see Figure 1). The ex- act formula for the output voltage is: Vout = Vret ( i+ fe ) + Tay (Re) Where: Vier = Reference Voltage, lap) = Adjustment Pin Current. In most applications, the second term is small enough to be ignored, typically about 0.5% of Vout. In more critical applications, the exact formula should be used, with lap equal to 65ua. Solving for Ro yields: Rp = Vout Veet Vret ahet 4 R, laps Smaller values of R; and Rp will reduce the influence of lapy On the output voltage, but the no-load current drain on the regulator will be increased. Typical values for Ry are between 1000 and 3009, giving 12.5mA and 4.2mA no-load current respectively. There is an additional consideration in selecting Rj, the minimum load current specification of the regulator. The operat- ing current of the LT 137A 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 R, and Rp is normally high enough to LI We absorb the current, but care must be taken in no-load situations where R; and Ry have high values. The maximum value for the operating current, which must be absorbed, is 5mA for the LT137A. If input-output voltage differential is less than 10V, the operating cur- rent that must be absorbed drops to 3mA. +, $ i ae R2 = + 10uF < + AS Ce ee > C3 5uF / 1yuF < 3 Vourt Figure 1 EXAMPLES: 1. A precision 10V regulator to supply up to 1Amp load current. a. Select Ry = 1009 to minimize effect of lap, 10V 1.25V Vet nt go 125V pg A 1 2. A 15V regulator to run off batteries and supply 50mA. Vin MAX = 25V a. To minimize battery drain, select Ry as high as possible Ry = 125V = 4170, use 4049, 1% 3mA b. Calculate Rp = our Vet _ = 7049 4-161LT137A/LM137 LT337A/LM337 b. The high value for Ry will exaggerate the error due to tany, $0 the exact formula to calculate Rp should be used. a = Vout Vet _ 15V 1.25V 9 = = Vhet 1.25V -6 -| 65x 10 Ry AO) 4040 Use Ro = 45300 = 45390 Capacitors and Protection Diodes: An output capacitor, C3, is required to provide proper frequency compen- sation of the regulator feedback loop. A 1,F or larger solid tantalum capacitor is generally sufficient for this purpose if the 1MHz impedance of the capacitor is 20 or less. High Q capacitors, such as Mylar, are not rec- ommended because they tend to reduce the phase margin at light load currents. Aluminum electrolytic capacitors may also be used, but the minimum value should be 10uF 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 ca- pacitor greater than 20uF 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 DI (see Figure 2) between the input and the output. The input capacitor, C2, is only required if the regula- tor is more than 4 inches from the raw supply filter Capacitor. Bypassing the Adjustment Pin: The adjustment pin of the LT137A 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 capaci- tor reduces ripple, noise, and impedance to that of a 1.25V regulator. Ina 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 R;. Ten microfarads is generally sufficient for 60Hz power line applications where the ripple fre- quency is 120Hz, since X, = 1300. The capacitor should have a voltage rating at least as high as the output voltage of the regulator. Values larger than 10uF 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). \} z oO oy Ri D2 ee IN4002 Vin Vout D1 * IN4002 *D1 protects the regulator from input shorts to **D2 protects the adjust pin of the requiator ground. It is required only when C3 is larger from output shorts if C2 is larger than 10uF than 20uF and Vout is larger than 6V. and Vout is larger than 25V. Figure 2 Proper Connection of Divider Resistors: The LT137A has an excellent load regulation specification of 0.5% 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, R1 and R2, 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. Lead resistance here does not affect load regulation. | Y I LOAD VN Connect R; directly to Regulator Pin. Lead resistance here degrades load regulation. Minimize the length of this lead. Figure 3 R1 should be connected directly to the output lead of the regulator, as close as possible to the specified point 1/8 from the case. R2 should be connected to the positive side of the load separately from the posi- tive (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 R1 is connected to the load, regulation will be degraded. 4-162 LI WeLT137A/LM137 LT337A/LM337 TYPICAL APPLICATIONS igh stabtty Regulator The output stability, load regulation, line regulation, LL 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 20PPM/C maximum drift and about 10 times lower noise than s the regulator. \l ar Vout | epg Nor 9.08 X 10 + ae Dual Tracking Supply + 1.25V to + 20V In the application shown below, regulators #2 to N geepen will track regulator #1 to within + 24mV initially, and to + 60mV over all load, line, and temperature condi- +VK vw T3174. Vout tions. 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 Voyr/1.25V compared to a standard regulator, so regulator #1 should be the one which has the lowest load current. Multiple Tracking Regulators * Solid Tantalum **A4 or Rg may be trimmed slightly to improve tracking Current Regulator Te, SOLID TANTALUM (-) (+) t 1.25 1 = 65A + Rs (0.89 < Rg< 2502) LT We 4-163LT137A/LM137 LT337A/LM337 SCHEMATIC DIAGRAM ADJ 3 L 2x a b cz 2 A 04 Seq | ely tek 7 ostty aA {] Your ny eA oy r NY : 800 Sey 750 Of pa 60k 100% 032m L 06 WA WA Wr 600 3 T* 220 R Yor ek < a12 05 > 100k Som 023 a3 ] 5pF as oe} r 1K e 1, Qi8 {ce 1027 028 7031. Hors NK Ny : | ok } 016 OW 3m 2k x 029 2 0.02 ats < 2 100 3 4a Sak Stk 3% 2M 2 500 {] K Package TO-3 STEEL Metal Can T Package TO-220 Plastic 3-Lead Metal Can Package (H) 0.7600.775 0.180 + 0.005 0.350-0.370 0.395~-0.4 23907 0.370_ 0.325 0.350 mason ees) t aoe 3a 20081 verceoee Peas 1.325 0. " . . +0.054 (8.255 8.890) 0.116 | OA ) 0.050 + 0.002 Ow ! ene (127 20.054) 0.305 0.335 Max 0.110 + 0.010 0.165 0.195 W747 8.509) y ss (2.794 = 0.254) 0.250 0.010 (4.181 4.953) on 0.420-0.490 $+ 1) SEATING PUNE (6.35 + 0.254) {10.68812192) } 0.038 0.043 oes oa = |. TAPERED 1, 2 SIDES t o.saos0010 | ~] 0800 0.035 t l [ 1.477= 1.197 (6.536 + 0.254) (12.70) 70.888) (29,896 30.404) 0.6600.670 i }e SEATING PLANE MN MAX rm __ _0.018-0.019 DA 0.2100.220 | (16.764 17.018) 1.020 + 0.015 A ~~ | {0.408 0.483) (5.334.588) (25.91 + 0.381) 0 150 Xr 0.168-0.178 | wen (4267 4.521) |-_ 2 MOUNTING HOLES 0.540 + 0.015 0.425 -0.435 0,151~-0.161 (13.72 0.381) (10.795 11.049} (3.835 4.089) O.410 ee DA (10.41) 0.490-0.510 B (12.446 12.954) +0.010 0.050 0.105 pois 0.0260.045 (1.27) 0.032 = 0.005 _ pes7 TOes4 (0.680- 1.143) 0.1000 010 | (0.813 + 0.127) BO! _ 9.381 o.0280.038 (2.542 0.254) aos *h toe (0.7110,864) 0.200 + 0.010 Those h K (5.08 + 0.254) 0.381 7 5 061 TJMAX ex Tmax 8x Ty MAX 8x 137A a7A | ss0c | acw 337A | 125C | 4C/W 137A | 50C | 15C 1 137 337A A 337 125C 3C/w 337 125C 4CwW 337, 125C | 15C/W 337 a a 4-164 LT 0106 REV A+ PRINTED IN USA LI We