LT138A/LT338A LM138/LM338 5A Positive Adjustable Voltage Regulator. Features. Description. Applications. Typical Application

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1 Features Guaranteed % Initia Toerance Guaranteed.3% Load Reguation Guaranteed A Output Current % Therma Limit Burn-In A Transient Output Current Appications OBSOLETE: FOR INFORMATION PURPOSES ONLY Contact Linear Technoogy for Potentia Repacement High Power Linear Reguator Battery Chargers Power Driver Constant-Current Reguator Description LT3A/ A Positive Adjustabe Votage Reguator The LT 3A series of adjustabe reguators provide A output current over an output votage range of.v to 3V. The interna votage reference is trimmed to ess than %, enabing a very tight output votage. In addition to exceent ine and oad reguation, with fu overoad protection, the LT3A incorporates new current imiting circuitry aowing arge transient oad currents to be handed for short periods. Transient oad currents of up to A can be suppied without imiting, eiminating the need for a arge output capacitor. The LT3A is an improved version of the popuar LM3 with improved circuit design and advanced process techniques to provide superior performance and reiabiity. The graph beow shows the significant improvement in output votage toerance achieved by using the LT3A or. L, LT, LTC, LTM, Linear Technoogy and the Linear ogo are registered trademarks of Linear Technoogy Corporation. A other trademarks are the property of their respective owners. Typica Appication Parae Reguators for Higher Current* LT3A.Ω Ω % 3Ω %.Ω** 3/33 TA * THIS CIRCUIT WILL NOT WORK WITH LM VERSION DEVICES ** CURRENT SHARING RESISTORS DEGRADE REGULATION TO % V A OUTPUT VOLTAGE ERROR (%) Output Votage Error % RESISTORS LM33 % RESISTORS LM33 % RESISTORS % RESISTORS OUTPUT VOLTAGE (V) 3A/33A TA

2 LT3A/LT339A Absoute Maximum Ratings Power Dissipation... Internay Limited Input-to-Output Votage Differentia... 3V Operating Junction Temperature Range LT3A/LM3... C to C /LM33... C to C (Note ) Storage Temperature Range... C to C Lead Temperature (Sodering, sec)...3 C Preconditioning % Therma Limit Burn-In Pin Configuration BOTTOM VIEW (GND*) K PACKAGE -LEAD TO-3 METAL CAN CASE IS OUTPUT T JMAX = C, θ JA = 3 C/W, θ JA = C/W (LT3A/LT3) T JMAX = C, θ JA = 3 C/W, θ JA = C/W (/LT33) OBSOLETE PACKAGE FRONT VIEW 3 P PACKAGE 3-LEAD PLASTIC TO-3P T JMAX = C, θ JA = C/W OBSOLETE PACKAGE

3 Eectrica Characteristics LT3A/ The denotes the specifications which appy over the fu operating temperature range, otherwise specifications are at T A = C. (Note ) SYMBOL PARAMETER CONDITIONS MIN LT3A TYP MAX MIN LM3 TYP MAX UNITS V REF Reference Votage I OUT = ma, T J = C.3.. V 3V ( ) 3V, ma I OUT A, P W V Δ Δ Line Reguation 3V ( ) 3V, (Note 3) Δ Load Reguation ma I OUT A, (Note 3) Δ V V V V Therma Reguation ms Puse.... %/W Rippe Rejection = V, f = Hz C = µf C = µf 7 7 db db I Adjust Pin Current µa ΔI Adjust Pin Current Change ma I OUT A,.. µa 3V ( ) 3V Minimum Load Current ( ) = 3V ma I SC Current Limit ( ) V DC.ms Peak Δ ΔTemp Δ ΔTime ( ) = 3V, T J = ºC A Temperature Stabiity % Long-Term Stabiity T A = ºC, Hours.3.3 % e n RMS Output Noise (% of ) HZ f khz..3 % θ JC Therma Resistance Junction-to-Case K Package ºC/W %/V %/V mv % mv % A A The denotes the specifications which appy over the fu operating temperature range, otherwise specifications are at T A = C. SYMBOL PARAMETER CONDITIONS MIN LT3A TYP MAX MIN LM3 TYP MAX UNITS V REF Reference Votage I OUT = ma.3.. V 3V ( ) 3V, ma I OUT A, P W V Δ Δ Line Reguation 3V ( ) 3V, (Note 3) Δ Load Reguation ma I OUT A, (Note 3) Δ V V V V Therma Reguation ms Puse.... %/W %/V %/V mv % mv % 3

4 LT3A/LT339A eectrica Characteristics The denotes the specifications which appy over the fu operating temperature range, otherwise specifications are at T A = C. SYMBOL PARAMETER CONDITIONS MIN Rippe Rejection = V, f = Hz C = µf C = µf LT3A TYP MAX MIN 7 LM3 TYP MAX UNITS I Adjust Pin Current µa ΔI Adjust Pin Current Change ma I OUT A,.. µa 3V ( ) 3V Minimum Load Current ( ) = 3V ma I SC Current Limit ( ) V DC.ms Peak Δ ΔTemp Δ ΔTime ( ) = 3V, T J = ºC A Temperature Stabiity % Long-Term Stabiity T A = ºC, Hours.3.3 % e n RMS Output Noise (% of ) Hz f khz..3 % θ JC Therma Resistance Junction-to-Case K Package ºC/W 7 db db A A Note : Stresses beyond those isted under Absoute Maximum Ratings may cause permanent damage to the device. Exposure to any Absoute Maximum Rating condition for extended periods may affect device reiabiity and ifetime. Note : Uness otherwise specified, these specifications appy: = V and I OUT =.A. These specifications are appicabe for power dissipations up to W. Note 3: See therma reguation specifications for changes in output votage due to heating effects. Load and ine reguation are measured at a constant junction temperature by ow duty cyce puse testing. Typica Performance Characteristics OUTPUT VOLTAGE DEVIATION (%) Load Reguation Dropout Votage Adjustment Current = V = V PRELOAD = ma I OUT = 3A I OUT = A INPUT-OUTPUT DIFFERENTIAL (V) 3 Δ = mv I OUT = A I OUT = A I OUT = 3A USTMENT CURRENT (μa) TEMPERATURE ( C) 7 7 TEMPERATURE ( C) TEMPERATURE ( C) 3/33 G 3/33 G 3A/33A G3

5 Typica Performance Characteristics LT3A/ REFERENCE VOLTAGE (V).7... Temperature Stabiity Output Impedance Minimum Operating Current OUTPUT IMPEDANCE (Ω)... = V = V I OUT = ma C = C OUT = μf C = C OUT = μf QUIESCENT CURRENT (ma) 3 T J = C T J = C T J = C.3 7 TEMPERATURE ( C). k k k M FREQUENCY (Hz) 3 3 INPUT-OUTPUT DIFFERENTIAL (V) 3A/33A G 3/33 G 3A/33A G Rippe Rejection Rippe Rejection Rippe Rejection C = μf C = μf RIPPLE REJECTION (db) = V I OUT = ma f = Hz T J = C C = μf 3 3 OUTPUT VOLTAGE (V) RIPPLE REJECTION (db) = V = V I OUT =.A C = μf C = μf k k k M FREQUENCY (Hz) RIPPLE REJECTION (db) 7. C = μf = V = V f = Hz T CASE = C OUTPUT CURRENT (A) 3A/33A G7 3A/33A G 3/33 G9 OUTPUT CURRENT (A) Current Limit Current Limit Current Limit PEAK CURRENT LIMIT DC CURRENT LIMIT T CASE = C PRELOAD = A PRELOAD = A PRELOAD = A 3 INPUT-OUTPUT DIFFERENTIAL (V) 3A/33A G OUTPUT CURRENT (A). PRELOAD = A = V = V T CASE = C PRELOAD = A TIME (ms) 3A/33A G OUTPUT CURRENT (A). PRELOAD CURRENT = T CASE = C = V = V = V = 3V TIME (ms) 3A/33A G

6 LT3A/LT339A typica performance characteristics OUTPUT VOLTAGE DEVIATION (V) INPUT VOLTAGE CHANGE (V) Line Transient Response = V I OUT = ma T J = C C L = μf C L = μf C OUT = C = 3 TIME (μs) 3A/33A G3 OUTPUT VOLTAGE DEVIATION (V) LOAD CURRENT (A) 3 3 Load Transient Response C L = μf C = μf C L = C = = V = V T CASE = C PRELOAD = ma 3 TIME (μs) 3A/33A G Appications Information Genera The LT3A deveops a.v reference votage between the output and the adjustabe termina (see Figure ). By pacing a resistor, R, between these two terminas, a constant current is caused to fow through R and down through R to set the overa output votage. Normay this current is the specified minimum oad current of ma or ma. Because I is very sma and constant when compared with the current through R, it represents a sma error and can usuay be ignored. It is easiy seen from the output votage equation, that even if the resistors were of exact vaue, the accuracy of the output is imited by the accuracy of V REF. Earier adjustabe reguators had a reference toerance of ± % which is dangerousy cose to the ±% suppy toerance required in many ogic and anaog systems. Further, even % resistors can drift.%/ C, adding additiona error to the output votage toerance. I μa V REF R ( ) = V R REF I R R R 3A/33A F For exampe, using % resistors and ±% toerance for V REF, cacuations wi show that the expected range of a V reguator design woud be.v.3v or approximatey ±7%. If the same exampe were used for a V reguator, the expected toerance woud be ±%. With these resuts most appications required some method of trimming, usuay a trim pot. This soution is both expensive and not conductive to voume production. One of the enhancements of Linear Technoogy s adjustabe reguators over existing devices is the tightened initia toerance of V REF. This aows reativey inexpensive % or % fim resistors to be used for R and R to set the output votage within an acceptabe toerance. With a guaranteed % reference, a V power suppy design, using ±% resistors, woud have a worst-case manufacturing toerance of ±%. If % resistors are used, the toerance wi drop to ±.%. A pot of the worst-case output votage toerance as a function of resistor toerance is shown on the front page of this data sheet. For convenience, a tabe of standard % resistor vaues is shown in Tabe. Figure. Basic Adjustabe Reguator

7 appications information Tabe..% and % Standard Resistance Vaues Standard resistance vaues are obtained from the Decade Tabe by mutipying by mutipes of. As an exampe,. can represent.ω,.ω, Ω,.k etc. Bypass Capacitors Input bypassing using a µf tantaum or µf eectroytic is recommended when the input fiter capacitors are more than inches from the device. Improved rippe rejection (db) can be accompished by adding a µf capacitor from the pin to ground. Increasing the size of the capacitor to µf wi hep rippe rejection at ow output votage since the reactance of this capacitor shoud be sma compared to the votage setting resistor, R. For improved AC transient response and to prevent the possibiity of osciation due to unknown reactive oad, a µf capacitor is aso recommended at the output. Because of their ow impedance at high frequencies, the best type of capacitor to use is soid tantaum. Protection Diodes The LT3A/ do not require a protection diode from the adjustment termina to the output (see Figure ). Improved interna circuitry eiminates the need for this diode when the adjustment pin is bypassed with a capacitor to improve rippe rejection. LT3A/ If a very arge output capacitor is used, such as a µf shown in Figure, the reguator coud be damaged or destroyed if the input is accidentay shorted to ground or crowbarred, due to the output capacitor discharging into the output termina of the reguator. To prevent this, a diode D as shown, is recommended to safey discharge the capacitor. D N C μf Figure R R NOT NEEDED C OUT μf 3A/33A F Load Reguation Because the LT3A is a three-termina device, it is not possibe to provide true remote oad sensing. Load reguation wi be imited by the resistance of the wire coecting the reguator to the oad. The data sheet specification for oad reguation is measured at the bottom of the package. Negative side sensing is a true Kevin coection, with the bottom of the output divider returned to the negative side of the oad. Athough it may not be immediatey obvious, best oad reguation is obtained when the top of the resistor divider, R, is coected directy to the case not to the oad. This is iustrated in Figure 3. If R were coected to the oad, the effective resistance between the reguator and the oad woud be: R P RR,R P = Parasitic Line Resistance R Coected as shown, R P is not mutipied by the divider ratio. R P is about.ω per foot using gauge wire. This transates to mv/ft at A oad current, so it is important to keep the positive ead between reguator and oad as short as possibe, and use arge wire or PC board traces. 7

8 LT3A/LT339A appications information R P PARASITIC LINE RESISTANCE CONNECT R TO CASE R R L R CONNECT R TO LOAD 3A/33A F3 Figure 3. Coections for Best Load Reguation Typica Appications Improving Rippe Rejection μf R Ω % R 3Ω % V C L * μf *C IMPROVES RIPPLE REJECTION, X C SHOULD BE SMALL COMPARED TO R 3A/33A TA3.V to V Adjustabe Reguator R Ω C* μf R k C** μf 3A/33A TA * NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS ** OPTIONAL, IMPROVES TRANSIENT RESPONSE ( ) =.V R R

9 LT3A/ typica Appications V Reguator with Shutdown μf Ω % V TTL k k N39 3Ω % 3A/33A TA Temperature Compensated Lead Acid Battery Charger 3A 3Ω % k Ω N39 V k k 3A/33A TA7 Remote Sensing Ω Ω 7 LM3A R P (MAX DROP 3mV) 3 k μf R L V 3Ω pf Ω RETURN RETURN 3A/33A TA 9

10 LT3A/LT339A Schematic Diagram LT3A/ 3Ω 3Ω 9Ω Ω.k Q Q Q Q9 Q Q 3k Q Q k.k 3k 3Ω Q Q Q Q Q Q Q3 Q3 Q7.k.k k Ω.k Ω k C 3pF C 3pF Q Q7 Q9 k.k Q Q.k Q Q3.7k Q C3 pf k Q k Ω 3Ω Q Ω Ω Q7 k Q D k D Ω 3Ω.Ω 3A/33A SS

11 Package Description Pease refer to for the most recent package drawings. LT3A/ K Package -Lead TO-3 Meta Can (Reference LTC DWG # --3).3.3 (.3.9).7.77 ( )..3 (. 3.9).. (.7.9).3.3 (.9.9).. (.33.9) (9.9 3.)..7 (. 7.).. (3..9) DIA, PLCS..3 (..).7.77 (.7.9).9. (..9) R.7.77 (..9) R K (TO-3) 9 OBSOLETE PACKAGE

12 LT3A/LT339A Package Description Pease refer to for the most recent package drawings. P Package 3-Lead Pastic TO-3P (Simiar to TO-7) (Reference LTC DWG # --). (.).3 (.).7 (.9)..O (.7.) MOUNTING HOLE.. (.9 3.) DIA.7.7 (.7.).. (..3. (.73).7 (7.7).3.7 (..)..OO (.73.).7.OO (.3.) EJECTOR PIN MARKS.. (.7 3.) DIA.9 (.9). (3.9).7. (9..3).7 (.3) MAX 3 7 BOTTOM VIEW OF TO-3P HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK.. (.7.3).7. (..3). (.) BSC.3.3 (.7 3.).7. (..9).. (..) P3 OBSOLETE PACKAGE

13 Revision History (Revision history begins at Rev D) LT3A/ REV DATE DESCRIPTION PAGE NUMBER D / Obsoete packaged parts.,, Information furnished by Linear Technoogy Corporation is beieved to be accurate and reiabe. However, no responsibiity is assumed for its use. Linear Technoogy Corporation makes no representation that the intercoection For more of its circuits information as described herein wi not infringe on existing patent rights. 3

14 LT3A/LT339A Typica Appication Lamp Fasher Automatic Light Contro V μf μf V.k OFF k μf k N39 k μf 3A/33A TA9 k 3A/33A TA Protected High Current Lamp Driver V V A TTL OR CMOS k 3A/33A TA Reated Parts PART NUMBER DESCRIPTION COMMENTS LT3/LT/ 3A/A/7.A Low Dropout Reguators Fixed Outputs, Up to 3V LT LT 7A Fast Transient Response Reguator with.7v Dropout For 3.3V to.xxv Appications LT A Fast Transient Response Reguator For 3.3V to.xxv Appications LT/LT/ 7A/.A/3A Low Dropout Fast Transient Response Reguator For.V to 3.3V Outputs from V LT7 LT7 3A Fast Transient Response Reguator Dropout Votage 3mV, Low Noise: µv RMS Linear Technoogy Corporation 3 McCarthy Bvd., Mipitas, CA () 3-9 FAX: () LT REV D PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 99

REF-01/REF-02 Precision Voltage References FEATURES DESCRIPTION

REF-01/REF-02 Precision Voltage References FEATURES DESCRIPTION REF-01/ Precision otage References FEATURES n Trimmed Output ±0.3 n Low Drift ppm/ C Typ n Low Noise 3ppm (P-P) n High Line Rejection n Temperature Output n Low Suppy Current 1.4mA Max APPLICATIONS n A/D