LT1117/LT LT /LT mA Low Dropout Positive Regulators Adjustable and Fixed 2.85V, 3.3V, 5V APPLICATIONS TYPICAL APPLICATION

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1 FEATURES n Space Saving SOT-223 Surface Mount Package n 3-Termina Adjustabe or Fixed 2.85, 3.3, 5 n Output Current of 8mA n Operates Down to Dropout n Guaranteed Dropout otage at Mutipe Current Leves n.2% Line Reguation Max n.4% Load Reguation Max APPLICATIONS n Active SCSI Terminators n High Effi ciency Linear Reguators n Post Reguators for Switching Suppies n Battery Chargers n 5 to 3.3 Linear Reguators L, LT, LTC, LTM, Linear Technoogy, OPTI-LOOP and the Linear ogo are registered trademarks of Linear Technoogy Corporation. UtraFast is a trademark of Linear Technoogy Corporation. A other trademarks are the property of their respective owners. DESCRIPTION / mA Low Dropout Positive Reguators Adjustabe and Fixed 2.85, 3.3, 5 The LT 7 is a positive ow dropout reguator designed to provide up to 8mA of output current. The device is avaiabe in an adjustabe version and fixed output votages of 2.85, 3.3 and 5. The 2.85 version is designed specificay to be used in Active Terminators for the SCSI bus. A interna circuitry is designed to operate down to input to output differentia. Dropout votage is guaranteed at a maximum of.2 at 8mA, decreasing at ower oad currents. On chip trimming adjusts the reference/output votage to within ±%. Current imit is aso trimmed in order to minimize the stress on both the reguator and the power source circuitry under overoad conditions. The ow profie surface mount SOT-223 package aows the device to be used in appications where space is imited. The requires a minimum of μf of output capacitance for stabiity. Output capacitors of this size or arger are normay incuded in most reguator designs. Unike PNP type reguators where up to % of the output current is wasted as quiescent current, the quiescent current of the fows into the oad, increasing efficiency. TYPICAL APPLICATION Active Terminator for SCSI-2 Bus Dropout otage ( ) TO 5.25 μf 22μF Ω Ω Ω Ω 8 TO 27 LES DROP OLTAGE () C T J < C C T J 25 C T J = 25 C T J = 25 C 7 TA.2 DICATES GUARANTEED TEST POT PUT CURRENT (ma) 7 TA2

2 ABSOLUTE MAXIMUM RATGS (Note ) Input otage Operating otage, -3.3, Surge otage, -3.3,...2 Operating JunctionTemperature Range C Grade... C to 25 C I Grade... 4 C to 25 C Storage Temperature Range C to 5 C Lead Temperature...(See Sodering Methods) P CONFIGURATION FRONT IEW FRONT IEW TAB IS 3 2 TAB IS 3 2 / / ST PACKAGE 3-LEAD PLASTIC SOT-223 T JMAX = 25 C, θ JC = 5 C/W M PACKAGE 3-LEAD PLASTIC DD-PAK T JMAX = 25 C, θ JC = C/W ORDER FORMATION LEAD FREE FISH TAPE AND REEL PART MARKG PACKAGE DESCRIPTION TEMPERATURE RANGE CST#PBF CST#TRPBF 7 3-Lead Pastic SOT-223 C to 25 C IST#PBF IST#TRPBF 7I 3-Lead Pastic SOT C to 25 C CST-2.85#PBF CST-2.85#TRPBF 72 3-Lead Pastic SOT-223 C to 25 C IST-2.85#PBF IST-2.85#TRPBF 7I2 3-Lead Pastic SOT C to 25 C CST-3.3#PBF CST-3.3#TRPBF 73 3-Lead Pastic SOT-223 C to 25 C IST-3.3#PBF IST-3.3#TRPBF 7I3 3-Lead Pastic SOT C to 25 C CST-5#PBF CST-5#TRPBF 75 3-Lead Pastic SOT-223 C to 25 C IST-5#PBF IST-5#TRPBF 7I5 3-Lead Pastic SOT C to 25 C CM#PBF CM#TRPBF CM 3-Lead Pastic DD-PAK C to 25 C CM-2.85#PBF CM-2.85#TRPBF CM Lead Pastic DD-PAK C to 25 C CM-3.3#PBF CM-3.3#TRPBF CM Lead Pastic DD-PAK C to 25 C CM-5#PBF CM-5#TRPBF CM-5 3-Lead Pastic DD-PAK C to 25 C 2

3 ORDER FORMATION LEAD BASED FISH TAPE AND REEL PART MARKG PACKAGE DESCRIPTION TEMPERATURE RANGE CST CST#TR 7 3-Lead Pastic SOT-223 C to 25 C IST IST#TR 7I 3-Lead Pastic SOT C to 25 C CST-2.85 CST-2.85#TR 72 3-Lead Pastic SOT-223 C to 25 C IST-2.85 IST-2.85#TR 7I2 3-Lead Pastic SOT C to 25 C CST-3.3 CST-3.3#TR 73 3-Lead Pastic SOT-223 C to 25 C IST-3.3 IST-3.3#TR 7I3 3-Lead Pastic SOT C to 25 C CST-5 CST-5#TR 75 3-Lead Pastic SOT-223 C to 25 C IST-5 IST-5#TR 7I5 3-Lead Pastic SOT C to 25 C CM CM#TR CM 3-Lead Pastic DD-PAK C to 25 C CM-2.85 CM-2.85#TR CM Lead Pastic DD-PAK C to 25 C CM-3.3 CM-3.3#TR CM Lead Pastic DD-PAK C to 25 C CM-5 CM-5#TR CM-5 3-Lead Pastic DD-PAK C to 25 C Consut LTC Marketing for parts specified with wider operating temperature ranges. For more information on ead free part marking, go to: For more information on tape and ree specifications, go to: ELECTRICAL CHARACTERISTICS The denotes the specifications which appy over the fu operating temperature range, otherwise specifications are at T J = 25 C. PARAMETER CONDITIONS M TYP MAX UNITS Reference otage I = ma, ( ) = 2, T J = 25 C ma I 8mA,.4 ( ) Output otage I = ma, = 4.85, T J = 25 C I 8mA, 4.25 I 5mA, = 3.95 Line Reguation Load Reguation -3.3 I = ma, = 5, T J = 25 C I 8mA, 4.75 I = ma, = 7, T J = 25 C I 8mA, I = ma,.5 5 (Note 2) I = ma, 4.25 (Note 2) I = ma, (Note 2) I = ma, (Note 2) ( ) = 3, ma I 8mA (Note 2) = 4.25, I 8mA (Note 2) = 4.75, I 8mA (Note 2) = 6.5, I 8mA (Note 2) Dropout otage I = ma, C T J 25 C (Note 3) I = 5mA, C T J 25 C (Note 3) I = 8mA, C T J 25 C (Note 3) I = ma, 4 C T J < C (Note 3) I = 5mA, 4 C T J < C (Note 3) I = 8mA, 4 C T J < C (Note 3) Current Limit ( ) = 5, T J = 25 C ma Minimum Load Current ( ) = 5 (Note 4).7 5 ma % m m m % m m m 3

4 ELECTRICAL CHARACTERISTICS The denotes the specifications which appy over the fu operating temperature range, otherwise specifications are at T J = 25 C. PARAMETER CONDITIONS M TYP MAX UNITS Quiescent Current ma ma ma Therma Reguation T A = 25 C, 3ms Puse.. %/W Rippe Rejection f RIPPLE = 2Hz, ( ) = 3, RIPPLE = P-P 6 75 db Adjust Pin Current 55 2 μa Adjust Pin Current Change ma I 8mA,.4 ( ).2 5 μa Temperature Stabiity.5 % Long Term Stabiity T A = 25 C, Hrs.3 % RMS Output Noise (% of ), Hz f khz.3 % Therma Resistance (Junction-to-Case, at Tab) 5 C/W 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 2: See therma reguation specification for changes in output votage due to heating effects. Load reguation and ine reguation are measured at a constant junction temperature by ow duty cyce puse testing. Note 3: Dropout votage is specified over the fu output current range of the device. Dropout votage is defined as the minimum input/output differentia measured at the specified output current. Test points and imits are aso shown on the Dropout otage curve. Note 4: Minimum oad current is defined as the minimum output current required to maintain reguation. TYPICAL PERFORMANCE CHARACTERISTICS MIMUM OPERATG CURRENT (ma) Minimum Operating Current (Adjustabe Device) Short-Circuit Current Load Reguation T J = 25 C T J = 25 C T J = 55 C SHORT CIRCUIT CURRENT (A) T J = 25 C T J = 25 C PUT OLTAGE DEIATION (%) ΔI LOAD = 8mA PUT/PUT DIFFERENTIAL () 5 5 PUT/PUT DIFFERENTIAL () TEMPERATURE ( C) 7 G 7 G2 7 G3 4

5 TYPICAL PERFORMANCE CHARACTERISTICS RIPPLE REJECTION (db) Rippe Rejection RIPPLE 3 P-P RIPPLE.5 P-P ( ) 3 ( ) DROP 2 C = 2μF AT f < 6Hz C = 25μF AT f > 6Hz I =.5A k k k FREQUENCY (Hz) 7 G4 RIPPLE REJECTION (db) Rippe Rejection vs Current = 5 C = 25μF C = 25μF f RIPPLE = 2Hz RIPPLE 3 P-P f RIPPLE = 2kHz RIPPLE.5 P-P PUT CURRENT (A) 7 G5 PUT OLTAGE CHANGE (%) Temperature Stabiity TEMPERATURE ( C) 7 G6 UST P CURRENT (μa) Adjust Pin Current TEMPERATURE ( C) 7 G7 PUT OLTAGE DEIATION () LOAD CURRENT (A) Load Transient Response C = μf C = μf TANTALUM = 4.25 PRELOAD =.A TIME (μs) 7 G8 PUT OLTAGE DEIATION () LOAD CURRENT (A) Load Transient Response C = μf C = μf TANTALUM = 6.5 PRELOAD =.A TIME (μs) 7 G9 PUT OLTAGE DEIATION (m) Line Transient Response C = μf C = μf TANTALUM I =.A PUT OLTAGE DEIATION (m) Line Transient Response C = μf C = μf TANTALUM I =.A PUT OLTAGE () TIME (μs) PUT OLTAGE () TIME (μs) 7 G 7 G 5

6 /-2.85 BLOCK DIAGRAM THERMAL LIMIT FOR FIXED OLTAGE DEICE 7 BD 6

7 APPLICATIONS FORMATION The famiy of 3-termina reguators are easy to use. They are protected against short circuit and therma overoads. Therma protection circuitry wi shut down the reguator shoud the junction temperature exceed 65 C at the sense point. These reguators are pin compatibe with oder 3-termina adjustabe reguators, offer ower dropout votage and more precise reference toerance. Reference stabiity over temperature is improved over oder types of reguators. Stabiity The famiy of reguators requires an output capacitor as part of the device frequency compensation. A minimum of μf of tantaum or 5μF of auminum eectroytic is required. The ESR of the output capacitor shoud be ess than.5ω. Surface mount tantaum capacitors, which have very ow ESR, are avaiabe from severa manufacturers. When using the adjustabe device, the adjust termina can be bypassed to improve rippe rejection. When the adjust termina is bypassed, the required vaue of the output capacitor increases. The device wi require an output capacitor of 22μF tantaum or 5μF auminum eectroytic when the adjust pin is bypassed. Normay, capacitor vaues on the order of μf are used in the output of many reguators to ensure good oad transient response with arge oad current changes. Output capacitance can be increased without imit and arger vaues of output capacitance further improve stabiity and transient response. Protection Diodes In norma operation, the famiy does not need any protection diodes. Oder adjustabe reguators required protection diodes between the adjust pin and the output and between the output and input to prevent over stressing the die. The interna current paths on the adjust pin are imited by interna resistors. Therefore, even with capacitors on the adjust pin, no protection diode is needed to ensure device safety under short-circuit conditions. The adjust pin can be driven, on a transient basis, ±25 with respect to the output without any device degradation. Diodes between input and output are not usuay needed. The interna diode between the output and input pins of the device can withstand microsecond surge currents of A to 2A. Norma power suppy cycing can not generate currents of this magnitude. Ony with extremey arge output capacitors, such as μf and arger, and with the input pin instantaneousy shorted to ground can damage occur. A crowbar circuit at the input of the in combination with a arge output capacitor coud generate currents arge enough to cause damage. In this case a diode from output to input is recommended, as shown in Figure. D N42 (OPTIONAL) C μf R R2 C 5μF 7 F Figure 7

8 APPLICATIONS FORMATION Output otage The deveops a.25 reference votage between the output and the adjust termina (see Figure 2). By pacing a resistor between these two terminas, a constant current is caused to fow through R and down through R2 to set the overa output votage. Normay this current is chosen to be the specified minimum oad current of ma. Because I is very sma and constant when compared to the current through R, it represents a sma error and can usuay be ignored. For fixed votage devices R and R2 are incuded in the device. I 5μA REF R2 = REF I R2 R R R2 7 F2 Figure 2. Basic Adjustabe Reguator Load Reguation Because the is a 3-termina device, it is not possibe to provide true remote oad sensing. Load reguation wi be imited by the resistance of the wire connecting the reguator to the oad. The data sheet specification for oad reguation is measured at the output pin of the device. Negative side sensing is a true Kevin connection, 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 returned directy to the output pin of the device, not to the oad. This is iustrated in Figure 3. Connected as shown, R P is not mutipied by the divider ratio. If R were connected to the oad, the effective resistance between the reguator and the oad woud be: R P R2 R, RP = Parasitic Line Resistance R R P PARASITIC LE RESISTANCE R CONNECT R TO CASE R2 CONNECT R2 TO LOAD R L 7 F3 Figure 3. Connections for Best Load Reguation For fixed votage devices the top of R is internay Kevin connected, and the ground pin can be used for negative side sensing. Therma Considerations series reguators have interna therma imiting circuitry designed to protect the device during overoad conditions. For continuous norma oad conditions however, the maximum junction temperature rating of 25 C must not be exceeded. It is important to give carefu consideration to a sources of therma resistance from junction to ambient. For the SOT-223 package, which is designed to be surface mounted, additiona heat sources mounted near the device must aso be considered. Heat sinking is accompished using the heat spreading capabiity of the PC board and its copper traces. The therma resistance of the is 5 C/W from the junction to the tab. Therma resistances from tab to ambient can be as ow as 3 C/W. The tota therma resistance from junction to ambient can be as ow as 45 C/W. This requires a reasonabe sized PC board with at east one ayer of copper to spread the heat across the board and coupe it into the surrounding air. 8

9 APPLICATIONS FORMATION Experiments have shown that the heat spreading copper ayer does not need to be eectricay connected to the tab of the device. The PC materia can be very effective at transmitting heat between the pad area, attached to the tab of the device, and a ground pane ayer either inside or on the opposite side of the board. Athough the actua therma resistance of the PC materia is high, the Length/ Area ratio of the therma resistor between ayers is sma. The data in Tabe was taken using /6" FR-4 board with oz. copper foi. It can be used as a rough guideine in estimating therma resistance. Tabe. COPPER AREA THERMAL RESISTANCE TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT) 25 Sq. mm 25 Sq. mm 25 Sq. mm 45 C/W Sq. mm 25 Sq. mm 25 Sq. mm 45 C/W 225 Sq. mm 25 Sq. mm 25 Sq. mm 53 C/W Sq. mm 25 Sq. mm 25 Sq. mm 59 C/W Sq. mm Sq. mm Sq. mm 52 C/W Sq. mm Sq. mm 55 C/W * Tab of device attached to topside copper The therma resistance for each appication wi be affected by therma interactions with other components on the board. Some experimentation wi be necessary to determine the actua vaue. The power dissipation of the is equa to: P D = ( )( I ) Maximum junction temperature wi be equa to: T J = T A(MAX) P D (Therma Resistance (junction-toambient)) Maximum junction temperature must not exceed 25 C. Rippe Rejection The curves for Rippe Rejection were generated using an adjustabe device with the adjust pin bypassed. These curves wi hod true for a vaues of output votage. For proper bypassing, and rippe rejection approaching the vaues shown, the impedance of the adjust pin capacitor, at the rippe frequency, shoud be < R. R is normay in the range of Ω to 2Ω. The size of the required adjust pin capacitor is a function of the input rippe frequency. At 2Hz, with R = Ω, the adjust pin capacitor shoud be >3μF. At khz ony.6μf is needed. For fixed votage devices, and adjustabe devices without an adjust pin capacitor, the output rippe wi increase as the ratio of the output votage to the reference votage ( / REF ). For exampe, with the output votage equa to 5, the output rippe wi be increased by the ratio of 5/.25. It wi increase by a factor of four. Rippe rejection wi be degraded by 2dB from the vaue shown on the curve. 9

10 TYPICAL APPLICATIONS.2 to Adjustabe Reguator 5 Reguator with Shutdown C* μf R2 k R 2Ω C2 μf TTL μf k k 2N394 2Ω % 365Ω % 5 μf * NEEDED IF DEICE IS FAR FROM FILTER CAPACITORS =.25 R2 R ( ) 7 TA3 7 TA4 Remote Sensing μf μf 25Ω 2Ω R P (MAX. DROP 3m) LM3A k 5μF R L PUT 5 RETURN 365Ω pf 25Ω RETURN 7 TA5 Adjusting Output otage of Fixed Reguators Reguator with Reference > 2 μf 5 TO μf >.5 μf μf μf* k 5 LT29 * OPTIONAL IMPROES RIPPLE REJECTION 7 TA7 7 TA6

11 TYPICAL APPLICATIONS Battery Charger Battery Backed Up Reguated Suppy IF.25 R S R ( ) ( ).25 R2 R IF = R S R2 R ΔIF = Δ R S R2 R ( ) 7 TA8 μf SELECT FOR CHARGE RATE 6.5 μf 5Ω 5.2 LE 5. BATTERY μf 7 TA9 Improving Rippe Rejection Automatic Light Contro μf R2 365Ω *C IMPROES RIPPLE % REJECTION. X C SHOULD BE R AT RIPPLE FREQUENCY R 2Ω % C μf 5 5μF 7 TA μf.2k μf 7 TA High Effi ciency Dua Suppy FEEDBACK PATH MUR4 3.3 PUT (TYPICAL) 47μF MUR4 47μF μf 5.5A N42 SWITCHG REGULATOR MUR4 47μF μf N42 5.5A 7 TA2

12 TYPICAL APPLICATIONS High Effi ciency Dua Linear Suppy (HEAT SK) 2N6667 (DARLGTON) MDA2 Q k 47μF MBR36 k L 285μH 5k /2 LT8 μf 2.4k 3k LT k* 3.k* μf 5.5A D N42 3AC TO 9AC STANCOR P-8685 (HEAT SK) 2N6667 (DARLGTON) MDA2 k 47μF MBR36 k L 285μH 5k /2 LT8 μf 2.4k 3k LT k* 3.k* μf D2 N42 * = % FILM RESISTORS MDA = MOTOROLA L = PULSE ENGEERG, C. #PE A 7 TA3 Low Dropout Negative Suppy μf μf FLOATG PUT = 5 7 TA4 2

13 PACKAGE DESCRIPTION M Package 3-Lead Pastic DD Pak (Reference LTC DWG # ).256 (6.52).6 (.524).6 (.524) TYP ( ) ( ) ( ).6 (.524).83 (4.648) ( ).59 (.499) ( ).3 (7.62).75 (.95) BOTTOM IEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SK ( ).5 (.27). (2.54) BSC.3.23 ( ).95.5 ( ).5 ±.2 (.27 ±.35) RECOMMENDED SOLDER PAD LAY NOTE:. DIMENSIONS CH/(MILLIMETER) 2. DRAWG NOT TO SCALE..7 RECOMMENDED SOLDER PAD LAY FOR THICKER SOLDER PASTE APPLICATIONS M (DD3) 24 3

14 PACKAGE DESCRIPTION ST Package 3-Lead Pastic SOT-223 (Reference LTC DWG # ) ( ).4.24 ( ).59 MAX.29 MAX ( ).3.46 ( ).39 MAX.248 BSC.59 MAX.95 (2.3) BSC.33.4 (.84.4).8 MAX.9 BSC RECOMMENDED SOLDER PAD LAY.7 (.8) MAX 6 MAX..4 (.25.36) (.6.84).8 (4.6) BSC.2 (.3) M.8.4 (.23.6) 6 ST3 (SOT-233) 52 4

15 REISION HISTORY (Revision history begins at Rev D) RE DATE DESCRIPTION PAGE NUMBER D 4/ Updated DD-Pak part markings in Order Information section and revised a other sections. to 6 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 interconnection of its circuits as described herein wi not infringe on existing patent rights. 5

16 TYPICAL APPLICATION High Effi ciency Reguator 28 PUT k mh MR22,μF 28 47Ω N94 24Ω 2k PUT UST PUT μf k M 4N28 k LT k 28 N94 7 TA5 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT8 Low I Q, Low Dropout, 8mA, Source and Sink Reguators Sources and Sinks Current, 6mA Quiescent Current, Dropout otage:, SOIC-8 and SOT-223 Packages LT29 7mA Micropower Low Dropout 5μA Quiescent Current Reguator LT763 5mA, Low Noise LDO 3m Dropout otage, Low Noise: 2μ RMS, =.8 to 2, SO-8 Package LT764, LT764A LT963, LT763A LT965 LT32 LT38, LT38- LT385 LTC325-, LTC325-2, LTC325-3, LTC325-4 LTC326 3A, Fast Transient Response, Low Noise LDO.5A Low Noise, Fast Transient Response LDO.A, Low Noise, Low Dropout Linear Reguator 5mA, Low otage, LDO Linear Reguator.A, Paraeabe, Low Noise, Low Dropout Linear Reguator 5mA, Paraeabe, Low Noise, Low Dropout Linear Reguator 5mA Micropower LDO Linear Reguator in 2 2 DFN.5A, Low Input otage LDO Linear Reguator 34m Dropout otage, Low Noise: 4μ RMS, = 2.7 to 2, TO-22 and DD Packages A version stabe aso with ceramic caps 34m Dropout otage, Low Noise: 4μ RMS, = 2.5 to 2, A version stabe with ceramic caps, TO-22, DD, SOT-223 and SO-8 Packages 29m Dropout otage, Low Noise: 4μ RMS, :.8 to 2, :.2 to 9.5, stabe with ceramic caps, TO-22, DDPak, MSOP and 3 3 DFN Packages :.9 to, Dropout otage: 6m Typica, Adjustabe Output ( REF = (M) = 2m), Fixed Output otages:.2,.5,.8, Stabe with Low ESR, Ceramic Output Capacitors 6-Pin DFN (5mm 5mm) and 8-Lead SO Packages 3m Dropout otage (2-suppy operation), Low Noise: 4μ RMS, :.2 to 36, : to 35.7, current-based reference with -resistor set; directy paraeabe (no op amp required), stabe with ceramic caps, TO-22, SOT-223, MS8E and 3 3 DFN-8 Packages; - version has integrated interna baast resistor 275m Dropout otage (2-suppy operation), Low Noise: 4μ RMS, :.2 to 36, : to 35.7, current-based reference with -resistor set; directy paraeabe (no op amp required), stabe with ceramic caps, MS8E and 2 3 DFN-6 packages =.9 to 5.5, Dropout otage: 75m, Low Noise 8μ RMS, Low I Q : 54μA, Fixed Output:.2 (LTC325-2),.5 (LTC325-3),.8 (LTC325-4); Adjustabe Output Range:.4 to 3.6 (LTC325-), 2mm 2mm 6-Lead DFN Package :.4 to 3.5 (Boost Enabed),.4 to 5.5 (with Externa 5), DO =., I Q = 95μA, Stabe with μf Ceramic Capacitors, -Lead MSOP-E and DFN- Packages 6 LT 4 RE D PRTED USA Linear Technoogy Corporation 63 McCarthy Bvd., Mipitas, CA (48) FAX: (48) LEAR TECHNOLOGY CORPORATION 993