LT3065 Series 45V V IN, 500mA Low Noise, Linear Regulator with Programmable Current Limit and Power Good. Applications. Typical Application

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1 Features n Input Votage Range: 1.8V to 45V n Output Current: 5mA n Dropout Votage: 3 n Programmabe Precision Current Limit: ±1% n Power Good Fag n Low Noise: 25µV RMS (1Hz to 1kHz) n Adjustabe Output (V REF = V OUT(M) = 6) n Output Toerance: ±2% Over Line, Load and Temperature n Stabe with Low ESR, Ceramic Output Capacitors (3.3µF Minimum) n Singe Capacitor Soft-Starts Reference and Lowers Output Noise n Current Limit Fodback Protection n Shutdown Current: <1µA n Reverse Battery and Therma Limit Protection n 1-Lead 3mm 3mm DFN and 12-ead MSOP Packages Appications n Battery-Powered Systems n Automotive Power Suppies n Industria Power Suppies n Avionic Power Suppies n Portabe Instruments LT365 Series 45V V, 5mA Low Noise, Linear Reguator with Programmabe Current Limit and Power Good Description The LT 365 Series are micropower, ow noise, ow dropout votage (LDO) inear reguators that operate over a 1.8V to 45V input votage range. The devices suppy 5mA of output current with a typica dropout votage of 3. A singe externa capacitor provides programmabe ow noise reference performance and output soft-start functionaity. A singe externa resistor programs the LT365 s current imit, accurate to ±1% over a wide input votage and temperature range. A PWRGD fag indicates output reguation. The LT365 optimizes stabiity and transient response with ow ESR ceramic capacitors, requiring a minimum of 3.3µF. Interna protection circuitry incudes current imiting with fodback, therma imiting, reverse battery protection, reverse current protection and reverse output protection. The LT365 is avaiabe in fixed output votages of 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, and 5V, and as an adjustabe device with an output votage range from.6v to 4V. The LT365 is avaiabe in the thermay-enhanced 1-ead 3mm 3mm DFN and 12-ead MSOP packages. L, LT, LTC, LTM, Linear Technoogy and the Linear ogo are registered trademarks and ThinSOT is a trademark of Anaog Devices, Inc. A other trademarks are the property of their respective owners. Typica Appication 5.6V TO 13V 5V Suppy with 2mA Precision Current Limit 3.3µF 5k 1nF OUT LT365-5 SENSE PWRGD ADJ REF/BYP GND I MAX 1nF 1.5k 22nF 3.3µF 5V OUT 2mA 365 TA1a CURRENT LIMIT (ma) Precision Current Limit, R IMAX = 1.5k 22 V OUT(NOMAL) = 5V V = 1V 2 V = 5.6V For more information TA1b 365fc 1

2 LT365 Series Absoute Maximum Ratings Pin Votage...±5V OUT Pin Votage... +4V, 5V Input-to-Output Differentia Votage (Note 2)...+5V, 4V ADJ Pin Votage...±5V SENSE Pin Votage...±5V Pin Votage...±5V PWRGD Pin Votage....3V, 5V I MAX Pin Votage....3V, 7V REF/BYP Pin Votage...1V Pin Configuration (Note 1) Output Short-Circuit Duration... Indefinite Operating Junction Temperature Range (Notes 3, 5, 14) E-, I-Grades... 4 C to 125 C MP-Grade C to 15 C H-Grade... 4 C to 15 C Storage Temperature Range C to 15 C Lead Temperature (Sodering, 1 sec) MSOP Package Ony...3 C TOP VIEW TOP VIEW PWRGD I MAX 1 1 OUT 2 9 OUT 3 11 GND 8 ADJ/SENSE* 4 7 GND/ADJ* 5 6 REF/BYP PWRGD I MAX NC GND OUT OUT ADJ/SENSE* GND/ADJ* REF/BYP NC DD PACKAGE 1-LEAD (3mm 3mm) PLASTIC DFN T JMAX = 15 C, θ JA = 31 C/W, θ JC = 9 C/W EXPOSED PAD (P 11) IS GND, MUST BE SOLDERED TO PCB *Pin 7: GND for LT365, ADJ for LT , LT , LT , LT , LT , LT365-5 *Pin 8: ADJ for LT365, SENSE for LT , LT , LT , LT , LT , LT365-5 MSE PACKAGE 12-LEAD PLASTIC MSOP T JMAX = 15 C, θ JA = 28 C/W, θ JC = 6 C/W EXPOSED PAD (P 13) IS GND, MUST BE SOLDERED TO PCB *Pin 9: GND for LT365, ADJ for LT , LT , LT , LT , LT , LT365-5 *Pin 1: ADJ for LT365, SENSE for LT , LT , LT , LT , LT , LT365-5 Order Information 2 LEAD FREE FISH TAPE AND REEL PART MARKG* PACKAGE DESCRIPTION TEMPERATURE RANGE LT365EDD#PBF LT365EDD#TRPBF LGKS 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365IDD#PBF LT365IDD#TRPBF LGKS 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365HDD#PBF LT365HDD#TRPBF LGKS 1-Lead (3mm x 3mm) Pastic DFN 4 C to 15 C LT365MPDD#PBF LT365MPDD#TRPBF LGKS 1-Lead (3mm x 3mm) Pastic DFN 55 c to 15 C LT365EDD-1.2#PBF LT365EDD-1.2#TRPBF LGQV 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365IDD-1.2#PBF LT365IDD-1.2#TRPBF LGQV 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365HDD-1.2#PBF LT365HDD-1.2#TRPBF LGQV 1-Lead (3mm x 3mm) Pastic DFN 4 C to 15 C LT365MPDD-1.2#PBF LT365MPDD-1.2#TRPBF LGQV 1-Lead (3mm x 3mm) Pastic DFN 55 C to 15 C LT365EDD-1.5#PBF LT365EDD-1.5#TRPBF LGQW 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365IDD-1.5#PBF LT365IDD-1.5#TRPBF LGQW 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365HDD-1.5#PBF LT365HDD-1.5#TRPBF LGQW 1-Lead (3mm x 3mm) Pastic DFN 4 C to 15 C LT365MPDD-1.5#PBF LT365MPDD-1.5#TRPBF LGQW 1-Lead (3mm x 3mm) Pastic DFN 55 C to 15 C LT365EDD-1.8#PBF LT365EDD-1.8#TRPBF LGQX 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365IDD-1.8#PBF LT365IDD-1.8#TRPBF LGQX 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365HDD-1.8#PBF LT365HDD-1.8#TRPBF LGQX 1-Lead (3mm x 3mm) Pastic DFN 4 C to 15 C LT365MPDD-1.8#PBF LT365MPDD-1.8#TRPBF LGQX 1-Lead (3mm x 3mm) Pastic DFN 55 C to 15 C LT365EDD-2.5#PBF LT365EDD-2.5#TRPBF LGQY 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C For more information 365fc

3 LT365 Series Order Information LEAD FREE FISH TAPE AND REEL PART MARKG* PACKAGE DESCRIPTION TEMPERATURE RANGE LT365IDD-2.5#PBF LT365IDD-2.5#TRPBF LGQY 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365HDD-2.5#PBF LT365HDD-2.5#TRPBF LGQY 1-Lead (3mm x 3mm) Pastic DFN 4 C to 15 C LT365MPDD-2.5#PBF LT365MPDD-2.5#TRPBF LGQY 1-Lead (3mm x 3mm) Pastic DFN 55 C to 15 C LT365EDD-3.3#PBF LT365EDD-3.3#TRPBF LGQZ 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365IDD-3.3#PBF LT365IDD-3.3#TRPBF LGQZ 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365HDD-3.3#PBF LT365HDD-3.3#TRPBF LGQZ 1-Lead (3mm x 3mm) Pastic DFN 4 C to 15 C LT365MPDD-3.3#PBF LT365MPDD-3.3#TRPBF LGQZ 1-Lead (3mm x 3mm) Pastic DFN 55 C to 15 C LT365EDD-5#PBF LT365EDD-5#TRPBF LGRB 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365IDD-5#PBF LT365IDD-5#TRPBF LGRB 1-Lead (3mm x 3mm) Pastic DFN 4 C to 125 C LT365HDD-5#PBF LT365HDD-5#TRPBF LGRB 1-Lead (3mm x 3mm) Pastic DFN 4 C to 15 C LT365MPDD-5#PBF LT365MPDD-5#TRPBF LGRB 1-Lead (3mm x 3mm) Pastic DFN 55 C to 15 C LT365EMSE#PBF LT365EMSE#TRPBF Lead Pastic MSOP 4 C to 125 C LT365IMSE#PBF LT365IMSE#TRPBF Lead Pastic MSOP 4 C to 125 C LT365HMSE#PBF LT365HMSE#TRPBF Lead Pastic MSOP 4 C to 15 C LT365MPMSE#PBF LT365MPMSE#TRPBF Lead Pastic MSOP 55 C to 15 C LT365EMSE-1.2#PBF LT365EMSE-1.2#TRPBF Lead Pastic MSOP 4 C to 125 C LT365IMSE-1.2#PBF LT365IMSE-1.2#TRPBF Lead Pastic MSOP 4 C to 125 C LT365HMSE-1.2#PBF LT365HMSE-1.2#TRPBF Lead Pastic MSOP 4 C to 15 C LT365MPMSE-1.2#PBF LT365MPMSE-1.2#TRPBF Lead Pastic MSOP 55 C to 15 C LT365EMSE-1.5#PBF LT365EMSE-1.5#TRPBF Lead Pastic MSOP 4 C to 125 C LT365IMSE-1.5#PBF LT365IMSE-1.5#TRPBF Lead Pastic MSOP 4 C to 125 C LT365HMSE-1.5#PBF LT365HMSE-1.5#TRPBF Lead Pastic MSOP 4 C to 15 C LT365MPMSE-1.5#PBF LT365MPMSE-1.5#TRPBF Lead Pastic MSOP 55 C to 15 C LT365EMSE-1.8#PBF LT365EMSE-1.8#TRPBF Lead Pastic MSOP 4 C to 125 C LT365IMSE-1.8#PBF LT365IMSE-1.8#TRPBF Lead Pastic MSOP 4 C to 125 C LT365HMSE-1.8#PBF LT365HMSE-1.8#TRPBF Lead Pastic MSOP 4 C to 15 C LT365MPMSE-1.8#PBF LT365MPMSE-1.8#TRPBF Lead Pastic MSOP 55 C to 15 C LT365EMSE-2.5#PBF LT365EMSE-2.5#TRPBF Lead Pastic MSOP 4 C to 125 C LT365IMSE-2.5#PBF LT365IMSE-2.5#TRPBF Lead Pastic MSOP 4 C to 125 C LT365HMSE-2.5#PBF LT365HMSE-2.5#TRPBF Lead Pastic MSOP 4 C to 15 C LT365MPMSE-2.5#PBF LT365MPMSE-2.5#TRPBF Lead Pastic MSOP 55 C to 15 C LT365EMSE-3.3#PBF LT365EMSE-3.3#TRPBF Lead Pastic MSOP 4 C to 125 C LT365IMSE-3.3#PBF LT365IMSE-3.3#TRPBF Lead Pastic MSOP 4 C to 125 C LT365HMSE-3.3#PBF LT365HMSE-3.3#TRPBF Lead Pastic MSOP 4 C to 15 C LT365MPMSE-3.3#PBF LT365MPMSE-3.3#TRPBF Lead Pastic MSOP 55 C to 15 C LT365EMSE-5#PBF LT365EMSE-5#TRPBF Lead Pastic MSOP 4 C to 125 C LT365IMSE-5#PBF LT365IMSE-5#TRPBF Lead Pastic MSOP 4 C to 125 C LT365HMSE-5#PBF LT365HMSE-5#TRPBF Lead Pastic MSOP 4 C to 15 C LT365MPMSE-5#PBF LT365MPMSE-5#TRPBF Lead Pastic MSOP 55 C to 15 C Consut LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a abe on the shipping container. For more information on ead free part marking, go to: For more information on tape and ree specifications, go to: Some packages are avaiabe in 5 unit rees through designated saes channes with #TRMPBF suffix. For more information 365fc 3

4 LT365 Series Eectrica Characteristics The denotes the specifications which appy over the fu operating temperature range, otherwise specifications are at T A = 25 C (Note 3). PARAMETER CONDITIONS M TYP MAX UNITS Minimum Input Votage (Notes 4, 9) I LOAD = 5mA V Reguated Output Votage LT : V = 2.2V, I LOAD = 1mA V 2.2V < V < 45V, 1mA < I LOAD < 5mA V LT : V = 2.2V, I LOAD = 1mA V 2.2V < V < 45V, 1mA < I LOAD < 5mA V LT : V = 2.4V, I LOAD = 1mA V 2.4V < V < 45V, 1mA < I LOAD < 5mA V LT : V = 3.1V, I LOAD = 1mA V 3.1V < V < 45V, 1mA < I LOAD < 5mA V LT : V = 3.9V, I LOAD = 1mA V 3.9V < V < 45V, 1mA < I LOAD < 5mA V LT365-5: V = 5.6V, I LOAD = 1mA V 5.6V < V < 45V, 1mA < I LOAD < 5mA V ADJ Pin Votage (Notes 4, 5) LT365: V = 2.2V, I LOAD = 1mA V < V < 45V, 1mA < I LOAD < 5mA Line Reguation I LOAD = 1mA Load Reguation I LOAD = 1mA to 5mA Dropout Votage, V = V OUT(NOMAL) (Notes 6, 7) GND Pin Current, V = V OUT(NOMAL) +.6V (Notes 7, 8) LT : ΔV = 2.2V to 45V LT : ΔV = 2.2V to 45V LT : ΔV = 2.4V to 45V LT : ΔV = 3.1V to 45V LT : ΔV = 3.9V to 45V LT365-5: ΔV = 5.6V to 45V LT365: ΔV = 2.2V to 45V (Note 4) LT , V = 2.2V LT , V = 2.2V LT , V = 2.4V LT V = 3.1V LT , V = 3.9V LT365-5, V = 5.6V LT365, V = 2.2V (Note 4) I LOAD = 1mA I LOAD = 5mA I LOAD = 1mA I LOAD = 5mA I LOAD = ma I LOAD = 1mA I LOAD = 1mA I LOAD = 1mA I LOAD = 5mA Quiescent Current in Shutdown V = 45V, V = V.2 1 µa ADJ Pin Bias Current (Notes 4, 1) V = 2.2V 16 6 na Output Votage Noise C OUT = 1µF, I LOAD = 5mA, V OUT = 6, 9 µv RMS BW = 1Hz to 1kHz C OUT = 1µF, C BYP = 1nF, I LOAD = 5mA, 25 µv RMS V OUT = 6, BW = 1Hz to 1kHz Shutdown Threshod V OUT = Off to On V V OUT = On to Off V µa µa µa ma ma 4 For more information 365fc

5 LT365 Series Eectrica Characteristics The denotes the specifications which appy over the fu operating temperature range, otherwise specifications are at T A = 25 C (Note 3). Pin Current (Note 11) Rippe Rejection V V OUT = 2V, V RIPPLE =.5V P-P, f RIPPLE = 12Hz, I LOAD = 5mA V = V, V = 45V V = 45V, V = 45V LT LT LT LT LT LT365-5 LT365.5 Input Reverse Leakage Current V = 45V, V OUT = 3 µa Reverse Output Current (Note 12) V OUT = 1.2V, V = V = 1 µa Interna Current Limit (Note 4) V = 2.2V, V OUT =, V IMAX = V = 2.2V, V OUT = 5% 52 Externa Programmed Current Limit (Notes 7, 13) 5.6V < V < 1V, V OUT = 95% of V OUT (Nomina), R IMAX = 1.5k 5.6V < V < 7V, V OUT = 95% of V OUT (Nomina), R IMAX = 64Ω ±1 3 µa µa db db db db db db db 9 ma ma PWRGD Logic Low Votage Pu-Up Current = 5µA.7.25 V PWRGD Leakage Current V PWRGD = 45V.1 1 µa PWRGD Trip Point % of Nomina Output Votage, Output Rising % PWRGD Trip Point Hysteresis % of Nomina Output Votage 1.6 % ma ma Note 1: 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: Absoute maximum input-to-output differentia votage is not achievabe with a combinations of rated pin and OUT pin votages. With at 5V, do not pu OUT beow V. The tota differentia votage from to OUT must not exceed +5V, 4V. If OUT is pued above and GND, the OUT to differentia votage must not exceed 4V. Note 3: The LT365 reguator is tested and specified under puse oad conditions such that T J T A. The LT365E reguators are 1% tested at T A = 25 C and performance is guaranteed from C to 125 C. Performance at 4 C to 125 C is assured by design, characterization and correation with statistica process contros. The LT365I reguators are guaranteed over the fu 4 C to 125 C operating junction temperature range. The LT365MP reguators are 1% tested over the 55 C to 15 C operating junction temperature range. The LT365H reguators are 1% tested at the 15 C operating junction temperature. High junction temperatures degrade operating ifetimes. Operating ifetime is derated at junction temperatures greater than 125 C. Note 4: The LT365 adjustabe version is tested and specified for these conditions with the ADJ pin connected to the OUT pin. Note 5: Maximum junction temperature imits operating conditions. Reguated output votage specifications do not appy for a possibe combinations of input votage and output current. If operating at the maximum input votage, imit the output current range. If operating at the maximum output current, imit the input votage range. Current imit fodback imits the maximum output current as a function of input-tooutput votage. See Current Limit vs V V OUT in the Typica Performance Characteristics section. Note 6: Dropout votage is the minimum -to-out differentia votage needed to maintain reguation at a specified output current. In dropout, the output votage equas (V V DROPOUT ). For some output votages, minimum input votage requirements imit dropout votage. Note 7: To satisfy minimum input votage requirements, the LT365 is tested and specified for these conditions with an externa resistor divider (6.4k bottom, 442k top) which sets V OUT to 5V. The divider adds 1uA of output DC oad. This externa current is not factored into GND pin current. Note 8: GND pin current is tested with V = V OUT(NOMAL) +.6V and a current source oad. GND pin current increases in dropout. See GND pin current curves in the Typica Performance Characteristics section. Note 9: To satisfy requirements for minimum input votage, current imit is tested at V = V OUT(NOMAL) + 1V or V = 2.2V, whichever is greater. Note 1: ADJ pin bias current fows out of the ADJ pin. Note 11: pin current fows into the pin. Note 12: Reverse output current is tested with the pin grounded and the OUT pin forced to the specified votage. This current fows into the OUT pin and out of the GND pin. Note 13: Current imit varies inversey with the externa resistor vaue tied from the IMAX pin to GND. For detaied information on seecting the IMAX resistor vaue, see the Operation section. If the externay programmed current imit feature is unused, tie the IMAX pin to GND. The interna current imit circuitry impements short-circuit protection as specified. Note 14: This IC incudes over temperature protection that protects the device during overoad conditions. Junction temperature exceeds 125 C (LT365E, LT365I) or 15 C (LT365MP, LT365H) when the over temperature circuitry is active. Continuous operation above the specified maximum junction temperature may impair device reiabiity. For more information 365fc 5

6 LT365 Series Typica Performance Characteristics T J = 25 C, uness otherwise noted. DROPOUT VOLTAGE () Typica Dropout Votage Guaranteed Dropout Votage Dropout Votage 7 65 = TEST POTS 6 55 TJ = 15 C 5 45 TJ = 15 C TJ = 125 C TJ = 25 C TJ = 25 C OUTPUT CURRENT (ma) OUTPUT CURRENT (ma) DROPOUT VOLTAGE () DROPOUT VOLTAGE () I L = 5mA 3 25 I L = 1mA I L = 5mA I L = 1mA G1 365 G2 365 G3 QUIESCENT CURRENT (µa) Quiescent Current V = V = 12V V OUT = 5V I L = 1µA V 1 = 12V ALL OTHER PS = V G4 OUTPUT VOLTAGE (V) LT Output Votage I 1.22 L = 1mA G5 OUTPUT VOLTAGE (V) LT Output Votage I L = 1mA G6 OUTPUT VOLTAGE (V) LT Output Votage LT Output Votage LT Output Votage I 1.83 L = 1mA OUTPUT VOLTAGE (V) 2.55 I L = 1mA OUTPUT VOLTAGE (V) I L = 1mA G7 365 G8 365 G9 6 For more information 365fc

7 Typica Performance Characteristics T J = 25 C, uness otherwise noted. LT365 Series OUTPUT VOLTAGE (V) LT365-5 Output Votage 5.1 I L = 1mA G1 ADJ P VOLTAGE () ADJ Pin Votage I L = 1mA G11 QUIESCENT CURRENT (µa) LT Quiescent Current T J = 25 C R L = 24k V OUT = 1.2V V = V V = V PUT VOLTAGE (V) 365 G12 LT Quiescent Current LT Quiescent Current LT Quiescent Current QUIESCENT CURRENT (µa) T J = 25 C R L = 3k V OUT = 1.5V V = V QUIESCENT CURRENT (µa) T J = 25 C R L = 36k V OUT = 1.8V V = V QUIESCENT CURRENT (µa) T J = 25 C R L = 5k V OUT = 2.5V V = V 25 V = V PUT VOLTAGE (V) 25 V = V PUT VOLTAGE (V) 25 V = V PUT VOLTAGE (V) 365 G G G15 QUIESCENT CURRENT (µa) LT Quiescent Current T J = 25 C R L = 66k V OUT = 3.3V V = V V = V PUT VOLTAGE (V) 365 G16 QUIESCENT CURRENT (µa) LT365-5 Quiescent Current T J = 25 C R L = 1M V OUT = 5V V = V V = V PUT VOLTAGE (V) 365 G17 QUIESCENT CURRENT (µa) Quiescent Current V = V V = V T J = 25 C V OUT = 5V I L = 1µA V (V) 365 G18 For more information 365fc 7

8 LT365 Series Typica Performance Characteristics GND P CURRENT (ma) LT GND Pin Current T J = 25 C *FOR V OUT = 1.2V V = V R L = 2.4Ω I L = 5mA* R L = 4.8Ω I L = 25mA* R L = 12Ω I L = 1mA* PUT VOLTAGE (V) R L = 12Ω I L = 1mA* GND P CURRENT (ma) LT GND Pin Current T J = 25 C *FOR V OUT = 1.5V V = V R L = 3Ω I L = 5mA* R L = 6Ω I L = 25mA* R L = 15Ω I L = 1mA* R L = 15Ω I L = 1mA* PUT VOLTAGE (V) GND P CURRENT (ma) LT GND Pin Current T J = 25 C *FOR V OUT = 1.8V V = V R L = 3.6Ω I L = 1mA* R L = 7.2Ω I L = 25mA* R L = 18Ω I L = 1mA* R L = 18Ω I L = 1mA* PUT VOLTAGE (V) 365 G G2 365 G21 GND P CURRENT (ma) LT GND Pin Current T J = 25 C *FOR V OUT = 2.5V V = V R L = 5Ω I L = 5mA* R L = 1Ω I L = 25mA* R L = 25Ω I L = 1mA* R L = 25Ω I L = 1mA* PUT VOLTAGE (V) GND P CURRENT (ma) LT GND Pin Current R L = 6.6Ω I L = 5mA* R L = 13.2Ω I L = 25mA* T J = 25 C *FOR V OUT = 3.3V V = V R L = 33Ω I L = 1mA* R L = 33Ω I L = 1mA* PUT VOLTAGE (V) GND P CURRENT (ma) LT365-5 GND Pin Current R L = 1Ω I L = 5mA* T J = 25 C *FOR V OUT = 5V V = V R L = 2Ω I L = 25mA* R L = 5Ω I L = 1mA* R L = 5Ω I L = 1mA* PUT VOLTAGE (V) 365 G G G24 GND P CURRENT (ma) GND Pin Current vs I LOAD V = 5.6V V OUT = 5V I LOAD (ma) P THRESHOLD (V) Pin Threshod OFF TO ON ON TO OFF P CURRENT (µa) Pin Current 3. = 45V G G G27 8 For more information 365fc

9 Typica Performance Characteristics T J = 25 C, uness otherwise noted. LT365 Series P CURRENT (µa) Pin Input Current ADJ Pin Bias Current Interna Current Limit P VOLTAGE (V) ADJ P CURRENT (na) CURRENT LIMIT (A) V = 6V 1.3 V OUT = V G G G3 CURRENT LIMIT (A) Interna Current Limit C 15 C C.7 55 C C V V OUT (V) 365 G31 OUTPUT CURRENT (µa) Reverse Output Current 1. V = V OUT (V) 365 G32 OUTPUT CURRENT (µa) Reverse Output Current V OUT = V ADJ = 1.2V V = V I ADJ I OUT G33 RIPPLE REJECTION (db) Input Rippe Rejection Input Rippe Rejection Input Rippe Rejection C REF/BYP = nf C REF/BYP = 1pF C REF/BYP = 1nF 2 I LOAD = 5mA C OUT = 1µF 1 V OUT = 3.3V V = 4.3V + 5 RMS RIPPLE 1 1 1k 1k 1k 1M 1M FREQUENCY (Hz) C REF/BYP = 1nF 365 G34 RIPPLE REJECTION (db) I LOAD = 5mA C REF/BYP = 1nF 1 V OUT = 3.3V V = 4.3V + 5 RMS RIPPLE 1 1 1k 1k 1k 1M 1M FREQUENCY (Hz) C OUT = 1µF C OUT = 3.3µF 365 G35 PSRR I LOAD = 5mA 2 C REF/BYP = 1nF V OUT = 3.3V 1 V = 4.3V + 5 RMS RIPPLE f = 12Hz G36 For more information 365fc 9

10 LT365 Series Typica Performance Characteristics T J = 25 C, uness otherwise noted. MIMUM PUT VOLTAGE (V) Minimum Input Votage I L = 5mA LOAD REGULATION () Load Reguation I L = 1mA TO 5mA V OUT =.6V V = 2.2V OUTPUT NOISE SPECTRAL DENSITY (µv/ Hz) 1 1 Output Noise Spectra Density C REF/BYP =, C FF = C OUT = 1µF I L = 5mA.1 V OUT = 5V V OUT = 3.3V V OUT = 2.5V V OUT = 1.2V V OUT =.6V k 1k 1k FREQUENCY (Hz) 365 G G G39 OUTPUT NOISE SPECTRAL DENSITY (µv/ Hz) Output Noise Spectra Density vs C REF/BYP, C FF = V OUT = 5V V OUT =.6V C OUT = 1µF I L = 5mA C REF/BYP = 1pF C REF/BYP = 1nF C REF/BYP = 1nF k 1k 1k FREQUENCY (Hz) 365 G4 OUTPUT NOISE SPECTRAL DENSITY (µv/ Hz) Output Noise Spectra Density vs C FF, C REF/BYP = 1nF V OUT = 5V C OUT = 1µF I L = 5mA C FF = pf C FF = 1pF C FF = 1nF C FF = 1nF k 1k 1k FREQUENCY (Hz) 365 G41 OUTPUT NOISE VOLTAGE (µv RMS ) RMS Output Noise, V OUT =.6V, C FF = f = 1Hz TO 1kHz C OUT = 1µF C REF/BYP = pf C REF/BYP = 1pF C REF/BYP = 1nF C REF/BYP = 1nF LOAD CURRENT (ma) 365 G42 OUTPUT VOLTAGE NOISE (µv RMS ) RMS Output Noise vs Load Current vs C REF/BYP = 1nF, C FF = 2.1 f = 1Hz TO 1kHz V OUT = 5V C OUT = 1µF V OUT = 3.3V V OUT = 2.5V V OUT = 1.8V V OUT = 1.5V V OUT = 1.2V V OUT =.6V LOAD CURRENT (ma) OUTPUT NOISE VOLTAGE (µv RMS ) RMS Output Noise, vs Feedforward Capacitor (C FF ) 12 f = 1Hz TO 1kHz 11 V OUT = 5V C REF/BYP = 1nF 1 C OUT = 1µF 9 V OUT = 3.3V I FB-DIVIDER = 1µA 8 I LOAD = 5mA 7 V OUT = 2.5V V OUT = 1.2V 2 V OUT =.6V FEEDFORWARD CAPACITOR, C FF (nf) START-UP TIME (ms) Start-Up Time vs REF/BYP Capacitor C FF = OPEN 1 1 REF/BYP CAPACITOR (nf) G G G45 1 For more information 365fc

11 Typica Performance Characteristics T J = 25 C, uness otherwise noted. LT365 Series 1Hz to 1kHz Output Noise C REF/BYP = 1nF, C FF = 1Hz to 1kHz Output Noise C REF/BYP = 1nF, C FF = 1nF 5V Transient Response C FF =, I OUT = 5mA to 5mA V OUT 2µV/DIV V OUT 2µV/DIV V OUT 1/DIV I OUT 5mA/DIV C OUT = 1µF I LOAD = 5mA V OUT = 5V 2ms/DIV 365 G46 C OUT = 1µF I LOAD = 5mA V OUT = 5V 2ms/DIV 365 G47 V = 6V 1µs/DIV C OUT = 1µF I FB-DIVIDER = 1µA V OUT = 5V 365 G48 5V Transient Response C FF = 1nF, I OUT = 5mA to 5mA Transient Response (Load Dump) V OUT 1/DIV V OUT 2/DIV 45V I OUT 5mA/DIV V 1V/DIV 12V V = 6V C OUT = 1µF I FB-DIVIDER = 1µA V OUT = 5V 2µs/DIV 365 G49 V OUT = 5V I OUT = 1mA C OUT = 1µF 1ms/DIV 365 G5 Transient Response C REF/BYP = Transient Response C REF/BYP = 1nF OUT 5V/DIV I L = 5mA REF/BYP 5/DIV OUT 5V/DIV I L = 5mA REF/BYP 5/DIV 2V/DIV 2V/DIV 2ms/DIV 365 G51 2ms/DIV 365 G52 For more information 365fc 11

12 LT365 Series Typica Performance Characteristics T J = 25 C, uness otherwise noted. CURRENT LIMIT (ma) Precision Current Limit, R IMAX = 1.5k 22 V OUT(NOMAL) = 5V V = 1V 2 V = 5.6V G53 CURRENT LIMIT (ma) Precision Current Limit, R IMAX = 64Ω 55 V OUT(NOMAL) = 5V V V 7V G54 ADJ P VOLTAGE () PWRGD Threshod Votage ADJ P RISG THRESHOLD ADJ P FALLG THRESHOLD G55 Pin Functions (DFN/MSOP) (Pins 1, 2/Pins 1, 2): Input. These pin(s) suppy power to the device. The LT365 requires a oca bypass capacitor if it is ocated more than six inches from the main input fiter capacitor. In genera, battery output impedance rises with frequency, so adding a bypass capacitor in battery-powered circuits is advisabe. An input bypass capacitor in the range of 1µF to 1µF generay suffices. See Input Capacitance and Stabiity in the Appications Information section for more information. The LT365 withstands reverse votages on the pin with respect to its GND and OUT pins. In such case, such as a battery pugged in backwards, the LT365 behaves as if a diode is in series with its input. No reverse current fows into the LT365 and no reverse votage appears at the oad. The device protects itsef and the oad. (Pin 3/Pin 3): Shutdown. Puing the pin ow puts the LT365 into a ow power state and turns the output off. Drive the pin with either ogic or an open coector/drain with a pu-up resistor. The resistor suppies the pu-up current to the open coector/drain ogic, normay severa microamperes, and the pin current, typicay ess than 2µA. If unused, connect the pin to. The LT365 does not function if the pin is not connected. PWRGD (Pin 4/Pin 4): Power Good. The PWRGD pin is an open-drain output that activey pus ow if the output is ess than 9% of the nomina output vaue. The PWRGD pin is capabe of sinking 5µA. There is no interna pu-up resistor; an externa pu-up resistor must be used. I MAX (Pin 5/Pin 5): Precision Current Limit Programming. This pin is the coector of a current mirror PNP that is 1/5th the size of the output power PNP. This pin is aso the input to the current imit ampifier. The current imit threshod is set by connecting a resistor between the I MAX pin and GND. For detaied information on how to set the I MAX pin resistor vaue, see the Appications Information section. The I MAX pin requires a 22nF de-couping capacitor to ground. If not used, tie I MAX to GND. NC (Pins 6, 7, MSE Package Ony): No Connect. These pins have no connection to interna circuitry. These pins may be foated or connected to GND. REF/BYP (Pin 6/Pin 8): Bypass/Soft Start. Connecting a capacitor from this pin to GND bypasses the LT365 s reference noise and soft-starts the reference. A 1nF bypass capacitor typicay reduces output votage noise to 25µV RMS in a 1Hz to 1kHz bandwidth. Soft-start time is directy 12 For more information 365fc

13 LT365 Series Pin Functions (DFN/MSOP) proportiona to the BYP capacitor vaue. If the LT365 is paced in shutdown, BYP is activey pued ow by an interna device to reset soft-start. If ow noise or soft-start performance is not required, this pin must be eft foating (unconnected). Do not drive this pin with any active circuitry. Because the REF/BYP pin is the reference input to the error ampifier, stray capacitance at this point shoud be minimized. Specia attention shoud be given to any stray capacitances that can coupe externa signas onto the REF/BYP pin producing undesirabe output transients or rippe. A minimum capacitance of 1pF from REF/BYP to GND is recommended. OUTPUT (Pins 9,1/Pins 11,12): Output. These pins suppy power to the oad. Stabiity requirements demand a minimum 3.3µF ceramic output capacitor with an ESR < 1Ω to prevent osciations. Appications with output votages ess than 1.2V require a minimum 4.7µF ceramic output capacitor. Large oad transient appications require arger output capacitors to imit peak votage transients. See the Appications Information section for detais on transient response and reverse output characteristics. Permissibe output votage range is 6 to 4V. Adjustabe Version Ony GND (Pin 7, Exposed Pad Pin 11/Pin 9, Exposed Pad Pin 13): Ground. The exposed pad of the DFN and MSOP packages is an eectrica connection to GND. To ensure proper eectrica and therma performance, soder Pin 11/Pin 13 to the PCB GND and tie it directy to Pin 7/Pin 9. For the adjustabe LT365, connect the bottom of the externa resistor divider that sets output votage directy to GND (Pin 7/Pin 9)for optimum oad reguation. ADJ (Pin 8/Pin 1): Adjust. This pin is the error ampifier s inverting termina. It s typica bias current of 16nA fows out of the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typica Performance Characteristics section). The ADJ pin votage is 6 referenced to GND. Connecting a capacitor from OUT to ADJ reduces output noise and improves transient response for output votages greater than 6. See the Appications Information section for cacuating the vaue of the feedforward capacitor. At output votages above.6v, the resistor divider connected to the ADJ pin is used to reguate votage at the oad. Parasitic resistances of PCB traces or cabes can therefore resut in oad reguation errors at high output currents. To eiminate these, connect the resistor divider directy to the oad for a Kevin sense connection, as shown in Figure 1. Fixed Votage Version Ony GND (Exposed Pad Pin 11, Exposed Pad Pin 13): Ground. The exposed pad of the DFN and MSOP packages is an eectrica connection to GND. To ensure proper eectrica and therma performance, soder Pin 11/Pin 13 to the PCB ground. SENSE (Pin 8/Pin 1): Sense. This pin is the top of the interna resistor divider network, and shoud be connected directy to the oad, as a Kevin sense, for optimum oad reguation and transient performance. Connecting this pin to the output pin at the package, rather than directy to the oad, can resut in oad reguation errors due to the current across the parasitic resistance of the PCB trace. ADJ (Pin 7/Pin 9): Adjust. This pin is the midpoint of the interna resistor divider network and the inverting input to the error ampifier. Connecting a capacitor from the OUT to ADJ reduces output noise and improves transient response. See the Appications Information section for cacuating the vaue of the feedforward capacitor; the interna divider current is 5µA. This pin shoud not be used for any other purpose. For more information 365fc 13

14 + + + LT365 Series Pin Functions ADJUSTABLE VERSION FIXED VOLTAGE VERSION + V + OUT LT365 ADJ GND R P R2 R1 LOAD + V + OUT LT365-X SENSE GND R P LOAD R P R P 365 F1 Figure 1. Kevin Sense Connection Bock Diagram Tabe 2. Fixed Votage Option Resistor Vaues V OUT (V) R1 (kω) R2 (kω) SENSE* R5 ADJ R2* 3k R4 THERMAL/ CURRENT LIMIT D1 QI MAX 1/5X QPOWER 1X R1* IDEAL DIODE D3 Q2 D2 ERROR AMPLIFIER Q3 CURRENT LIMIT AMPLIFIER 1k R3 OUT I MAX + 6 REFERENCE PWRGD QPWRGD + 54 REFERENCE REF/BYP GND *FIXED VOLTAGE OPTIONS ONLY Figure 2. System Bock Diagram 365 F2 14 For more information 365fc

15 Appications Information The LT365 are micropower, ow noise and ow drop-out votage, 5mA inear reguators with micropower shutdown, programmabe current imit, and a Power-good fag. The devices suppy up to 5mA at a typica dropout votage of 3 and operates over a 1.8V to 45V input range. A singe externa capacitor provides ow noise reference performance and output soft-start functionaity. For exampe, connecting a 1nF capacitor from the REF/BYP pin to GND owers output noise to 25μV RMS over a 1Hz to 1kHz bandwidth. This capacitor aso soft starts the reference and prevents output votage overshoot at turn-on. The LT365 s quiescent current is merey 55μA but provides fast transient response with a ow ESR, minimum vaue 3.3μF ceramic output capacitor. In shutdown, quiescent current is ess than 1μA and the reference soft-start capacitor is reset. The LT365 optimizes stabiity and transient response with ow ESR, ceramic output capacitors. The reguator does not require the addition of ESR as is common with other reguators. The LT365 typicay provides better than.1% ine reguation and.1% oad reguation. Interna protection circuitry incudes reverse battery protection, reverse output protection, reverse current protection, current imit with fodback and therma shutdown. This buet-proof protection set makes it idea for use in battery-powered, automotive and industria systems.in battery backup appications where the output is hed up by a backup battery and the input is pued to ground, the LT365 acts ike it has a diode in series with its output and prevents reverse current. Adjustabe Operation The adjustabe LT365 has an output votage range of.6v to 4V. Output votage is set by the ratio of two externa resistors, as shown in Figure 3. The device reguates the output to maintain the ADJ pin votage at.6v referenced to ground. The current in R1 equas.6v/r1, and R2 s current is R1 s current minus the ADJ pin bias current. LT365 Series The ADJ pin bias current, 16nA at 25 C, fows from the ADJ pin through R1 to GND. Cacuate the output votage using the formua in Figure 3. R1 s vaue shoud not be greater than 62k to provide a minimum 1μA oad current so that output votage errors, caused by the ADJ pin bias current, are minimized. Note that in shutdown, the output is turned off and the divider current is zero. Curves of ADJ Pin Votage vs Temperature and ADJ Pin Bias Current vs Temperature appear in the Typica Performance Characteristics section. + V LT365 Figure 3. Adjustabe Operation The LT365 is tested and specified with the ADJ pin tied to the OUT pin, yieding V OUT =.6V. Specifications for output votages greater than.6v are proportiona to the ratio of the desired output votage to.6v: V OUT /.6V. For exampe, oad reguation for an output current change of 1mA to 5mA is.1 (typica) at V OUT =.6V. At V OUT = 12V, oad reguation is: 12V (.1) = 2.6V OUT ADJ GND R2 R1 365 F3 V OUT =.6V 1+ R2 I ADJ R2 R1 V ADJ =.6V I ADJ = 16nA AT 25 C ( ) OUTPUT RANGE =.6V TO 4V V OUT For more information 365fc 15

16 LT365 Series Appications Information Tabe 3 shows 1% resistor divider vaues for some common output votages with a resistor divider current of 1μA. Tabe 3. Output Votage Resistor Divider Vaues 16 V OUT (V) R1 (kω) R2 (kω) Bypass Capacitance and Output Votage Noise The LT365 reguator provides ow output votage noise over a 1Hz to 1kHz bandwidth whie operating at fu oad with the addition of a bypass capacitor (C REF/BYP ) from the REF/BYP pin to GND. A high quaity ow eakage capacitor is recommended. This capacitor bypasses the interna reference of the reguator, providing a ow frequency noise poe for the interna reference. With the use of 1nF for C REF/BYP, output votage noise decreases to as ow as 25μV RMS when the output votage is set for.6v. For higher output votages (generated by using a feedback resistor divider), the output votage noise gains up proportionatey when using C REF/BYP. To ower the higher output votage noise, connect a feedforward capacitor (C FF ) from V OUT to the ADJ pin. A high quaity, ow eakage capacitor is recommended. This capacitor bypasses the error ampifier of the reguator, providing an additiona ow frequency noise poe. With the use of 1nF for both C FF and C REF/BYP, output votage noise decreases to 25μV RMS when the output votage is set to 5V by a 1μA feedback resistor divider. If the current in the feedback resistor divider is doubed, C FF must aso be doubed to achieve equivaent noise performance. Feedforward capacitance can aso be used in fixed-votage parts; the feedforward capacitor is connected from OUT to ADJ in the same manner. In this case, the current in the interna feedback resistor divider is 5μA. Higher vaues of output votage noise can occur if care is not exercised with regard to circuit ayout and testing. Crosstak from nearby traces induces unwanted noise For more information onto the LT365 s output. Power suppy rippe rejection must aso be considered. The LT365 reguator does not have unimited power suppy rejection and passes a sma portion of the input noise through to the output. Using a feedforward capacitor (C FF ) connected between V OUT and ADJ has the added benefit of improving transient response for output votages greater than.6v. With no feedforward capacitor, the setting time increases as the output votage increases above.6v. Use the equation in Figure 4 to determine the minimum vaue of C FF to achieve a transient response that is simiar to the.6v output votage performance regardess of the chosen output votage (See Figure 5 and Transient Response in the Typica Performance Characteristics section). Figure 4. Feedforward Capacitor for Fast Transient Response FEEDFORWARD CAPACITOR, CFF V + 1pF 1nF 1nF OUT LT365 ADJ GND REF/BYP C REF/BYP LOAD CURRENT 5mA/DIV V OUT = 5V 1µs/DIV C OUT = 1µF I FB-DIVIDER = 1µA 365 F5 V OUT 365 F4 V OUT 1/DIV Figure 5. Transient Response vs Feedforward Capacitor R2 R1 C FF 1nF 1µA ( I FB_DIVIDER) I FB_DIVIDER = V OUT R1+R2 C FF C OUT 365fc

17 Appications Information During start-up, the interna reference soft-starts when a REF/BYP capacitor is used. Reguator start-up time is directy proportiona to the size of the bypass capacitor (see Start-Up Time vs REF/BYP Capacitor in the Typica Performance Characteristics section). The reference bypass capacitor is activey pued ow during shutdown to reset the interna reference. Using a feedforward capacitor aso affects start-up time. Start-up time is directy proportiona to the size of the feedforward capacitor and the output votage, and is inversey proportiona to the feedback resistor divider current, sowing to 15ms with a 1nF feedforward capacitor and a 1μF output capacitor for an output votage set to 5V by a 1μA feedback resistor divider. Output Capacitance and Transient Response The LT365 reguator is stabe with a wide range of output capacitors. The ESR of the output capacitor affects stabiity, most notaby with sma capacitors. Use a minimum output capacitor of 3.3μF with an ESR of 1Ω or ess to prevent osciations. For V OUT ess than 1.2V, use a minimum C OUT of 4.7µF. If a feedforward capacitor is used with output votages set for greater than 24V, use a minimum output capacitor of 1μF. The LT365 is a micropower device and output oad transient response is a function of output capacitance. Larger vaues of output capacitance decrease the peak deviations and provide improved transient response for arger oad current changes. Bypass capacitors, used to decoupe individua components powered by the LT365, increase the effective output capacitor vaue. For appications with arge oad current transients, a ow ESR ceramic capacitor in parae with a buk tantaum capacitor often provides an optimay damped response. Give extra consideration to the use of ceramic capacitors. Manufacturers make ceramic capacitors with a variety of dieectrics, each with different behavior across temperature and appied votage. The most common dieectrics are specified with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V dieectrics provide high C-V products in a sma package at ow cost, but exhibit strong votage and temperature coefficients, as shown in Figures 6 and 7. When used with a 5V reguator, a 16V 1μF Y5V capacitor can exhibit an effective vaue CHANGE VALUE (%) For more information DC BIAS VOLTAGE (V) LT365 Series as ow as 1μF to 2μF for the DC bias votage appied, and over the operating temperature range. The X5R and X7R dieectrics yied much more stabe characteristics and are more suitabe for use as the output capacitor. The X7R type works over a wider temperature range and has better temperature stabiity, whie the X5R is ess expensive and is avaiabe in higher vaues. Care sti must be exercised when using X5R and X7R capacitors; the X5R and X7R codes ony specify operating temperature range and maximum capacitance change over temperature. Capacitance change due to DC bias with X5R and X7R capacitors is better than Y5V and Z5U capacitors, but can sti be significant enough to drop capacitor vaues beow appropriate eves. Capacitor DC bias characteristics tend to improve as component case size increases, but expected capacitance at operating votage shoud be verified. BOTH CAPACITORS ARE 16V, 121 CASE SIZE, 1µF X5R Y5V 365 F6 Figure 6. Ceramic Capacitor DC Bias Characteristics CHANGE VALUE (%) Y5V BOTH CAPACITORS ARE 16V, 121 CASE SIZE, 1µF X5R Figure 7. Ceramic Capacitor Temperature Characteristics F7 365fc 17

18 LT365 Series Appications Information Votage and temperature coefficients are not the ony sources of probems. Some ceramic capacitors have a piezoeectric response. A piezoeectric device generates votage across its terminas due to mechanica stress, simiar to the way a piezoeectric acceerometer or microphone works. For a ceramic capacitor, the stress is induced by vibrations in the system or therma transients. The resuting votages produced cause appreciabe amounts of noise. A ceramic capacitor produced the trace in Figure 8 in response to ight tapping from a penci. Simiar vibration induced behavior can masquerade as increased output votage noise. V OUT 1/DIV V OUT = 5V C OUT = 1µF C REF/BYP = 1nF 1ms/DIV 365 F8 Figure 8. Noise Resuting from Tapping On a Ceramic Capacitor Stabiity and Input Capacitance Low ESR, ceramic input bypass capacitors are acceptabe for appications without ong input eads. However, appications connecting a power suppy to an LT365 circuit s and GND pins with ong input wires combined with a ow ESR, ceramic input capacitors are prone to votage spikes, reiabiity concerns and appication-specific board osciations. The input wire inductance found in many battery-powered appications, combined with the ow ESR ceramic input capacitor, forms a high Q LC resonant tank circuit. In some instances this resonant frequency beats against the output current dependent LDO bandwidth and interferes with proper operation. Simpe circuit modifications/soutions are then required. This behavior is not indicative of LT365 instabiity, but is a common ceramic input bypass capacitor appication issue. The sef-inductance, or isoated inductance, of a wire is directy proportiona to its ength. Wire diameter is not a major factor on its sef-inductance. For exampe, the sefinductance of a 2-AWG isoated wire (diameter =.26") is about haf the sef-inductance of a 3-AWG wire (diameter =.1"). One foot of 3-AWG wire has approximatey 465nH of sef-inductance. Two methods can reduce wire sef-inductance. One method divides the current fowing towards the LT365 between two parae conductors. In this case, the farther apart the wires are from each other, the more the sef-inductance is reduced; up to a 5% reduction when paced a few inches apart. Spitting the wires connects two equa inductors in parae, but pacing them in cose proximity creates mutua inductance adding to the sef-inductance. The second and most effective way to reduce overa inductance is to pace both forward and return current conductors (the input and GND wires) in very cose proximity. Two 3-AWG wires separated by ony.2", used as forward and return current conductors, reduce the overa sef-inductance to approximatey one-fifth that of a singe isoated wire. If a battery, mounted in cose proximity, powers the LT365, a 1µF input capacitor suffices for stabiity. However, if a distant suppy powers the LT365, use a arger vaue input capacitor. Use a rough guideine of 1µF (in addition to the 1µF minimum) per 8 inches of wire ength. The minimum input capacitance needed to stabiize the appication aso varies with power suppy output impedance variations. Pacing additiona capacitance on the LT365 s output aso heps. However, this requires an order of magnitude more capacitance in comparison with additiona LT365 input bypassing. Series resistance between the suppy and the LT365 input aso heps stabiize the appication; as itte as.1ω to.5ω suffices. This impedance dampens the LC tank circuit at the expense of dropout votage. A better aternative is to use higher ESR tantaum or eectroytic capacitors at the LT365 input in pace of ceramic capacitors. I MAX Pin Operation The I MAX pin is the coector of a PNP that sources a current equa to 1/5th of output oad current (see Bock Diagram). The I MAX pin is aso the input to the precision 18 For more information 365fc

19 Appications Information current imit ampifier. Connecting a resistor (R IMAX ) from I MAX to GND sets the current imit threshod. If the output oad increases to a eve such that the I MAX pin votage reaches.6v, the current imit ampifier takes contro and reguates the I MAX votage to.6v, regardess of the output votage. Cacuate the required R IMAX vaue for a given current imit from the foowing formua: R IMAX = 5.6V I LIMIT In cases where the to OUT differentia votage exceeds 1V, current imit fodback owers the interna current imit eve, possiby causing it to override the externa programmabe current imit. See the Interna Current Limit vs V V OUT graph in the Typica Performance Characteristics section. The I MAX pin requires a 22nF decouping capacitor. If the externa programmabe current imit is not used, connect the I MAX pin directy to GND. LT365 power dissipation increases the I MAX threshod at a rate of approximatey.5 percent per watt. PWRGD Pin Operation The PWRGD pin is an open-drain high votage NMOS digita output capabe of sinking 5µA. The PWRGD pin de-asserts and becomes high impedance if the output rises above 9% of its nomina vaue. If the output fas beow 88.4% of its nomina vaue for more than 25μs, the PWRGD pin asserts ow. The PWRGD comparator has 1.6% hysteresis and 25μs of degitching. The PWRGD comparator has a dedicated reference that does not soft-start if a capacitor is used on the REF/BYP pin. The use of a feed-forward capacitor, C FF, as shown in Figure 4, can resut in the ADJ pin being pued artificiay high during startup transients, which causes the PWRGD fag to assert eary. To avoid this probem, ensure that LT365 Series the REF/BYP capacitor is significanty arger than the feed-forward capacitor, causing REF/BYP time constant to dominate over the time constant of the resistor divider network. Operation in Dropout Some degradation of the I MAX current mirror accuracy occurs for output currents ess than 5mA when operating in dropout. Overoad Recovery Like many IC power reguators, the LT365 has safe operating area protection. The safe area protection decreases current imit as input-to-output votage increases, and keeps the power transistor inside a safe operating region for a vaues of input-to-output votage. The LT365 provides some output current at a vaues of input-to-output votage up to the device s Absoute Maximum Rating. When power is first appied, the input votage rises and the output foows the input; aowing the reguator to start-up into very heavy oads. During start-up, as the input votage is rising, the input-to-output votage differentia is sma, aowing the reguator to suppy arge output currents. With a high input votage, a probem can occur wherein the remova of an output short wi not aow the output to recover. Other reguators, such as the LT183/LT184/ LT185 famiy and LT1764A aso exhibit this phenomenon, so it is not unique to the LT365. The probem occurs with a heavy output oad when the input votage is high and the output votage is ow. Common situations are immediatey after the remova of a short circuit or if the shutdown pin is pued high after the input votage is aready turned on. The oad ine intersects the output current curve at two points. If this happens, there are two stabe output operating points for the reguator. With this doube intersection, the input power suppy needs to be cyced down to zero and back up again to recover the output. For more information 365fc 19

20 LT365 Series Appications Information Therma Considerations The LT365 s maximum rated junction temperature of 125 C (E-, I-grades) or 15 C (MP-, H-grades) imits its power handing capabiity. Two components comprise the power dissipated by the device: 1. Output current mutipied by the input/output votage differentia: I OUT (V V OUT ), and 2. GND pin current mutipied by the input votage: I GND V GND pin current is determined using the GND Pin Current curves in the Typica Performance Characteristics section. Power dissipation equas the sum of the two components isted above. The LT365 reguator has interna therma imiting that protects the device during overoad conditions. For continuous norma conditions, do not exceed the maximum junction temperature of 125 C (E-, I-grades) or 15 C (MP-, H-grades). Carefuy consider a sources of therma resistance from junction-to-ambient incuding other heat sources mounted in proximity to the LT365. The undersides of the LT365 DFN and MSE packages have exposed meta from the ead frame to the die attachment. These packages aow heat to directy transfer from the die junction to the printed circuit board meta to contro maximum operating junction temperature. The dua-inine pin arrangement aows meta to extend beyond the ends of the package on the topside (component side) of a PCB. Connect this meta to GND on the PCB. The mutipe and OUT pins of the LT365 aso assist in spreading heat to the PCB. For surface mount devices, heat sinking is accompished by using the heat spreading capabiities of the PC board and its copper traces. Copper board stiffeners and pated through-hoes aso can spread the heat generated by power devices. Tabes 4 and 5 ist therma resistance as a function of copper area in a fixed board size. A measurements were taken in sti air on a 4-ayer FR-4 board with 1oz soid interna panes, and 2oz externa trace panes with a tota board thickness of 1.6mm. For further information on therma resistance and using therma information, refer to JEDEC standard JESD51, notaby JESD Tabe 4. MSOP Measured Therma Resistance COPPER AREA THERMAL RESISTANCE TOPSIDE BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT) 25 sq mm 25 sq mm 25 sq mm 28 C/W 1 sq mm 25 sq mm 25 sq mm 31 C/W 225 sq mm 25 sq mm 25 sq mm 32 C/W 1 sq mm 25 sq mm 25 sq mm 33 C/W Tabe 5. DFN Measured Therma Resistance COPPER AREA TOPSIDE THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) BOARD AREA 25 sq mm 25 sq mm 31 C/W 1 sq mm 25 sq mm 32 C/W 225 sq mm 25 sq mm 34 C/W 1 sq mm 25 sq mm 35 C/W Cacuating Junction Temperature Exampe: Given an output votage of 5V, an input votage range of 12V ±5%, a maximum output current range of 75mA and a maximum ambient temperature of 85 C, what is the maximum junction temperature? The power dissipated by the device equas: I OUT(MAX) (V (MAX) V OUT ) + I GND V (MAX) where: I OUT(MAX) = 75mA V (MAX) = 12.6V I GND at (I OUT = 75mA, V = 12V) = 3.5mA So: P = 75mA (12.6V 5V) + 3.5mA 12.6V =.614W 2 For more information 365fc