LT1121/LT1121-3.3/LT1121-5 Micropower Low Dropout Regulators with Shutdown FEATURES DESCRIPTION n 0.4V Dropout Voltage The LT®1121/LT1121-3.3/LT1121-5 are micropower low n 150mA Output Current dropout regulators with shutdown. These devices are ca- n 30µA Quiescent Current pable of supplying 150mA of output current with a dropout n No Protection Diodes Needed voltage of 0.4V. Designed for use in battery-powered sys- n Adjustable Output from 3.75V to 30V tems, the low quiescent current, 30µA operating and 16µA n 3.3V and 5V Fixed Output Voltages in shutdown, makes them an ideal choice. The quiescent n Controlled Quiescent Current in Dropout current is well-controlled; it does not rise in dropout as it n Shutdown does with many other low dropout PNP regulators. n 16µA Quiescent Current in Shutdown Other features of the LT1121/LT1121-3.3/LT1121-5 include n Stable with 0.33µF Output Capacitor the ability to operate with very small output capacitors. n Reverse Battery Protection They are stable with only 0.33µF on the output while most n No Reverse Current with Input Low older devices require between 1µF and 100µF for stability. n Thermal Limiting Small ceramic capacitors can be used, enhancing manu- n Available in the 8-Lead SO, 8-Lead PDIP, 3-Lead facturability. Also the input may be connected to ground SOT-23 and 3-Lead TO-92 Packages or a reverse voltage without reverse current flow from output to input. This makes the LT1121 series ideal for APPLICATIONS backup power situations where the output is held high and the input is at ground or reversed. Under these conditions n Low Current Regulator only 16µA will flow from the output pin to ground. n Regulator for Battery-Powered Systems L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear n Post Regulator for Switching Supplies Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 5V Battery-Powered Supply with Shutdown Dropout Voltage 0.5 8 IN OUT 1 3.3VOUT 150mA 0.4 + 5V LT1121-3.3 1SμOFLID TANTALUM GE (V) A 0.3 5 T SHDN OL GND T V 3 OU 0.2 P O R D VSHDN (PIN 5) OUTPUT 0.1 <0.25 OFF >2.8 ON NC ON 0 LT1121 • TA01 0 20 40 60 80 100 120 140 160 OUTPUT CURRENT (mA) LT1121 • TA02 1121fg 1

LT1121/LT1121-3.3/LT1121-5 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage Output Short-Circuit Duration ....................... Indefinite LT1121 .............................................................. ±30V Operating Junction Temperature Range (Note 3) LT1121HV ............................................... +36V, –30V LT1121C-X ............................................ 0°C to 125°C Output Pin Reverse Current ................................. 10mA LT1121I-X ........................................ –40°C to 125°C Adjust Pin Current ................................................ 10mA Storage Temperature Range ..................–65°C to 150°C Shutdown Pin Input Voltage (Note 2) .......... 6.5V, –0.6V Lead Temperature (Soldering, 10 sec) ...................300°C Shutdown Pin Input Current (Note 2) .................. 20mA PIN CONFIGURATION TOP VIEW *PIN 2 = NC FOR LT1121-3.3/LT1121-5 OUT 1 8 IN = ADJ FOR LT1121 FRONT VIEW BOTTOM VIEW NC/ADJ* 2 7 NC** **PINS 6 AND 7 ARE FLOATING (NO 3 OUTPUT INTERNAL CONNECTION) ON THE GND 3 6 NC** STANDARD S8 PACKAGE. TAB IS IN GND OUT NC 4 5 SHDN PINS 6 AND 7 CONNECTED TO GROUND GND 2 GND ON THE A VERSION OF THE LT1121 (S8 ONLY). N8 PACKAGE CONNECTING PINS 6 AND 7 TO THE 1 VIN 8-LEAD PDIP GROUND PLANE WILL REDUCE THERMAL RESISTANCE. SEE THERMAL RESISTANCE ST PACKAGE Z PACKAGE S8 PACKAGE TABLES IN THE APPLICATIONS INFORMATION 3-LEAD PLASTIC SOT-223 3-LEAD PLASTIC TO-92 8-LEAD PLASTIC SO SECTION. TJMAX = 150°C, θJA = 50°C/W TJMAX = 150°C, θJA = 150°C/W TJMAX = 150°C, θJA = 120°C/W (N8, S8) TJMAX = 150°C, θJA = 70°C/W (AS8) ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT1121CN8#PBF LT1121CN8#TRPBF LT1121CN8 8-Lead Plastic PDIP 0°C to 125°C LT1121CN8-3.3#PBF LT1121CN8-3.3#TRPBF LT1121CN8-3.3 8-Lead Plastic PDIP 0°C to 125°C LT1121CN8-5#PBF LT1121CN8-5#TRPBF LT1121CN8-5 8-Lead Plastic PDIP 0°C to 125°C LT1121IN8#PBF LT1121IN8#TRPBF LT1121IN8 8-Lead Plastic PDIP –40°C to 125°C LT1121IN8-3.3#PBF LT1121IN8-3.3#TRPBF LT1121IN8-3.3 8-Lead Plastic PDIP –40°C to 125°C LT1121IN8-5#PBF LT1121IN8-5#TRPBF LT1121IN8-5 8-Lead Plastic PDIP –40°C to 125°C LT1121CS8#PBF LT1121CS8#TRPBF 1121 8-Lead Plastic S0 0°C to 125°C LT1121CS8-3.3#PBF LT1121CS8-3.3#TRPBF 11213 8-Lead Plastic S0 0°C to 125°C LT1121CS8-5#PBF LT1121CS8-5#TRPBF 11215 8-Lead Plastic S0 0°C to 125°C LT1121HVCS8#PBF LT1121HVCS8#TRPBF 1121HV 8-Lead Plastic S0 –40°C to 125°C LT1121IS8#PBF LT1121IS8#TRPBF 1121I 8-Lead Plastic S0 –40°C to 125°C LT1121IS8-3.3#PBF LT1121IS8-3.3#TRPBF 121I3 8-Lead Plastic S0 –40°C to 125°C LT1121IS8-5#PBF LT1121IS8-5#TRPBF 121I5 8-Lead Plastic S0 –40°C to 125°C LT1121HVIS8#PBF LT1121HVIS8#TRPBF 121HVI 8-Lead Plastic S0 –40°C to 125°C LT1121ACS8#PBF LT1121ACS8#TRPBF 1121A 8-Lead Plastic S0 0°C to 125°C LT1121ACS8-3.3#PBF LT1121ACS8-3.3#TRPBF 1121A3 8-Lead Plastic S0 0°C to 125°C LT1121ACS8-5#PBF LT1121ACS8-5#TRPBF 1121A5 8-Lead Plastic S0 0°C to 125°C 1121fg 2

LT1121/LT1121-3.3/LT1121-5 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT1121AHVCS8#PBF LT1121AHVCS8#TRPBF 121AHV 8-Lead Plastic S0 0°C to 125°C LT1121AIS8#PBF LT1121AIS8#TRPBF 121AI 8-Lead Plastic S0 –40°C to 125°C LT1121AIS8-3.3#PBF LT1121AIS8-3.3#TRPBF 121AI3 8-Lead Plastic S0 –40°C to 125°C LT1121AIS8-5#PBF LT1121AIS8-5#TRPBF 121AI5 8-Lead Plastic S0 –40°C to 125°C LT1121AHVIS8#PBF LT1121AHVIS8#TRPBF 21AHVI 8-Lead Plastic S0 –40°C to 125°C LT1121CST-3.3#PBF LT1121CST-3.3#TRPBF 11213 3-Lead Plastic SOT-223 0°C to 125°C LT1121IST-3.3#PBF LT1121IST-3.3#TRPBF 121I3 3-Lead Plastic SOT-223 –40°C to 125°C LT1121CST-5#PBF LT1121CST-5#TRPBF 11215 3-Lead Plastic SOT-223 0°C to 125°C LT1121IST-5#PBF LT1121IST-5#TRPBF 1121I5 3-Lead Plastic SOT-223 –40°C to 125°C LT1121CZ3-3#PBF LT1121CZ3-3#TRPBF LT1121CZ3-3 3-Lead Plastic TO-92 0°C to 125°C LT1121IZ3-3#PBF LT1121IZ3-3#TRPBF LT1121IZ3-3 3-Lead Plastic TO-92 –40°C to 125°C LT1121CZ-5#PBF LT1121CZ-5#TRPBF LT1121CZ-5 3-Lead Plastic TO-92 0°C to 125°C LT1121IZ-5#PBF LT1121IZ-5#TRPBF LT1121IZ-5 3-Lead Plastic TO-92 –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on nonstandard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25°C. A PARAMETER CONDITIONS MIN TYP MAX UNITS Regulated Output Voltage (Note 4) LT1121-3.3 V = 3.8V, I = 1mA, T = 25ºC 3.25 3.3 3.35 V IN OUT J 4.3V < V < 20V, 1mA < I < 150mA l 3.2 3.3 3.4 V IN OUT LT1121-5 V = 5.5V, I = 1mA, T = 25ºC 4.925 5 5.075 V IN OUT J 6V < V < 20V, 1mA < I < 150mA l 4.85 5 5.15 V IN OUT LT1121 (Note 5) V = 4.3V, I = 1mA, T = 25ºC 3.695 3.75 3.805 V IN OUT J 4.8V < V < 20V, 1mA < I < 150mA l 3.64 3.75 3.86 V IN OUT Line Regulation LT1121-3.3 ΔVIN = 4.8V TO 20V, IOUT = 1mA l 1.5 10 mV LT1121-5 ΔVIN = 5.5V TO 20V, IOUT = 1mA l 1.5 10 mV LT1121 (Note 5) ΔVIN = 4.3V TO 20V, IOUT = 1mA l 1.5 10 mV Load Regulation LT1121-3.3 ΔILOAD = 1mA to 150mA, TJ = 25ºC –12 –25 mV ΔILOAD = 1mA to 150mA l –20 –40 mV LT1121-5 ΔILOAD = 1mA to 150mA, TJ = 25ºC –17 –35 mV ΔILOAD = 1mA to 150mA l –28 –50 mV LT1121 (Note 5) ΔILOAD = 1mA to 150mA, TJ = 25ºC –12 –25 mV ΔILOAD = 1mA to 150mA l –18 –40 mV Dropout Voltage (Note 6) I = 1mA, T = 25ºC 0.13 0.16 V LOAD J I = 1mA l 0.25 V LOAD I = 50mA, T = 25ºC 0.3 0.35 V LOAD J I = 50mA l 0.5 V LOAD I = 100mA, T = 25ºC 0.37 0.45 V LOAD J I = 100mA l 0.6 V LOAD I = 150mA, T = 25ºC 0.42 0.55 V LOAD J I = 150mA l 0.7 V LOAD 1121fg 3

LT1121/LT1121-3.3/LT1121-5 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25°C. A PARAMETER CONDITIONS MIN TYP MAX UNITS Ground Pin Current (Note 7) I = 0mA l 30 50 µA LOAD I = 1mA l 90 120 µA LOAD I = 10mA l 350 500 µA LOAD I = 50mA l 1.5 2.5 mA LOAD I = 100mA l 4 7 mA LOAD I = 150mA l 7 14 mA LOAD Adjust Pin Bias Current (Notes 5, 8) T = 25ºC 150 300 nA J Shutdown Threshold V = Off to On l 1.2 2.8 V OUT V = On to Off l 0.25 0.75 V OUT Shutdown Pin Current (Note 9) V = 0V l 6 10 µA SHDN Quiescent Current in Shutdown (Note 10) V = 6V, V = 0V l 16 22 µA IN SHDN Ripple Rejection V – V = 1V (Avg), V = 0.5V , f = 120Hz, 50 58 dB IN OUT RIPPLE P-P RIPPLE I = 0.1A LOAD Current Limit V – V = 7V, T = 25ºC 200 500 mA IN OUT J Input Reverse Leakage Current V = –20V, V = 0V l 1 mA IN OUT Reverse Output Current (Note 11) LT1121-3.3 V = 3.3V, V = 0V 16 25 µA OUT IN LT1121-5 V = 5V, V = 0V 16 25 µA OUT IN LT1121 (Note 5) V = 3.8V, V = 0V 16 25 µA OUT IN Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 5: The LT1121 (adjustable version) is tested and specified with the may cause permanent damage to the device. Exposure to any Absolute adjust pin connected to the output pin. Maximum Rating condition for extended periods may affect device Note 6: Dropout voltage is the minimum input/output voltage required to reliability and lifetime. maintain regulation at the specified output current. In dropout the output Note 2: The shutdown pin input voltage rating is required for a low voltage will be equal to: (V – V ). IN DROPOUT impedance source. Internal protection devices connected to the shutdown Note 7: Ground pin current is tested with V = V (nominal) and a IN OUT pin will turn on and clamp the pin to approximately 7V or –0.6V. This current source load. This means that the device is tested while operating in range allows the use of 5V logic devices to drive the pin directly. For high its dropout region. This is the worst case ground pin current. The ground impedance sources or logic running on supply voltages greater than 5.5V, pin current will decrease slightly at higher input voltages. the maximum current driven into the shutdown pin must be limited to less Note 8: Adjust pin bias current flows into the adjust pin. than 20mA. Note 9: Shutdown pin current at V = 0V flows out of the shutdown pin. SHDN Note 3: For junction temperatures greater than 110°C, a minimum load Note 10: Quiescent current in shutdown is equal to the sum total of the of 1mA is recommended. For T > 110°C and I < 1mA, output voltage J OUT shutdown pin current (6µA) and the ground pin current (9µA). may increase by 1%. Note 11: Reverse output current is tested with the input pin grounded and Note 4: Operating conditions are limited by maximum junction the output pin forced to the rated output voltage. This current flows into temperature. The regulated output voltage specification will not apply the output pin and out of the ground pin. for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be limited. When operating at maximum output current the input voltage range must be limited. 1121fg 4

LT1121/LT1121-3.3/LT1121-5 TYPICAL PERFORMANCE CHARACTERISTICS Guaranteed Dropout Voltage Dropout Voltage Quiescent Current 0.7 0.7 50 VIN = 6V RLOAD = ∞ LTAGE (V) 000...654 TJ ≤ 125°C LTAGE (V) 000...654 ILOAD = 100mA ILOAD = 150mA RRENT (A)μ 4300 VSHDN = OPEN VO TJ ≤ 25°C VO CU UT 0.3 UT 0.3 ILOAD = 50mA NT 20 DROPO 0.2 DROPO 0.2 ILOAD = 1mA UIESCE VSHDN = 0V Q 10 0.1 0.1 = TEST POINTS 0 0 0 0 20 40 60 80 100 120 140 160 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 OUTPUT CURRENT (mA) TEMPERATURE (°C) TEMPERATURE (°C) 1121 G01 1121 G02 1121 G03 LT1121-3.3 LT1121-5 LT1121 Quiescent Current Quiescent Current Quiescent Current 120 120 120 TJ = 25°C TJ = 25°C TJ = 25°C RLOAD = ∞ RLOAD = ∞ RLOAD = ∞ 100 100 100 VOUT = VADJ A) A) A) μ μ μ T ( 80 T ( 80 T ( 80 N N N RRE VSHDN = OPEN RRE VSHDN = OPEN RRE VSHDN = OPEN CU 60 CU 60 CU 60 T T T N N N E E E SC 40 SC 40 SC 40 E E E UI UI UI Q Q Q 20 VSHDN = 0V 20 VSHDN = 0V 20 VSHDN = 0V 0 0 0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) 1121 G04 1121 G05 1121 G06 LT1121-3.3 LT1121-5 LT1121 Output Voltage Output Voltage Adjust Pin Voltage 3.38 5.08 3.83 IOUT = 1mA IOUT = 1mA IOUT = 1mA 3.36 5.06 3.81 3.34 5.04 3.79 V) V) V) GE (3.32 GE (5.02 GE (3.77 A A A T T T OL3.30 OL5.00 OL3.75 V V V T T N TPU3.28 TPU4.98 J PI3.73 U U D O3.26 O4.96 A3.71 3.24 4.94 3.69 3.22 4.92 3.67 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1121 G07 1121 G08 1121 G09 1121fg 5

LT1121/LT1121-3.3/LT1121-5 TYPICAL PERFORMANCE CHARACTERISTICS LT1121-3.3 LT1121-5 LT1121 Ground Pin Current Ground Pin Current Ground Pin Current 800 800 800 700 TJ = 25°C 700 TJ = 25°C RLOAD = 200Ω 700 VTJO U=T 2 =5 °VCADJ IRLLOOAADD = = 2 155m0AΩ* T (A)μ 600 IRLLOOAADD = = 2 153m0AΩ* T (A)μ 600 ILOAD = 25mA* T (A)μ 600 N N N E 500 E 500 E 500 R R R PIN CUR 400 IRLLOOAADD = = 1 303m0AΩ* PIN CUR 400 IRLLOOAADD = = 1 500m0AΩ* PIN CUR 400 IRLLOOAADD = = 1 308m0AΩ* D 300 D 300 D 300 UN *FOR VOUT = 3.3V UN *FOR VOUT = 5V UN *FOR VOUT = 3.75V RO 200 RO 200 RO 200 G RLOAD = 3.3k G RLOAD = 5k G RLOAD = 3.8k 100 ILOAD = 1mA* 100 ILOAD = 1mA* 100 ILOAD = 1mA* 0 0 0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) 1121 G10 1121 G11 1121 G12 LT1121-3.3 LT1121-5 LT1121 Ground Pin Current Ground Pin Current Ground Pin Current 10 10 10 TJ = 25°C TJ = 25°C TJ = 25°C 9 9 9 VOUT = VADJ RENT (mA) 876 IRLLOOAADD = = 1 2520ΩmA* RENT (mA) 876 IRLLOOAADD = = 1 3530ΩmA* RENT (mA) 876 IRLLOOAADD = = 1 2550ΩmA* D PIN CUR 54 IRLLOOAADD = = 1 3030ΩmA* D PIN CUR 54 IRLLOOAADD = = 1 5000ΩmA* D PIN CUR 54 IRLLOOAADD = = 1 3080ΩmA* N N N U 3 U 3 U 3 RO RLOAD = 66Ω RO RLOAD = 100Ω RO RLOAD = 75Ω G 2 ILOAD = 50mA* G 2 ILOAD = 50mA* G 2 ILOAD = 50mA* 1 1 1 *FOR VOUT = 3.3V *FOR VOUT = 5V *FOR VOUT = 3.75V 0 0 0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) 1121 G13 1121 G14 1121 G15 Shutdown Pin Threshold Shutdown Pin Threshold Ground Pin Current (On-to-Off) (Off-to-On) 14 2.0 2.0 VIN = 3.3V (LT1121-3.3) ILOAD = 1mA VIN = 5V (LT1121-5) 1.8 1.8 NT (mA) 1120 VDINIEN VD =IRC O3E.P 7IOS5 VUO T(PLETR1A1T2I1N)G OLD (V) 11..64 OLD (V) 11..64 ILOAD = 150mA URRE 8 TJ = 125°C RESH 1.2 RESH 1.2 ILOAD = 1mA C H 1.0 H 1.0 OUND PIN 64 TJ = 25°C TJ = –55°C UTDOWN T 00..86 UTDOWN T 00..86 GR SH 0.4 SH 0.4 2 0.2 0.2 0 0 0 0 20 40 60 80 100 120 140 160 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 OUTPUT CURRENT (mA) TEMPERATURE (°C) TEMPERATURE (°C) 1121 G16 1121 G17 1121 G18 1121fg 6

LT1121/LT1121-3.3/LT1121-5 TYPICAL PERFORMANCE CHARACTERISTICS LT1121 Shutdown Pin Current Shutdown Pin Input Current Adjust Pin Bias Current 10 25 400 VSHDN = 0V SHUTDOWN PIN CURRENT (A)μ 98765432 UTDOWN PIN INPUT CURRENT (mA) 1210055 ADJUST PIN BIAS CURRENT (nA) 332211505050000000 1 SH 50 0 0 0 –50 –25 0 25 50 75 100 125 0 1 2 3 4 5 6 7 8 9 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) SHUTDOWN PIN VOLTAGE (V) TEMPERATURE (°C) 1121 G19 1121 G20 1121 G21 Reverse Output Current Current Limit Current Limit 30 400 400 VIN = 0V VOUT = 0V VIN = 7V VOUT = 5V (LT1121-5) 350 350 VOUT = 0V 25 VOUT = 3.3V (LT1121-3.3) A) RRENT (A)μ 20 VOUT = 3.8V (LT1121) URRENT (m320500 MIT (mA)320500 OUTPUT PIN CU 1150 HORT-CIRCUIT C211050000 CURRENT LI211050000 5 S 50 50 0 0 0 –50 –25 0 25 50 75 100 125 0 1 2 3 4 5 6 7 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) INPUT VOLTAGE (V) TEMPERATURE (°C) 1121 G22 1121 G23 1121 G24 Reverse Output Current Ripple Rejection Ripple Rejection 100 64 100 TJ = 25°C VIN = VOUT (NOMINAL) + 1V IOUT = 100mA A) 9800 VCINIUNTR O=R O0EVUNTTP FULTO WPISN 62 I+O 0U.T5 V=P 1-0P0 RmIPAPLE AT f = 120Hz 9800 VIN = 6V + 50mVRMS RIPPLE UTPUT PIN CURRENT (μ 7654300000 (LVTO11U2T 1=L- T3V1.A31D2J1) RIPPLE REJECTION (dB) 65550864 RIPPLE REJECTION (dB) 7654300000 CSOOUTLC IO=DU 1TTμ A=FN 4T7AμLFUM O 20 20 SOLID TANTALUM LT1121-5 52 10 10 0 50 0 0 1 2 3 4 5 6 7 8 9 10 –50 –25 0 25 50 75 100 125 10 100 1k 10k 100k 1M OUTPUT VOLTAGE (V) TEMPERATURE (°C) FREQUENCY (Hz) 1121 G25 1121 G26 1121 G27 1121fg 7

LT1121/LT1121-3.3/LT1121-5 TYPICAL PERFORMANCE CHARACTERISTICS LT1121-5 LT1121-5 Load Regulation Load Transient Response Load Transient Response 0 ΔILOAD = 1mA TO 150mA VIN = 6V VIN = 6V TION (mV)–––11505 LT1121* LT1121-3.3 UTPUT VOLTAGEDEVIATION (V)–000...2101 CCIONU =T =0 .11μμFF UTPUT VOLTAGEDEVIATION (V)–000...2101 CCIONU =T =0 .31.μ3FμF LA–20 O –0.2 O –0.2 U G E R–25 LOAD ––3305 * OADUJT PPUINT TPIIEND TO LT1121-5 AD CURRENT(mA) 115000 AD CURRENT(mA) 11505000 –40 LO LO –50 –25 0 25 50 75 100 125 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 TEMPERATURE (°C) TIME (ms) TIME (ms) 1121 G28 1121 G29 1121 G30 PIN FUNCTIONS Input Pin: Power is supplied to the device through the off. This pin is active low. The device will be shut down if input pin. The input pin should be bypassed to ground if the shutdown pin is pulled low. The shutdown pin current the device is more than six inches away from the main with the pin pulled to ground will be 6µA. The shutdown input filter capacitor. In general the output impedance of pin is internally clamped to 7V and –0.6V (one V ). This BE a battery rises with frequency so it is usually adviseable to allows the shutdown pin to be driven directly by 5V logic or include a bypass capacitor in battery-powered circuits. A by open collector logic with a pull-up resistor. The pull-up bypass capacitor in the range of 0.1µF to 1µF is sufficient. resistor is only required to supply the leakage current of The LT1121 is designed to withstand reverse voltages on the open collector gate, normally several microamperes. the input pin with respect to both ground and the output Pull-up current must be limited to a maximum of 20mA. pin. In the case of a reversed input, which can happen if A curve of shutdown pin input current as a function of a battery is plugged in backwards, the LT1121 will act as voltage appears in the Typical Performance Characteristics. if there is a diode in series with its input. There will be If the shutdown pin is not used it can be left open circuit. no reverse current flow into the LT1121 and no reverse The device will be active, output on, if the shutdown pin voltage will appear at the load. The device will protect both is not connected. itself and the load. Adjust Pin: For the adjustable LT1121, the adjust pin Output Pin: The output pin supplies power to the load. An is the input to the error amplifier. This pin is internally output capacitor is required to prevent oscillations. See clamped to 6V and –0.6V (one V ). It has a bias current BE the Applications Information section for recommended of 150nA which flows into the pin. See Bias Current curve value of output capacitance and information on reverse in the Typical Performance Characteristics. The adjust output characteristics. pin reference voltage is 3.75V referenced to ground. The output voltage range that can be produced by this device Shutdown Pin: This pin is used to put the device into is 3.75V to 30V. shutdown. In shutdown the output of the device is turned 1121fg 8

LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION The LT1121 is a micropower low dropout regulator with approximately 15ppm/°C. The adjust pin bias current has shutdown, capable of supplying up to 150mA of output a negative temperature coefficient. These effects are small current at a dropout voltage of 0.4V. The device operates and will tend to cancel each other. with very low quiescent current (30µA). In shutdown the The adjustable device is specified with the adjust pin tied quiescent current drops to only 16µA. In addition to the to the output pin. This sets the output voltage to 3.75V. low quiescent current the LT1121 incorporates several Specifications for output voltage greater than 3.75V will protection features which make it ideal for use in battery- be proportional to the ratio of the desired output voltage powered systems. The device is protected against both to 3.75V (V /3.75V). For example: load regulation for an OUT reverse input voltages and reverse output voltages. In output current change of 1mA to 150mA is –12mV typical battery backup applications where the output can be held at V = 3.75V. At V = 12V, load regulation would be: OUT OUT up by a backup battery when the input is pulled to ground, the LT1121 acts like it has a diode in series with its output ⎛ 12V ⎞ •(–12mV)=(–38mV) ⎜ ⎟ and prevents reverse current flow. ⎝3.75V⎠ Adjustable Operation Thermal Considerations The adjustable version of the LT1121 has an output voltage Power handling capability will be limited by maximum range of 3.75V to 30V. The output voltage is set by the rated junction temperature (125°C). Power dissipated by ratio of two external resistors as shown in Figure 1. The the device will be made up of two components: device servos the output voltage to maintain the voltage 1. Output current multiplied by the input/output voltage at the adjust pin at 3.75V. The current in R1 is then equal differential: I • (V – V ), and to 3.75V/R1. The current in R2 is equal to the sum of the OUT IN OUT current in R1 and the adjust pin bias current. The adjust 2. Ground pin current multiplied by the input voltage: pin bias current, 150nA at 25°C, flows through R2 into the IGND • VIN. adjust pin. The output voltage can be calculated according The ground pin current can be found by examining the to the formula in Figure 1. The value of R1 should be less Ground Pin Current curves in the Typical Performance than 400k to minimize errors in the output voltage caused Characteristics. Power dissipation will be equal to the by the adjust pin bias current. Note that in shutdown the sum of the two components listed above. output is turned off and the divider current will be zero. The LT1121 series regulators have internal thermal limiting Curves of Adjust Pin Voltage vs Temperature and Adjust designed to protect the device during overload conditions. Pin Bias Current vs Temperature appear in the Typical For continuous normal load conditions the maximum junc- Performance Characteristics. The reference voltage at the tion temperature rating of 125°C must not be exceeded. adjust pin has a slight positive temperature coefficient of It is important to give careful consideration to all sources of thermal resistance from junction to ambient. Additional IN OUT VOUT heat sources mounted nearby must also be considered. LT1121 R2 Heat sinking, for surface mount devices, is accomplished + SHDN ADJ by using the heat spreading capabilities of the PC board GND R1 and its copper traces. Copper board stiffeners and plated 1121 • F01 through holes can also be used to spread the heat gener- ated by power devices. Tables 1 through 5 list thermal VOUT = 3.75V (1 + RR 21 ) + ( IADJ • R2) resistances for each package. Measured values of thermal VADJ = 3.75V resistance for several different board sizes and copper IADJ = 150nA AT 25°C OUTPUT RANGE = 3.75V TO 30V areas are listed for each package. All measurements were taken in still air, on 3/32" FR-4 board with 1oz copper. All Figure 1. Adjustable Operation 1121fg 9

LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION NC leads were connected to the ground plane. Table 5. TO-92 Package THERMAL RESISTANCE Package alone 220ºC/W Package soldered into PC board with plated through 175ºC/W Table 1. N8 Package* holes only COPPER AREA THERMAL RESISTANCE Package soldered into PC board with 1/4 sq. inch of 145ºC/W TOPSIDE BACKSIDE BOARD AREA JUNCTION TO AMBIENT copper trace per lead 2500 sq mm 2500 sq mm 2500 sq mm 80ºC/W Package soldered into PC board with plated through 160ºC/W holes in board, no extra copper trace, and a clip-on type 1000 sq mm 2500 sq mm 2500 sq mm 80ºC/W heat sink: Thermalloy type 2224B 225 sq mm 2500 sq mm 2500 sq mm 85ºC/W Aavid type 5754 135ºC/W 1000 sq mm 1000 sq mm 1000 sq mm 91ºC/W * Device is mounted on topside. Leads are through hole and are Calculating Junction Temperature soldered to both sides of board. Example: given an output voltage of 3.3V, an input voltage Table 2. S8 Package range of 4.5V to 7V, an output current range of 0mA to COPPER AREA 100mA, and a maximum ambient temperature of 50°C, THERMAL RESISTANCE TOPSIDE* BACKSIDE BOARD AREA JUNCTION TO AMBIENT what will the maximum junction temperature be? 2500 sq mm 2500 sq mm 2500 sq mm 120ºC/W Power dissipated by the device will be equal to: 1000 sq mm 2500 sq mm 2500 sq mm 120ºC/W I • (V – V ) + (I • V ) 225 sq mm 2500 sq mm 2500 sq mm 125ºC/W OUT MAX IN MAX OUT GND IN 100 sq mm 1000 sq mm 1000 sq mm 131ºC/W where, I = 100mA OUT MAX * Device is mounted on topside. VIN MAX = 7V I at (I = 100mA, V = 7V) = 5mA GND OUT IN Table 3. AS8 Package* so, P = 100mA • (7V – 3.3V) + (5mA • 7V) COPPER AREA = 0.405W THERMAL RESISTANCE TOPSIDE** BACKSIDE BOARD AREA JUNCTION TO AMBIENT If we use an SOT-223 package, then the thermal resistance 2500 sq mm 2500 sq mm 2500 sq mm 60ºC/W will be in the range of 50°C/W to 65°C/W depending on 1000 sq mm 2500 sq mm 2500 sq mm 60ºC/W copper area. So the junction temperature rise above ambi- 225 sq mm 2500 sq mm 2500 sq mm 68ºC/W ent will be less than or equal to: 100 sq mm 2500 sq mm 2500 sq mm 74ºC/W 0.405W • 60°C/W = 24°C * Pins 3, 6 and 7 are ground. ** Device is mounted on topside. The maximum junction temperature will then be equal to the maximum junction temperature rise above ambient Table 4. SOT-223 Package plus the maximum ambient temperature or: (Thermal Resistance Junction-to-Tab 20ºC/W) COPPER AREA TJMAX = 50°C + 24°C = 74°C THERMAL RESISTANCE TOPSIDE* BACKSIDE BOARD AREA JUNCTION TO AMBIENT Output Capacitance and Transient Performance 2500 sq mm 2500 sq mm 2500 sq mm 50ºC/W 1000 sq mm 2500 sq mm 2500 sq mm 50ºC/W The LT1121 is designed to be stable with a wide range of 225 sq mm 2500 sq mm 2500 sq mm 58ºC/W output capacitors. The minimum recommended value is 1µF 100 sq mm 2500 sq mm 2500 sq mm 64ºC/W with an ESR of 3Ω or less. For applications where space is very limited, capacitors as low as 0.33µF can be used if 1000 sq mm 2500 sq mm 1000 sq mm 57ºC/W combined with a small series resistor. Assuming that the 1000 sq mm 0 1000 sq mm 60ºC/W ESR of the capacitor is low (ceramic) the suggested series * Tab of device attached to topside copper. 1121fg 10

LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION resistor is shown in Table 6. The LT1121 is a micropower short-circuit current of the device and will protect itself by device and output transient response will be a function of thermal limiting. For the adjustable version of the device, output capacitance. See the Transient Response curves the output pin is internally clamped at one diode drop in the Typical Performance Characteristics. Larger values below ground. Reverse current for the adjustable device of output capacitance will decrease the peak deviations must be limited to 5mA. and provide improved output transient response. Bypass In circuits where a backup battery is required, several capacitors, used to decouple individual components different input/output conditions can occur. The output powered by the LT1121, will increase the effective value voltage may be held up while the input is either pulled of the output capacitor. to ground, pulled to some intermediate voltage, or is left open circuit. Current flow back into the output will vary Table 6. Suggested Series Resistor Values depending on the conditions. Many battery-powered cir- OUTPUT CAPACITANCE SUGGESTED SERIES RESISTOR cuits incorporate some form of power management. The 0.33µF 2Ω following information will help optimize battery life. Table 0.47µF 1Ω 7 summarizes the following information. 0.68µF 1Ω The reverse output current will follow the curve in Figure >1µF None Needed 2 when the input pin is pulled to ground. This current flows through the output pin to ground. The state of the Protection Features shutdown pin will have no effect on output current when The LT1121 incorporates several protection features the input pin is pulled to ground. which make it ideal for use in battery-powered circuits. In some applications it may be necessary to leave the In addition to the normal protection features associated input to the LT1121 unconnected when the output is held with monolithic regulators, such as current limiting and high. This can happen when the LT1121 is powered from thermal limiting, the device is protected against reverse a rectified AC source. If the AC source is removed, then input voltages, reverse output voltages, and reverse volt- the input of the LT1121 is effectively left floating. The ages from output to input. reverse output current also follows the curve in Figure 2 Current limit protection and thermal overload protection if the input pin is left open. The state of the shutdown pin are intended to protect the device against current overload will have no effect on the reverse output current when the conditions at the output of the device. For normal opera- input pin is floating. tion, the junction temperature should not exceed 125°C. The input of the device will withstand reverse voltages of 100 TJ = 25°C 30V. Current flow into the device will be limited to less 90 VIN < VOUT CURRENT FLOWS than 1mA (typically less than 100µA) and no negative A) 80 INTO OUTPUT PIN μ voltage will appear at the output. The device will protect T ( 70 TO GROUND N both itself and the load. This provides protection against URRE 60 (VOUT =L TV1A1D2J1) C 50 batteries that can be plugged in backwards. N PI 40 For fixed voltage versions of the device, the output can PUT 30 LT1121-3.3 T U be pulled below ground without damaging the device. If O 20 LT1121-5 the input is open circuit or grounded the output can be 10 pulled below ground by 20V. The output will act like an 0 0 1 2 3 4 5 6 7 8 9 10 open circuit, no current will flow out of the pin. If the input OUTPUT VOLTAGE (V) is powered by a voltage source, the output will source the 1121• F02 Figure 2. Reverse Output Current 1121fg 11

LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION When the input of the LT1121 is forced to a voltage below 5 VOUT = 3.3V (LT1121-3.3) its nominal output voltage and its output is held high, the VOUT = 5V (LT1121-5) reverse output current will still follow the curve in Figure 4 A) 2. This condition can occur if the input of the LT1121 is μ connected to a discharged (low voltage) battery and the ENT ( 3 R R output is held up by either a backup battery or by a second U C T 2 regulator circuit. When the input pin is forced below the U P N output pin or the output pin is pulled above the input pin, I 1 the input current will typically drop to less than 2µA (see Figure 3). The state of the shutdown pin will have no effect 0 on the reverse output current when the output is pulled 0 1 2 3 4 5 INPUT VOLTAGE (V) above the input. 1121 F03 Figure 3. Input Current Table 7. Fault Conditions INPUT PIN SHDN PIN OUTPUT PIN <V (Nominal) Open (Hi) Forced to V (Nominal) Reverse Output Current ≈ 15µA (See Figure 2) OUT OUT Input Current ≈ 1µA (See Figure 3) <V (Nominal) Grounded Forced to V (Nominal) Reverse Output Current ≈ 15µA (See Figure 2) OUT OUT Input Current ≈ 1µA (See Figure 3) Open Open (Hi) Forced to V (Nominal) Reverse Output Current ≈ 15µA (See Figure 2) OUT Open Grounded Forced to V (Nominal) Reverse Output Current ≈ 15µA (See Figure 2) OUT ≤0.8V Open (Hi) ≤0V Output Current = 0 ≤0.8V Grounded ≤0V Output Current = 0 >1.5V Open (Hi) ≤0V Output Current = Short-Circuit Current –30V < V < 30V Grounded ≤0V Output Current = 0 IN 1121fg 12

LT1121/LT1121-3.3/LT1121-5 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. N Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510 Rev I) .400* (10.160) .300 – .325 .045 – .065 .130 ±.005 MAX (7.620 – 8.255) (1.143 – 1.651) (3.302 ±0.127) 8 7 6 5 .065 .255 ±.015* (1.651) .008 – .015 TYP (6.477 ±0.381) (0.203 – 0.381) .120 (3.048) .020 .325+.035 MIN (0.508) 1 2 3 4 –.015 .100 .018 ±.003 MIN ( +0.889) 8.255 (2.54) (0.457 ±0.076) N8 REV I 0711 –0.381 BSC NOTE: INCHES 1. DIMENSIONS ARE MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610 Rev G) .189 – .197 .045 ±.005 (4.801 – 5.004) .050 BSC NOTE 3 8 7 6 5 .245 MIN .160 ±.005 .150 – .157 .228 – .244 (3.810 – 3.988) (5.791 – 6.197) NOTE 3 .030 ±.005 TYP 1 2 3 4 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° .053 – .069 (0.254 – 0.508) (1.346 – 1.752) .004 – .010 .008 – .010 (0.203 – 0.254) 0°– 8° TYP (0.101 – 0.254) .016 – .050 .014 – .019 .050 (0.406 – 1.270) (0.355 – 0.483) (1.270) NOTE: INCHES TYP BSC 1. DIMENSIONS IN (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) SO8 REV G 0212 4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE 1121fg 13

LT1121/LT1121-3.3/LT1121-5 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. ST Package 3-Lead Plastic SOT-223 (Reference LTC DWG # 05-08-1630) .248 – .264 .129 MAX (6.30 – 6.71) .114 – .124 (2.90 – 3.15) .059 MAX .264 – .287 .248 BSC (6.70 – 7.30) .130 – .146 (3.30 – 3.71) .039 MAX .059 MAX .090 BSC .181 MAX .0905 .033 – .041 RECOMMENDED SOLDER PAD LAYOUT (2.30) (0.84 – 1.04) BSC 10° – 16° .010 – .014 .071 10° (0.25 – 0.36) (1.80) MAX MAX 10° – 16° .024 – .033 .012 .0008 – .0040 (0.60 – 0.84) (0.31) (0.0203 – 0.1016) .181 MIN (4.60) ST3 (SOT-233) 0502 BSC Z Package 3-Lead Plastic TO-92 (Similar to TO-226) (Reference LTC DWG # 05-08-1410 Rev C) .180 ± .005 .060 ± .005 (4.572 ± 0.127) .060 ± .010 (1.524± 0.127) (1.524 ± 0.254) DIA .90 (2.286) .140 ± .010 NOM 3 2 1 .180 ± .005 (3.556 ± 0.127) (4.572 ± 0.127) 10° NOM 5° NOM .500 .050 UNCONTROLLED (12.70) (1.270)LEAD DIMENSION MIN MAX .016 ± .003 .015 ± .002 .050 (0.406 ± 0.076) (0.381 ± 0.051) Z3 (TO-92) 1008 REV C (1.27) .098 +.016/–.04 BSC (2.5 +0.4/–0.1) 2 PLCS BULK PACK TO-92 TAPE AND REEL REFER TO TAPE AND REEL SECTION OF LTC DATA BOOK FOR ADDITIONAL INFORMATION 1121fg 14

LT1121/LT1121-3.3/LT1121-5 REVISION HISTORY (Revision history begins at Rev G) REV DATE DESCRIPTION PAGE NUMBER G 05/12 Changed Order Information top marking for 8-lead SO 3.3V and 5V options, C-grade 2 1121fg Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 15 However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LT1121/LT1121-3.3/LT1121-5 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20µA I Includes 2.5V Reference and Comparator Q LT1129 700mA Micropower Low Dropout Regulator 50µA Quiescent Current LT1175 500mA Negative Low Dropout Micropower Regulator 45µA I , 0.26V Dropout Voltage, SOT-223 Package Q LT1521 300mA Low Dropout Micropower Regulator with Shutdown 15µA, I , Reverse Battery Protection Q LT1529 3A Low Dropout Regulator with 50µA I 500mV Dropout Voltage Q LT1611 Inverting 1.4MHz Switching Regulator 5V to –5V at 150mA, Low Output Noise, SOT-23 Package LT1613 1.4MHz Single-Cell Micropower DC/DC Converter SOT-23 Package, Internally Compensated LT1627 High Efficiency Synchronous Step-Down Switching Regulator Burst Mode™ Operation, Monolithic, 100% Duty Cycle LT1682 Doubler Charge Pump with Low Noise Linear Regulator Low Output Noise: 60µV (100kHz BW) RMS LT1762 Series 150mA, Low Noise, LDO Micropower Regulator 25µA Quiescent Current, 20µV Noise RMS LT1763 Series 500mA, Low Noise, LDO Micropower Regulator 30µA Quiescent Current, 20µV Noise RMS LT1764 Series 3A Fast Transient Response LDO 300mV Dropout, 40µV Noise RMS LT1962 Series 300mA, Low Noise, LDO Micropower Regulator 30µA Quiescent Current, 20µV Noise RMS LT1963 Series 1.5A Fast Transient Response LDO 300mV Dropout, 40µV Noise RMS Burst Mode is a trademark of Linear Technology Corporation. 1121fg 16 Linear Technology Corporation LT 0512 REV G • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com  LINEAR TECHNOLOGY CORPORATION 1994