LT1073 Micropower DC/DC Converter Adjustable and Fixed 5V, 12V FEATURES DESCRIPTION n No Design Required The LT 1073 is a versatile micropower DC/DC converter. The n Operates at Supply Voltages from 1V to 30V device requires only three external components to deliver n Consumes Only 95A Supply Current a fixed output of 5V or 12V. The very low minimum supply n Works in Step-Up or Step-Down Mode voltage of 1V allows the use of the LT1073 in applications n Only Three External Off-the-Shelf Components where the primary power source is a single cell. An on-chip Required auxiliary gain block can function as a low-battery detector n Low-Battery Detector Comparator On-Chip or linear post-regulator. n User-Adjustable Current Limit Average current drain of the LT1073-5 used as shown in n Internal 1A Power Switch the Typical Application circuit below is just 135A unloaded, n Fixed or Adjustable Output Voltage Versions making it ideal for applications where long battery life is n Space-Saving 8-Pin PDIP or SO-8 Package important. The circuit shown can deliver 5V at 40mA from an input as low as 1.25V and 5V at 10mA from a 1V input. APPLICATIONS The device can easily be configured as a step-up or step- n Pagers down converter, although for most step-down applications n Cameras or input sources greater than 3V, the LT1173 is recom- n Single-Cell to 5V Converters mended. Switch current limiting is user-adjustable by n Battery Backup Supplies adding a single external resistor. Unique reverse-battery n Laptop and Palmtop Computers protection circuitry limits reverse current to safe, non- n Cellular Telephones destructive levels at reverse supply voltages up to 1.6V. n Portable Instruments L, LTC, and LT are registered trademarks of Linear Technology Corporation. n 4mA to 20mA Loop Powered Instruments n Hand-Held Inventory Computers n Battery-Powered , , and Particle Detectors TYPICAL APPLICATION Single Alkaline AA Cell Operating Single-Cell to 5V Converter Hours vs DC Load Current 1000 CADDELL-BURNS 7300-12 1N5818 82H 5V 40mA 100 2 1 I V LIM IN 3 SW1 L = 180H 1.5V AA CELL* LT1073-5 10 8 SENSE + 100F GND SW2 SANYO L = 82H 5 4 0S-CON 1 1 10 100 OPERATES WITH CELL VOLTAGE 1V LOAD CURRENT (mA) * ADD 10F DECOUPLING CAPACITOR IF LT1073 TA02 BATTERY IS MORE THAN 2 AWAY FROM LT1073 1073 TA01 1 CONTINUOUS OPERATION (HOURS)LT1073 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) ORDER PART Supply Voltage, Step-Up Mode .................................15V NUMBER Supply Voltage, Step-Down Mode ............................36V TOP VIEW SW1 Pin Voltage .......................................................50V LT1073CN8 I 1 8 FB (SENSE)* LIM SW2 Pin Voltage ............................................0.4 to V LT1073CN8-5 IN V SET 2 7 IN Feedback Pin Voltage (LT1073) ...................................5V LT1073CN8-12 SW1 3 6 A0 Switch Current .........................................................1.5A LT1073CS8 SW2 4 5 GND Maximum Power Dissipation ............................. 500mW LT1073CS8-5 N8 PACKAGE S8 PACKAGE Operating Temperature Range ..................... 0C to 70C LT1073CS8-12 8-LEAD PDIP 8-LEAD PLASTIC SO Storage Temperature Range .................. 65C to 150C *FIXED VERSIONS S8 PART MARKING Lead Temperature (Soldering, 10 sec) ...................300C T = 125C, = 100C/W (N8) JMAX JA T = 125C, = 120C/W (S8) 1073 JMAX JA 10735 107312 Consult factory for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 1.5V unless otherwise specified. A IN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS l I Quiescent Current Switch Off 95 130 A Q I Quiescent Current, Step-Up No Load LT1073-5 135 A Q Mode Configuration LT1073-12 250 A l V Input Voltage Step-Up Mode 1.15 12.6 V IN 1.0 12.6 V l Step-Down Mode 30 V l Comparator Trip Point Voltage LT1073 (Note 2) 202 212 222 mV l V Output Sense Voltage LT1073-5 (Note 3) 4.75 5 5.25 V OUT l LT1073-12 (Note 3) 11.4 12 12.6 V Comparator Hysteresis LT1073 l 5 10 mV Output Hysteresis LT1073-5 l 125 250 mV LT1073-12 l 300 600 mV f Oscillator Frequency l 15 19 23 kHz OSC DC Duty Cycle Full Load (V = V ) l 65 72 80 % FB REF t Switch ON Time l 30 38 50 s ON I Feedback Pin Bias Current LT1073, V = 0V l 10 50 nA FB FB I Set Pin Bias Current V = V l 60 120 nA SET SET REF V AO Output Low I = 100A l 0.15 0.4 V AO AO Reference Line Regulation 1V V 1.5V l 0.35 1.0 %V IN 1.5V V 12V l 0.05 0.1 %V IN V Switch Saturation Voltage V = 1.5V, I = 400mA 300 400 mV CESAT IN SW Set-Up Mode l 600 mV V = 1.5V, I = 500mA 400 550 mV IN SW l 750 mV V = 5V, I = 1A 700 1000 mV IN SW l 1500 mV A A2 Error Amp Gain R = 100k (Note 4) l 400 1000 V/V V L 2