LT1111 Micropower DC/DC Converter Adjustable and Fixed 5V, 12V FEATURES DESCRIPTIO n Operates at Supply Voltages from 2V to 30V The LT 1111 is a versatile micropower DC/DC converter. n Works with Surface Mount Inductors The device requires only three external components to n 72kHz Oscillator deliver a fixed output of 5V or 12V. Supply voltage ranges n Only Three External Components Required from 2V to 12V in step-up mode and to 30V in step-down n Step-Up or Step-Down Mode mode. The LT1111 functions equally well in step-up, step- n Low-Battery Detector Comparator On-Chip down, or inverting applications. n User Adjustable Current Limit The LT1111 oscillator is set at 72kHz, optimizing the n Internal 1A Power Switch device to work with off-the-shelf surface mount inductors. n Fixed or Adjustable Output Voltage Versions The device can deliver 5V at 100mA from a 3V input in n Space Saving 8-Pin MiniDIP or SO-8 Package step-up mode or 5V at 200mA from a 12V input in step- U down mode. APPLICATIO S Switch current limit can be programmed with a single n 3V to 5V, 5V to 12V Converters resistor. An auxiliary open-collector gain block can be n 9V to 5V, 12V to 5V Converters configured as a low-battery detector, linear post regulator, n Remote Controls undervoltage lock-out circuit, or error amplifier. n Peripherals and Add-On Cards n Battery Backup Supplies For input sources of less than 2V use the LT1110. n Uninterruptible Supplies , LTC and LT are registered trademarks of Linear Technology Corporation n Laptop and Palmtop Computers n Cellular Telephones n Portable Instruments n Flash Memory VPP Generators TYPICAL APPLICATIO Typical Load Regulation All Surface Mount 3V to 5V Step-Up Converter 6 SUMIDA 5 CD54-220M MBRS120T3 22m H 5V V = 2V 2.2 2.4 2.6 2.8 3V 3V INPUT IN 4 100mA I V 3 LIM IN SW1 + + 2 10 F*m LT1111CS8-5 33 Fm SENSE 1 GND SW2 0 0 25 50 75 100 125 150 175 200 LOAD CURRENT (mA) *OPTIONAL LT1111 TA01 LT1111 TA02 1111fd 1 OUTPUT VOLTAGE (V) U ULT1111 (Note 1) ABSOLUTEXAI U RATI GS Supply Voltage (V ) ............................................... 36V Operating Temperature Range IN SW1 Pin Voltage (V ) ......................................... 50V LT1111C............................................... 0 C to 70 C SW1 SW2 Pin Voltage (V ) ............................ 0.5V to V LT1111I ......................................... 40 C to 105 C SW2 IN Feedback Pin Voltage (LT1111) ............................. 5.5V LT1111M (OBSOLETE) ............. 55 C to 125 C Switch Current ....................................................... 1.5A Storage Temperature Range ................ 65 C to 150 C Maximum Power Dissipation ............................ 500mW Lead Temperature (Soldering, 10 sec)................. 300 C PACKAGE/ORDER I FOR ATIO TOP VIEW ORDER PART ORDER PART NUMBER NUMBER I 1 8 FB (SENSE)* LIM TOP VIEW LT1111CS8 LT1111CN8 V 2 7 SET IN I 1 8 FB (SENSE)* LT1111CS8-5 LT1111CN8-5 LIM SW1 3 A0 6 LT1111CN8-12 LT1111CS8-12 V 2 7 SET IN SW2 4 5 GND LT1111IS8 SW1 A0 3 6 N8 PACKAGE SW2 GND 4 5 8-LEAD PLASTIC DIP S8 PART MARKING *FIXED VERSIONS S8 PACKAGE 1111 T = 90 C, q = 130 C/W (N) JMAX JA 8-LEAD PLASTIC SO *FIXED VERSION 11115 J8 PACKAGE LT1111MJ8 8-LEAD CERAMIC DIP 11111 T = 90 C, q = 150 C/W JMAX JA T = 150 C, q = 120 C/W (J) LT1111MJ8-5 JMAX JA 1111I LT1111MJ8-12 OBSOLETE PACKAGE Consider the N8 Package for Alternate Source Consult LTC Marketing for parts specified with wider operating temperature ranges. LECTR AL CHARACTERIST E IC ICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C.V = 3V, Military or Commercial Version A IN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS I Quiescent Current Switch OFF 300 400 m A Q V Input Voltage Step-Up Mode l 2.0 12.6 V IN Step-Down Mode l 30.0 V Comparator Trip Point Voltage LT1111 (Note 2) l 1.20 1.25 1.30 V V Output Sense Voltage LT1111-5 (Note 3 l 4.75 5.00 5.25 V OUT LT1111-12 (Note 3) l 11.40 12.00 12.60 V Comparator Hysteresis LT1111 l 8 12.5 mV Output Hysteresis LT1111-5 l 32 50 mV LT1111-12 l 75 120 mV f Oscillator Frequency 54 72 88 kHz OSC DC Duty Cycle: Step-Up Mode Full Load 43 50 59 % Step-Down Mode 24 34 50 % t Switch ON Time: Step-Up Mode I Tied to V 579 m s ON LIM IN Step-Down Mode V , = 5V, V = 12V 3.3 5 7.8 m s OUT IN V SW Saturation Voltage, Step-Up Mode V = 3.0V, I = 650mA 0.5 0.65 V SAT IN SW V = 5.0V, I = 1A 0.8 1.0 V IN SW SW Saturation Voltage, Step-Down Mode V = 12V, I = 650mA 1.1 1.5 V IN SW 1111fd 2 U WU U W W W