LTC1556 Datasheet | Linear Technology

LTC1555/LTC1556 SIM Power Supply and Level Translator Features s s s DESCRIPTION The LTC®1555/LTC1556 provide power conversion and level shifting needed for 3V GSM cellular telephones to interface with either 3V or 5V Subscriber Identity Modules (SIMs). These parts contain a charge pump DC/DC converter that delivers a regulated 5V to the SIM card. Input voltage may range from 2.7V to 10V, allowing direct connection to the battery. Output voltage may be programmed to 3V, 5V or direct connection to the VIN pin. A soft start feature limits inrush current at turn-on, mitigating start-up problems that may result when the input is supplied by another low power DC/DC converter. The LTC1556 also includes an auxiliary LDO regulator/ power switch that may be used to power the frequency synthesizer or other low power circuitry. Battery life is maximized by 60µA operating current and 1µA shutdown current. Board area is minimized by miniature 16- and 20-pin narrow SSOP packages and the need for only three small external capacitors. , LTC and LT are registered trademarks of Linear Technology Corporation. s s s s s s s s s s Step-Up/Step-Down Charge Pump Generates 5V Input Voltage Range: 2.7V to 10V Output Current: 10m A (VIN ≥ 2.7V) 20m A (VIN ≥ 3V) 3V to 5V Signal Level Translators > 10k V ESD on All SIM Contact Pins Short-Circuit and Overtemperature Protected Very Low Operating Current: 60µA Very Low Shutdown Current: < 1µA Soft Start Limits Inrush Current at Turn-On Programmable 3V or 5V Output Voltage 650k Hz Switching Frequency Auxiliary 4.3V LDO/Power Switch (LTC1556 Only) Available in a 16- and 20-Pin Narrow SSOP U APPLICATIONS s s SIM Interface in GSM Cellular Telephones Smart Card Readers TYPICAL APPLICATION GSM Cellular Telephone SIM Interface 3V GSM CONTROLLER 3V 1 2 3 4 LTC1555 CIN RIN DATA DDRV DVCC SS M1 M0 CLK RST I/O VCC VIN C1 + 16 15 14 13 12 11 VIN 2.7V TO 10V CLK RST I/O 5 6 7 8 10 C1 - 9 GND 0.1µF + 10µF GND 1555/56...