DESCRIPTION
The LTC® 1555L provides power conversion and level shifting needed for low voltage GSM cellular telephones to interface with either 3V or 5V Subscriber Identity Modules (SIMs). The part contains a patented buck/boost charge pump DC/DC converter* that delivers a regulated VCC supply voltage to the SIM card. Input voltage may range from 2.6V to 6V allowing direct connection to the battery. The output voltage may be programmed to 3V, 5V or direct connection to the VIN pin.

FEATURES
■ Buck/Boost Charge Pump Generates 3V or 5V
■ Input Voltage Range: 2.6V to 6V
■ Controller VCC Range: 1.425V to 4.4V
■ >10kV ESD on All SIM Contact Pins
■ Short-Circuit and Overtemperature Protected
■ 3V to 5V Signal Level Translators
■ Very Low Operating Current: 40µA
■ Very Low Shutdown Current: <1µA
■ Soft-Start Limits Inrush Current at Turn-On
■ 1MHz Switching Frequency
■ Available in 16-Pin Narrow SSOP Package