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.

FEATURES
■ Step-Up/Step-Down Charge Pump Generates 5V
■ Input Voltage Range: 2.7V to 10V
■ Output Current: 10mA (VIN ≥2.7V)
                          20mA (VIN ≥3V)
■ 3V to 5V Signal Level Translators
■ > 10kV 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
■ 650kHz Switching Frequency
■ Auxiliary 4.3V LDO/Power Switch (LTC1556 Only)
■ Available in a 16- and 20-Pin Narrow SSOP