SIM Power Supply and Level Translator

The LTC1555L-1.8 provides power conversion and level shifting needed for low voltage GSM and WCDMA cellular telephones to interface with either 1.8V, 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 1.8V, 3V, 5V or direct connection to the VIN pin.

Internal level translators allow controllers operating with supplies as low as 1.425V to interface with 1.8V, 3V and 5V SIMs. 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. Battery life is maximized by 32µA operating current, and 1µA shutdown current. Board area is minimized by the miniature 16-pin narrow SSOP packages and the need for only three small external capacitors.

Applications

* SIM Interface in GSM Cellular Telephones

* WCDMA SIM Interface

* Smart Card Readers

* Buck/Boost Charge Pump Generates 1.8V, 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

* Meets all ETSI and IMT-2000 SIM Interface Requirements

* 1.8V to 5V Signal Level Translators

* Very Low Operating Current: 32µA

* Very Low Shutdown Current: <1µA

* Soft-Start Limits Inrush Current at Turn-On

* 1MHz Switching Frequency

* Available in 16-Pin Narrow SSOP Package