LTC1555L-1.8

` Buck/Boost Charge Pump Generates 1.8V, 3V or 5V
` Input Voltage Range: 2.6V to 6V
` Controller V<sub>CC</sub> 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: 32A
` Very Low Shutdown Current: <1A
` Soft-Start Limits Inrush Current at Turn-On
`1MHz Switching Frequency
` Available in 16-Pin Narrow SSOP Package

· SIM Interface in GSM Cellular Telephones
· WCDMA SIM Interface
· Smart Card Readers

V_IN, DV_CC to GND ......................................... 0.3V to 6.5V
V_CC to GND ...................................................0.3V to 6.5V
Digital Inputs to GND ....................................0.3V to 6.5V
CLK, RST, I/O to GND ......................... 0.3V to V_CC + 0.3V
V_CC Short-Circuit Duration ................................... Indefinite
Operating Temperature Range (Note 2) .. 40°C to 85°C
Storage Temperature Range ................. 65°C to 150°C
Lead Temperature (Soldering,10 sec)....................... 300°C

The LTC^®1555L-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 apatented 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 V_IN pin.

Internal level translators of LTC1555L-1.8 allow controllers operating withsupplies as low as 1.425V to interface with 1.8V, 3V and5V SIMs. A soft-start feature limits inrush current at turnon, mitigating start-up problems that may result when the input is supplied by another low-power DC/DC converter.Battery life is maximized by 32A operating current, and1A shutdown current. Board area is minimized by theminiature 16-pin narrow SSOP packages and the need for only three small external capacitors.