The LTC4557 provides power conversion and signal level translation needed for 2.5G and 3G cellular telephones to interface with 1.8V or 3V subscriber identity modules (SIMs). The part meets all requirements for 1.8V and 3V SIMs. The part contains LDO regulators to power 1.8V or 3V SIM cards from a 2.7V to 5.5V input. The output voltages can be set using the two voltage selection pins and up to 50mA of load current can be supplied.Internal level translators allow controllers operating with supplies as low as 1.2V to interface with 1.8V or 3V smart cards. Battery life is maximized by a low operating current of less than 100µA and a shutdown current of less than 1µA. Board area is minimized by the low profile 3mm x 3mm x 0.75mm leadless QFN package.ApplicationsGSM and 3G Cellular PhonesWireless P.O.S. TerminalsMultiple SAM Card Interface