LTC4555

6

4555fb

APPLICATIONS INFORMATION

The LTC4555 provides both regulated power and internal

level translators to allow low voltage controllers to interface

with 1.8V or 3V SIMs or smart cards. The part meets all

ETSI, IMT-2000 and ISO7816 requirements for SIM and

smart card interfaces.

regulator with a digitally selected 1.8V or 3V output.

is internally current limited and is capable of surviving an

indefinite short to GND.

The LTC4555 can use either a low ESR ceramic capacitor

no special ESR requirements.

Level Translators

All SIMs and smart cards contain a clock input, a reset

input and a bidirectional data input/output. The LTC4555

provides level translators to allow controllers to com-

municate with the SIM. The CLK and RST lines to the

SIM are level shifted from the controller supply (GND to

the SIM requires an open-drain output on the controller.

On-chip pull-up resistors are provided for both the DATA

and I/O lines.

Shutdown Modes

The LTC4555 enters a low current shutdown mode by

pulling the SHDN pin low. The SHDN pin is an active low

input that the controller can use to directly shut down

the part.

ESD Protection

All pins that connect to the SIM/smart card will withstand

14kV of human body model ESD. In order to ensure

proper ESD protection, careful board layout is required.

The GND pin should be tied directly to a GND plane. The

and tied directly to the GND plane.