TXS4555

The TXS4555 is a complete Smart Identity Module (SIM) card solution for interfacing wireless baseband processors with a SIM card to store I/O for mobile handset applications. The device complies with ISO/IEC Smart-Card Interface requirements as well as GSM and 3G mobile standards. It includes a high-speed level translator capable of supporting Class-B (2.95 V) and Class-C (1.8 V) interfaces, a low-dropout (LDO) voltage regulator that has output voltages that are selectable between 2.95-V Class-B and 1.8-V Class-C interfaces.

Note: The Exposed center thermal pad must be connected to Ground

The device has two supply voltage pins. VCC can be operated over the full range of 1.65 V to 3.3 V and V_BATT from 2.3 to 5.5 V. VPWR is set to either 1.8 V or 2.95 V and is supplied by an internal LDO. The integrated LDO accepts input voltages as high as 5.5 V and outputs either 1.8 V or 2.95 V at 50 mA to the B-side circuitry and to the external SIM card. The TXS4555 enables system designers to easily interface low-voltage microprocessors to SIM cards operating at 1.8 V or 2.95 V.

The TXS4555 also incorporates shutdown sequence for the SIM card pins based on the ISO 7816-3 specification for SIM cards. Proper shutdown of the SIM card signals helps in prevention of corruption of data during accidental shutdown of the phone. The device also has 8kV HBM protection for the SIM pins and standard 2kV HBM protection for all the other pins.