TXS4555

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

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

The TXS4555 incorporates shutdown sequence for the SIM card pins based on the ISO 7816-3 specification for SIM cards. During an accidental shutdown of the phone, shutting down the SIM card helps prevent data corruption. The device has 8 kV HBM protection for the SIM pins and standard 2 kV HBM protection for all other pins.