1FEATURES

• Level Translator

– VCC Range of 1.65 V to 3.3 V

– VBATT Range from 2.3 to 5.5V

• Low-Dropout (LDO) Regulator

– 50-mA LDO Regulator With Enable

– 1.8-V or 2.95-V Selectable Output Voltage

– 2.3-V to 5.5-V Input Voltage Range

– Very Low Dropout: 100mV (Max) at 50mA

• Incorporates Shutdown Feature for the SIM

Card Signals According to ISO-7816-3

• ESD Protection Exceeds JESD 22

– 2000-V Human-Body Model (A114-B)

– 500-V Charged-Device Model (C101)

– 8kV HBM for SIM Pins

• Package

– 16-Pin QFN (3 mm x 3 mm)

– 12-Pin QFN (2mm x 1.7mm)

DESCRIPTION

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 highspeed

level translator capable of supporting Class-B

(2.95 V) and Class-C (1.8 V) interfaces, a lowdropout

(LDO) voltage regulator that has output

voltages that are selectable between 2.95-V Class-B

and 1.8-V Class-C interfaces.

The device has two supply voltage pins. VCC can be operated over the full range of 1.65 V to 3.3 V and VBATT

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.