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.