SIM Power Supply
and Level Translator
4555 provides power conversion and signal
level shifting needed for low voltage 2.5G and 3G cellular
telephones to interface with 1.8V or 3V subscriber identity
modules (SIMs). The part meets all type approval require-
ments for 1.8V and 3V SIMs and smart cards. The part
contains an LDO linear regulator to supply SIM power at
either 1.8V or 3V from a 3V to 6V input. The output volt-
age is selected with a single pin and up to 50mA of load
current can be supplied.
Internal level translators allow controllers operating with
supplies as low as 1.2V to interface with 1.8V or 3V smart
cards. Battery life is maximized by 20μA operating current
and <1μA shutdown current. Board area is minimized by
3mm leadless QFN package.
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
SIM Power Supply: 1.8V/3V at 50mA
Input Voltage Range: 3V to 6V
Controller Voltage Range: 1.2V to 4.4V
14kV ESD On All SIM Contact Pins
Meets All ETSI, IMT-2000 and ISO7816 SIM/Smart
Card Interface Requirements
Level Translators to 1.8V or 3V
20μA Operating Current
Logic-Controlled Shutdown (I
Available in a Low Proﬁle, 16-Pin (3mm
SIM Interface in 3G Cellular Telephones
Smart Card Readers
Typical SIM Interface
(1.2V TO 4.4V)
(3V TO 6V)