ltc4555 Linear Technology Corporation, ltc4555 Datasheet - Page 6

• Manufacturer Part Number: ltc4555
• Description: Sim Power Supply And Level Translator
• Manufacturer: Linear Technology Corporation

LTC4555
APPLICATIO S I FOR ATIO
The LTC4555 provides both regulated power and internal
level translators to allow low voltage controllers to inter-
face with 1.8V or 3V SIMs or smart cards. The part meets
all ETSI, IMT-2000 and ISO7816 requirements for SIM
and smart card interfaces.
V
The V
regulator with a digitally selected 1.8V or 3V output.
The output voltage is selected via the V
is internally current limited and is capable of surviving an
indefinite short to GND.
The V
The LTC4555 can use either a low ESR ceramic capacitor
or a tantalum electrolytic capacitor on the V
special ESR requirements.
V
Level Translators
All SIMs and smart cards contain a clock input, a reset
input and a bidirectional data input/output. The LTC4555
provides level translators to allow controllers to commu-
6
CC
BAT
Voltage Regulator
should be bypassed with a 0.1µF ceramic capacitor.
CC
CC
output should be bypassed with a 1µF capacitor.
voltage regulator is a 50mA low dropout (LDO)
U
U
W
SEL
pin. The output
CC
pin, with no
U
nicate with the SIM. The CLK and RST lines to the SIM are
level shifted from the controller supply (GND to DV
the SIM supply (GND to V
requires an open-drain output on the controller. On-chip
pull-up resistors are provided for both the DATA and I/O
lines.
Shutdown Modes
The LTC4555 can enter a low current shutdown mode by
one of two methods. First, the SHDN pin is an active low
input that the controller can use to directly shut down the
part. The other way is to lower DV
point and undervoltage lockout circuit puts the part into
shutdown mode.
ESD Protection
All pins that connect to the SIM/smart card will withstand
14kV of human body model ESD. In order to ensure proper
ESD protection, careful board layout is required. The GND
pin should be tied directly to a GND plane. The V
capacitor should be located very close to the V
tied directly to the GND plane.
CC
). The data input to the SIM
CC
below 1.1V at which
CC
pin and
CC
4555fa
) to
CC