LTC1556_15 Datasheet, PDF (1/12 Pages) Linear Technology – SIM Power Supply and Level Translator

LTC1555/LTC1556
SIM Power Supply
and Level Translator
FEATURES
s _{Step-Up/Step-Down Charge Pump Generates 5V}
s _{Input Voltage Range: 2.7V to 10V}
s _{Output Current: 10mA (VIN ≥ 2.7V)}
20mA (V_IN ≥ 3V)
s _{3V to 5V Signal Level Translators}
s _{> 10kV ESD on All SIM Contact Pins}
s _{Short-Circuit and Overtemperature Protected}
s _{Very Low Operating Current: 60µA}
s _{Very Low Shutdown Current: < 1µA}
s _{Soft Start Limits Inrush Current at Turn-On}
s _{Programmable 3V or 5V Output Voltage}
s _{650kHz Switching Frequency}
s _{Auxiliary 4.3V LDO/Power Switch (LTC1556 Only)}
s _{Available in a 16- and 20-Pin Narrow SSOP}
U
APPLICATIONS
s _{SIM Interface in GSM Cellular Telephones}
s _{Smart Card Readers}
DESCRIPTION
The LTC^®1555/LTC1556 provide power conversion and
level shifting needed for 3V GSM cellular telephones to
interface with either 3V or 5V Subscriber Identity Mod-
ules (SIMs). These parts contain a charge pump DC/DC
converter that delivers a regulated 5V to the SIM card.
Input voltage may range from 2.7V to 10V, allowing
direct connection to the battery. Output voltage may be
programmed to 3V, 5V or direct connection to the V_IN pin.
A soft start feature limits inrush current at turn-on,
mitigating start-up problems that may result when the
input is supplied by another low power DC/DC converter.
The LTC1556 also includes an auxiliary LDO regulator/
power switch that may be used to power the frequency
synthesizer or other low power circuitry.
Battery life is maximized by 60µA operating current and
1µA shutdown current. Board area is minimized by minia-
ture 16- and 20-pin narrow SSOP packages and the need
for only three small external capacitors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
GSM Cellular Telephone SIM Interface
3V GSM
CONTROLLER
V_CC
3V
LTC1555
1
CIN
2
RIN
3
DATA
4
DDRV
5
DV_CC
6
SS
7
M1
8
M0
16
CLK
15
RST
14
I/O
13
V_CC
12
V_IN
C1^{+ 11}
C1^{– 10}
9
GND
V_IN
2.7V TO 10V
+
0.1µF
10µF
SIM
10µF
CLK
RST
I/O
V_CC
5V ± 5%
I_VCC ≤ 10mA
GND
1555/56 TA01
1