LTC1986_15 Datasheet, PDF (1/8 Pages) Linear Technology – 3V/5V SIM Power Supply in ThinSOT

FEATURES
s _{VIN Range: 2.6V to 4.4V}
s _{Ultralow Power}
Operating Current: 14µA
Shutdown Current: <1µA
s _{No Inductors}
s _{Short-Circuit/Thermal Protected}
s _{Ultrasmall Application Circuit (< 0.045in}²₎
s _{Low Profile (1mm) ThinSOT}^TM
s _{Step-Up Charge Pump Generates 5V}
s _{Output Current: 10mA}
s _{VIN to VOUT Direct Connection for 3V SIMs}
s _{Switching Frequency: 900kHz}
s _{Soft-Start Limits Inrush Current at Turn-On}
s _{Output Driven to Ground During Shutdown}
U
APPLICATIO S
s _{GSM Cellular Telephones}
s _{PCS/DCS Cellular Telephones}
s _{Portable POS Terminals}
LTC1986
3V/5V SIM Power Supply
in ThinSOT
DESCRIPTIO
The LTC^®1986 is a micropower charge pump DC/DC
converter that provides power for either 3V or 5V GSM
SIM cards. It operates in one of three modes: V_OUT = 5V
(5V mode), V_OUT = V_IN (3V mode) or shutdown. The input
voltage range is 2.6V to 4.4V and the part can provide
10mA of output current. The LTC1986 allows V_IN to drop
as low as 2.6V by providing a boost feature in 3V mode. In
3V mode, V_OUT is connected directly to V_IN through a 2.5Ω
switch until V_IN drops below 2.85V. When V_IN is below
2.85V, the part automatically boosts V_OUT to maintain a
regulated 2.9V output, thereby ensuring V_OUT stays within
the 3V SIM V_CC specification.
Extremely low operating current (14µA typical with no
load) and low external parts count make the part ideally
suited for small, light load battery-powered applications.
The total PCB area of the application circuit shown below
is less than 0.045in². Protection features include inrush
current limiting, undervoltage lockout, short circuit and
thermal overload protection. The LTC1986 is available in
a low profile (1mm) SOT-23 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
GSM
CONTROLLER
3/5
SHDN
3V/5V SIM Power Supply
V_OUT = 5V
OR V_IN
V_IN = 2.6V TO 4.4V
2.2µF
1M
750k
LTC1986
1
6
V_OUT V_IN
2
GND
C1^{+ 5}
3 _{MODE C1–} 4
0.1µF
0.047µF
SHDN 3/5 MODE
0 0 SHUTDOWN
0 1 SHUTDOWN
1 0 V_OUT = 5V
1
1 V_OUT = V_IN
1986 TA01
Output Voltage vs Input Voltage
6
T_A = 25°C
I_OUT = 10mA
5
5V MODE
4
3V MODE
(V_OUT = V_IN)
3
2
2.5
3.0
3.5
4.0
4.5
INPUT VOLTAGE (V)
1986 TA02
1986fa
1