LTC1986
3V/5V SIM Power Supply
in SOT-23
FEATURES
s
s
s
s
s
DESCRIPTIO
s
s
s
s
s
s
s
V
IN
Range: 2.6V to 4.4V
Step-Up Charge Pump Generates 5V
Output Current: 10mA
V
IN
to V
OUT
Direct Connection for 3V SIMs
Ultralow Power
Operating Current: 14
碌
A
Shutdown Current: <1
碌
A
No Inductors
Short-Circuit/Thermal Protected
Switching Frequency: 900kHz
Soft-Start Limits Inrush Current at Turn-On
Output Driven to Ground During Shutdown
Ultrasmall Application Circuit (< 0.045in
2
)
6-Lead SOT-23 Package
The LTC
廬
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 2.5鈩?/div>
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 (14碌A 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 0.045in
2
. Protection features include inrush
current limiting, undervoltage lockout, short circuit and
thermal overload protection. The LTC1986 is available in
a 6-lead SOT-23 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
GSM Cellular Telephones
PCS/DCS Cellular Telephones
Portable POS Terminals
TYPICAL APPLICATIO
V
OUT
= 5V
OR V
IN
GSM
CONTROLLER
3/5
1M
3
750k
SHDN
2.2碌F
3V/5V SIM Power Supply
6
V
IN
= 2.6V TO 4.4V
LTC1986
V
OUT
GND
V
IN
C1
+
6
5
4
0.047碌F
Output Voltage vs Input Voltage
T
A
= 25擄C
I
OUT
= 10mA
OUTPUT VOLTAGE (V)
1
2
0.1碌F
5
4
MODE C1
鈥?/div>
3
SHDN 3/5
MODE
0
0 SHUTDOWN
0
1 SHUTDOWN
1
0
V
OUT
= 5V
V
OUT
= V
IN
1
1
2
2.5
1986 TA01
U
5V MODE
3V MODE
(V
OUT
= V
IN
)
3.0
3.5
INPUT VOLTAGE (V)
1986 TA02
U
U
4.0
4.5
1
1
2
3
4
5
6
7
8
