Datasheet

1
LTC1522
Micropower, Regulated
5V Charge Pump
DC/DC Converter
The LTC
®
1522 is a micropower charge pump DC/DC
converter that produces a regulated 5V output from a 2.7V
to 5V input supply. Extremely low supply current (6µA
typical with no load, <1µA in shutdown) and low external
parts count (one 0.22µF flying capacitor and two 10µF
capacitors at V
IN
and V
OUT
) make the LTC1522 ideally
suited for small, light load battery-powered applications.
Typical efficiency (V
IN
= 3V) exceeds 75% with load
currents between 50µA and 20mA. Modulating the SHDN
pin keeps the typical efficiency above 75% with load
currents all the way down to 10µA.
The LTC1522 has thermal shutdown and can survive a
continuous short from V
OUT
to GND. In shutdown the
load is disconnected from V
IN
. The part is available in
8-pin MSOP and SO packages. The LTC1522 is pin
compatible with the LTC1516 in applications where
V
IN
≥ 2.7V and I
OUT
≤ 20mA.
■
Ultralow Power: Typical Operating I
CC
= 6µA
■
Short-Circuit/Thermal Protected
■
Regulated 5V ±4% Output Voltage
■
2.7V to 5V Input Range
■
No Inductors
■
Very Low I
CC
in Shutdown: <1µA
■
Output Current:10mA (V
IN
≥ 2.7V)
20mA (V
IN
≥ 3V)
■
Shutdown Disconnects Load from V
IN
■
Internal Oscillator: 700kHz
■
Compact Application Circuit (<0.1 in
2
)
■
8-Pin MSOP and SO Packages
FEATURES
DESCRIPTION
U
APPLICATIONS
U
■
SIM Interface Supplies for GSM Cellular Telephones
■
Li-Ion Battery Backup Supplies
■
Local 3V to 5V Conversion
■
Smart Card Readers
■
PCMCIA Local 5V Supplies
TYPICAL APPLICATION
U
1
2
3
4
8
7
6
5

NC
SHDN
GND
C
–
NC
V
IN

V
OUT

C
+
LTC1522
ON/OFF
10µF
10µF
V
OUT
= 5V ±4%
I
OUT
= 0mA TO 10mA, V
IN
≥ 2.7V
I
OUT
= 0mA TO 20mA, V
IN
≥ 3V
0.22µF
V
IN
2.7V TO 5V

+
+
1522 TA01
Regulated 5V Output from a 2.7V to 5V Input
Efficiency vs Output Current
OUTPUT CURRENT (mA)
50
60
70
80
90
EFFICIENCY (%)
100
1522 TA02
0.01 0.1 1 10
SHDN = 0V
V
IN
= 3V
LOW I
Q
MODE
(SEE FIGURE 2)
, LTC and LT are registered trademarks of Linear Technology Corporation.