LTC1514-3.3 Datasheet, PDF (1/8 Pages) Linear Technology – Step-Up/Step-Down Switched Capacitor DC/DC Converters with Low-Battery Comparator

FEATURES
s _{3.3V or 5V Output Voltages}
s _{2V to 10V Input Voltage Range}
s _{Up to 50mA Output Current}
s _{Only Three External Capacitors Required}
s _{Soft Start Limits Inrush Current at Turn-On}
s _{Low Operating Current: 60µA}
s _{Low Shutdown Current: 10µA}
s _{Shutdown Disconnects Load from VIN}
s _{Short-Circuit and Overtemperature Protected}
s _{650kHz Switching Frequency}
s _{Low-Battery Comparator Active in Shutdown}
s _{Available in SO-8 Package}
U
APPLICATIONS
s _{Battery-Operated Equipment}
s _{Smart Card Readers}
s _{Local Power Supplies}
s _{Handheld Instruments}
s _{Battery Backup Supplies}
LTC1514-3.3/LTC1514-5
Step-Up/Step-Down Switched
Capacitor DC/DC Converters
with Low-Battery Comparator
DESCRIPTION
The LTC^®1514-3.3/LTC1514-5 are micropower switched
capacitor DC/DC converters that produce a regulated
output voltage by either stepping up or stepping down
the input voltage. Output voltage is fixed at either 3.3V
(LTC1514-3.3) or 5V (LTC1514-5) by an internal resistor
divider.
A unique architecture allows the parts to accommodate
a wide input voltage range (2V to 10V) while maintaining
±4% regulation. Additional circuitry prevents excessive
inrush current and output voltage ripple when large V_IN
to V_OUT differentials are present.
An internal uncommitted comparator is kept active in
shutdown. The comparator has an open-drain output for
flexible interfacing.
The parts are short-circuit and overtemperature pro-
tected. Battery life is maximized by very low operating
currents (I_CC = 60µA typ, 10µA in shutdown). Both parts
are available in an SO-8 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
5V Step-Up/Step-Down Power Supply with Low-Battery Detect
ON OFF
LOW BAT
1.33M
1%
499k
1%
100k
LTC1514-5
1
SHDN
2
LBO
3
LBI
4
GND
8
V_OUT
7
V_IN
C1^{+ 6}
C1^{– 5}
+
0.22µF
V_OUT = 5V
I_OUT = 50mA
10µF
+
10µF
V_IN
4-CELL
NiCd
1514 TA01
LTC1514-5 Output Voltage
vs Input Voltage
5.2
I_OUT = 10mA
5.1
5.0
4.9
4.8
2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
LT1514 • TA02
1