LTC1515 Datasheet, PDF (1/8 Pages) Linear Technology – Step-Up/Step-Down Switched Capacitor DC/DC Converters with Reset

LTC1515 Series
Step-Up/Step-Down
Switched Capacitor DC/DC
Converters with Reset
FEATURES
s _{Adjustable/Selectable 3V, 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 _{Very Low Shutdown Current: < 1µA}
s _{Shutdown Disconnects Load from VIN}
s _{VOUT Programmable to 3V/5V or 3.3V/5V}
s _{Short-Circuit and Overtemperature Protected}
s _{650kHz Switching Frequency}
s _{Open-Drain Power-On Reset Output}
s _{Available in SO-8 P}D_acis_ky_a-C_gh_eained Control Outputs
U
APPLICATIONS
s _{SIM Interface in GSM Cellular Telephones}
s _{Smart Card Readers}
s _{Local Power Supplies}
s _{Portable Equipment}
DESCRIPTION
The LTC^®1515, LTC1515-3/5 and LTC1515-3.3/5 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
adjustable using an external resistor divider (LTC1515) or
programmable to either 3V/5V (LTC1515-3/5) or 3.3V/5V
(LTC1515-3.3/5) using a logic pin.
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 power-on reset circuit forces the POR pin low
on initial power-up. The POR output remains low until
200ms (typ) after V_OUT is in regulation.
The parts are short-circuit and overtemperature protected.
Battery life is maximized by very low operating currents
(I_CC = 60µA typ, I_CC < 1µA in shutdown). All three parts are
available in an SO-8 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
Programmable 3.3V/5V Power Supply with Power-On Reset
100k
ON OFF
RESET
5V 3.3V
1 _SHDN
V_OUT ⁸
2 _POR
V_IN ⁷
3
LTC1515-3.3/5
5/3
C1⁺
6
4
GND
C1^{– 5}
V_OUT = 3.3V OR 5V
I_OUT = 50mA
+
+
10µF
10µF
0.22µF
V_IN
4-CELL
NiCd
LTC1515 • TA01
LTC1515-X 5V Output vs Input Voltage
5.2
I_OUT = 10mA
5/3 = 3V
5.1
5.0
4.9
4.8
2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
LT1515 • TA02
1