Step-Up/Step-Down Switched Capacitor DC/DC Converters with RESET

The LTC1515, 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 VIN to VOUT 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 VOUT is in regulation.

The parts are short-circuit and over-temperature protected. Battery life is maximized by very low operating currents (ICC = 60µA typ, ICC<1µA in shutdown). All three parts are available in an SO-8 package.

Applications

* SIM Interface in GSM Cellular Telephones

* Smart Card Readers

* Local Power Supplies

* Portable Equipment

* Adjustable/Selectable 3V, 3.3V or 5V Output Voltages

* 2V to 10V Input Voltage Range

* Up to 50mA Output Current

* Only Three External Capacitors Required

* Soft Start Limits Inrush Current at Turn-On

* Low Operating Current: 60µA

* Very Low Shutdown Current: < 1µA

* Shutdown Disconnects Load from VIN

* VOUT Programmable to 3V/5V or 3.3V/5V

* Short-Circuit and Overtemperature Protected

* 650kHz Switching Frequency

* Open-Drain Power-On Reset Output

* Available in SO-8 Package