Micropower DC/DC Converter Adjustable and Fixed 5V, 12V

The LT1108 is a versatile micropower DC/DC converter. The device requires only four external components to deliver a fixed output of 5V or 12V. Supply voltage ranges from 2V to 12V in step-up mode and to 30V in step-down mode.The LT1108 functions equally well in step-up, step-down, or inverting applications.

The LT1108 is pin-for-pin compatible with the LT1173, but has a duty cycle of 70%, resulting in increased outputcurrent in many applications. The LT1108 can deliver 150mA at 5V from a 2 AA cell input and 5V at 300mA from 9V in step-down mode. Quiescent current is just 110µA, making the LT1108 ideal for power conscious battery-operated systems.

Switch current limit can be programmed with a single resistor.An auxiliary gain block can be configured as a low battery detector, linear post regulator, under voltage lock-out circuit, or error amplifier.

Applications

* Palmtop Computers

* 3V to 5V, 5V to 12V Converters

* 9V to 5V, 12V to 5V Converters

* LCD Bias Generators

* Peripherals and Add-On Cards

* Battery Backup Supplies

* Cellular Telephones

* Operates at Supply Voltages from 2V to 30V

* Consumes Only 110µA Supply Current

* Works in Step-Up or Step-Down Mode

* Only Four External Components Required

* Low Battery Detector Comparator On-Chip

* User Adjustable Current Limit

* Internal 1A Power Switch

* Fixed or Adjustable Output Voltage Versions

* Space Saving 8-Pin MiniDIP or S8 Package