LT1109

Features:

·Uses Off-the-Shelf Inductors
·Only 33mH Inductor Required
·Low Cost
·3-Lead TO-92, SO8, or 8-Pin DIP
·Adjustable or Fixed 5V or 12V Output
·120kHz Oscillator
·Only Three External Components Required
·320mA I_Q
·1.6V Minimum Start-Up Voltage
Logic Controlled Shutdown


Application

·Flash Memory VPP Generators
·3V to 5V Converters
·5V to 12V Converters
·Disk Drives
·PC Plug-In Cards
·Peripherals
·Battery-Powered Equipment


Pinout




Specifications

Supply Voltage (VOUT) ................................ 0.4V to 20V
SW Pin Voltage .............................................0.4V to 50V
SHUTDOWN Pin Voltage.............................................. 6.0V
Maximum Power Dissipation .................................. 300mW
Operating Temperature Range .................... 0°C to 70°C
Storage Temperature Range ................ 65°C to 150°C
Lead Temperature (Soldering, 10 sec.).................... 300°C
Switch Current ............................................................ 1.2A


Description

The LT1109 is a simple step-up DC/DC converter. Available in 8-pin SO, 3-lead TO-92 (fixed output only) or miniDIP packages, the devices require only three external components to construct a complete DC/DC converter.
Current drain is just 320mA at no load, making the device ideal for cost-sensitive applications where standby current must be kept to a minimum.
The LT1109-5 can deliver 5V at 100mA from a 3V input and the LT1109-12 can deliver 12V at 60mA from a 5V input. The 8-pin versions also feature a logic controlled SHUTDOWN pin that turns off the oscillator when taken low. The gated-oscillator design requires no frequency compensation components. The high frequency 120kHz oscillator permits the use of small surface mount inductors and capacitors. For a 5V to 12V at 120mA converter, see the LT1109A. Foa a 5V to 12V at 200mA converter with 20mA shutdown current, see the LT1301.