LT1613

Features:

Uses Tiny Capacitors and Inductor
Internally Compensated
Fixed Frequency 1.4MHz Operation
Operates with VIN as Low as 1.1V
3V at 30mA from a Single Cell
5V at 200mA from 3.3V Input
15V at 60mA from Four Alkaline Cells
High Output Voltage: Up to 34V
Low Shutdown Current: <1mA
Low VCESAT Switch: 300mV at 300mA
Tiny 5-Lead SOT-23 Package


Application

Digital Cameras
Pagers
Cordless Phones
Battery Backup
LCD Bias
Medical Diagnostic Equipment
Local 5V or 12V Supply
External Modems
PC Cards


Pinout


PIN FUNCTIONS
SW (Pin 1): Switch Pin. Connect inductor/diode here.Minimize trace area at this pin to keep EMI down.
GND (Pin 2): Ground. Tie directly to local ground plane.
FB (Pin 3): Feedback Pin. Reference voltage is 1.23V.Connect resistive divider tap here. Minimize trace area at FB. Set VOUT according to VOUT = 1.23V(1 + R1/R2).
SHDN(Pin 4): Shutdown Pin. Tie to 1V or more to enable device. Ground to shut down.
VIN (Pin 5): Input Supply Pin. Must be locally bypassed.



Specifications

VIN Voltage ........................................................... 10V
SW Voltage .............................................0.4V to 36V
FB Voltage .................................................. VIN + 0.3V
Current into FB Pin ............................................ ±1mA
SHDN Voltage ....................................................... 10V
Maximum Junction Temperature ....................... 125°C
Operating Temperature Range
Commercial ............................................. 0°C to 70°C
Extended Commercial (Note 2) .......... 40°C to 85°C
Storage Temperature Range ............ 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................ 300°C


Description

The LT®1613 is the industry's first 5-lead SOT-23 current mode DC/DC converter. Intended for small, low power applications, it operates from an input voltage as low as 1.1V and switches at 1.4MHz, allowing the use of tiny, low cost capacitors and inductors 2mm or less in height. Its small size and high switching frequency enables the complete DC/DC converter function to take up less than 0.2 square inches of PC board area. Multiple output power supplies can now use a separate regulator for each output voltage, replacing cumbersome quasi-regulated approaches using a single regulator and a custom transformer.

A constant frequency, internally compensated current mode PWM architecture results in low, predictable output noise that is easy to filter. The high voltage switch on the LT1613 is rated at 36V, making the device ideal for boost converters up to 34V as well as for Single-Ended Primary Inductance Converter (SEPIC) and flyback designs. The device can generate 5V at up to 200mA from a 3.3V supply or 5V at 175mA from four alkaline cells in a SEPIC design. The LT1613 is available in the 5-lead SOT-23 package.