 2003 Microchip Technology Inc.

DS21361C-page 1

M

TC115

Features

• High Efficiency at Low Output Load Currents via

PFM Mode

• Assured Start-up at 0.9V

• 80 µA (Typ) Supply Current

• 85% Typical Efficiency at 100 mA

• Low Power Shutdown Mode

• No External Switching Transistor Needed

• Space-Saving SOT-89 Package

Applications

• Pagers

• Cellular Phones

• Palmtops

• 1-Cell to 3-Cell Battery Powered Systems

• Cameras, Video Recorders

• Local +3V to +5V Supplies

Package Type

General Description

The TC115 is a high-efficiency step-up DC/DC

converter for small, low input voltage or battery-

powered systems. This device has a start-up voltage

of 0.9V and a typical supply current of 80 µA. Phase

compensation and soft-start circuitry are included on-

chip. Unlike conventional PWM step-up converters,

the TC115 automatically shifts to pulse frequency

modulation (PFM) at low loads, resulting in reduced

supply current and improved efficiency.

The TC115 requires only an external diode, an inductor

and a capacitor, while supporting typical output cur-

rents of 140 mA. Supply current is reduced to less than

0.5 µA (max) when SHDN input is brought low.

Small size, low installed cost and low supply current

make the TC115 step-up converter ideal for use in a

wide range of battery-powered systems.

Functional Block Diagram

5

4

TC115

1

3

2

GND

LX

NC

PS

SHDN

SOT-89-5

PS

1.5V

10 µF

100 µH

1.5V to +3V, 50 mA Supply

5

4

TC115

1

3

2

SHDN

PS

NC

47 µF

Tantalum

IN5817

GND

LX

+3V

OUT

+

+

+

PS

PFM/PWM Step-Up DC/DC Converter