© 2002 Microchip Technology Inc.

DS21372B-page 1

TC125/TC126

Features

• Assured Start-up at 0.9V

• PFM (100kHz Max Operating Frequency)

•40

µA Maximum Supply Current

•0.5

µA Shutdown Mode (TC125)

• Voltage Sense Input (TC126)

• Requires Only Three External Components

• 80mA Maximum Output Current

• Small Package: 5-Pin SOT-23A

Applications

• Palmtops/PDAs

• Battery-Operated Systems

• Cameras

• Portable Communicators

Device Selection Table

*Other

output

voltages

are

available.

Please

contact

Microchip Technology Inc. for details.

Package Type

General Description

The TC125/126 step-up (Boost) switching regulators

furnish output currents to a maximum of 80mA

80%. These devices employ pulse frequency modula-

tion (PFM) for minimum supply current at low loads.

They are ideal for battery-operated applications

powered from one or more cells.

Maximum supply

current is less than 70

µA at full output load, and less

than 5

only an external inductor, diode, and capacitor to

implement a complete DC/DC regulator.

The TC126 has separate output voltage sensing and

chip power inputs for greater application flexibility. The

TC125 combines the output voltage sensing and chip

power inputs onto a single package pin, but adds a

power-saving shutdown mode that suspends regulator

operation and reduces supply current to less than

0.5

µA when the shutdown control input (SHDN)islow.

The TC125/TC126 are available in a small 5-Pin

SOT-23A package, occupy minimum board space and

use small external components. The TC125 accepts

input voltages from 2V to 10V. The TC126 accepts

input voltages from 2.2V to 10V. Both the TC125 and

TC126 have a start-up voltage of 0.9V at light load.

Typical Application

Part

Number

Output

Voltage

(V)*

Package

Operating

Temp.

Range

TC125501ECT

5.0

5-Pin SOT-23A

-40

°Cto +85°C

TC125331ECT

3.3

5-Pin SOT-23A

-40

°Cto +85°C

TC125301ECT

3.0

5-Pin SOT-23A

-40

°Cto +85°C

TC126503ECT

5.0

5-Pin SOT-23A

-40

°Cto +85°C

TC126333ECT

3.3

5-Pin SOT-23A

-40

°Cto +85°C

TC126303ECT

3.0

5-Pin SOT-23A

-40

°Cto +85°C

5-Pin SOT-23A

NOTE: 5-Pin SOT-23A is equivalent to the EIAJ SC-74A

SENSE

TC125

1

23

5

4

PS

LX

GND

NC

SHDN

TC126

1

23

5

4

LX

GND

NC

3V

2 x "AA"

Cell

+

–

Two Cell to 5V Boost Regulator

1

2

3

5

4

TC125

LX

SHDN

NC

PS

GND

MA735

+

Sumida

100

µH CD54

5V @80mA

47

µF/16V

Tantalum

PFM Step-Up DC/DC Regulators