August 2007

1

MIC2570

MIC2570

Micrel, Inc.

MIC2570

Two-Cell Switching Regulator

General Description

Micrel’s MIC2570 is a micropower boost switching regulator

that operates from two alkaline, two nickel-metal-hydride

cells, or one lithium cell.

The MIC2570 accepts a positive input voltage between 1.3V

and 15V. Its typical no-load supply current is 130µA.

The MIC2570 is available in selectable fixed output or ad-

justable output versions. The MIC2570-1 can be configured

for 2.85V, 3.3V, or 5V by connecting one of three separate

feedback pins to the output. The MIC2570-2 can be config-

ured for an output voltage ranging between its input voltage

and 36V, using an external resistor network.

The MIC2570 has a fixed switching frequency of 20kHz. An

external SYNC connection allows the switching frequency to

be synchronized to an external signal.

The MIC2570 requires only four components (diode, inductor,

input capacitor and output capacitor) to implement a boost

regulator. A complete regulator can be constructed in a 0.6

All versions are available in an 8-lead SOIC with an operating

range from –40°C to +85°.

Typical Applications

Features

• Operates from a two-cell supply

1.3V to 15V operation

• 130µA typical quiescent current

• 2.85V/3.3V/5V selectable output voltage (MIC2570-1)

• Adjustable output up to 36V (MIC2570-2)

• 1A current limited pass element

• Frequency synchronization input

• 8-lead SOIC package

Applications

• LCD bias generator

• Glucose meters

• Single-cell lithium to 3.3V or 5V converters

• Two-cell alkaline to ±5V converters

• Two-cell alkaline to –5V converters

• Battery-powered, hand-held instruments

• Palmtop computers

• Remote controls

• Detectors

• Battery Backup Supplies

Two-Cell to 5V DC-to-DC Converter

IN

SW

GND

MIC2570-1

C2

220µF

10V

5V/100mA

C1

100µF

10V

2.0V–3.1V

2 AA Cells

2.85V

3.3V

5V

2

4

5

6

1

7

8

L1

47µH

S YNC

D1

MBRA140

Single-Cell Lithium to 3.3V/80mARegulator

GND

3.3V

S W

MIC2570

S Y NC

7

5

1

2

8

IN

C3

330µF

6.3V

3.3V/80mA

2.5V to 4.2V

1 Li Cell

C1

100µF

10V

D1

MBRA140

L1

50µH

L1

C2

100µF

10V

U1

1

2

3

4

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com