1997

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MIC2571

MIC2571

Micrel

MIC2571

Single-Cell Switching Regulator

Final Information

General Description

Micrel’s MIC2571 is a micropower boost switching regulator

that operates from one alkaline, nickel-metal-hydride cell, or

lithium cell.

The MIC2571 accepts a positive input voltage between 0.9V

and 15V. Its typical no-load supply current is 120

µA.

The MIC2571 is available in selectable fixed output or adjust-

able output versions. The MIC2571-1 can be configured for

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

feedback pins to the output. The MIC2571-2 can be config-

ured for an output voltage ranging between its input voltage

and 36V, using an external resistor network.

The MIC2571 has a fixed switching frequency of 20kHz. An

external SYNC connection allows the switching frequency to

be synchronized to an external signal.

The MIC2571 requires only four components (diode, induc-

tor, input capacitor and output capacitor) to implement a

boost regulator. A complete regulator can be constructed in

All versions are available in an 8-lead MSOP with an operat-

ing range from –40

°C to +85°.

Typical Applications

Features

• Operates from a single-cell supply

0.9V to 15V operation

• 120

µA typical quiescent current

• 2.85V/3.3V/5V selectable output voltage (MIC2571-1)

• Adjustable output up to 36V (MIC2571-2)

• 1A current limited pass element

• Frequency synchronization input

• 8-lead MSOP package

Applications

• Pagers

• LCD bias generator

• Battery-powered, hand-held instruments

• Palmtop computers

• Remote controls

• Detectors

• Battery Backup Supplies

Single-Cell to 5V DC-to-DC Converter

IN

SW

GND

MIC2571-1

C2

47µF

16V

5V/5mA

C1*

47µF

16V

1V to1.5V

1 Cell

2.85V

3.3V

5V

2

4

5

6

1

7

8

L1

150µH

SYNC

D1

MBR0530

* Needed if battery is

≥ 4" from MIC2571

Single-Cell to 3.3V DC-to-DC Converter

IN

SW

GND

MIC2571-1

C2

47µF

16V

3.3V/8mA

C1*

47µF

16V

1V to1.5V

1 Cell

2.85V

3.3V

5V

2

4

5

6

1

7

8

L1

150µH

SYNC

D1

MBR0530

* Needed if battery is

≥ 4" from MIC2571

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com