REV. A

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reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

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otherwise under any patent or patent rights of Analog Devices.

a

ADM8828/ADM8829

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 1999

Switched-Capacitor

Voltage Inverter with Shutdown

FUNCTIONAL BLOCK DIAGRAMS

TOP VIEW

(Not to Scale)

OUT

IN

CAP–

CAP+

SHDN

GND

ADM8828

1

2

3

6

5

4

TOP VIEW

(Not to Scale)

OUT

IN

CAP+

NC

GND

ADM8829

1

2

3

6

5

4

CAP–

NC = NO CONNECT

FEATURES

Inverts Input Supply Voltage

99% Voltage Conversion Efficiency

25 mA Output Current

Shutdown Function

Requires Only Two Capacitors

1

F Capacitors

18

Output Resistance

+1.5 V to +5.5 V Input Range

600

A Quiescent Current

20 nA Shutdown Current (ADM8828)

APPLICATIONS

Handheld Instruments

LCD Panels

Cellular Phones

PDAs

Remote Data Acquisition

Op Amp Power Supplies

GENERAL DESCRIPTION

The ADM8828/ADM8829 is a charge-pump voltage inverter

which may be used to generate a negative supply from a positive

input. Input voltages ranging from +1.5 V to +5.5 V can be

inverted into a negative –1.5 V to –5.5 V output supply. This

inverting scheme is ideal for generating a negative rail in single

power-supply systems. Only two small external capacitors are

needed for the charge pump. Output currents up to 25 mA with

greater than 99% efficiency are achievable.

The ADM8828 also features a low power shutdown (SHDN)

pin. This can be used to disable the device and reduce the quies-

cent current to 20 nA.

The ADM8828/ADM8829 is available in a 6-lead SOT-23

package.

+

+

+1.5V TO +5.5V

INPUT

SHUTDOWN

CONTROL

C1

1 F

C2

1 F

INVERTED

NEGATIVE

OUTPUT

ADM8828/

ADM8829

CAP+

CAP–

GND

IN

SHDN

OUT

Figure 1. Typical Circuit Configuration