Datasheet

ManualsBrandsANALOG DEVICES ManualsPMICsPMIC - DC/DC voltage regulator Switched-capacitor voltage converter SOT 23 6

REV. A

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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

CAP–

CAP+

SHDN

GND

ADM8828

TOP VIEW

(Not to Scale)

OUT

CAP+

GND

ADM8829

CAP–

NC = NO CONNECT

FEATURES

Inverts Input Supply Voltage

99% Voltage Conversion Efficiency

25 mA Output Current

Shutdown Function

Requires Only Two Capacitors

1 mF Capacitors

18 V Output Resistance

+1.5 V to +5.5 V Input Range

600 mA 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

1mF

INVERTED

NEGATIVE

OUTPUT

ADM8828/

ADM8829

CAP+

CAP–

GND

SHDN

OUT

Figure 1. Typical Circuit Configuration

Summary of content (6 pages)

PAGE 1
a FEATURES Inverts Input Supply Voltage 99% Voltage Conversion Efficiency 25 mA Output Current Shutdown Function Requires Only Two Capacitors 1 mF Capacitors 18 V Output Resistance +1.5 V to +5.
PAGE 2
ADM8828/ADM8829–SPECIFICATIONS Parameter Min Input Voltage, IN 1.5 Supply Current Output Current Output Resistance Output Ripple 25 Charge-Pump Frequency 50 65 Power Efficiency Voltage Conversion Efficiency 99.5 Shutdown Supply Current, ISHDN Shutdown Input Voltage, VSHDN 2.0 Typ (VIN = +5 V, C1, C2 = 1 mF,1 TA = TMIN to TMAX unless otherwise noted) Max Units Test Conditions/Comments 5.
PAGE 3
Typical Performance Characteristics– ADM8828/ADM8829 60 0.8 IL = 5mA OUTPUT VOLTAGE RIPPLE – mV p-p SUPPLY CURRENT – mA 0.7 0.6 0.5 0.4 0.3 0.2 50 OUTPUT VOLTAGE RIPPLE @ VIN = 4.75V 40 OUTPUT VOLTAGE RIPPLE @ VIN = 1.9V 30 20 OUTPUT VOLTAGE RIPPLE @ VIN = 3.15V 10 0.1 0 1 1.5 2 2.5 3 3.5 4 SUPPLY VOLTAGE – V 4.5 5 0 0.47 5.5 Figure 2. Power Supply Current vs. Voltage 350 OUTPUT VOLTAGE RIPPLE – mV p-p OUTPUT RESISTANCE – V 30 25 20 15 10 5 2 2.5 3 3.5 4 SUPPLY VOLTAGE – V 4.
PAGE 4
ADM8828/ADM8829 100 200 PEFF @ VIN = 5.0V 180 80 160 PEFF – % 70 PUMP FREQUENCY – kHz 90 PEFF @ VIN = 3.3V 60 PEFF @ VIN = 2.0V 50 40 30 100 60 10 20 5 10 15 20 25 30 IOUT – mA 35 40 45 0 –50 50 Figure 8. Power Efficiency vs. Output Current PUMP FREQUENCY @ VIN = 1.5V 80 40 0 PUMP FREQUENCY @ VIN = 5.0V 120 20 0 PUMP FREQUENCY @ VIN = 3.3V 140 –30 –10 10 25 40 60 80 TEMPERATURE – 8C 90 110 125 Figure 10. Charge Pump Frequency vs.
PAGE 5
ADM8828/ADM8829 GENERAL INFORMATION Capacitor Selection The ADM8828/ADM8829 is a switched capacitor voltage converter that can be used to invert the input supply voltage. The flying capacitor C1 can be increased to reduce the output resistance. The voltage conversion task is achieved using a switched capacitor technique using two external charge storage capacitors. An on-chip oscillator and switching network transfers charge between the charge storage capacitors.
PAGE 6
ADM8828/ADM8829 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 6-Lead SOT-23 (RT-6) 0.071 (1.80) 0.059 (1.50) 6 5 4 1 2 3 C3352a–0–10/99 0.122 (3.10) 0.106 (2.70) 0.118 (3.00) 0.098 (2.50) PIN 1 0.037 (0.95) BSC 0.075 (1.90) BSC 0.006 (0.15) 0.000 (0.00) 0.057 (1.45) 0.035 (0.90) 0.020 (0.50) SEATING 0.010 (0.25) PLANE 108 0.009 (0.23) 08 0.003 (0.08) 0.022 (0.55) 0.014 (0.35) PRINTED IN U.S.A. 0.051 (1.30) 0.035 (0.90) –6– REV.