Rainbow-electronics MAX868 Manual de usuario descargar pdf

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 408-737-7600 ext. 3468.

General Description

The MAX868 inverting charge pump provides a low-cost

and compact means of generating a regulated negative

voltage up to -2 x V

from a positive input voltage

between 1.8V and 5.5V. It uses a pulse-frequency-

modulation (PFM) control scheme to generate the regulat-

ed negative output voltage. PFM operation is obtained

by gating the internal 450kHz oscillator on and off as

needed to maintain output voltage regulation. This

unique on-demand switching scheme gives the MAX868

excellent light-load efficiency without degrading its full-

load operation (up to 30mA), permitting smaller capaci-

tors to take advantage of the oscillator’s high switching

frequency.

The MAX868 requires no inductors; only four capacitors

are required to build a complete DC-DC converter.

Output voltage regulation is achieved by adding just two

resistors. The MAX868 comes in a 10-pin µMAX pack-

age, which is only 1.11mm high and occupies just half

the board area of a standard 8-pin SO.

________________________Applications

Small LCD Panels

Cell Phones

Cordless Phones

Camcorders

Handy-Terminals, PDAs

Medical Instruments

Battery-Operated Equipment

____________________________Features

♦ Regulated Negative Output Voltage

(up to -2 x V

)

♦ Ultra-Small, 10-Pin µMAX Package

♦ On-Demand Switching at up to 450kHz

♦ 30µA Quiescent Supply Current

♦ Requires Only Four Small External Capacitors

♦ 1.8V to 5.5V Input Voltage Range

♦ 0.1µA Logic-Controlled Shutdown

♦ Up to 30mA Output Current

MAX868

Regulated, Adjustable -2x

Inverting Charge Pump

________________________________________________________________

Maxim Integrated Products

SHDN

C2+

INPGND

C1-

OUT

GND

MAX868

µMAX

TOP VIEW

C2-C1+

Configuration

MAX868

C1+

PGND

SHDN

GND

OUT

0.1µF

1µF

2.2µF

OUT

= 0V TO -2 x V

= 1.8V TO 5.5V

0.1µF

C1-

C2+

C2-

Typical Operating Circuit

19-1290; Rev 1; 2/98

PART

MAX868C/D

MAX868EUB -40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

Dice*

10 µMAX

Ordering Information

Dice are tested at T

= +25°C.

1 2 3 4 5 6 ... 11 12

Indice de contenidos

Pagina 1 - Inverting Charge Pump

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.For small orders, phone 408-737-7600 ext. 3468.General

Pagina 2

MAX868Regulated, Adjustable -2xInverting Charge Pump10 ______________________________________________________________________________________Figure 8a

Pagina 3

MAX868Regulated, Adjustable -2x Inverting Charge Pump______________________________________________________________________________________ 11Package

Pagina 4

MAX868Regulated, Adjustable -2xInverting Charge PumpMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied

Pagina 5

MAX868Regulated, Adjustable -2xInverting Charge Pump2 _______________________________________________________________________________________ABSOLUTE

Pagina 6

MAX868Regulated, Adjustable -2x Inverting Charge Pump_______________________________________________________________________________________ 3ELECTRIC

Pagina 7

MAX868Regulated, Adjustable -2xInverting Charge Pump4 ________________________________________________________________________________________________

Pagina 8

Detailed DescriptionThe MAX868 inverting charge pump uses pulse-frequency-modulation (PFM) control to generate a reg-ulated negative output voltage up

Pagina 9

MAX868__________________Design ProcedureSetting the Output VoltageSet the output voltage using two external resistors, R1and R2, as shown in Figure 4.

Pagina 10

Capacitor SelectionChoosing the Flying CapacitorsProper choice of the flying capacitors is dependent pri-marily upon the desired output current. For f

Pagina 11

MAX868Regulated, Adjustable -2xInverting Charge Pump8 _____________________________________________Applications InformationLow-Output-Voltage Operatio

Pagina 12

MAX868Regulated, Adjustable -2x Inverting Charge Pump_______________________________________________________________________________________ 9Figure 7

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Rainbow-electronics MAX868 Manual de usuario

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