Rainbow-electronics MAX685 Manual do Utilizador descarregar 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 MAX685 DC-DC converter provides low-noise dual

outputs for powering CCD imaging devices and LCDs.

This device uses a single inductor to provide indepen-

dently regulated positive and negative outputs.

Integrated power switches are included in the small

16-pin QSOP package (same size as an 8-pin SO) to

save space and reduce cost.

Each output delivers up to 10mA from a +2.7V to +5.5V

input voltage range. Output voltages are set indepen-

dently up to 24V and down to -9V. With a few additional

low-cost components, the output voltages can be set at

up to 45V and down to -16V. Output ripple magnitude is

30mVp-p. The MAX685 uses a fixed-frequency, pulse-

width-modulated (PWM) control scheme at 220kHz or

400kHz to permit output noise filtering and to reduce

the size of external components. The frequency can

also be synchronized to an external clock signal

between 200kHz and 480kHz.

The MAX685 has a power-OK indicator output (POK)

that signals when both outputs are within regulation. A

logic-controlled shutdown completely turns off both out-

puts and reduces supply current to 0.1µA. The user

can also set which output turns on first.

The preassembled MAX685 evaluation kit is available to

reduce design time.

Applications

Camcorders LCDs

Digital Cameras CCD Imaging Devices

Notebooks

Features

♦ Dual Output Using a Single Inductor

♦ Low-Noise Output, 30mVp-p Ripple

♦ Output Voltages up to 24V and down to -9V

(up to 45V and down to -16V with added

components)

♦ Internal Switches in a Small Package

♦ 220kHz/400kHz Fixed-Frequency PWM Operation

♦ Frequency Can Be Synchronized to

External Clock

♦ Power-OK Indicator

♦ Selectable Power-On Sequencing

♦ 0.1µA Logic-Controlled Shutdown

MAX685

Dual-Output (Positive and Negative),

DC-DC Converter for CCD and LCD

________________________________________________________________

Maxim Integrated Products

MAX685

OFF

INPUT

2.7V TO 5.5V

LXN

FBP

LXP

FBN

REFGND

NEGATIVE

OUTPUT

DOWN TO -9V,

10mA

POSITIVE

OUTPUT

UP TO 24V,

10mA

SHDN

SYNC

SEQ

POK

POS

NEG

OPTIONAL

POWER-OK

INDICATOR

LXP LXN

I.C.

PGND

FBP

REF

FBN

GND

TOP VIEW

MAX685

QSOP

I.C.

I.C. = INTERNALLY CONNECTED

SHDN

POK

SEQ

SYNC

Typical Operating Circuit

19-1353; Rev 0; 4/98

PART

MAX685EEE -40°C to +85°C

TEMP. RANGE PIN-PACKAGE

16 QSOP

EVALUATION KIT

AVAILABLE

Pin Configuration

Ordering Information

1 2 3 4 5 6 ... 11 12

Resumo do Conteúdo

Página 1 - Maxim Integrated Products

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

Página 2 - ELECTRICAL CHARACTERISTICS

MAX685Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD10 _________________________________________________________________________

Página 3

MAX685Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD____________________________________________________________________________

Página 4 - = -7.5V, T

MAX685Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCDNOTES12 ____________________________________________________________________

Página 5 - MAX685-12

MAX685Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD2 __________________________________________________________________________

Página 6 - Pin Description

MAX685Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD____________________________________________________________________________

Página 7 - Frequency Selection

1.2401.2421.2441.2481.2461.2501.2521.254-40 200-20 40 60 80 100REFERENCE VOLTAGEvs. TEMPERATUREMAX685-13TEMPERATURE (°C)REFERENCE VOLTAGE (V)VIN = 5.0

Página 8 - Higher Output Voltages

MAX685Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD____________________________________________________________________________

Página 9 - Damping LX

_______________Detailed DescriptionThe MAX685 DC-DC converter accepts an input voltagebetween +2.7V and +5.5V and generates both a positiveand negativ

Página 10 - QSOP.EPS

SEQ and Power OK (POK)The SEQ pin controls the power-up sequence. If SEQ islow, the positive output is disabled until the negativeoutput is within 90%

Página 11

MAX685Applications InformationFigure 3 shows the standard application circuit for theMAX685. The values shown in Table 1 will work well foroutput curr

Página 12

Setting the Output VoltageThe resistor-divider formed by R4 and R3 sets the neg-ative output voltage; the resistor-divider formed by R1and R2 sets the

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Rainbow-electronics MAX685 Manual do Utilizador

Consulte online ou descarregue Manual do Utilizador para Sensores Rainbow-electronics MAX685. Rainbow Electronics MAX685 User Manual Manual do Utilizador

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