Rainbow-electronics MAX1678 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 MAX1678 is a high-efficiency, low-voltage, syn-

chronous-rectified, step-up DC-DC converter intended

for use in devices powered by 1 to 3-cell alkaline,

NiMH, or NiCd batteries or a 1-cell lithium battery. It

guarantees a 0.87V start-up voltage and features a low

37µA quiescent supply current.

The device includes a 1Ω, N-channel MOSFET power

switch, a synchronous rectifier that acts as the catch

diode, a reference, pulse-frequency-modulation (PFM)

control circuitry, and circuitry to reduce inductor ring-

ing—all in an ultra-small, 1.1mm-high µMAX package.

The output voltage is preset to 3.3V or can be adjusted

from +2V to +5.5V using only two resistors. Efficiencies

up to 90% are achieved for loads up to 50mA. The

device also features an independent undervoltage

comparator (PFI/PFO) and a logic-controlled 2µA shut-

down mode.

Applications

Pagers

Remote Controls

Pointing Devices

Personal Medical Monitors

Single-Cell Battery-Powered Devices

Features

♦ 0.87V Guaranteed Start-Up

♦ Up to 90% Efficiency

♦ Built-In Synchronous Rectifier (no external diode)

♦ Ultra-Small µMAX Package, 1.1mm High

♦ 37µA Quiescent Current (85µA from 1.5V battery)

♦ 2µA Logic-Controlled Shutdown

♦ Power-Fail Detector

♦ Dual Mode™ Output: Fixed 3.3V

Adjustable 2V to 5.5V

♦ 45mA Output Current at 3.3V for 1-Cell Input

♦ 90mA Output Current at 3.3V for 2-Cell Input

♦ Inductor-Damping Switch Suppresses EMI

MAX1678

1-Cell to 2-Cell, Low-Noise,

High-Efficiency, Step-Up DC-DC Converter

________________________________________________________________

Maxim Integrated Products

OUT

GND

FBSHDN

PFO

PFI

BATT

MAX1678

µMAX

TOP VIEW

OUT

OUTPUT

3.3V

INPUT

0.87V TO V

OUT

LOW-BATTERY

DETECTOR INPUT

LOW-BATTERY

DETECTOR OUTPUT

OFF

PFO

BATT

MAX1678

SHDN

PFI

GND FB

Typical Operating Circuit

19-1381; Rev 0; 7/98

PART

MAX1678EUA -40°C to +85°C

TEMP. RANGE PIN-PACKAGE

8 µMAX

EVALUATION KIT

AVAILABLE

Note: To order these devices shipped in tape-and-reel, add a -T

to the part number.

Pin Configuration

Ordering Information

Dual Mode is a trademark of Maxim Integrated Products.

1 2 3 4 5 6 ... 11 12

1-Cell to 2-Cell, Low-Noise 1

Indice de contenidos

Pagina 1 - 1-Cell to 2-Cell, Low-Noise

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

MAX1678Applications InformationOutput Voltage SelectionThe MAX1678 operates with a fixed 3.3V or adjustableoutput. To select fixed-voltage operation,

Pagina 3

Capacitor SelectionChoose input and output capacitors to service inputand output peak currents with acceptable voltage rip-ple. Capacitor ESR is a maj

Pagina 4

MAX16781-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter12 _______________________________________________________________________

Pagina 5

MAX16781-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter2 ________________________________________________________________________

Pagina 6

MAX16781-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter__________________________________________________________________________

Pagina 7

MAX16781-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter4 ________________________________________________________________________

Pagina 8

MAX16781-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter__________________________________________________________________________

Pagina 9

MAX16781-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter6 ________________________________________________________________________

Pagina 10

MAX16781-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter__________________________________________________________________________

Pagina 11

MAX1678Operating PrincipleThe MAX1678 employs a proprietary constant-peak-current control scheme that combines the ultra-low qui-escent current of tra

Pagina 12

Shutdown ModePulling the SHDN pin low places the MAX1678 in shut-down mode (ISHDN= 2µA typical). In shutdown, theinternal switching MOSFET turns off,

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