Rainbow-electronics MAX1837 User Manual download pdf

General Description

The MAX1836/MAX1837 high-efficiency step-down

converters provide a preset 3.3V or 5V output voltage

from supply voltages as high as 24V. Using external

feedback resistors, the output voltage may be adjusted

from 1.25V to V

. An internal current-limited switching

MOSFET delivers load currents up to 125mA

(MAX1836) or 250mA (MAX1837).

The unique current-limited control scheme, operating

with duty cycles up to 100%, minimizes the dropout

voltage (120mV at 100mA). Additionally, this control

scheme reduces supply current under light loads to

12µA. High switching frequencies allow the use of tiny

surface-mount inductors and output capacitors.

The MAX1836/MAX1837 step-down converters with

internal switching MOSFETs are available in a 6-pin

SOT23 package, making them ideal for low-cost, low-

power, space-sensitive applications. For increased out-

put drive capability, use the MAX1776 step-down

converter that uses an internal 24V switch to deliver up

to 500mA. For even higher currents, use the MAX1626/

MAX1627 step-down controllers that drive an external

P-channel MOSFET to deliver up to 20W.

________________________Applications

9V Battery Systems

Notebook Computers

Distributed Power Systems

Backup Supplies

4mA to 20mA Loop Power Supplies

Industrial Control Supplies

Hand-Held Devices

____________________________Features

♦ 4.5V to 24V Input Voltage Range

♦ Preset 3.3V or 5V Output

♦ Adjustable Output from 1.25V to V

♦ Output Currents Up to 125mA (MAX1836) or

250mA (MAX1837)

♦ Internal P-Channel MOSFET

♦ Efficiency Over 90%

♦ 12µA Quiescent Current

♦ 3µA Shutdown Current

♦ 100% Maximum Duty Cycle for Low Dropout

♦ Current-Limiting and Overtemperature Protection

♦ Small 6-Pin SOT23 Package

MAX1836/MAX1837

24V Internal Switch, 100% Duty Cycle,

Step-Down Converters

________________________________________________________________ Maxim Integrated Products 1

19-1919; Rev 1; 01/02

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART

PRESET OUTPUT

VOLTAGE (V)

LOAD

CURRENT (mA)

MAX1836EUT50 5 125

MAX1836EUT33 3.3 125

MAX1837EUT50 5 250

MAX1837EUT33 3.3 250

Selector Guide

MAX1836

MAX1837

GND

SHDN

OUT

NOTE: HIGH-CURRENT PATHS SHOWN WITH BOLD LINES.

OUTPUT

3.3V OR 5V

INPUT

4.5V TO 24V

Typical Operating Circuit

GND

LXIN

16OUT

5 SHDN

MAX1836

MAX1837

SOT23

TOP VIEW

Pin Configuration

Note: The MAX1836/MAX1837 require special solder tempera-

ture profile described in the Absolute Maximum Ratings.

PART

TEMP RANGE

PIN-

PA C K A G E

TOP

M ARK

MAX1836EUT50-T

-40°C to +85°C

6 SOT23-6

AANW

MAX1836EUT33-T

-40°C to +85°C

6 SOT23-6

AANY

MAX1837EUT50-T

-40°C to +85°C

6 SOT23-6

AANX

MAX1837EUT33-T

-40°C to +85°C

6 SOT23-6

AANZ

Ordering Information

1 2 3 4 5 6 ... 12 13

Summary of Contents

Page 1 - Step-Down Converters

General DescriptionThe MAX1836/MAX1837 high-efficiency step-downconverters provide a preset 3.3V or 5V output voltagefrom supply voltages as high as 2

Page 2

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters10 __________________________________________________________________________

Page 3

MAX1836/MAX1837 StabilityCommonly, instability is caused by excessive noise onthe feedback signal or ground due to poor layout orimproper component se

Page 4

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters12 __________________________________________________________________________

Page 5

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down ConvertersMaxim cannot assume responsibility for use of any circuitry other than circui

Page 6

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters2 ___________________________________________________________________________

Page 7

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters_____________________________________________________________________________

Page 8

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters4 ___________________________________________________________________________

Page 9

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters_____________________________________________________________________________

Page 10

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters6 ___________________________________________________________________________

Page 11

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters_____________________________________________________________________________

Page 12

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters8 ___________________________________________________________________________

Page 13

MAX1836/MAX183724V Internal Switch, 100% Duty Cycle, Step-Down Converters_____________________________________________________________________________

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Rainbow-electronics MAX1837 User Manual

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