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

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

o 4.5V to 24V Input Voltage Range

o Preset 3.3V or 5V Output

o Output Currents Up to 125mA (MAX1836) or

250mA (MAX1837)

o Internal P-Channel MOSFET

o Efficiency Over 90%

o 12µA Quiescent Current

o 3µA Shutdown Current

o 100% Maximum Duty Cycle for Low Dropout

o Current-Limiting and Overtemperature Protection

o Small 6-Pin SOT23 Package

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

IN

GND

LX

SHDN

FB

OUT

NOTE: HIGH-CURRENT PATHS SHOWN WITH BOLD LINES.

OUTPUT

3.3V OR 5V

INPUT

4.5V TO 24V

Typical Operating Circuit

GND

LX

IN

16

OUT

5

SHDN

FB

MAX1836

MAX1837

SOT23

TOP VIEW

2

34

Pin Configuration

Note: The MAX1836/MAX1837 require special solder tempera-

ture profile described in the Absolute Maximum Ratings.

PART

TEMP RANGE

PIN-

PACKAGE

TOP

MARK

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