MAX1836/MAX1837
EVALUATION KIT AVAILABLE
24V Internal Switch, 100% Duty Cycle,
Step-Down Converters
General Description
The MAX1836/MAX1837 high-efficiency step-down con-
verters provide a preset 3.3V or 5V output voltage from
supply voltages as high as 24V. Using external feedback
resistors, the output voltage can be adjusted from 1.25V
to VIN. 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 volt-
age (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 inter-
nal switching MOSFETs are available in 6-pin SOT23
and 3mm x 3mm TDFN packages, making them ideal
for low-cost, low-power, space-sensitive applications.
For increased output 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
●● Handheld Devices
Typical Operating Circuit
INPUT
4.5V TO 24V
IN
LX
SHDN
MAX1836
MAX1837 OUT
OUTPUT
3.3V OR 5V
GND
FB
NOTE: HIGH-CURRENT PATHS SHOWN WITH BOLD LINES.
Features
●● 4.5V to 24V Input Voltage Range
●● Preset 3.3V or 5V Output
●● Adjustable Output from 1.25V to VIN
●● Output Currents Up to 125mA (MAX1836) or
250mA (MAX1837)
●● Efficiency Over 90%
●● 12μA Quiescent Current
●● 3μA Shutdown Current
●● 100% Maximum Duty Cycle for Low Dropout
●● Small 6-Pin SOT23 and TDFN Packages
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
MAX1836ETT33-T -40°C to +85°C 6 TDFN-EP*
MAX1836ETT50-T -40°C to +85°C 6 TDFN-EP*
MAX1836EUT33-T -40°C to +85°C 6 SOT23
MAX1836EUT50-T -40°C to +85°C 6 SOT23
MAX1837ETT33-T -40°C to +85°C 6 TDFN-EP*
MAX1837ETT50-T -40°C to +85°C 6 TDFN-EP*
MAX1837EUT33-T -40°C to +85°C 6 SOT23
MAX1837EUT50-T
*EP = Exposed pad.
T = Tape and reel.
-40°C to +85°C
6 SOT23
Selector Guide appears at end of data sheet.
TOP
MARK
AJG
AJE
AANY
AANW
AJH
AJF
AANZ
AANX
Pin Configurations
TOP VIEW
FB 1
GND 2
IN 3
6 OUT
FB 1
MAX1836
MAX1837
5
SHDN
GND 2
IN 3
4 LX
MAX1836
MAX1837
TDFN
6 OUT
5 SHDN
4 LX
SOT23
19-1919; Rev 3; 7/06